Metal-doped molybdenum sulfide powder and its manufacturing method

Abstract

The metal-doped molybdenum sulfide powder of the present invention is doped with Group 3 to Group 13 metals and contains a 3R crystal structure of molybdenum disulfide. A first embodiment of the manufacturing method of the metal-doped molybdenum sulfide powder of the present invention includes: dry mixing molybdenum trioxide powder containing an aggregate of primary particles with an α- or β-crystal structure containing molybdenum trioxide, with powder containing a sulfur source and a Group 3 to Group 13 metal salt, and then heating at a temperature of 200°C to 1000°C. A second embodiment of the manufacturing method includes: obtaining a solid substance by removing the dispersion medium from a mixture of self-mixed molybdenum trioxide powder containing an aggregate of primary particles with an α- or β-crystal structure containing molybdenum trioxide, a Group 3 to Group 13 metal salt, and a dispersion medium, and then heating the solid substance at a temperature of 200°C to 1000°C in the presence of a sulfur source.

Description

[Technical Field]

[0001] This invention relates to a metal-doped molybdenum sulfide powder and a method for manufacturing the same. This application claims priority based on Japanese Patent Application No. 2021-019046, filed on February 9, 2021, the contents of which are incorporated herein by reference. [Previous Technology]

[0002] Molybdenum sulfides, represented by molybdenum disulfide (MoS2), are widely known as lubricants, steel additives, and raw materials for molybdates. These molybdenum sulfides have been used in applications that effectively utilize their inertness.

[0003] However, recently, with an eye toward its activity, attempts have begun to explore its application in fine-grained applications such as semiconductor materials and catalysts. While this activity can be improved to some extent by miniaturizing or de-aggregating molybdenum sulfides obtained through any manufacturing method, such as sulfidation of molybdenum oxide, these methods alone often fail to achieve the desired superior performance. Therefore, in order to achieve even better performance for their respective applications, methods for manufacturing molybdenum sulfides with unique shapes such as monolayers, nanoflowers, and fullerenes are being investigated (see Patent Documents 1 to 2).

[0004] On the other hand, hydrogen has attracted much attention in the fields of renewable energy and fuel cells in recent years, increasing the importance of hydrogen production technology. To date, methods utilizing hydrogen production reactions on electrodes have been studied as hydrogen production methods, and platinum (Pt) is considered the best electrode catalyst in terms of high activity. However, platinum is a precious metal, with low production and high price, therefore, exploration is underway for electrode catalysts to replace platinum. Furthermore, molybdenum disulfide possesses a certain degree of catalytic activity, while also being inexpensive and highly stable, thus it is expected to be used as an electrode catalyst to replace platinum (see Non-Patent Literature 1). [Prior Art Literature] [Patent Literature]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2004-277199 [Patent Document 2] Japanese Patent Publication No. 2004-512250 [Non-Patent Document]

[0006] [Non-patent literature 1] "Chem.Rev.", 1 (2016), pp.699-726 [Summary of the Invention]

[0007] [The problem the invention aims to solve]

[0008] However, there is still room for improvement in the catalytic activity of molybdenum disulfide as an electrode catalyst in hydrogen production reactions, and further improvement in its activity as a hydrogen production catalyst is desired. Here, the application of molybdenum disulfide is exemplified by its use as an electrode catalyst in hydrogen production reactions, but it also includes the previously listed semiconductor materials, and various applications are conceivable. Therefore, it would be very useful to use molybdenum disulfide and develop novel materials with the desired activity.

[0009] Therefore, the object of the present invention is to provide a novel material using molybdenum disulfide. [Means for Solving the Problem]

[0010] The present invention includes the following forms. [1]. A metal-doped molybdenum sulfide powder, doped with metals from Group 3 to Group 13, and containing a 3R crystal structure of molybdenum disulfide.

[0011] [2]. The metal-doped molybdenum sulfide powder as described in [1], wherein the metal-doped molybdenum sulfide powder comprises a 2H crystal structure and a 3R crystal structure of molybdenum disulfide.

[0012] [3]. The metal-doped molybdenum sulfide powder as described in [2], wherein in the spectrum of the metal-doped molybdenum sulfide powder obtained by powder X-ray diffraction (XRD) using Cu-Kα rays as the X-ray source, the peaks near 39.5° and the peaks near 49.5° both contain the combined peaks of the 2H crystal structure and the 3R crystal structure, and the half-width is greater than 1°.

[0013] [4]. The metal-doped molybdenum sulfide powder as described in any one of [1] to [3], wherein the primary particles of the molybdenum disulfide particles constituting the metal-doped molybdenum sulfide powder are in the shape of rope, strip or sheet, and the thickness is in the range of 1 nm to 40 nm.

[0014] [5]. The metal-doped molybdenum sulfide powder as described in any one of [1] to [4], wherein the specific surface area determined by the Brunauer-Emmett-Teller (BET) method is 10 m2 / g or more.

[0015] [6]. The metal-doped molybdenum sulfide powder as described in any one of [1] to [5], wherein the median particle size D50 determined by the dynamic light scattering particle size distribution measuring device is 10 nm to 2000 nm.

[0016] [7]. The metal-doped molybdenum sulfide powder as described in any one of [1] to [6], wherein the ratio (I / II) of the peak intensity I caused by Mo-S to the peak intensity II caused by Mo-Mo in the radial distribution function obtained from the extended X-Ray Absorption Fine Structure (EXAFS) spectrum of the K absorption end of molybdenum is greater than 1.0.

[0017] [8]. Metal-doped molybdenum sulfide powder as described in any one of [1] to [7], wherein the metal of group 3 to group 13 is one or more selected from the group consisting of cobalt, palladium, iridium, manganese, iron, nickel, zirconium, ruthenium, indium and zinc.

[0018] [9]. A method for manufacturing metal-doped molybdenum sulfide powder, comprising: after obtaining a mixed powder by dry mixing molybdenum trioxide powder containing an aggregate of primary particles with an α-crystal structure or a β-crystal structure containing molybdenum trioxide, a sulfur source and a metal salt of Group 3 to Group 13, heating the mixed powder at a temperature of 200°C to 1000°C.

[0019]

[10] . A method for manufacturing metal-doped molybdenum sulfide powder, comprising: obtaining a solid material by removing the dispersion medium from a mixture of molybdenum trioxide powder containing an aggregate of primary particles with an α-crystal structure or a β-crystal structure of molybdenum trioxide, a group 3 to group 13 metal salt and a dispersion medium, and then heating the solid material at a temperature of 200°C to 1000°C in the presence of a sulfur source.

[0020]

[11] . A method for manufacturing metal-doped molybdenum sulfide powder as described in

[10] , wherein the dispersion medium is removed from the mixture by freeze-drying of the mixture.

[0021]

[12] . A method for manufacturing metal-doped molybdenum sulfide powder as described in

[10] , wherein the dispersion medium is removed from the mixture by heating the mixture. [Effects of the Invention]

[0022] According to the present invention, a novel material using molybdenum disulfide is provided.

Implementation Method

[0024] <<Metal-Doped Molybdenum Sulfide Powder>> The metal-doped molybdenum sulfide powder of this embodiment is doped with metals from Group 3 to Group 13 and contains a 3R crystal structure of molybdenum disulfide. In this specification, the term "metal-doped molybdenum sulfide powder" has the same meaning as "molybdenum disulfide powder doped with metals from Group 3 to Group 13" and "molybdenum disulfide powder containing metals from Group 3 to Group 13 as dopants". Furthermore, in this specification, the description of "molybdenum sulfide powder" alone does not refer to "metal-doped molybdenum sulfide powder", but rather to molybdenum sulfide powder without doping with metals from Group 3 to Group 13.

[0025] The metal-doped molybdenum sulfide powder of this embodiment contains at least the 3R crystal structure of molybdenum disulfide. For example, the metal-doped molybdenum sulfide powder of this embodiment may also contain both the 2H and 3R crystal structures of molybdenum disulfide. Furthermore, in the spectrum obtained by powder X-ray diffraction (XRD) using Cu-Kα rays as the X-ray source for the metal-doped molybdenum sulfide powder containing the 2H and 3R crystal structures of molybdenum disulfide of this embodiment, the peaks near 39.5° and near 49.5° both contain the combined peaks of the 2H and 3R crystal structures, and the half-width at half-maximum (WWHM) may be 1° or more.

[0026] Furthermore, the metal-doped molybdenum sulfide powder of this embodiment may also include other crystal structures that are not equivalent to either the 2H crystal structure or the 3R crystal structure of molybdenum disulfide. Examples of such metal-doped molybdenum sulfide powders include: metal-doped molybdenum sulfide powders containing the 3R crystal structure of molybdenum disulfide and the other crystal structures but not the 2H crystal structure; metal-doped molybdenum sulfide powders containing the 2H crystal structure, the 3R crystal structure, and the other crystal structures; and metal-doped molybdenum sulfide powders containing the 2H crystal structure, the 3R crystal structure, and the other crystal structures, wherein in the spectrum obtained by powder X-ray diffraction (XRD) using Cu-Kα rays as the X-ray source, the peak values ​​near 39.5° and near 49.5° of the metal-doped molybdenum sulfide powder both contain the combined peak values ​​of the 2H crystal structure and the 3R crystal structure, and the half-width is 1° or more. Examples of such other crystal structures include the 1T crystal structure.

[0027] Metal-doped molybdenum sulfide powder containing this crystal structure is suitable as a catalyst, semiconductor material, etc. in the Hydrogen Evolution Reaction (HER).

[0028] The molybdenum sulfide particles constituting commercially available molybdenum disulfide powder are molybdenum sulfide with a 2H crystal structure. In contrast, the metal-doped molybdenum sulfide particles constituting the metal-doped molybdenum sulfide powder of this embodiment contain a metastable 3R crystal structure. This can be distinguished by the fact that, in the spectrum obtained by powder X-ray diffraction (XRD) of the metal-doped molybdenum sulfide powder using Cu-Kα rays as an X-ray source, peaks are observed near 39.5° and 49.5°. Furthermore, the metal-doped molybdenum sulfide particles contain both a 2H crystal structure and a 3R crystal structure. This can also be distinguished by the fact that, in the spectrum obtained by powder X-ray diffraction (XRD), the peaks near 39.5° and 49.5° both contain composite peaks of the 2H crystal structure and the 3R crystal structure.

[0029] In addition to the aspect of not being doped with Group 3 to Group 13 metals, the molybdenum sulfide particles of the undoped molybdenum sulfide powder, manufactured using the same method as the metal-doped molybdenum sulfide powder of this embodiment, also contain a metastable 3R crystal structure. The aspect of these molybdenum sulfide particles containing a metastable 3R crystal structure, and the aspect containing both 2H and 3R crystal structures, can be distinguished by the fact that the spectrum obtained by powder X-ray diffraction (XRD) using Cu-Kα rays as the X-ray source shows the same pattern as that of the metal-doped molybdenum sulfide powder.

[0030] In the metal-doped molybdenum sulfide powder of this embodiment, the shape of the primary particles of the metal-doped molybdenum sulfide in a two-dimensional image taken using a transmission electron microscope (TEM) of the metal-doped molybdenum sulfide particles constituting the metal-doped molybdenum sulfide powder can be particle-shaped, spherical, plate-shaped, needle-shaped, rope-shaped, ribbon-shaped, or sheet-shaped when observed visually or in photographs. These shapes can also be combined. The shape of the primary particles of the metal-doped molybdenum sulfide is preferably rope-shaped, ribbon-shaped, or sheet-shaped. The shape of 50 primary particles of the metal-doped molybdenum sulfide is preferably, on average, a size ranging from 50 nm to 2000 nm × 50 nm to 2000 nm in length (vertical) × width (horizontal), more preferably a size ranging from 100 nm to 1000 nm × 100 nm to 1000 nm, and particularly preferably a size ranging from 150 nm to 500 nm × 150 nm to 500 nm. The primary particles of the metal-doped molybdenum sulfide are preferably shaped with a thickness ranging from 1 nm to 40 nm as measured by atomic force microscopy (AFM), more preferably from 3 nm to 20 nm, and particularly preferably from 5 nm to 10 nm. Here, "sheet-like" refers to a thin layer shape. "Ribbon-like" refers to a long, thin layer shape. By being sheet-like, the specific surface area of ​​the metal-doped molybdenum sulfide powder can be increased, and various activities of the metal-doped molybdenum sulfide powder, such as catalytic activity in the hydrogen evolution reaction (HER), become more superior. Here, "rope-like" refers to a long, thin shape. The aspect ratio (length (longitudinal) / thickness) of the primary particles of the metal-doped molybdenum sulfide, on an average of 50 particles, is preferably 1.2 to 1200, more preferably 2 to 800, further preferably 5 to 400, and particularly preferably 10 to 200.

[0031] The specific surface area of ​​the metal-doped molybdenum sulfide powder of this embodiment, as measured by the BET method, is preferably 10 m² / g or more, more preferably 30 m² / g or more, and particularly preferably 40 m² / g or more. The larger the specific surface area of ​​the metal-doped molybdenum sulfide powder of this embodiment, the higher the various activities of the metal-doped molybdenum sulfide powder, such as its catalytic activity in the hydrogen evolution reaction (HER). The specific surface area of ​​the metal-doped molybdenum sulfide powder of this embodiment, as measured by the BET method, can be 300 m² / g or less, or 200 m² / g or less, or 100 m² / g or less.

[0032] The median particle size D50 of the metal-doped molybdenum sulfide powder (the metal-doped molybdenum sulfide particles constituting the metal-doped molybdenum sulfide powder) in this embodiment, determined by a dynamic light scattering particle size distribution measuring device, is preferably 10 nm to 2000 nm. Furthermore, regarding the resulting product being made from molybdenum trioxide (MoO3), which has a large surface area and better reactivity with sulfur, the median particle size D50 of the metal-doped molybdenum sulfide particles is preferably 2000 nm or less, more preferably 1500 nm or less, and particularly preferably 1000 nm or less. On the other hand, the median particle size D50 of the metal-doped molybdenum sulfide particles can be 10 nm or more, or 20 nm or more, or 40 nm or more.

[0033] In the radial distribution function obtained from the extended X-ray absorption fine structure (EXAFS) spectrum of the K absorption end of the molybdenum powder of this embodiment, the ratio (I / II) of the intensity I of the peak caused by Mo-S to the intensity II of the peak caused by Mo-Mo is preferably 0.1 or more, more preferably 0.5 or more, and particularly preferably 1.0 or more.

[0034] The conversion rate RC of the metal-doped molybdenum sulfide powder to MoS2 in this embodiment is preferably 70% or more, more preferably 80% or more, and especially preferably 90% or more. Because the conversion rate RC of the metal-doped molybdenum sulfide powder to MoS2 is high, the catalytic activity and other activities of the metal-doped molybdenum sulfide powder in the hydrogen evolution reaction (HER) are increased.

[0035] The conversion rate RC of the metal-doped molybdenum sulfide powder to MoS2 can be determined by the reference intensity ratio (RIR) method based on the spectral data obtained by X-ray diffraction (XRD) measurement of the metal-doped molybdenum sulfide powder. The conversion rate RC of the metal-doped molybdenum sulfide powder to MoS2 can be determined by the following formula (1): the RIR value KA of the metal-doped molybdenum sulfide (MoS2) and the integral intensity IA of the peak value near 2θ=14.4°±0.5° of the (002) or (003) plane of the metal-doped molybdenum sulfide (MoS2), the RIR value KB of each molybdenum oxide (MoO3 as raw material, and Mo9O25, Mo4O11, MoO2, etc. as reaction intermediates) and the integral intensity IB of the strongest line peak value of each molybdenum oxide (MoO3 as raw material, and Mo9O25, Mo4O11, MoO2, etc. as reaction intermediates). RC (%) = (IA / KA) / (Σ(IB / KB)) × 100 … (1) Here, the RIR values ​​can be the values ​​recorded in the Inorganic Crystal Structure Database (ICSD database), and the analysis can be performed using the comprehensive powder X-ray analysis software (PDXL) (manufactured by Rigaku Corporation).

[0036] The molybdenum sulfide powder (molybdenum sulfide powder without group 3 to group 13 metals) is the same as the metal-doped molybdenum sulfide powder of this embodiment in terms of the shape, size, and aspect ratio of the primary particles of molybdenum sulfide in a two-dimensional image of molybdenum sulfide particles taken by a transmission electron microscope (TEM); the specific surface area determined by the BET method; the median particle size D50 obtained by a dynamic light scattering particle size distribution measuring device; the ratio (I / II) of the intensity I of the peak caused by Mo-S to the intensity II of the peak caused by Mo-Mo; and the conversion rate RC to MoS2. Here, examples of molybdenum sulfide powder include the molybdenum sulfide powders of Comparative Examples 1 to 5 described later (i.e., molybdenum sulfide powders manufactured using the same method as the metal-doped molybdenum sulfide powder of this embodiment, except for the aspect of not being doped with metals), and the molybdenum sulfide powder of Test Example 2 described later.

[0037] For example, the specific surface area of ​​the molybdenum sulfide powder, as determined by the BET method, is preferably 10 m² / g or more, more preferably 30 m² / g or more, and particularly preferably 40 m² / g or more. The specific surface area of ​​the molybdenum sulfide powder, as determined by the BET method, can be less than 300 m² / g, less than 200 m² / g, or less than 100 m² / g. The median particle size D50 of the molybdenum sulfide powder, as determined by a dynamic light scattering particle size distribution measuring device, is preferably 10 nm to 1000 nm. The median particle size D50 of the molybdenum sulfide powder is preferably less than 600 nm, more preferably less than 500 nm, and particularly preferably less than 400 nm. The median particle size D50 of the molybdenum sulfide powder can be more than 10 nm, more than 20 nm, or more than 40 nm. The ratio (I / II) in the molybdenum sulfide powder is preferably greater than 1.0, more preferably 1.1 or more, and particularly preferably 1.2 or more. The conversion rate (RC) of the molybdenum sulfide powder is preferably 70% or more, more preferably 80% or more, and particularly preferably 90% or more. Furthermore, the conversion rate (RC) of the molybdenum sulfide powder to MoS2 is determined using the same method as for the conversion rate (RC) of the metal-doped molybdenum sulfide powder to MoS2, except that the X-ray diffraction (XRD) measurement is performed on the molybdenum sulfide powder itself rather than the metal-doped molybdenum sulfide powder.

[0038] The metals of Group 3 to Group 13 are not particularly limited as long as they are metals in the periodic table that correspond to Group 3, Group 13, and any group in between. More specifically, examples of Group 3 to Group 13 metals include: scandium (Sc), yttrium (Y), lanthanum (La), cerium (Ce), beryl (Pr), neodymium (Nd), protium (Pm), samarium (Sm), europium (Eu), thorium (Gd), tbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thorium (Tm), ytterbium (Yb), argonium (Lu), actinium (Ac), thorium (Th), arsenic (Pa), uranium (U), ruthenium (Np), plutonium (Pu), ammonium (Am), ferromonium (Cm), dragonium (Bk), calcite (Cf), sterium (Es), fermium (Fm), menthium (Md), sterium (No), and tungsten (Lr), etc. Group 4 metals including titanium (Ti), zirconium (Zr), hafnium (Hf), and ruthenium (Rf); Group 5 metals including vanadium (V), niobium (Nb), tantalum (Ta), and argon (Db); Group 6 metals including chromium (Cr), molybdenum (Mo), tungsten (W), and argon (Sg); Group 7 metals including manganese (Mn), tris(tc), rhenium (Re), and argon (Bh); Group 8 metals including iron (Fe), ruthenium (Ru), osmium (Os), and argon (Hs); Group 9 metals including cobalt (Co), rhodium (Rh), iridium (Ir), and tungsten (Mt); Group 10 metals including nickel (Ni), palladium (Pd), platinum (Pt), and argon (Ds); and Group 11 metals including copper (Cu), silver (Ag), gold (Au), and rhodium (Rg). Group 12 metals such as zinc (Zn), cadmium (Cd), mercury (Hg), and strontium (Cn); Group 13 metals such as boron (B), aluminum (Al), gallium (Ga), indium (In), thallium (Tl), and ethium (Nh).

[0039] The group 3 to group 13 metals doped in the metal-doped molybdenum sulfide powder may be only one type or two or more types.

[0040] The metals of Group 3 to Group 13 are preferably selected from one or more of the group consisting of cobalt, palladium, iridium, manganese, iron, nickel, zirconium, ruthenium, indium and zinc.

[0041] In the metal-doped molybdenum sulfide powder, the ratio of the amount (molar amount) of the Group 3 to Group 13 metals to the amount (molar amount) of molybdenum (sometimes referred to as "metal doping amount" in this specification) is preferably 0.01 molar% to 30 molar%, more preferably 0.1 molar% to 20 molar%, and even more preferably 0.2 molar% to 10 molar%. By using this range of ratios, the various activities of the metal-doped molybdenum sulfide powder become higher.

[0042] <<Method for manufacturing metal-doped molybdenum sulfide powder>> The metal-doped molybdenum sulfide powder of this embodiment can be manufactured, for example, by the following manufacturing method (in this specification, it is sometimes referred to as "manufacturing method (1)"), which includes: after obtaining a mixed powder (in this specification, it is sometimes referred to as "raw material powder (1)") by dry mixing molybdenum trioxide powder containing an aggregate of primary particles with an α crystal structure or a β crystal structure containing molybdenum trioxide (MoO3), a sulfur source and a metal salt of Group 3 to Group 13, the mixed powder is heated at a temperature of 200°C to 1000°C (in this specification, the heating is sometimes referred to as "calcination").

[0043] The metal-doped molybdenum sulfide powder of this embodiment can also be manufactured by the following manufacturing method (sometimes referred to as "manufacturing method (2)" in this specification), which includes: removing the dispersion medium from a mixture of molybdenum trioxide powder containing an aggregate of primary particles with an α-crystal structure or a β-crystal structure of molybdenum trioxide (MoO3), a group 3 to 13 metal salt and a dispersion medium (sometimes referred to as "raw material mixture (1)" in this specification) to obtain a solid substance (sometimes referred to as "solid substance (1)" in this specification), and then heating (calcining) the solid substance at a temperature of 200°C to 1000°C in the presence of a sulfur source.

[0044] The metal-doped molybdenum sulfide powder of this embodiment can also be manufactured by the following manufacturing method (sometimes referred to as "manufacturing method (3)" in this specification), which includes: heating (calcining) the solid material at a temperature of 200°C to 1000°C after removing the dispersion medium from the mixture while setting the temperature of the mixture to 40°C or below, containing an aggregate of primary particles with an α-crystal structure or a β-crystal structure of molybdenum trioxide (MoO3), a group 3 to 13 metal salt, a sulfur source, and a dispersion medium.

[0045] <Manufacturing Method (1)> The molybdenum trioxide (MoO3) powder used in the manufacturing method (1) contains an aggregate of primary particles with an α-crystal structure or a β-crystal structure containing molybdenum trioxide. Compared with existing molybdenum trioxide powder containing only α-crystals as its crystal structure, the molybdenum trioxide powder containing the β-crystal structure has good reactivity with sulfur and can increase the conversion rate RC to MoS2 in the reaction with a sulfur source.

[0046] The β crystal structure of molybdenum trioxide can be confirmed by the presence of a peak at the (011) plane of the β crystal of MoO3 (around 2θ: 23.01°, No. 86426 (Inorganic Crystal Structure Database, ICSD)) in the spectrum obtained by powder X-ray diffraction (XRD) using Cu-K α rays as the X-ray source. The α crystal structure of molybdenum trioxide can be confirmed by the presence of a peak at the (021) plane of the α crystal of MoO3 (around 2θ: 27.32°, No. 166363 (Inorganic Crystal Structure Database, ICSD)).

[0047] The β crystal structure of molybdenum trioxide can also be confirmed by the presence of peaks at frequencies of 773, 848 cm⁻¹ and 905 cm⁻¹ in the Raman spectrum obtained by Raman spectrometry. The α crystal structure of molybdenum trioxide can be confirmed by the presence of peaks at frequencies of 663, 816 cm⁻¹ and 991 cm⁻¹.

[0048] The average particle size of the primary particles of the molybdenum trioxide powder is preferably 5 nm to 2000 nm.

[0049] The average particle size of primary particles of molybdenum trioxide powder refers to the average of the primary particle size of 50 randomly selected primary particles when the major axis (Feret's diameter of the longest observed part) and minor axis (the shorter Feret's diameter in the vertical direction relative to the Feret's diameter of the longest part) of the smallest unit constituting the aggregate (i.e., primary particles) of molybdenum trioxide powder are photographed using a scanning electron microscope (SEM).

[0050] The average particle size of the primary particles of the molybdenum trioxide powder is preferably less than 2000 nm, more preferably less than 600 nm, further preferably less than 400 nm, and particularly preferably less than 200 nm, in terms of reactivity with sulfur. The average particle size of the primary particles of the molybdenum trioxide powder may be more than 10 nm, more than 20 nm, or more than 40 nm.

[0051] Preferably, the molybdenum trioxide powder has a MoO3 content (purity) of 99.6% or more as determined by X-ray fluorescence (XRF). This can increase the conversion rate RC to MoS2 and obtain molybdenum sulfide with high purity, no risk of generating sulfides from impurities, and good storage stability.

[0052] Preferably, in the spectrum obtained by powder X-ray diffraction (XRD) using Cu-Kα rays as the X-ray source, the ratio of the peak intensity of the (011) facet of the β crystal belonging to MoO3 to the peak intensity of the (021) facet of the α crystal belonging to MoO3 (β(011) / α(021)) is 0.1 or more, more preferably 1.0 or more, and particularly preferably 2.0 or more.

[0053] The peak intensity of the (011) facet of the β crystal belonging to MoO3 and the peak intensity of the (021) facet of the α crystal belonging to MoO3 are read respectively, and the ratio (β(011) / α(021)) is calculated.

[0054] The specific surface area of ​​the molybdenum trioxide powder, as determined by the BET method, is preferably 10 m2 / g to 100 m2 / g.

[0055] In the molybdenum trioxide powder, the specific surface area is preferably 10 m² / g or more, more preferably 20 m² / g or more, and even more preferably 30 m² / g or more, in order to improve the reactivity with sulfur. In the molybdenum trioxide powder, the specific surface area is preferably 150 m² / g or less, or 120 m² / g or less, or 100 m² / g or less, in order to facilitate the manufacture of the molybdenum trioxide powder.

[0056] Preferably, in the radial distribution function obtained from the extended X-ray absorption fine structure (EXAFS) spectrum of the K absorption end of molybdenum, the ratio (I / II) of the peak intensity I caused by Mo-O to the peak intensity II caused by Mo-Mo is preferably 0.1 or more, more preferably 0.5 or more, and particularly preferably 1.0 or more.

[0057] The maximum intensity of the peak caused by Mo-O (I) and the peak caused by Mo-Mo (II) are read respectively, and the ratio (I / II) is calculated. It is considered that the ratio (I / II) is the standard for obtaining the β crystal structure of MoO3 in molybdenum trioxide powder. The larger the ratio (I / II), the better the reactivity with sulfur.

[0058] The molybdenum trioxide powder can be manufactured by vaporizing a molybdenum oxide precursor compound to form molybdenum trioxide vapor and cooling the molybdenum trioxide vapor.

[0059] The preferred method for manufacturing the molybdenum trioxide powder includes: calcining a raw material mixture containing a molybdenum oxide precursor compound and a metal compound other than the molybdenum oxide precursor compound, causing the molybdenum oxide precursor compound to vaporize and form molybdenum trioxide vapor, wherein the proportion of the metal compound relative to the raw material mixture is 70% or less in terms of oxides.

[0060] The method for manufacturing molybdenum trioxide powder can be appropriately implemented using the manufacturing apparatus 1 shown in FIG1.

[0061] Figure 1 is a schematic diagram of an example of the apparatus used in the manufacture of the molybdenum trioxide powder. The manufacturing apparatus 1 includes: a calcining furnace 2, which calcines a molybdenum oxide precursor compound or the raw material mixture to vaporize the molybdenum oxide precursor compound; a cross-shaped cooling pipe 3 connected to the calcining furnace 2 to pulverize the molybdenum trioxide vapor vapor vaporized by the calcination; and a recovery machine 4, which is a recovery unit for recovering the pulverized molybdenum trioxide powder in the cooling pipe 3. At this time, the calcining furnace 2 and the cooling pipe 3 are connected via an exhaust port 5. In addition, the cooling pipe 3 is provided with an opening adjustment damper 6 at the left end of an external gas intake port (not shown) and an observation window 7 at the upper end. An exhaust device 8, which serves as a first air supply unit, is connected to the recovery machine 4. The exhaust device 8 exhausts air while simultaneously drawing in the recovery unit 4 and the cooling pipes 3, directing external gas through the adjustable damper 6 on the cooling pipes 3. In other words, the exhaust device 8 performs a suction function, passively generating airflow into the cooling pipes 3. Furthermore, the manufacturing apparatus 1 may also have an external cooling device 9, thereby allowing arbitrary control of the cooling conditions of the molybdenum trioxide vapor generated from the calcining furnace 2.

[0062] By adjusting the opening of the damper 6, air is drawn in from the external gas intake port, and the molybdenum trioxide vapor vaporized in the calcining furnace 2 is cooled in an air environment to produce molybdenum trioxide powder. This allows the ratio (I / II) to be set to 0.1 or higher, making it easier to obtain the β-crystal structure of MoO3 in the molybdenum trioxide powder. When using liquid nitrogen to cool the molybdenum trioxide vapor, cooling the molybdenum trioxide vapor in a nitrogen environment with low oxygen concentration tends to increase the oxygen defect density and decrease the ratio (I / II).

[0063] As the molybdenum oxide precursor compound, there is no particular limitation as long as it is a compound that forms molybdenum trioxide vapor by calcination. Examples include: metallic molybdenum, molybdenum trioxide, molybdenum dioxide, molybdenum sulfide, ammonium molybdate, phosphomolybdic acid (H3PMo12O40), silicomolybdic acid (H4SiMo12O40), aluminum molybdate, silicon molybdate, magnesium molybdate (MgMonO3n+1 (n=1~3)), sodium molybdate (Na2MonO3n+1 (n=1~3)), titanium molybdate, iron molybdate, potassium molybdate (K2MonO3n+1 (n=1~3)), zinc molybdate, boron molybdate, lithium molybdate (Li2MonO3n+1 (n=1~3)), cobalt molybdate, nickel molybdate, manganese molybdate, chromium molybdate, cesium molybdate, barium molybdate, strontium molybdate, yttrium molybdate, zirconium molybdate, copper molybdate, etc. These molybdenum oxide precursor compounds can be used alone or in combination of two or more. The form of the molybdenum oxide precursor compounds is not particularly limited; for example, they can be in powder form such as molybdenum trioxide, or in liquid form such as an aqueous solution of ammonium molybdate. A powder form with good processability and energy efficiency is preferred.

[0064] Preferably, commercially available α-crystal molybdenum trioxide is used as the molybdenum oxide precursor compound. Alternatively, when ammonium molybdate is used as the molybdenum oxide precursor compound, it is converted into thermodynamically stable molybdenum trioxide by calcination, and thus the vaporized molybdenum oxide precursor compound becomes the molybdenum trioxide.

[0065] Among these, in terms of ease of control over the purity, average particle size of primary particles, and crystal structure of the obtained molybdenum trioxide powder, the molybdenum oxide precursor compound preferably contains molybdenum trioxide.

[0066] Molybdenum trioxide vapor can also be formed by calcining a mixture of raw materials containing a molybdenum oxide precursor compound and a metal compound other than the molybdenum oxide precursor compound.

[0067] The metal compound other than the molybdenum oxide precursor compound is not particularly limited, and examples include: aluminum compounds, silicon compounds, titanium compounds, magnesium compounds, sodium compounds, potassium compounds, zirconium compounds, yttrium compounds, zinc compounds, copper compounds, iron compounds, etc. Among these, the aluminum compound, silicon compound, titanium compound, or magnesium compound is preferred as the metal compound.

[0068] Molybdenum oxide precursor compounds and metal compounds other than the molybdenum oxide precursor compounds may sometimes form intermediates, but even in this case, the intermediates can be decomposed by calcination, so that molybdenum trioxide is vaporized in a thermodynamically stable form.

[0069] As a metal compound other than the molybdenum oxide precursor compound, an aluminum compound is preferably used to prevent damage to the calcination furnace. In the manufacturing method, to improve the purity of the molybdenum trioxide powder, a metal compound other than the molybdenum oxide precursor compound may not be used.

[0070] Examples of aluminum compounds include: aluminum chloride, aluminum sulfate, basic aluminum acetate, aluminum hydroxide, gibbsite, pseudogibbsite, aluminum oxide (α-alumina, γ-alumina, δ-alumina, θ-alumina, etc.), and mixed aluminum oxide having two or more crystalline phases.

[0071] When calcining a raw material mixture containing a molybdenum oxide precursor compound and a metal compound other than the molybdenum oxide precursor compound, the content of the molybdenum oxide precursor compound relative to 100% by mass of the raw material mixture is preferably 40% to 100% by mass, or 45% to 100% by mass, or 50% to 100% by mass.

[0072] The calcination temperature also varies depending on the molybdenum oxide precursor compound and the metal compound used, as well as the desired molybdenum trioxide powder, but is generally preferred to be the temperature at which the intermediate can decompose. For example, when a molybdenum compound is used as the molybdenum oxide precursor compound and the aluminum compound is used as the metal compound, the calcination temperature is preferably 500°C to 1500°C, more preferably 600°C to 1550°C, and even more preferably 700°C to 1600°C, in terms of forming aluminum molybdate as the intermediate.

[0073] The calcination time is not particularly limited. For example, it can be set to 1 min to 30 h, 10 min to 25 h, or 100 min to 20 h.

[0074] The heating rate also varies depending on the molybdenum oxide precursor compound and the metal compound used, as well as the desired characteristics of the molybdenum trioxide powder, but from the point of view of manufacturing efficiency, it is preferably 0.1℃ / min to 100℃ / min, more preferably 1℃ / min to 50℃ / min, and even more preferably 2℃ / min to 10℃ / min.

[0075] The internal pressure within the calcining furnace is not particularly limited; it can be either positive or reduced pressure. However, from the viewpoint of properly discharging the molybdenum oxide precursor compound from the calcining furnace to the cooling piping, calcination is preferably carried out under reduced pressure. Specifically, the pressure reduction is preferably -5000 Pa to -10 Pa, more preferably -2000 Pa to -20 Pa, and even more preferably -1000 Pa to -50 Pa. If the pressure reduction is above -5000 Pa, the high airtightness and mechanical strength of the calcining furnace are not excessively required, thus reducing manufacturing costs, which is preferable. On the other hand, if the pressure reduction is below -10 Pa, blockage of the molybdenum oxide precursor compound at the discharge port of the calcining furnace can be prevented, which is also preferable.

[0076] When air is supplied to the calcining furnace during calcination, the temperature of the air supplied is preferably 5°C to 500°C, and more preferably 10°C to 100°C.

[0077] For a calcining furnace with an effective volume of 100 L, the gas supply velocity is preferably 1 L / min to 500 L / min, and more preferably 10 L / min to 200 L / min.

[0078] The temperature of the vaporized molybdenum trioxide vapor varies depending on the type of molybdenum oxide precursor compound used, but is preferably 200°C to 2000°C, and more preferably 400°C to 1500°C. If the temperature of the vaporized molybdenum trioxide vapor is below 2000°C, it tends to be easily pulverized in the cooling piping by the supply of external gas (0°C to 100°C).

[0079] The discharge rate of molybdenum trioxide vapor from the calcining furnace can be controlled by the amount of the molybdenum oxide precursor compound and the amount of the metal compound used, the temperature of the calcining furnace, the gas supply to the calcining furnace, and the diameter of the calcining furnace exhaust port. The discharge rate of molybdenum trioxide vapor from the calcining furnace to the cooling pipes also varies depending on the cooling capacity of the cooling pipes, but is preferably 0.001 g / min to 100 g / min, more preferably 0.1 g / min to 50 g / min.

[0080] The content of molybdenum trioxide vapor in the gas discharged from the calcining furnace is preferably 0.01 mg / L to 1000 mg / L, more preferably 1 mg / L to 500 mg / L.

[0081] Next, the molybdenum trioxide vapor is cooled and pulverized. The cooling of the molybdenum trioxide vapor is carried out by keeping the cooling pipes at a low temperature. Examples of such cooling include: cooling by supplying air to the cooling pipes as described above, cooling by the cooling mechanism provided with the cooling pipes, and cooling by an external cooling device.

[0082] Cooling of molybdenum trioxide vapor is preferably carried out in an air environment. By cooling molybdenum trioxide vapor in an air environment to produce molybdenum trioxide powder, the ratio (I / II) can be set to 0.1 or more, and the β crystal structure of MoO3 can be easily obtained in the molybdenum trioxide powder.

[0083] The cooling temperature (temperature of cooling piping) is not particularly limited, but it is preferably -100℃ to 600℃, and more preferably -50℃ to 400℃.

[0084] The cooling rate of molybdenum trioxide vapor is not particularly limited, but it is preferably 100℃ / s to 100000℃ / s, and more preferably 1000℃ / s to 50000℃ / s. The faster the cooling rate of molybdenum trioxide vapor, the more likely it is to obtain molybdenum trioxide powder with small particle size and large specific surface area, and also contains many β crystal structures of molybdenum trioxide.

[0085] When the cooling method is to cool by supplying air to the cooling pipe, the temperature of the supplied air is preferably -100°C to 300°C, and more preferably -50°C to 100°C.

[0086] The gas supply velocity is preferably 0.1 m³ / min to 20 m³ / min, more preferably 1 m³ / min to 10 m³ / min. If the gas supply velocity is 0.1 m³ / min or higher, a high cooling rate can be achieved, preventing blockage of the cooling pipes, which is therefore preferable. On the other hand, if the gas supply velocity is 20 m³ / min or lower, an expensive first air supply unit (exhaust fan, etc.) is not required, reducing manufacturing costs, which is also preferable.

[0087] The powder obtained by cooling molybdenum trioxide vapor is conveyed to a recycling machine for recovery.

[0088] In the method for manufacturing molybdenum trioxide powder, the powder obtained by cooling the molybdenum trioxide vapor may also be calcined again at a temperature of 100°C to 320°C.

[0089] That is, the molybdenum trioxide powder obtained by the aforementioned method for manufacturing molybdenum trioxide powder can also be calcined again at a temperature of 100°C to 320°C. The calcination temperature for the second calcination can be 120°C to 280°C, or 140°C to 240°C. The calcination time for the second calcination can be, for example, 1 min to 4 h, 10 min to 5 h, or 100 min to 6 h. However, due to the second calcination at a temperature above 350°C, the crystal size of molybdenum trioxide grows, and the β crystal structure in the molybdenum trioxide powder disappears, the ratio (β(011) / α(021)) becomes 0, and the reactivity with sulfur is impaired.

[0090] The sulfur source is a component containing sulfur atoms, and examples of such sources include sulfur, hydrogen sulfide, etc.

[0091] The sulfur source contained in the raw material powder (1) may be only one type or more types.

[0092] In the raw material powder (1), the amount of sulfur source is preferably 3 to 20 times the amount of molybdenum trioxide powder, more preferably 4 to 15 times the amount of molybdenum trioxide powder, and even more preferably 5 to 10 times the amount of molybdenum trioxide powder. By having the amount of sulfur source be above the lower limit, the yield of metal-doped molybdenum sulfide powder is further improved. By having the amount of sulfur source be below the upper limit, the amount of sulfur source or impurities present in the metal-doped molybdenum sulfide powder is further reduced.

[0093] The group 3 to group 13 metal salts are not particularly limited as long as they are considered to be salts containing cations and anions of group 3 to group 13 metals.

[0094] The group 3 to group 13 metal salts contained in the raw material powder (1) may be only one type or more types.

[0095] The anion may be any one of inorganic anions (formed by anionization of inorganic components) and organic anions (formed by anionization of organic components).

[0096] Examples of inorganic anions include: halide ions such as chloride ion (Cl-), bromide ion (Br-), and iodide ion (I-); oxyanions such as nitrate ion (NO3-), sulfate ion (SO42-), carbonate ion (CO32-), bicarbonate ion (HCO3-), phosphate ion (PO43-), hydrogen phosphate ion (HPO42-), and dihydrogen phosphate ion (H2PO4-).

[0097] Examples of the organic anions include: acetate ion (CH3COO-), diacetate ion, lactate ion, bis(L-lactic acid) ion, gluconate ion, citrate ion, propionate ion, 2-ethylhexanoate ion, tartrate ion, dibenzyldithiocarbamate ion, succinate ion, hydroxyethanesulfonate ion, and other organic acid anions.

[0098] Group 3 to Group 13 metal salts are preferably salts containing cations of Group 3 to Group 13 metals and inorganic anions, more preferably salts containing cations, halide ions or oxo anions of Group 3 to Group 13 metals, and even more preferably chlorides or nitrates.

[0099] Examples of the chlorides include: cobalt chloride (CoCl2), palladium chloride (PdCl2), iridium chloride (IrCl3), manganese chloride (MnCl2), ferric chloride (III) (FeCl3), nickel chloride (NiCl2), ruthenium chloride (RuCl3), zinc chloride (ZnCl2), etc. Examples of the nitrates include: cobalt nitrate (Co(NO3)2), zirconium oxynitrate (ZrO(NO3)2), indium nitrate (In(NO3)3), etc.

[0100] Hydrates can also be used as group 3 to group 13 metal salts. Examples of hydrates of group 3 to group 13 metal salts include: cobalt nitrate hexahydrate (Co(NO3)2·6H2O), cobalt chloride hexahydrate (CoCl2·6H2O), manganese chloride tetrahydrate (MnCl2·4H2O), ferric(III) chloride hexahydrate (FeCl3·6H2O), nickel chloride hexahydrate (NiCl2·6H2O), zirconium oxynitrate dihydrate (ZrO(NO3)2·2H2O), and indium nitrate trihydrate (In(NO3)3·3H2O).

[0101] The group 3 to group 13 metal salts prepared in manufacturing method (1) are preferably selected from one or more of the group consisting of cobalt nitrate hexahydrate, cobalt chloride hexahydrate, palladium chloride, iridium chloride, manganese chloride tetrahydrate, ferric(III) chloride hexahydrate, nickel chloride hexahydrate, zirconium oxynitrate dihydrate, ruthenium chloride, indium nitrate trihydrate and zinc chloride.

[0102] In the raw material powder (1), the amount of Group 3 to Group 13 metal salts is preferably 0.2 mol% to 10 mol% relative to the amount of molybdenum trioxide powder, more preferably 0.4 mol% to 7 mol%, and even more preferably 0.6 mol% to 4 mol%. By using the amount of Group 3 to Group 13 metal salts in this range, the various activities of the metal-doped molybdenum sulfide powder become higher.

[0103] In the raw material powder (1), the ratio of the total amount of the molybdenum trioxide powder, the sulfur source, and the Group 3 to Group 13 metal salts to the total amount of all blended components is preferably 90% by mass or more, more preferably 95% by mass or more, further preferably 97% by mass or more, and particularly preferably 99% by mass or more. By having the ratio at or above the lower limit value, the various activities of the metal-doped molybdenum sulfide powder become higher. On the other hand, the ratio is 100% by mass or less.

[0104] In the raw material powder (1) of the manufacturing method (1), it is sufficient to dry mix all the formulation components, preferably to uniformly mix all the formulation components, for example, to grind them to the point that no particles can be visually identified. In this specification, "dry mixing" means mixing the target components at room temperature without intentionally using liquid components.

[0105] The dry mixing of the raw material powder (1) can be carried out at a temperature of, for example, 5°C to 40°C. The dry mixing time of the raw material powder (1) can also be, for example, 5 minutes to 120 minutes.

[0106] There is no particular limitation on the method of dry mixing the ingredients. For example, the ingredients can be mixed using an automatic mixing device such as a magnetic mortar and pestle or a dicing mill, or by grinding a small amount of the ingredients with a mortar and pestle.

[0107] In the manufacturing method (1), the calcination conditions of the raw material powder (1) can be appropriately adjusted. The calcination temperature is only required to ensure that the sulfidation reaction of molybdenum trioxide proceeds sufficiently, preferably above 320°C, more preferably above 340°C, and especially preferably above 360°C. The calcination temperature can be, for example, 320°C to 1000°C, 340°C to 800°C, or 360°C to 600°C.

[0108] The calcination time is as long as the temperature at which the sulfidation reaction of molybdenum trioxide is fully carried out, preferably 2 hours to 8 hours, more preferably 2.5 hours to 6.5 hours, and even more preferably 3 hours to 5 hours.

[0109] Calcination is preferably carried out in the presence of an inert gas, such as nitrogen. For example, when calcination is carried out while an inert gas is being introduced, the flow rate of the inert gas is preferably such that it can replace the total amount of gas in the calcination chamber once every 1 to 5 minutes. For example, when the volume of the calcination chamber is 1 L, the flow rate of the inert gas is preferably 200 mL / min to 1000 mL / min.

[0110] In the manufacturing method (1), the amount of raw material powder (1) used relative to the total amount of all components used for heating (calcination) at a temperature of 200°C to 1000°C is preferably 90% by mass or more, more preferably 95% by mass or more, further preferably 97% by mass or more, and particularly preferably 99% by mass or more. By having the proportion at or above the lower limit value, the various activities of the metal-doped molybdenum sulfide powder become higher. On the other hand, the proportion is 100% by mass or less.

[0111] In manufacturing method (1), at least by preparing raw material powder (1) and heating (calcining) the raw material powder (1) at a temperature of 200°C to 1000°C, metal-doped molybdenum sulfide powder can be manufactured. In manufacturing method (1), as long as metal-doped molybdenum sulfide powder can be obtained, in addition to the preparation and calcination of raw material powder (1), one or more other operations can be performed at appropriate times.

[0112] The manufacturing method (1) is excellent in that it can produce metal-doped molybdenum sulfide powder inexpensively through simple operation.

[0113] <Manufacturing Method (2)> The molybdenum trioxide (MoO3) powder, group 3 to group 13 metal salts and sulfur source used in the manufacturing method (2) are the same as those used in the manufacturing method (1).

[0114] The dispersion medium used in manufacturing method (2) is not particularly limited, and can generally be appropriately selected from dispersion media that can be used as solvents. Regarding the dispersion medium, a low boiling point is preferred if removal from the raw material mixture (1) is taken into consideration.

[0115] Examples of dispersion media include: water, acetone, acetonitrile, tetrahydrofuran (THF), hexane, heptane, toluene, methanol, ethanol, propanol (1-propanol, 2-propanol), butanol (1-butanol, 2-butanol), hexanol (1-hexanol, 2-hexanol), etc. In terms of the ability to dissolve Group 3 to Group 13 metal salts, preferred dispersion media include, for example, water, acetone, acetonitrile, and methanol.

[0116] The dispersion medium contained in the raw material mixture (1) may be only one type or more types.

[0117] The molybdenum trioxide powder is dispersed in the raw material mixture (1), and Group 3 to Group 13 metal salts are dissolved or dispersed. That is, the dispersion medium can function as a solvent relative to a portion of the formulation components.

[0118] In the raw material mixture (1), the amount of Group 3 to Group 13 metal salts is preferably 0.2 mol% to 10 mol% relative to the amount of molybdenum trioxide powder, more preferably 0.4 mol% to 7 mol%, and even more preferably 0.6 mol% to 4 mol%. By using the amount of Group 3 to Group 13 metal salts in this range, the various activities of the metal-doped molybdenum sulfide powder become higher.

[0119] In the raw material mixture (1), the amount of dispersion medium is preferably 1 to 300 times the mass of the molybdenum trioxide powder, more preferably 25 to 200 times the mass, and even more preferably 50 to 100 times the mass of the dispersion medium. By using this range of dispersion medium amounts, the processability of the raw material mixture (1) becomes higher.

[0120] In the raw material mixture (1), the total amount of the molybdenum trioxide powder, the Group 3 to Group 13 metal salts, and the dispersion medium relative to the total amount of all the blended components is preferably 90% by mass or more, more preferably 95% by mass or more, further preferably 97% by mass or more, and particularly preferably 99% by mass or more. By having the proportion at or above the lower limit value, the various activities of the metal-doped molybdenum sulfide powder become higher, and the processability of the raw material mixture (1) becomes higher. On the other hand, the proportion is 100% by mass or less.

[0121] The raw material mixture (1) can be prepared by blending the molybdenum trioxide powder, Group 3 to Group 13 metal salts and a dispersion medium. There is no particular limitation on the order of blending these components. Each component can be blended independently in sequence, or a portion of the components can be mixed and blended in advance to obtain the mixture. For example, the raw material mixture (1) can also be prepared by mixing a dispersion of the molybdenum trioxide powder as a blending agent of the molybdenum trioxide powder and the dispersion medium, and a dispersion or solution of the Group 3 to Group 13 metal salts as a blending agent of the Group 3 to Group 13 metal salts and the dispersion medium (solvent).

[0122] In the manufacturing method (2), when preparing the raw material mixture (1), the raw material mixture (1) can also be prepared by stirring the resulting mixture at 10°C to 35°C for 0.5 hours to 12 hours after mixing all the components.

[0123] In the manufacturing method (2), the method for removing the dispersion medium from the raw material mixture (1) is not particularly limited as long as the removal of the dispersion medium (solvent) (i.e., drying) can be achieved. For example, the drying method using a blower dryer or a rotary evaporator, or the drying method using freeze drying, can be listed. For example, the method suitable for mass production can be listed as: the method of removing the dispersion medium from the raw material mixture (1) by freeze drying (in this specification, it is sometimes referred to as "drying method (1)"); and the method of removing the dispersion medium from the raw material mixture (1) by heating (in this specification, it is sometimes referred to as "drying method (2)").

[0124] In the drying method (1), the conditions for freeze drying are not particularly limited. For example, a mixture of dry ice and methanol is used as a refrigerant to freeze the raw material mixture (1), and then a rotary pump or the like is used to maintain the environment in which the raw material mixture (1) exists as a vacuum, thereby removing the dispersion medium from the raw material mixture (1).

[0125] In the drying method (2), the raw material mixture (1) may also be heated at 50°C to 200°C for 0.5 hours to 6 hours, for example. Moreover, it is preferable to heat in the manner described above while supplying air.

[0126] Regarding the method of removing the dispersion medium from the raw material mixture (1), in terms of obtaining the solid substance (1) with more uniform quality by means of a simpler method, the drying method (1) is preferred.

[0127] In the manufacturing method (2), the amount of sulfur source coexisting with the solid substance (1) relative to the amount of molybdenum trioxide powder (the amount of sulfur source) is preferably 3 to 20 times the amount of molybdenum trioxide powder, more preferably 4 to 15 times the amount of molybdenum trioxide powder, and even more preferably 5 to 10 times the amount of molybdenum trioxide powder. By having the amount of sulfur source be at or above the lower limit, the yield of metal-doped molybdenum sulfide powder is further improved. By having the amount of sulfur source be at or below the upper limit, the amount of sulfur source or impurities present in the metal-doped molybdenum sulfide powder is further reduced. Here, the amount (moles) of molybdenum trioxide powder refers to the amount obtained by multiplying the amount (moles) of molybdenum trioxide powder used in the preparation of the raw material mixture (1) by the amount (parts by mass) of solid substance (1) used and dividing by the total amount (parts by mass) of solid substance (1) ([amount (moles) of molybdenum trioxide powder used in the preparation of the raw material mixture (1)] × [amount (parts by mass) of solid substance (1)] / [total amount (parts by mass) of solid substance (1)]). Therefore, in the case of the total amount of solid substance (1) used, the amount (moles) of molybdenum trioxide powder used refers to the amount (moles) of molybdenum trioxide powder used in the preparation of the raw material mixture (1).

[0128] In manufacturing method (2), the calcination conditions of solid substance (1) can be appropriately adjusted. For example, the calcination conditions of solid substance (1) in the presence of sulfur source in manufacturing method (2) can also be the same as the calcination conditions of raw material powder (1) in manufacturing method (1).

[0129] In the manufacturing method (2), the total amount of solid material (1) and sulfur source used relative to the total amount of all components used for heating (calcination) at a temperature of 200°C to 1000°C is preferably 90% by mass or more, more preferably 95% by mass or more, further preferably 97% by mass or more, and particularly preferably 99% by mass or more. When the ratio is at or above the lower limit, the various activities of the metal-doped molybdenum sulfide powder become higher. On the other hand, the ratio is 100% by mass or less.

[0130] In manufacturing method (2), at least by obtaining solid substance (1) from raw material mixture (1) and then calcining solid substance (1) in the presence of a sulfur source, metal-doped molybdenum sulfide powder can be manufactured. In manufacturing method (2), if metal-doped molybdenum sulfide powder can be obtained, in addition to calcining solid substance (1) in the presence of a sulfur source after obtaining solid substance (1) from raw material mixture (1), one or more other operations can be performed at appropriate times.

[0131] The manufacturing method (2) is superior in that it can produce metal-doped molybdenum sulfide powder with more uniform quality, and the manufacturing method (2) using the drying method (1) is particularly superior in that it can produce metal-doped molybdenum sulfide powder with more uniform quality.

[0132] <Manufacturing Method (3)> The molybdenum trioxide (MoO3) powder, group 3 to group 13 metal salts and sulfur source used in the manufacturing method (3) are the same as those used in the manufacturing method (1).

[0133] The dispersion medium used in manufacturing method (3) is the same as the dispersion medium used in manufacturing method (2).

[0134] The dispersion medium contained in the raw material mixture (2) may be only one type or more types.

[0135] The molybdenum trioxide powder is dispersed in the raw material mixture (2), a sulfur source is dissolved or dispersed, and group 3 to group 13 metal salts are dissolved or dispersed. That is, the dispersion medium can function as a solvent relative to a portion of the formulation components.

[0136] In the raw material mixture (2), the amount of Group 3 to Group 13 metal salts is preferably 0.2 mol% to 10 mol% relative to the amount of molybdenum trioxide powder, more preferably 0.4 mol% to 7 mol%, and even more preferably 0.6 mol% to 4 mol%. By using the amount of Group 3 to Group 13 metal salts in this range, the various activities of the metal-doped molybdenum sulfide powder become higher.

[0137] In the raw material mixture (2), the amount of sulfur source is preferably 3 to 20 times the amount of molybdenum trioxide powder, more preferably 4 to 15 times the amount of molybdenum trioxide powder, and even more preferably 5 to 10 times the amount of molybdenum trioxide powder. By having the amount of sulfur source be above the lower limit, the yield of metal-doped molybdenum sulfide powder is further increased. By having the amount of sulfur source be below the upper limit, the amount of sulfur source or impurities present in the metal-doped molybdenum sulfide powder is further reduced.

[0138] In the raw material mixture (2), the amount of dispersion medium is preferably 1 to 300 times the mass of the molybdenum trioxide powder, more preferably 5 to 150 times the mass, and even more preferably 10 to 90 times the mass of the dispersion medium. By using this range of dispersion medium amounts, the processability of the raw material mixture (2) becomes higher.

[0139] In the raw material mixture (2), the total amount of the molybdenum trioxide powder, Group 3 to Group 13 metal salts, sulfur source, and dispersion medium relative to the total amount of all blended components is preferably 90% by mass or more, more preferably 95% by mass or more, further preferably 97% by mass or more, and particularly preferably 99% by mass or more. By having the proportion at or above the lower limit value, the various activities of the metal-doped molybdenum sulfide powder become higher, and the processability of the raw material mixture (2) becomes higher. On the other hand, the proportion is 100% by mass or less.

[0140] The raw material mixture (2) can be prepared by blending the molybdenum trioxide powder, Group 3 to Group 13 metal salts, sulfur source and dispersion medium. There is no particular limitation on the order of blending these components. Each component can be blended independently in sequence, or a portion of the components can be mixed together in advance to obtain the mixture. For example, the raw material mixture (2) can be prepared by mixing a dispersion of the molybdenum trioxide powder as a blending agent of the molybdenum trioxide powder and the dispersion medium, a dispersion or solution of the Group 3 to Group 13 metal salts as a blending agent of the Group 3 to Group 13 metal salts and the dispersion medium (solvent), and a sulfur source.

[0141] In the manufacturing method (3), when preparing the raw material mixture (2), the raw material mixture (2) can also be prepared by mixing all the components and stirring the resulting mixture at 10°C to 35°C for 0.5 hours to 12 hours.

[0142] In the manufacturing method (3), the method for removing the dispersion medium from the raw material mixture (2) is not particularly limited as long as the dispersion medium (solvent) can be removed (i.e. dried) when the temperature of the raw material mixture (2) is set to below 100°C. As a method for removing the dispersion medium in the manner described above, for example, the method of removing the dispersion medium using a rotary evaporator and the method of removing the dispersion medium using freeze drying can be listed. As a preferred method, for example, the method of removing the dispersion medium from the raw material mixture (2) at a temperature near room temperature by freeze drying of the raw material mixture (2) can be listed (in this specification, it is sometimes referred to as "drying method (3)"). The drying method (3) is better in that it obtains the solid substance (2) with a more uniform quality by a simpler method.

[0143] In the drying method (3), the conditions for freeze drying are not particularly limited. For example, the conditions for freeze drying in the drying method (3) may be the same as those for freeze drying in the drying method (1).

[0144] In manufacturing method (3), the calcination conditions of the solid substance (2) can be appropriately adjusted. For example, the calcination conditions of the solid substance (2) in manufacturing method (3) can be the same as the calcination conditions of the raw material powder (1) in manufacturing method (1).

[0145] In the manufacturing method (3), the amount of solid material (2) used relative to the total amount of all components used in the heating (calcination) at a temperature of 200°C to 1000°C is preferably 90% by mass or more, more preferably 95% by mass or more, even more preferably 97% by mass or more, and particularly preferably 99% by mass or more. When the proportion is at or above the lower limit, the various activities of the metal-doped molybdenum sulfide powder become higher. On the other hand, the proportion is 100% by mass or less.

[0146] In the manufacturing method (3), at least by obtaining a solid substance (2) from the raw material mixture (2) and then calcining the solid substance (2), metal-doped molybdenum sulfide powder can be manufactured. In the manufacturing method (3), if metal-doped molybdenum sulfide powder can be obtained, in addition to calcining the solid substance (2) after obtaining it from the raw material mixture (2), one or more other operations can be performed at appropriate times.

[0147] The manufacturing method (3) is particularly excellent in that it can produce metal-doped molybdenum sulfide powder with more uniform quality.

[0148] <<Hydrogen-Generating Catalyst>> The metal-doped molybdenum sulfide powder is suitable for use as a catalyst in hydrogen generation reactions (HER) (sometimes referred to as "hydrogen-generating catalyst" in this specification). Furthermore, the metal-doped molybdenum sulfide powder can be used in conjunction with a conductive material as a hydrogen-generating catalyst. That is, as a preferred hydrogen-generating catalyst, examples include catalysts containing the metal-doped molybdenum sulfide powder, which may also contain a conductive material in addition to the metal-doped molybdenum sulfide powder. The hydrogen-generating catalyst containing the metal-doped molybdenum sulfide powder and the conductive material exhibits higher catalytic activity in the hydrogen generation reaction (HER).

[0149] The conductive material may also be a known material. Examples of such conductive materials include highly conductive materials such as carbon and metals. The hydrogen-producing catalyst may contain only one type of conductive material or two or more types.

[0150] Examples of carbon include acetylene black, Cabot carbon black, and Ketjen black.

[0151] The hydrogen-producing catalyst may contain only one type of carbon or two or more types of carbon.

[0152] The carbon is preferably selected from one or more of the group consisting of acetylene black, Cabot carbon black, and Ketjen black, more preferably Ketjen black, and even more preferably from one or more of the group consisting of Ketjen black EC300J and Ketjen black EC600JD. Ketjen black has a high specific surface area and electrical conductivity, and is therefore excellent in suppressing the agglomeration of molybdenum sulfide.

[0153] Examples of metals used as conductive materials include: gold, silver, copper, aluminum, rhodium, molybdenum, tungsten, iron, nickel, cobalt, indium, etc. The metal used as a conductive material differs from the metal doped in metal-doped molybdenum sulfide powder; in the hydrogen-generating catalyst, it is simply mixed with metal-doped molybdenum sulfide powder.

[0154] The hydrogen-producing catalyst may contain only one type of metal as a conductive material, or it may contain two or more types of metals.

[0155] The hydrogen-generating catalyst may contain carbon but not metal, or it may contain metal but not carbon, or it may contain both metal and carbon as a conductive material.

[0156] In the hydrogen-generating catalyst, the content of conductive material relative to the content of the molybdenum sulfide powder is preferably 1% to 50% by mass, more preferably 5% to 40% by mass, and even more preferably 10% to 30% by mass. By having such a content, the effect of improving the activity of the hydrogen-generating catalyst becomes greater.

[0157] In the hydrogen-generating catalyst, the total content (parts by mass) of the metal-doped molybdenum sulfide powder and the conductive material relative to the total mass of the hydrogen-generating catalyst is preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more. For example, it can also be either 97% by mass or more or 99% by mass or more, or it can be 100% by mass. By having the ratio at or above the lower limit value, the catalytic activity of the hydrogen-generating catalyst in the hydrogen generation reaction (HER) becomes higher. The ratio only needs to be 100% by mass or less.

[0158] <<Catalyst Ink>> The hydrogen-producing catalyst described above is suitable as a component of catalyst ink. Examples of such catalyst inks include inks containing the hydrogen-producing catalyst and a solvent, and inks containing a polymeric electrolyte may also be listed.

[0159] The hydrogen-producing catalyst contained in the catalytic ink may be only one type or may be two or more types.

[0160] Examples of solvents include those that can disperse hydrogen-generating catalysts and form a catalyst layer by coating them onto a substrate for the active electrode. Preferably, the solvent is one capable of dispersing a polymeric electrolyte and one that can be removed at room temperature or below 100°C during the formation of the catalyst layer.

[0161] As a solvent, more specifically, examples include: water, acetone, acetonitrile, tetrahydrofuran (THF), hexane, heptane, toluene, methanol, ethanol, propanol (1-propanol, 2-propanol), butanol (1-butanol, 2-butanol), pentanol (1-pentanol, 2-pentanol), hexanol (1-hexanol, 2-hexanol), heptanol (1-heptanol, 2-heptanol), etc.

[0162] The solvent contained in the catalytic ink may be only one type or may be two or more types.

[0163] In the catalytic ink, the solvent content is preferably 1 to 300 times the mass of the hydrogen-producing catalyst, more preferably 10 to 150 times the mass of the catalyst, and even more preferably 30 to 75 times the mass of the catalyst. By having the solvent content in this range, the processability of the catalytic ink becomes higher, and the formation of agglomerates can be suppressed in the catalytic ink.

[0164] By containing the aforementioned polymeric electrolyte, the conductivity of the catalyst ink is increased, thereby suppressing the aggregation of molybdenum sulfide in the catalyst ink. The polymeric electrolyte can be a general user in the catalyst layer for fuel cells. Examples of polymeric electrolytes include perfluorinated carbon polymers with sulfonation groups (e.g., Nafion (registered trademark)), hydrocarbon polymers with sulfonation groups, polymers doped with inorganic acids such as phosphoric acid, organic / inorganic mixed polymers partially substituted with proton-conducting functional groups, and proton conductors in which a phosphoric acid solution or sulfuric acid solution is impregnated in a polymer matrix.

[0165] The polymer electrolyte contained in the catalytic ink may be only one type or two or more types.

[0166] When the catalytic ink contains a polymeric electrolyte, the content of the polymeric electrolyte in the catalytic ink is preferably 0.1% to 20% by mass, more preferably 0.5% to 10% by mass, and even more preferably 1% to 5% by mass, relative to the content of the hydrogen-producing catalyst. By having the content of the polymeric electrolyte within this range, the catalytic effect in the hydrogen production reaction (HER) becomes higher.

[0167] In the catalyst ink, the total content (parts by mass) of the hydrogen-generating catalyst, polymeric electrolyte, and solvent relative to the total mass of the catalyst ink is preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more. For example, it can also be any one of 97% by mass or more and 99% by mass or more, or it can be 100% by mass. By having the ratio at or above the lower limit value, the catalyst activity of the catalyst ink and the catalyst layer formed therefrom relative to the hydrogen generation reaction (HER) becomes higher. The ratio only needs to be 100% by mass or less. [Example]

[0168] Hereinafter, the present invention will be described in more detail by way of specific embodiments. However, the present invention is not limited to any of the embodiments shown below.

[0169] The physical property evaluation of each item is carried out by the method shown below.

[0170] <Method for determining the average particle size of primary particles in molybdenum trioxide powder> Molybdenum trioxide particles constituting the molybdenum trioxide powder were imaged using a scanning electron microscope (SEM). For the smallest unit of aggregates (i.e., primary particles) in the two-dimensional image (i.e., primary particles), their major axis (Ferret diameter of the longest observed portion) and minor axis (the shorter Ferret diameter perpendicular to its longest portion) were measured, and their average value was taken as the primary particle size. The same operation was performed on 50 randomly selected primary particles, and the average particle size of the primary particles was calculated based on the average primary particle size.

[0171] <Purity Determination of Molybdenum Trioxide: XRF Analysis> Using a Primus IV fluorescence X-ray analyzer (manufactured by Rigaku Corporation), approximately 70 mg of the recovered molybdenum trioxide powder sample was taken onto filter paper, covered with a polypropylene (PP) membrane, and subjected to compositional analysis. The molybdenum content was determined by converting the molybdenum content obtained from the XRF analysis results to molybdenum trioxide content (mass%) relative to 100% by mass of the molybdenum trioxide powder.

[0172] <Determination of Metal Doping Content in Metal-Doped Molybdenum Sulfide Powder: XRF Analysis> Using a Primus IV fluorescence X-ray analyzer (manufactured by Rigaku Corporation), approximately 70 mg of a sample of metal-doped molybdenum sulfide powder was taken onto filter paper, covered with a PP film, and subjected to compositional analysis. The ratio of the metal content (molar amount) obtained from the XRF (fluorescence X-ray) analysis results to the molybdenum content (molar amount) in the metal-doped molybdenum sulfide powder was calculated and used as the metal doping content.

[0173] <Crystal Structure Analysis: XRD Method> A sample of molybdenum trioxide powder, molybdenum sulfide powder, or metal-doped molybdenum sulfide powder is filled to a depth of 0.5 mm in a sample holder for measurement and placed in a wide-angle X-ray diffraction (XRD) device (Ultima IV manufactured by Rigaku Corporation). Measurements are performed under conditions of Cu / Kα rays, 40 kV / 40 mA, a scanning speed of 2° / min, and a scanning range of 10° or more and 70° or less.

[0174] <Specific Surface Area Determination: BET Method> The surface area of ​​molybdenum trioxide powder, molybdenum sulfide powder or metal-doped molybdenum sulfide powder samples was measured using a specific surface area meter (manufactured by MicrotracBEL, BELSORP-mini) and the surface area of ​​each 1 g sample determined based on the amount of nitrogen adsorption was calculated by the BET method as the specific surface area (m2 / g).

[0175] <Calculation of the conversion rate RC to MoS2> X-ray diffraction (XRD) was performed on the black molybdenum sulfide powder. Next, the conversion rate RC to MoS2 was calculated by the following formula (1) using the RIR (reference intensity ratio) method, which is based on the RIR value KA of molybdenum sulfide (MoS2) and the integral intensity IA of the peak value near 2θ=14.4°±0.5° of the (002) or (003) plane of molybdenum sulfide (MOS2), the RIR value KB of each molybdenum oxide (MoO3 as raw material, and Mo9O25, Mo4O11, MoO2, etc. as reaction intermediates) and the integral intensity IB of the strongest line peak value of each molybdenum oxide (MoO3 as raw material, and Mo9O25, Mo4O11, MoO2, etc. as reaction intermediates). RC (%) = (IA / KA) / (Σ(IB / KB))×100 …(1) Here, the RIR values ​​are used from the Inorganic Crystal Structure Database (ICSD), and the analysis is performed using the Comprehensive Powder X-ray Analysis Software (PDXL) (manufactured by Rigaku Corporation).

[0176] <Extended X-ray Absorption Fine Structure (EXAFS) Measurement> 36.45 mg of molybdenum sulfide powder and 333.0 mg of boron nitride were mixed in a mortar. 123.15 mg of this mixture was measured and compressed into an ϕ8 mm ingot to obtain the measurement sample. Using this measurement sample, the extended X-ray absorption fine structure (EXAFS) was measured by transmission method using BL5S1 at the Aichi Synchrotron Light Center. Athena (Internet <Uniform Resource Locator, URL: https: / / bruceravel.github.io / demeter / >) was used in the analysis.

[0177] <Determination of the median particle size D50 of metal-doped molybdenum sulfide powder or molybdenum sulfide powder> Add 0.1 g of metal-doped molybdenum sulfide powder or molybdenum sulfide powder to 20 mL of acetone, and perform ultrasonic treatment in an ice bath for 4 hours. Then, using acetone, adjust the concentration appropriately to the measurable range of the dynamic light scattering particle size distribution measuring device (Nanotrac WaveII manufactured by MicrotracBEL) to obtain the test sample. Using the test sample, measure the particle size distribution in the range of 0.0001 μm to 10 μm using the dynamic light scattering particle size distribution measuring device (Nanotrac WaveII manufactured by MicrotracBEL), and calculate the median particle size D50. For those with a median particle size D50 exceeding 10 μm, solutions were prepared in the same manner, and the particle size distribution in the range of 0.015 μm to 500 μm was measured using a laser diffraction particle size distribution measuring device (SALD-7000 manufactured by Shimadzu Corporation), and the median particle size D50 was calculated.

[0178] <Method for observing the particle shape of metal-doped molybdenum sulfide powder or molybdenum sulfide powder (1)>The shape of 50 primary particles in the field of view of the two-dimensional image was observed by using a transmission electron microscope (TEM) (JEM1400 of JEOL).

[0179] <Method for observing the particle shape of metal-doped molybdenum sulfide powder or molybdenum sulfide powder (2)>The particle shape of metal-doped molybdenum sulfide powder or molybdenum sulfide powder was observed by taking pictures of the powder using a scanning electron microscope (SEM) (JCM7000 of JEOL).

[0180] <Method for observing the particle shape of metal-doped molybdenum sulfide powder or molybdenum sulfide powder (3)>Metal-doped molybdenum sulfide powder was measured using atomic force microscopy (AFM) (Oxford Cypher-ES) to observe the particle shape.

[0181] <Elemental Distribution Analysis of Metal-Doped Molybdenum Sulfide Powder> Metal-doped molybdenum sulfide powder was observed using a scanning electron microscope (SEM) (JEOL JCM7000) by energy dispersive X-ray spectroscopy (EDS), and the distribution of elements in the powder was analyzed.

[0182] [Example 1] <<Manufacturing of metal-doped molybdenum sulfide powder (manufacturing method (1))>> <Manufacturing of molybdenum trioxide powder containing β crystal structure> 1 kg of transition alumina (manufactured by Wako Pure Chemical Industries, Ltd., activated alumina, average particle size 45 μm) and 1 kg of molybdenum trioxide (manufactured by Taiyo Mining Co., Ltd.) were mixed and then placed into a sagger. The mixture was then calcined for 10 hours at 1100°C using the calcining furnace 2 in the manufacturing apparatus 1 shown in FIG. 1. During calcination, external gas was introduced from the side and bottom of the calcining furnace 2 (air flow rate: 50 L / min, external gas temperature: 25°C). After the molybdenum trioxide evaporated in the calcining furnace 2, it was cooled near the recovery machine 4 and precipitated in the form of particles. As the calcining furnace 2, a roller kiln (RHK) simulator (manufactured by Noritake Company Limited) was used, and as the recovery machine 4, a VF-5N dust collector (manufactured by Amano Co., Ltd.) was used.

[0183] After calcination, 1.0 kg of alumina (blue powder) and 0.85 kg of molybdenum trioxide powder recovered using recycling machine 4 were removed from the sagger. The average particle size of the primary particles of the recovered molybdenum trioxide powder was 80 nm, and the purity of molybdenum trioxide was confirmed to be 99.7% by X-ray fluorescence (XRF) determination. The specific surface area (SA) of the molybdenum trioxide powder, determined by the BET method, was 44.0 m2 / g.

[0184] In addition, X-ray diffraction (XRD) of the molybdenum trioxide powder was measured. The results of the X-ray diffraction pattern are shown in Figure 2 together with the standard patterns of α crystal and β crystal of molybdenum trioxide. The peak values ​​of α crystal and β crystal belonging to MoO3 were observed, and no other peak values ​​were observed. Then the peak intensity ratio (β(011) / α(021)) of the (011) plane of the β crystal (2θ: around 23.01°, No. 86426 (Inorganic Crystal Structure Database (ICSD))) and the (021) plane of the α crystal (2θ: around 27.32°, No. 166363 (Inorganic Crystal Structure Database (ICSD))) was calculated, and the result was β(011) / α(021) = 5.2.

[0185] 32.76 mg of molybdenum trioxide powder and 333.0 mg of boron nitride were mixed using a mortar and pestle. 121.92 mg of the mixture was measured, compressed into an ingot with a diameter of ϕ8 mm, and the extended X-ray absorption fine structure (EXAFS) was measured. The EXAFS spectrum of the K-end of molybdenum is shown in Figure 3. In the radial distribution function obtained from this spectrum, the ratio (I / II) of the intensity I of the peak caused by Mo-O to the intensity II of the peak caused by Mo-Mo is 2.0.

[0186] <Preparation of Cobalt-Doped Molybdenum Sulfide Powder> In a mortar, using a mortar rod, the raw material powder (1) containing 0.25 g of molybdenum trioxide powder, sulfur powder (manufactured by Kanto Chemical Co., Ltd., at 7 moles relative to molybdenum trioxide powder) and 5.06 mg of cobalt nitrate hexahydrate (manufactured by Kanto Chemical Co., Ltd., at 1 mole relative to molybdenum trioxide powder) was ground for 30 minutes at room temperature to obtain a uniform grayish-white powder. Subsequently, in a magnetic crucible, under a nitrogen flow of 300 mL / min, the obtained grayish-white powder was heated (calcined) at 400°C for 4 hours to obtain powder (cobalt-doped molybdenum sulfide powder).

[0187] The X-ray diffraction (XRD) pattern of the powder from Example 1 was confirmed, and only peaks belonging to molybdenum disulfide (MoS2) were detected. No peaks not belonging to molybdenum disulfide (MoS2) were observed. That is, no peaks of reaction intermediates such as molybdenum dioxide (MoO2) as byproducts were observed, and only peaks belonging to molybdenum disulfide (MoS2) were observed. Based on this, it can be confirmed that the conversion rate RC of the metal-doped molybdenum disulfide powder to MoS2 obtained above is above 99%, and the reaction with sulfur proceeds rapidly. The crystal structure analysis of the metal-doped molybdenum disulfide powder of Example 1 by X-ray diffraction (XRD) confirmed that it contains 2H crystal structure and 3R crystal structure.

[0188] Furthermore, a magnified pattern of the region around 2θ / degree 14 in the X-ray diffraction (XRD) pattern is shown in FIG4 together with the pattern of the molybdenum sulfide powder of Comparative Example 1 described later. According to FIG4, it is shown that the peak value of the metal-doped molybdenum sulfide powder of Example 1 is shifted to the lower angle side compared with the peak value of the molybdenum sulfide powder of Comparative Example 1, and the interlayer distance in the crystal of the metal-doped molybdenum sulfide powder of Example 1 is extended compared with the molybdenum sulfide powder of Comparative Example 1.

[0189] The metal doping amount (cobalt doping amount) of the metal-doped molybdenum sulfide powder (cobalt-doped molybdenum sulfide powder) of Example 1 was determined by XRF analysis, and the result was 0.77 moles.

[0190] The specific surface area of ​​the metal-doped molybdenum sulfide powder of Example 1 was determined by the BET method, and the result was 59.8 m2 / g.

[0191] In the radial distribution function obtained from the extended X-ray absorption fine structure (EXAFS) spectrum of the K absorption end of molybdenum powder of Example 1, the ratio (I / II) of the intensity I of the peak caused by Mo-S to the intensity II of the peak caused by Mo-Mo was calculated, and the result was 1.737.

[0192] The particle size distribution of the metal-doped molybdenum sulfide powder of Example 1 was measured by a dynamic light scattering particle size distribution measuring device, and the median particle size D50 was determined to be 562 nm.

[0193] A TEM image of the metal-doped molybdenum sulfide powder of Example 1 is shown in Figure 5.

[0194] The AFM image of the metal-doped molybdenum sulfide powder of Example 1 is shown in Figure 6. Figure 6 is the AFM image obtained from the measurement and shows the upper surface of the particles of the metal-doped molybdenum sulfide powder. Based on this AFM image, the length (longitudinal) × width (horizontal) was calculated, and the result was 180 nm × 80 nm. Figure 7 shows a cross-section of the metal-doped molybdenum sulfide powder shown in Figure 6. Based on this cross-section, the thickness was calculated, and the result was 16 nm. Therefore, the aspect ratio (length (longitudinal) / thickness) of the primary particles of the metal-doped molybdenum sulfide powder of Example 1 is 11.25.

[0195] Based on various analytical results represented by the X-ray diffraction pattern, it can be confirmed that the target metal-doped molybdenum sulfide powder has indeed been obtained.

[0196] <<Manufacturing of molybdenum sulfide powder (manufacturing method (1'))>> [Comparative Example 1] Molybdenum sulfide powder was manufactured using the same method as in Example 1, except that cobalt nitrate hexahydrate was not used. In this specification, the method in which the use of Group 3 to Group 13 metal salts is omitted is sometimes referred to as "manufacturing method (1')".

[0197] The pattern obtained by magnifying the region near 2θ / degree 14 in the X-ray diffraction (XRD) pattern of the molybdenum sulfide powder of Comparative Example 1 is shown in FIG4 together with the pattern of the metal-doped molybdenum sulfide powder of Example 1.

[0198] The metal doping amount (zinc doping amount) of the molybdenum sulfide powder of Comparative Example 1 was determined by XRF analysis, and the result was 0.00 moles.

[0199] The specific surface area of ​​the molybdenum sulfide powder of Comparative Example 1 was determined by the BET method, and the result was 38.9 m2 / g.

[0200] The ratio (I / II) of the molybdenum sulfide powder in Comparative Example 1 was determined to be 1.362.

[0201] The particle size distribution of molybdenum sulfide powder in Comparative Example 1 was measured by a dynamic light scattering particle size distribution measuring device, and the median particle size D50 was determined to be 797 nm.

[0202] A TEM image of the molybdenum sulfide powder of Comparative Example 1 is shown in Figure 8.

[0203] <<Manufacturing of Metal-Doped Molybdenum Sulfide Powder (Manufacturing Method (3))>> [Example 2] <Manufacturing of Cobalt-Doped Molybdenum Sulfide Powder> Using 5 g of molybdenum trioxide powder obtained in Example 1 and 195 g of ion-exchanged water, an aqueous dispersion of molybdenum trioxide powder with a concentration of 2.5% by mass was obtained. Using 0.18 g of cobalt chloride hexahydrate (manufactured by Kanto Chemical Co., Ltd.) and 9.82 g of ion-exchanged water, an aqueous solution of cobalt chloride with a concentration of 1% by mass was obtained. 20 g of the above-obtained aqueous dispersion of molybdenum trioxide powder, 0.9 g of cobalt chloride aqueous solution, 19.1 g of ion-exchanged water, and 0.8 g of sulfur powder (manufactured by Kanto Chemical Co., Ltd.) were mixed and stirred at room temperature for 3 hours to obtain a raw material mixture (2). In the obtained raw material mixture (2), the amount of sulfur powder is 7 moles relative to the amount of molybdenum trioxide powder, the amount of cobalt chloride hexahydrate is 2 moles relative to the amount of molybdenum trioxide powder, and the amount of water is 80 times the amount of molybdenum trioxide powder.

[0204] Water was removed from the above-obtained raw material mixture (2) by freeze drying to obtain solid material (2). Then, the obtained solid material (2) was heated (calcined) at 400°C for 4 hours in a magnetic crucible under a nitrogen flow of 300 mL / min to obtain powder (cobalt-doped molybdenum sulfide powder).

[0205] The X-ray diffraction (XRD) pattern of the powder from Example 2 was examined. The results showed that only peaks belonging to molybdenum disulfide (MoS2) were detected, and no peaks not belonging to MoS2 were observed. That is, no reaction intermediate peaks such as molybdenum dioxide (MoO2) as byproducts were observed. This confirms that the conversion rate (RC) of the metal-doped molybdenum sulfide powder to MoS2 obtained above is over 99%, and the reaction with sulfur proceeds rapidly. Crystal structure analysis of the metal-doped molybdenum sulfide powder from Example 2 using X-ray diffraction (XRD) confirmed the presence of both 2H and 3R crystal structures.

[0206] Furthermore, the pattern obtained by magnifying the region around 2θ / degree 14 in the X-ray diffraction (XRD) pattern, along with the patterns of the metal-doped molybdenum sulfide powder of other embodiments described later, and the pattern of the molybdenum sulfide powder of Comparative Example 2 described later, are shown together in FIG9. However, in FIG9, normalization was performed by setting the maximum peak intensity of each spectrum to 100. According to FIG9, it is indicated that the peak value of the metal-doped molybdenum sulfide powder (cobalt-doped molybdenum sulfide powder) of Example 2 is shifted to the lower angle side compared to the peak value of the molybdenum sulfide powder of Comparative Example 2, and the interlayer distance in the crystal of the metal-doped molybdenum sulfide powder of Example 2 is extended compared to the molybdenum sulfide powder of Comparative Example 2.

[0207] The metal doping amount (cobalt doping amount) of the metal-doped molybdenum sulfide powder (cobalt-doped molybdenum sulfide powder) of Example 2 was determined by XRF analysis, and the result was 0.77 moles.

[0208] The specific surface area of ​​the metal-doped molybdenum sulfide powder of Example 2 was determined by the BET method, and the result was 35.6 m2 / g.

[0209] The ratio (I / II) of the metal-doped molybdenum sulfide powder in Example 2 was determined to be 1.704.

[0210] The particle size distribution of the metal-doped molybdenum sulfide powder of Example 2 was measured by a dynamic light scattering particle size distribution measuring device, and the median particle size D50 was determined to be 810 nm.

[0211] A TEM image of the metal-doped molybdenum sulfide powder of Example 2 is shown in Figure 10.

[0212] The SEM image of the metal-doped molybdenum sulfide powder of Example 2 is shown in Figure 11. According to Figure 11, aggregates of particles with a size of about several μm were observed in the metal-doped molybdenum sulfide powder of Example 2.

[0213] The EDS image of the metal-doped molybdenum sulfide powder of Example 2 is shown in FIG12. According to FIG12, it can be confirmed that in the metal-doped molybdenum sulfide powder of Example 2, cobalt (represented as "Co-K" in FIG12), molybdenum (represented as "Mo-L" in FIG12), and sulfur (represented as "SK" in FIG12) are generally and uniformly distributed.

[0214] Based on various analysis results, such as the X-ray diffraction pattern and EDS image, it can be confirmed that the target metal-doped molybdenum sulfide powder has indeed been obtained.

[0215] [Example 3] <Preparation of Palladium-Doped Molybdenum Sulfide Powder> Using 5 g of molybdenum trioxide powder obtained in Example 1 and 195 g of ion-exchanged water, an aqueous dispersion of molybdenum trioxide powder with a concentration of 2.5% by mass was obtained. Using 0.1 g of palladium chloride (manufactured by Kanto Chemical Co., Ltd.) and 9.9 g of ion-exchanged water, an aqueous solution of palladium chloride with a concentration of 1% by mass was obtained. 20 g of the above-obtained aqueous dispersion of molybdenum trioxide powder, 1.3 g of the aqueous solution of palladium chloride, 18.7 g of ion-exchanged water, and 0.8 g of sulfur powder (manufactured by Kanto Chemical Co., Ltd.) were mixed and stirred at room temperature for 3 hours to obtain raw material mixture (2). In the obtained raw material mixture (2), the amount of sulfur powder was 7 moles relative to the amount of molybdenum trioxide powder, the amount of palladium chloride was 2 moles relative to the amount of molybdenum trioxide powder, and the amount of water was 80 times by mass relative to the amount of molybdenum trioxide powder.

[0216] In addition to using the raw material mixture (2) obtained above, powder (palladium-doped molybdenum sulfide powder) was obtained by the same method as in Example 2.

[0217] The X-ray diffraction (XRD) pattern of the powder in Example 3 is the same as that of the powder (cobalt-doped molybdenum sulfide powder) in Example 2. In the XRD pattern of Example 3, only peaks belonging to molybdenum disulfide (MoS2) were detected; no peaks not belonging to MoS2 were observed. That is, no reaction intermediate peaks such as molybdenum dioxide (MoO2) as byproducts were observed, confirming that the conversion rate RC of the metal-doped molybdenum sulfide powder to MoS2 obtained above is over 99%, and the reaction with sulfur proceeds rapidly. Crystal structure analysis of the metal-doped molybdenum sulfide powder of Example 3 by X-ray diffraction (XRD) confirmed the presence of both 2H and 3R crystal structures.

[0218] A magnified pattern of the region around 2θ / degree 14 in the X-ray diffraction (XRD) pattern, along with the patterns of the metal-doped molybdenum sulfide powder of other embodiments and the pattern of the molybdenum sulfide powder of Comparative Example 2 described later, is shown in FIG9. According to FIG9, it is shown that the peak value of the metal-doped molybdenum sulfide powder (palladium-doped molybdenum sulfide powder) of Example 3 is shifted to the higher angle side compared with the peak value of the molybdenum sulfide powder of Comparative Example 2, and the interlayer distance in the crystal of the metal-doped molybdenum sulfide powder of Example 3 is shorter than that of the molybdenum sulfide powder of Comparative Example 2.

[0219] The metal doping amount (palladium doping amount) of the metal-doped molybdenum sulfide powder (palladium-doped molybdenum sulfide powder) of Example 3 was determined by XRF analysis, and the result was 2.07 moles.

[0220] The specific surface area of ​​the metal-doped molybdenum sulfide powder of Example 3 was determined by the BET method, and the result was 42.3 m2 / g.

[0221] The ratio (I / II) of the metal-doped molybdenum sulfide powder in Example 3 was determined to be 1.720.

[0222] The particle size distribution of the metal-doped molybdenum sulfide powder of Example 3 was measured by a dynamic light scattering particle size distribution measuring device, and the median particle size D50 was determined to be 703 nm.

[0223] A TEM image of the metal-doped molybdenum sulfide powder of Example 3 is shown in Figure 13.

[0224] The SEM image of the metal-doped molybdenum sulfide powder of Example 3 is shown in Figure 14. According to Figure 14, aggregates of particles with a size of about several μm were observed in the metal-doped molybdenum sulfide powder of Example 3.

[0225] The EDS image of the metal-doped molybdenum sulfide powder of Example 3 is shown in FIG15. According to FIG15, it can be confirmed that palladium (represented as "Pd-L" in FIG15), molybdenum (represented as "Mo-L" in FIG15), and sulfur (represented as "SK" in FIG15) are generally and uniformly distributed in the metal-doped molybdenum sulfide powder of Example 3.

[0226] Based on various analysis results, such as the X-ray diffraction pattern and EDS image, it can be confirmed that the target metal-doped molybdenum sulfide powder has indeed been obtained.

[0227] [Example 4] <Preparation of Iridium-Doped Molybdenum Sulfide Powder> Using 5 g of molybdenum trioxide powder obtained in Example 1 and 195 g of ion-exchanged water, an aqueous dispersion of molybdenum trioxide powder with a concentration of 2.5% by mass was obtained. Using 0.1 g of iridium chloride (manufactured by Kanto Chemical Co., Ltd.) and 9.9 g of ion-exchanged water, an aqueous solution of iridium chloride with a concentration of 1% by mass was obtained. 20 g of the above-obtained aqueous dispersion of molybdenum trioxide powder, 2.1 mg of iridium chloride aqueous solution, 17.9 g of ion-exchanged water, and 0.8 g of sulfur powder (manufactured by Kanto Chemical Co., Ltd.) were mixed and stirred at room temperature for 3 hours to obtain raw material mixture (2). In the obtained raw material mixture (2), the amount of sulfur powder was 7 moles relative to the amount of molybdenum trioxide powder, the amount of iridium chloride was 2 moles relative to the amount of molybdenum trioxide powder, and the amount of water was 80 times by mass relative to the amount of molybdenum trioxide powder.

[0228] In addition to using the raw material mixture (2) obtained above, powder (iridium-doped molybdenum sulfide powder) was obtained by the same method as in Example 2.

[0229] The X-ray diffraction (XRD) pattern of the powder in Example 4 is the same as that of the powder (cobalt-doped molybdenum sulfide powder) in Example 2. In the XRD pattern of Example 4, only peaks belonging to molybdenum disulfide (MoS2) were detected; no peaks not belonging to MoS2 were observed. That is, no reaction intermediate peaks such as molybdenum dioxide (MoO2) as byproducts were observed, confirming that the conversion rate RC of the metal-doped molybdenum sulfide powder to MoS2 obtained above is over 99%, and the reaction with sulfur proceeds rapidly. Crystal structure analysis of the metal-doped molybdenum sulfide powder of Example 4 by X-ray diffraction (XRD) confirmed the presence of both 2H and 3R crystal structures.

[0230] A magnified pattern of the region around 2θ / degree 14 in the X-ray diffraction (XRD) pattern, along with the patterns of the metal-doped molybdenum sulfide powder of other embodiments and the pattern of the molybdenum sulfide powder of Comparative Example 2 described later, is shown in FIG9. According to FIG9, it is shown that the peak value of the metal-doped molybdenum sulfide powder (iridium-doped molybdenum sulfide powder) of Example 4 is shifted to the lower angle side compared with the peak value of the molybdenum sulfide powder of Comparative Example 2, and the interlayer distance in the crystal of the metal-doped molybdenum sulfide powder of Example 4 is shorter than that of the molybdenum sulfide powder of Comparative Example 2.

[0231] The metal doping amount (iridium doping amount) of the metal-doped molybdenum sulfide powder (iridium-doped molybdenum sulfide powder) of Example 4 was determined by XRF analysis, and the result was 1.13 moles.

[0232] The specific surface area of ​​the metal-doped molybdenum sulfide powder of Example 4 was determined by the BET method, and the result was 29.6 m2 / g.

[0233] The ratio (I / II) of the metal-doped molybdenum sulfide powder in Example 4 was determined to be 1.561.

[0234] The particle size distribution of the metal-doped molybdenum sulfide powder of Example 4 was measured by a dynamic light scattering particle size distribution measuring device, and the median particle size D50 was determined to be 1123 nm.

[0235] A TEM image of the metal-doped molybdenum sulfide powder of Example 4 is shown in Figure 16.

[0236] The SEM image of the metal-doped molybdenum sulfide powder of Example 4 is shown in Figure 17. According to Figure 17, aggregates of particles with a size of about several μm were observed in the metal-doped molybdenum sulfide powder of Example 4.

[0237] The EDS image of the metal-doped molybdenum sulfide powder of Example 4 is shown in FIG18. According to FIG18, it can be confirmed that iridium (represented as "Ir-M" in FIG18), molybdenum (represented as "Mo-L" in FIG18), and sulfur (represented as "SK" in FIG18) are generally and uniformly distributed in the metal-doped molybdenum sulfide powder of Example 4.

[0238] Based on various analysis results, such as the X-ray diffraction pattern and EDS image, it can be confirmed that the target metal-doped molybdenum sulfide powder has indeed been obtained.

[0239] <<Manufacturing of molybdenum sulfide powder (manufacturing method (3'))>> [Comparative Example 2] Molybdenum sulfide powder was manufactured using the same method as in Example 2, except that the cobalt chloride aqueous solution was not used. In this specification, the method of omitting the use of Group 3 to Group 13 metal salts in manufacturing method (3) is sometimes referred to as "manufacturing method (3')".

[0240] The pattern obtained by magnifying the region near 2θ / degree 14 in the X-ray diffraction (XRD) pattern of the powder of Comparative Example 2, together with the patterns of the metal-doped molybdenum sulfide powder of other embodiments, is shown in FIG9.

[0241] The metal doping amount (zinc doping amount) of the molybdenum sulfide powder of Comparative Example 2 was determined by XRF analysis, and the result was 0.00 moles.

[0242] The specific surface area of ​​the molybdenum sulfide powder in Comparative Example 2 was determined by the BET method, and the result was 31.7 m2 / g.

[0243] The ratio (I / II) of the molybdenum sulfide powder in Comparative Example 2 was determined to be 1.734.

[0244] The particle size distribution of molybdenum sulfide powder in Comparative Example 2 was measured by a dynamic light scattering particle size distribution measuring device, and the median particle size D50 was determined to be 1006 nm.

[0245] A TEM image of the molybdenum sulfide powder of Comparative Example 2 is shown in Figure 19.

[0246] The SEM image of the molybdenum sulfide powder of Comparative Example 2 is shown in Figure 20. According to Figure 20, aggregates of particles with a size of about several μm were observed in the molybdenum sulfide powder of Comparative Example 2.

[0247] <<Manufacturing of Metal-Doped Molybdenum Sulfide Powder (Manufacturing Method (2))>> [Example 5] <Manufacturing of Cobalt-Doped Molybdenum Sulfide Powder> Using 5 g of molybdenum trioxide powder obtained in Example 1 and 195 g of ion-exchanged water, an aqueous dispersion of molybdenum trioxide powder with a concentration of 2.5% by mass was obtained. Using 0.18 g of cobalt chloride hexahydrate (manufactured by Kanto Chemical Co., Ltd.) and 9.82 g of ion-exchanged water, an aqueous solution of cobalt chloride with a concentration of 1% by mass was obtained. 20 g of the above-obtained aqueous dispersion of molybdenum trioxide powder, 0.9 g of the cobalt chloride aqueous solution, and 19.1 g of ion-exchanged water were mixed and stirred at room temperature for 3 hours to obtain a raw material mixture (1). In the obtained raw material mixture (1), the amount of cobalt chloride hexahydrate was 2 mol% relative to the amount of molybdenum trioxide powder, and the amount of water was 80 times by mass relative to the amount of molybdenum trioxide powder.

[0248] Water is removed from the raw material mixture (1) obtained above by heating it at 150°C for 2 hours, thereby obtaining a solid substance (1).

[0249] Next, 0.8 g of solid material (1) was mixed with sulfur powder (manufactured by Kanto Chemical Co., Ltd.). In this mixture, the amount of sulfur powder was 7 moles relative to the amount of molybdenum trioxide powder (the amount of molybdenum trioxide powder in solid material (1)). Then, in a magnetic crucible, the resulting mixture was heated (calcined) at 400°C for 4 hours under a nitrogen flow of 300 mL / min to obtain powder (cobalt-doped molybdenum sulfide powder).

[0250] The X-ray diffraction (XRD) pattern of the powder from Example 5 was confirmed, and only peaks belonging to molybdenum disulfide (MoS2) were detected. No peaks not belonging to molybdenum disulfide (MoS2) were observed. That is, no reaction intermediate peaks such as molybdenum dioxide (MoO2) as byproducts were observed, confirming that the conversion rate RC of the metal-doped molybdenum sulfide powder to MoS2 obtained above is above 99%, and the reaction with sulfur proceeds rapidly. The crystal structure analysis of the metal-doped molybdenum sulfide powder from Example 5 by X-ray diffraction (XRD) confirmed that it contains both 2H and 3R crystal structures.

[0251] Furthermore, the pattern obtained by magnifying the region around 2θ / degree of 14 in the X-ray diffraction (XRD) pattern, together with the patterns of the metal-doped molybdenum sulfide powder of other embodiments described later, and the pattern of the molybdenum sulfide powder of Comparative Example 3 described later, is shown in FIG21. However, in FIG21, normalization was performed by setting the maximum peak intensity of each spectrum to 100. According to FIG21, it is indicated that the peak value of the metal-doped molybdenum sulfide powder (cobalt-doped molybdenum sulfide powder) of Example 5 is shifted to the lower angle side compared with the peak value of the molybdenum sulfide powder of Comparative Example 3, and the interlayer distance in the crystal of the metal-doped molybdenum sulfide powder of Example 5 is extended compared with the molybdenum sulfide powder of Comparative Example 3.

[0252] The metal doping amount (cobalt doping amount) of the metal-doped molybdenum sulfide powder (cobalt-doped molybdenum sulfide powder) of Example 5 was determined by XRF analysis, and the result was 0.77 moles.

[0253] The specific surface area of ​​the metal-doped molybdenum sulfide powder of Example 5 was determined by the BET method, and the result was 53.2 m2 / g.

[0254] The ratio (I / II) of the metal-doped molybdenum sulfide powder in Example 5 was determined to be 1.807.

[0255] The particle size distribution of the metal-doped molybdenum sulfide powder of Example 5 was measured by a dynamic light scattering particle size distribution measuring device, and the median particle size D50 was determined to be 569 nm.

[0256] A TEM image of the metal-doped molybdenum sulfide powder of Example 5 is shown in Figure 22.

[0257] The SEM image of the metal-doped molybdenum sulfide powder of Example 5 is shown in Figure 23. According to Figure 23, aggregates of particles with a size of about several μm were observed in the metal-doped molybdenum sulfide powder of Example 5.

[0258] Based on various analytical results represented by the X-ray diffraction pattern, it can be confirmed that the target metal-doped molybdenum sulfide powder has indeed been obtained.

[0259] [Example 6] <Preparation of palladium-doped molybdenum sulfide powder> Except that sulfur powder was not used in the preparation of the raw material mixture (2), the raw material mixture (1) was obtained using the same method as in Example 3. In the obtained raw material mixture (1), the amount of palladium chloride was 2 mol% relative to the amount of molybdenum trioxide powder, and the amount of water was 80 times the amount of molybdenum trioxide powder.

[0260] In addition to using the raw material mixture (1) obtained above, powder (palladium-doped molybdenum sulfide powder) was obtained by the same method as in Example 5.

[0261] The X-ray diffraction (XRD) pattern of the powder in Example 6 is the same as that of the powder (cobalt-doped molybdenum sulfide powder) in Example 2. In the XRD pattern of Example 6, only peaks belonging to molybdenum disulfide (MoS2) were detected; no peaks not belonging to MoS2 were observed. That is, no reaction intermediate peaks such as molybdenum dioxide (MoO2) as byproducts were observed, confirming that the conversion rate RC of the metal-doped molybdenum sulfide powder to MoS2 obtained above is over 99%, and the reaction with sulfur proceeds rapidly. Crystal structure analysis of the metal-doped molybdenum sulfide powder of Example 6 by X-ray diffraction (XRD) confirmed the presence of both 2H and 3R crystal structures.

[0262] A magnified pattern of the region around 2θ / degree 14 in the X-ray diffraction (XRD) pattern, along with the patterns of the metal-doped molybdenum sulfide powder of other embodiments and the pattern of the molybdenum sulfide powder of Comparative Example 3 described later, is shown in FIG21. FIG21 shows that the peak value of the metal-doped molybdenum sulfide powder (palladium-doped molybdenum sulfide powder) of Example 6 is shifted to the higher angle side compared with the peak value of the molybdenum sulfide powder of Comparative Example 3, and the interlayer distance in the crystal of the metal-doped molybdenum sulfide powder of Example 6 is shorter than that of the molybdenum sulfide powder of Comparative Example 3.

[0263] The metal doping amount (palladium doping amount) of the metal-doped molybdenum sulfide powder (palladium-doped molybdenum sulfide powder) of Example 6 was determined by XRF analysis, and the result was 2.07 moles.

[0264] The specific surface area of ​​the metal-doped molybdenum sulfide powder of Example 6 was determined by the BET method, and the result was 51.7 m2 / g.

[0265] The ratio (I / II) of the metal-doped molybdenum sulfide powder in Example 6 was determined to be 1.685.

[0266] The particle size distribution of the metal-doped molybdenum sulfide powder of Example 6 was measured by a dynamic light scattering particle size distribution measuring device, and the median particle size D50 was determined to be 606 nm.

[0267] A TEM image of the metal-doped molybdenum sulfide powder of Example 6 is shown in Figure 24.

[0268] The SEM image of the metal-doped molybdenum sulfide powder of Example 6 is shown in Figure 25. According to Figure 25, aggregates of particles with a size of about several μm were observed in the metal-doped molybdenum sulfide powder of Example 6.

[0269] Based on various analytical results represented by the X-ray diffraction pattern, it can be confirmed that the target metal-doped molybdenum sulfide powder has indeed been obtained.

[0270] [Example 7] <Preparation of Iridium-Doped Molybdenum Sulfide Powder> Except that sulfur powder was not used in the preparation of the raw material mixture (2), the raw material mixture (1) was obtained using the same method as in Example 4. In the obtained raw material mixture (1), the amount of iridium chloride was 2 mol% relative to the amount of molybdenum trioxide powder, and the amount of water was 80 times the amount of molybdenum trioxide powder.

[0271] Except for the use of the raw material mixture (1) obtained above, powder (iridium-doped molybdenum sulfide powder) was obtained by the same method as in Example 5.

[0272] The X-ray diffraction (XRD) pattern of the powder in Example 7 is the same as that of the powder (cobalt-doped molybdenum sulfide powder) in Example 2. In the XRD pattern of Example 7, only peaks belonging to molybdenum disulfide (MoS2) were detected; no peaks not belonging to MoS2 were observed. That is, no reaction intermediate peaks such as molybdenum dioxide (MoO2) as byproducts were observed, confirming that the conversion rate RC of the metal-doped molybdenum sulfide powder to MoS2 obtained above is over 99%, and the reaction with sulfur proceeds rapidly. Crystal structure analysis of the metal-doped molybdenum sulfide powder of Example 7 by X-ray diffraction (XRD) confirmed the presence of both 2H and 3R crystal structures.

[0273] A magnified pattern of the region around 2θ / degree 14 in the X-ray diffraction (XRD) pattern, along with the patterns of the metal-doped molybdenum sulfide powder of other embodiments and the pattern of the molybdenum sulfide powder of Comparative Example 3 described later, is shown in FIG21. According to FIG21, it is shown that the peak value of the metal-doped molybdenum sulfide powder (iridium-doped molybdenum sulfide powder) of Example 7 is shifted to the lower angle side compared with the peak value of the molybdenum sulfide powder of Comparative Example 3, and the interlayer distance in the crystal of the metal-doped molybdenum sulfide powder of Example 7 is extended compared with the molybdenum sulfide powder of Comparative Example 3.

[0274] The metal doping amount (iridium doping amount) of the metal-doped molybdenum sulfide powder (iridium-doped molybdenum sulfide powder) of Example 7 was determined by XRF analysis, and the result was 1.13 moles.

[0275] The specific surface area of ​​the metal-doped molybdenum sulfide powder of Example 7 was determined by the BET method, and the result was 49.7 m2 / g.

[0276] The ratio (I / II) of the metal-doped molybdenum sulfide powder in Example 7 was determined to be 1.643.

[0277] The particle size distribution of the metal-doped molybdenum sulfide powder of Example 7 was measured by a dynamic light scattering particle size distribution measuring device, and the median particle size D50 was determined to be 661 nm.

[0278] A TEM image of the metal-doped molybdenum sulfide powder of Example 7 is shown in Figure 26.

[0279] The SEM image of the metal-doped molybdenum sulfide powder of Example 7 is shown in Figure 27. According to Figure 27, aggregates of particles with a size of about several μm were observed in the metal-doped molybdenum sulfide powder of Example 7.

[0280] Based on various analytical results represented by the X-ray diffraction pattern, it can be confirmed that the target metal-doped molybdenum sulfide powder has indeed been obtained.

[0281] <<Manufacturing of molybdenum sulfide powder (manufacturing method (2'))>> [Comparative Example 3] Molybdenum sulfide powder was manufactured using the same method as in Example 5, except that the cobalt chloride aqueous solution was not used. In this specification, the method of omitting the use of Group 3 to Group 13 metal salts in manufacturing method (2) is sometimes referred to as "manufacturing method (2')".

[0282] The pattern obtained by magnifying the region near 2θ / degree 14 in the X-ray diffraction (XRD) pattern of the powder of Comparative Example 3, together with the patterns of the metal-doped molybdenum sulfide powder of other embodiments, is shown in FIG21.

[0283] The metal doping amount (zinc doping amount) of the molybdenum sulfide powder of Comparative Example 3 was determined by XRF analysis, and the result was 0.00 moles.

[0284] The specific surface area of ​​the molybdenum sulfide powder in Comparative Example 3 was determined by the BET method, and the result was 46.1 m2 / g.

[0285] The ratio (I / II) of the molybdenum sulfide powder in Comparative Example 3 was determined to be 1.640.

[0286] The particle size distribution of molybdenum sulfide powder in Comparative Example 3 was measured by a dynamic light scattering particle size distribution measuring device, and the median particle size D50 was determined to be 707 nm.

[0287] A TEM image of the molybdenum sulfide powder of Comparative Example 3 is shown in Figure 28.

[0288] The SEM image of the molybdenum sulfide powder of Comparative Example 3 is shown in Figure 29. According to Figure 29, aggregates of particles with a size of about several μm were observed in the molybdenum sulfide powder of Comparative Example 3.

[0289] <<Manufacturing of Metal-Doped Molybdenum Sulfide Powder (Manufacturing Method (3))>> [Example 8] <Manufacturing of Manganese-Doped Molybdenum Sulfide Powder> Using 5 g of molybdenum trioxide powder obtained in Example 1 and 195 g of ion-exchanged water, an aqueous dispersion of molybdenum trioxide powder with a concentration of 2.5% by mass was obtained. Using 0.16 g of manganese chloride tetrahydrate (manufactured by Kanto Chemical Co., Ltd.) and 9.84 g of ion-exchanged water, an aqueous solution of manganese chloride with a concentration of 1% by mass was obtained. 20 g of the above-obtained aqueous dispersion of molybdenum trioxide powder, 0.9 g of manganese chloride aqueous solution, 19.1 g of ion-exchanged water, and 0.8 g of sulfur powder (manufactured by Kanto Chemical Co., Ltd.) were mixed and stirred at room temperature for 3 hours to obtain a raw material mixture (2). In the obtained raw material mixture (2), the amount of sulfur powder is 7 moles relative to the amount of molybdenum trioxide powder, the amount of manganese chloride tetrahydrate is 2 moles relative to the amount of molybdenum trioxide powder, and the amount of water is 80 times the mass relative to the amount of molybdenum trioxide powder.

[0290] In addition to using the raw material mixture (2) obtained above, powder (manganese-doped molybdenum sulfide powder) was obtained by the same method as in Example 2.

[0291] The X-ray diffraction (XRD) pattern of the powder in Example 8 is the same as that of the powder (cobalt-doped molybdenum sulfide powder) in Example 2. In the XRD pattern of Example 8, only peaks belonging to molybdenum disulfide (MoS2) were detected; no peaks not belonging to MoS2 were observed. That is, no reaction intermediate peaks such as molybdenum dioxide (MoO2) as byproducts were observed, confirming that the conversion rate RC of the metal-doped molybdenum sulfide powder to MoS2 obtained above is over 99%, and the reaction with sulfur proceeds rapidly. Crystal structure analysis of the metal-doped molybdenum sulfide powder of Example 8 by X-ray diffraction (XRD) confirmed the presence of both 2H and 3R crystal structures.

[0292] The metal doping amount (manganese doping amount) of the metal-doped molybdenum sulfide powder (manganese-doped molybdenum sulfide powder) of Example 8 was determined by XRF analysis, and the result was 1.23 moles. The specific surface area of ​​the metal-doped molybdenum sulfide powder of Example 8 was determined by the BET method, and the result was 39.7 m2 / g. The ratio (I / II) of the metal-doped molybdenum sulfide powder of Example 8 was determined, and the result was 1.572. The particle size distribution of the metal-doped molybdenum sulfide powder of Example 8 was measured by a dynamic light scattering particle size distribution measuring device, and the median particle size D50 was determined, and the result was 776 nm.

[0293] The various analytical results show that the target metal-doped molybdenum sulfide powder can be reliably obtained.

[0294] [Example 9] <Preparation of iron-doped molybdenum sulfide powder> Using 5 g of molybdenum trioxide powder obtained in Example 1 and 195 g of ion-exchanged water, an aqueous dispersion of molybdenum trioxide powder with a concentration of 2.5% by mass was obtained. Using 0.16 g of ferric chloride (III) hexahydrate (manufactured by Kanto Chemical Co., Ltd.) and 9.84 g of ion-exchanged water, an aqueous solution of ferric chloride with a concentration of 1% by mass was obtained. 20 g of the above-obtained aqueous dispersion of molybdenum trioxide powder, 1.1 g of ferric chloride aqueous solution, 18.9 g of ion-exchanged water, and 0.8 g of sulfur powder (manufactured by Kanto Chemical Co., Ltd.) were mixed and stirred at room temperature for 3 hours to obtain raw material mixture (2). In the obtained raw material mixture (2), the amount of sulfur powder is 7 moles relative to the amount of molybdenum trioxide powder, the amount of ferric chloride (III) hexahydrate is 2 moles relative to the amount of molybdenum trioxide powder, and the amount of water is 80 times the mass relative to the amount of molybdenum trioxide powder.

[0295] In addition to using the raw material mixture (2) obtained above, powder (iron-doped molybdenum sulfide powder) was obtained by the same method as in Example 8.

[0296] The X-ray diffraction (XRD) pattern of the powder in Example 9 is the same as that of the powder (cobalt-doped molybdenum sulfide powder) in Example 2. In the XRD pattern of Example 9, only peaks belonging to molybdenum disulfide (MoS2) were detected; no peaks not belonging to MoS2 were observed. That is, no reaction intermediate peaks such as molybdenum dioxide (MoO2) as byproducts were observed, confirming that the conversion rate RC of the metal-doped molybdenum sulfide powder to MoS2 obtained above is over 99%, and the reaction with sulfur proceeds rapidly. Crystal structure analysis of the metal-doped molybdenum sulfide powder of Example 9 by X-ray diffraction (XRD) confirmed the presence of both 2H and 3R crystal structures.

[0297] The metal doping amount (iron doping amount) of the metal-doped molybdenum sulfide powder (iron-doped molybdenum sulfide powder) of Example 9 was determined by XRF analysis, and the result was 0.72 moles. The specific surface area of ​​the metal-doped molybdenum sulfide powder of Example 9 was determined by the BET method, and the result was 41.2 m2 / g. The ratio (I / II) of the metal-doped molybdenum sulfide powder of Example 9 was determined, and the result was 1.597. The particle size distribution of the metal-doped molybdenum sulfide powder of Example 9 was measured by a dynamic light scattering particle size distribution measuring device, and the median particle size D50 was determined, and the result was 711 nm.

[0298] The various analytical results show that the target metal-doped molybdenum sulfide powder can be reliably obtained.

[0299] [Example 10] <Preparation of nickel-doped molybdenum sulfide powder> Using 5 g of molybdenum trioxide powder obtained in Example 1 and 195 g of ion-exchanged water, an aqueous dispersion of molybdenum trioxide powder with a concentration of 2.5% by mass was obtained. Using 0.18 g of nickel chloride hexahydrate (manufactured by Kanto Chemical Co., Ltd.) and 9.82 g of ion-exchanged water, an aqueous solution of nickel chloride with a concentration of 1% by mass was obtained. 20 g of the above-obtained aqueous dispersion of molybdenum trioxide powder, 0.9 g of the nickel chloride aqueous solution, 19.1 g of ion-exchanged water, and 0.8 g of sulfur powder (manufactured by Kanto Chemical Co., Ltd.) were mixed and stirred at room temperature for 3 hours to obtain raw material mixture (2). In the obtained raw material mixture (2), the amount of sulfur powder was 7 moles relative to the amount of molybdenum trioxide powder, the amount of nickel chloride hexahydrate was 2 moles relative to the amount of molybdenum trioxide powder, and the amount of water was 80 times by mass relative to the amount of molybdenum trioxide powder.

[0300] In addition to using the raw material mixture (2) obtained above, powder (nickel-doped molybdenum sulfide powder) was obtained by the same method as in Example 8.

[0301] The X-ray diffraction (XRD) pattern of the powder in Example 10 is the same as that of the powder (cobalt-doped molybdenum sulfide powder) in Example 2. In the XRD pattern of Example 10, only peaks belonging to molybdenum disulfide (MoS2) were detected; no peaks not belonging to MoS2 were observed. That is, no reaction intermediate peaks such as molybdenum dioxide (MoO2) as byproducts were observed, confirming that the conversion rate RC of the metal-doped molybdenum sulfide powder to MoS2 obtained above is over 99%, and the reaction with sulfur proceeds rapidly. Crystal structure analysis of the metal-doped molybdenum sulfide powder of Example 10 by X-ray diffraction (XRD) confirmed the presence of both 2H and 3R crystal structures.

[0302] The metal doping amount (nickel doping amount) of the metal-doped molybdenum sulfide powder (nickel-doped molybdenum sulfide powder) of Example 10 was determined by XRF analysis, and the result was 1.65 moles. The specific surface area of ​​the metal-doped molybdenum sulfide powder of Example 10 was determined by the BET method, and the result was 50.3 m2 / g. The ratio (I / II) of the metal-doped molybdenum sulfide powder of Example 10 was determined, and the result was 1.672. The particle size distribution of the metal-doped molybdenum sulfide powder of Example 10 was measured by a dynamic light scattering particle size distribution measuring device, and the median particle size D50 was determined, and the result was 616 nm.

[0303] The various analytical results show that the target metal-doped molybdenum sulfide powder can be reliably obtained.

[0304] [Example 11] <Preparation of Zirconium-doped Molybdenum Sulfide Powder> Using 5 g of molybdenum trioxide powder obtained in Example 1 and 195 g of ion-exchanged water, an aqueous dispersion of molybdenum trioxide powder with a concentration of 2.5% by mass was obtained. Using 0.11 g of zirconium oxynitrate dihydrate (manufactured by Kanto Chemical Co., Ltd.) and 9.89 g of ion-exchanged water, an aqueous solution of zirconium oxynitrate with a concentration of 1% by mass was obtained. 20 g of the above-obtained aqueous dispersion of molybdenum trioxide powder, 1.6 g of zirconium oxynitrate aqueous solution, 18.4 g of ion-exchanged water, and 0.8 g of sulfur powder (manufactured by Kanto Chemical Co., Ltd.) were mixed and stirred at room temperature for 3 hours to obtain raw material mixture (2). In the obtained raw material mixture (2), the amount of sulfur powder is 7 moles relative to the amount of molybdenum trioxide powder, the amount of zirconium oxynitrate dihydrate is 2 moles relative to the amount of molybdenum trioxide powder, and the amount of water is 80 times the mass relative to the amount of molybdenum trioxide powder.

[0305] In addition to using the raw material mixture (2) obtained above, powder (zirconium-doped molybdenum sulfide powder) was obtained by the same method as in Example 8.

[0306] The X-ray diffraction (XRD) pattern of the powder in Example 11 is the same as that of the powder (cobalt-doped molybdenum sulfide powder) in Example 2. In the XRD pattern of Example 11, only peaks belonging to molybdenum disulfide (MoS2) were detected; no peaks not belonging to MoS2 were observed. That is, no reaction intermediate peaks such as molybdenum dioxide (MoO2) as byproducts were observed, confirming that the conversion rate RC of the metal-doped molybdenum sulfide powder to MoS2 obtained above is over 99%, and the reaction with sulfur proceeds rapidly. Crystal structure analysis of the metal-doped molybdenum sulfide powder of Example 11 by X-ray diffraction (XRD) confirmed the presence of both 2H and 3R crystal structures.

[0307] The metal doping amount (zirconium doping amount) of the metal-doped molybdenum sulfide powder (zirconium-doped molybdenum sulfide powder) of Example 11 was determined by XRF analysis, and the result was 2.09 moles%. The specific surface area of ​​the metal-doped molybdenum sulfide powder of Example 11 was determined by the BET method, and the result was 46.2 m2 / g. The ratio (I / II) of the metal-doped molybdenum sulfide powder of Example 11 was determined, and the result was 1.604. The particle size distribution of the metal-doped molybdenum sulfide powder of Example 11 was measured by a dynamic light scattering particle size distribution measuring device, and the median particle size D50 was determined, and the result was 723 nm.

[0308] The various analytical results show that the target metal-doped molybdenum sulfide powder can be reliably obtained.

[0309] [Example 12] <Preparation of Ruthenium-doped Molybdenum Sulfide Powder> Using 5 g of molybdenum trioxide powder obtained in Example 1 and 195 g of ion-exchanged water, an aqueous dispersion of molybdenum trioxide powder with a concentration of 2.5% by mass was obtained. Using 0.10 g of ruthenium chloride (manufactured by Kanto Chemical Co., Ltd.) and 9.90 g of ion-exchanged water, an aqueous solution of ruthenium chloride with a concentration of 1% by mass was obtained. 20 g of the above-obtained aqueous dispersion of molybdenum trioxide powder, 1.4 g of ruthenium chloride aqueous solution, 18.6 g of ion-exchanged water, and 0.8 g of sulfur powder (manufactured by Kanto Chemical Co., Ltd.) were mixed and stirred at room temperature for 3 hours to obtain raw material mixture (2). In the obtained raw material mixture (2), the amount of sulfur powder is 7 moles relative to the amount of molybdenum trioxide powder, the amount of ruthenium chloride is 2 moles relative to the amount of molybdenum trioxide powder, and the amount of water is 80 times the amount of the amount of molybdenum trioxide powder.

[0310] In addition to using the raw material mixture (2) obtained above, powder (ruthenium-doped molybdenum sulfide powder) was obtained by the same method as in Example 8.

[0311] The X-ray diffraction (XRD) pattern of the powder in Example 12 is the same as that of the powder (cobalt-doped molybdenum sulfide powder) in Example 2. In the XRD pattern of Example 12, only peaks belonging to molybdenum disulfide (MoS2) were detected; no peaks not belonging to MoS2 were observed. That is, no reaction intermediate peaks such as molybdenum dioxide (MoO2) as byproducts were observed, confirming that the conversion rate RC of the metal-doped molybdenum sulfide powder to MoS2 obtained above is over 99%, and the reaction with sulfur proceeds rapidly. Crystal structure analysis of the metal-doped molybdenum sulfide powder of Example 12 by X-ray diffraction (XRD) confirmed the presence of both 2H and 3R crystal structures.

[0312] The metal doping amount (ruthenium doping amount) of the metal-doped molybdenum sulfide powder (ruthenium-doped molybdenum sulfide powder) of Example 12 was determined by XRF analysis, and the result was 2.95 moles%. The specific surface area of ​​the metal-doped molybdenum sulfide powder of Example 12 was determined by the BET method, and the result was 38.8 m2 / g. The ratio (I / II) of the metal-doped molybdenum sulfide powder of Example 12 was determined, and the result was 1.536. The particle size distribution of the metal-doped molybdenum sulfide powder of Example 12 was measured by a dynamic light scattering particle size distribution measuring device, and the median particle size D50 was determined, and the result was 779 nm.

[0313] The various analytical results show that the target metal-doped molybdenum sulfide powder can be reliably obtained.

[0314] [Example 13] <Preparation of Indium-Doped Molybdenum Sulfide Powder> Using 5 g of molybdenum trioxide powder obtained in Example 1 and 195 g of ion-exchanged water, an aqueous dispersion of molybdenum trioxide powder with a concentration of 2.5% by mass was obtained. Using 0.12 g of indium nitrate trihydrate (manufactured by Kanto Chemical Co., Ltd.) and 9.88 g of ion-exchanged water, an aqueous solution of indium nitrate with a concentration of 1% by mass was obtained. 20 g of the above-obtained aqueous dispersion of molybdenum trioxide powder, 2.1 g of indium nitrate aqueous solution, 17.9 g of ion-exchanged water, and 0.8 g of sulfur powder (manufactured by Kanto Chemical Co., Ltd.) were mixed and stirred at room temperature for 3 hours to obtain raw material mixture (2). In the obtained raw material mixture (2), the amount of sulfur powder was 7 moles relative to the amount of molybdenum trioxide powder, the amount of indium nitrate trihydrate was 2 moles relative to the amount of molybdenum trioxide powder, and the amount of water was 80 times by mass relative to the amount of molybdenum trioxide powder.

[0315] In addition to using the raw material mixture (2) obtained above, powder (indium-doped molybdenum sulfide powder) was obtained by the same method as in Example 8.

[0316] The X-ray diffraction (XRD) pattern of the powder in Example 13 is the same as that of the powder (cobalt-doped molybdenum sulfide powder) in Example 2. In the XRD pattern of Example 13, only peaks belonging to molybdenum disulfide (MoS2) were detected; no peaks not belonging to MoS2 were observed. That is, no reaction intermediate peaks such as molybdenum dioxide (MoO2) as byproducts were observed, confirming that the conversion rate RC of the metal-doped molybdenum sulfide powder to MoS2 obtained above is over 99%, and the reaction with sulfur proceeds rapidly. Crystal structure analysis of the metal-doped molybdenum sulfide powder of Example 13 by X-ray diffraction (XRD) confirmed the presence of both 2H and 3R crystal structures.

[0317] The metal doping amount (indium doping amount) of the metal-doped molybdenum sulfide powder (indium-doped molybdenum sulfide powder) of Example 13 was determined by XRF analysis, and the result was 1.00 moles. The specific surface area of ​​the metal-doped molybdenum sulfide powder of Example 13 was determined by the BET method, and the result was 36.7 m2 / g. The ratio (I / II) of the metal-doped molybdenum sulfide powder of Example 13 was determined, and the result was 1.656. The particle size distribution of the metal-doped molybdenum sulfide powder of Example 13 was measured by a dynamic light scattering particle size distribution measuring device, and the median particle size D50 was determined, and the result was 823 nm.

[0318] The various analytical results show that the target metal-doped molybdenum sulfide powder can be reliably obtained.

[0319] <<Manufacturing of Metal-Doped Molybdenum Sulfide Powder (Manufacturing Method (2))>> [Example 14] <Manufacturing of Zinc-Doped Molybdenum Sulfide Powder> Using 5 g of molybdenum trioxide powder obtained in Example 1 and 195 g of ion-exchanged water, an aqueous dispersion of molybdenum trioxide powder with a concentration of 2.5% by mass was obtained. Using 0.2 g of zinc chloride (manufactured by Kanto Chemical Co., Ltd.) and 19.8 g of ion-exchanged water, an aqueous solution of zinc chloride with a concentration of 1% by mass was obtained. 73.2 g of the above-obtained aqueous dispersion of molybdenum trioxide powder and 5.8 g of the aqueous solution of zinc chloride were mixed and stirred at room temperature for 3 hours to obtain a raw material mixture (1). In the obtained raw material mixture (1), the amount of zinc chloride was 2 mol% relative to the amount of molybdenum trioxide powder, and the amount of water was 40 times by mass relative to the amount of molybdenum trioxide powder.

[0320] Water is removed from the raw material mixture (1) obtained above by heating it at 150°C for 2 hours, thereby obtaining solid substance (1).

[0321] Next, 6.1 g of solid material (1) was mixed with sulfur powder (manufactured by Kanto Chemical Co., Ltd.). In this mixture, the amount of sulfur powder was 7 moles relative to the amount of molybdenum trioxide powder (the amount of molybdenum trioxide powder in solid material (1)). Then, in a magnetic crucible, the resulting mixture was heated (calcined) at 400°C for 4 hours under a nitrogen flow of 300 mL / min to obtain powder (zinc-doped molybdenum sulfide powder).

[0322] The X-ray diffraction (XRD) pattern of the powder in Example 14 is the same as that of the powder (cobalt-doped molybdenum sulfide powder) in Example 2. In the XRD pattern of Example 14, only peaks belonging to molybdenum disulfide (MoS2) were detected; no peaks not belonging to MoS2 were observed. That is, no reaction intermediate peaks such as molybdenum dioxide (MoO2) as byproducts were observed, confirming that the conversion rate RC of the metal-doped molybdenum sulfide powder to MoS2 obtained above is over 99%, and the reaction with sulfur proceeds rapidly. Crystal structure analysis of the metal-doped molybdenum sulfide powder of Example 14 by X-ray diffraction (XRD) confirmed the presence of both 2H and 3R crystal structures.

[0323] The metal doping amount (zinc doping amount) of the metal-doped molybdenum sulfide powder (zinc-doped molybdenum sulfide powder) of Example 14 was determined by XRF analysis, and the result was 1.07 moles%. The specific surface area of ​​the metal-doped molybdenum sulfide powder of Example 14 was determined by the BET method, and the result was 51.0 m2 / g. The ratio (I / II) of the metal-doped molybdenum sulfide powder of Example 14 was determined, and the result was 1.611. The particle size distribution of the metal-doped molybdenum sulfide powder of Example 14 was measured by a dynamic light scattering particle size distribution measuring device, and the median particle size D50 was determined, and the result was 634 nm.

[0324] The various analytical results show that the target metal-doped molybdenum sulfide powder can be reliably obtained.

[0325] <<Manufacturing of molybdenum sulfide powder (manufacturing method (2'))>> [Comparative Example 4] Except for the aspect of not using zinc chloride aqueous solution, molybdenum sulfide powder was manufactured using the same method as in Example 14.

[0326] The metal doping content (zinc doping content) of the molybdenum sulfide powder of Comparative Example 4 was determined by XRF analysis, and the result was 0.00 moles%. The specific surface area of ​​the molybdenum sulfide powder of Comparative Example 4 was determined by the BET method, and the result was 45.1 m² / g. The ratio (I / II) of the molybdenum sulfide powder of Comparative Example 4 was determined, and the result was 1.756. The particle size distribution of the molybdenum sulfide powder of Comparative Example 4 was measured by a dynamic light scattering particle size distribution measuring device, and the median particle size D50 was determined, and the result was 761 nm.

[0327] <<Manufacturing of Metal-Doped Molybdenum Sulfide Powder (Manufacturing Method (3))>> [Example 15] <Manufacturing of Zinc-Doped Molybdenum Sulfide Powder> Using 5 g of molybdenum trioxide powder obtained in Example 1 and 195 g of ion-exchanged water, an aqueous dispersion of molybdenum trioxide powder with a concentration of 2.5% by mass was obtained. Using 0.2 g of zinc chloride (manufactured by Kanto Chemical Co., Ltd.) and 19.8 g of ion-exchanged water, an aqueous solution of zinc chloride with a concentration of 1% by mass was obtained. 73.2 g of the above-obtained aqueous dispersion of molybdenum trioxide powder, 5.8 g of zinc chloride aqueous solution, and 6.1 g of sulfur powder (manufactured by Kanto Chemical Co., Ltd.) were mixed and stirred at room temperature for 3 hours to obtain a raw material mixture (2). In the obtained raw material mixture (2), the amount of sulfur powder is 7 moles relative to the amount of molybdenum trioxide powder, the amount of zinc chloride is 2 moles relative to the amount of molybdenum trioxide powder, and the amount of water is 40 times the amount of the amount of molybdenum trioxide powder.

[0328] In addition to using the raw material mixture (2) obtained above, powder (zinc-doped molybdenum sulfide powder) was obtained by the same method as in Example 2.

[0329] The X-ray diffraction (XRD) pattern of the powder in Example 15 is the same as that of the powder (cobalt-doped molybdenum sulfide powder) in Example 2. In the XRD pattern of Example 15, only peaks belonging to molybdenum disulfide (MoS2) were detected; no peaks not belonging to MoS2 were observed. That is, no reaction intermediate peaks such as molybdenum dioxide (MoO2) as byproducts were observed, confirming that the conversion rate RC of the metal-doped molybdenum sulfide powder to MoS2 obtained above is over 99%, and the reaction with sulfur proceeds rapidly. Crystal structure analysis of the metal-doped molybdenum sulfide powder of Example 15 by X-ray diffraction (XRD) confirmed the presence of both 2H and 3R crystal structures.

[0330] The metal doping amount (zinc doping amount) of the metal-doped molybdenum sulfide powder (zinc-doped molybdenum sulfide powder) of Example 15 was determined by XRF analysis, and the result was 1.07 moles%. The specific surface area of ​​the metal-doped molybdenum sulfide powder of Example 15 was determined by the BET method, and the result was 38.8 m2 / g. The ratio (I / II) of the metal-doped molybdenum sulfide powder of Example 15 was determined, and the result was 1.688. The particle size distribution of the metal-doped molybdenum sulfide powder of Example 15 was measured by a dynamic light scattering particle size distribution measuring device, and the median particle size D50 was determined, and the result was 862 nm.

[0331] The various analytical results show that the target metal-doped molybdenum sulfide powder can be reliably obtained.

[0332] <<Manufacturing of molybdenum sulfide powder (manufacturing method (3'))>> [Comparative Example 5] Except for the aspect of not using zinc chloride aqueous solution, molybdenum sulfide powder was manufactured using the same method as in Example 15.

[0333] The metal doping content (zinc doping content) of the molybdenum sulfide powder of Comparative Example 5 was determined by XRF analysis, and the result was 0.00 moles%. The specific surface area of ​​the molybdenum sulfide powder of Comparative Example 5 was determined by the BET method, and the result was 46.6 m² / g. The ratio (I / II) of the molybdenum sulfide powder of Comparative Example 5 was determined, and the result was 1.662. The particle size distribution of the molybdenum sulfide powder of Comparative Example 5 was measured by a dynamic light scattering particle size distribution measuring device, and the median particle size D50 was determined, and the result was 738 nm.

[0334] [Table 1] Manufacturing method Doped metals (metal doping amount (mol%)) Physical properties of powder Specific surface area (m²) 2 / g) Ratio (I / II) Median particle size D 50 (nm) Example 1 (1) Co (0.77) 59.8 1.737 562 Comparative Example 1 (1') -(0.00) 38.9 1.362 797 Example 2 (3) Co (0.77) 35.6 1.704 810 Example 3 (3) Pd (2.07) 42.3 1.720 703 Example 4 (3) Ir (1.13) 29.6 1.651 1123 Comparative Example 2 (3') -(0.00) 31.7 1.734 1006 Example 5 (2) Co (0.77) 53.2 1.807 569 Example 6 (2) Pd (2.07) 51.7 1.685 606 Example 7 (2) Ir (1.13) 49.7 1.643 661 Comparative Example 3 (2') -(0.00) 46.1 1.640 707 Example 8 (3) Mn (1.23) 39.7 1.572 776 Example 9 (3) Fe (0.72) 41.2 1.597 711 Example 10 (3) Ni (1.65) 50.3 1.672 616 Example 11 (3) Zr (2.09) 46.2 1.604 723 Example 12 (3) Ru (2.95) 38.8 1.536 779 Example 13 (3) In (1.00) 36.7 1.656 823 Example 14 (2) Zn (1.07) 51.0 1.611 634 Comparative Example 4 (2') -(0.00) 45.1 1.756 761 Example 15 (3) Zn (1.07) 38.8 1.688 862 Comparative Example 5 (3') -(0.00) 46.6 1.662 738

[0335] [Experimental Example 1] <<Evaluation of Hydrogen-Generating Catalyst>> <Preparation of Catalyst Ink> A 1 wt% Nafion (registered trademark) dispersion (manufactured by Fujifilm and Koko Pure Chemical Industries, Ltd., DE520 CS type) was prepared by diluting a 5% Nafion (registered trademark) dispersion with a mixed solvent of ultrapure water and 1-propanol at a mass ratio of 1:1. 2.0 mg of cobalt-doped molybdenum sulfide powder obtained in Example 2 was added to a mixed solution of 100 μL of 1-hexanol and 4.1 μL of 1 wt% Nafion (registered trademark), and dispersed by ultrasonic treatment, thereby preparing a catalyst ink.

[0336] <Fabrication of the Functional Electrode> Using a glassy carbon rod (manufactured by Tokai Carbon Co., Ltd., ϕ5 mm × 10 mm) as the substrate for the functional electrode, 5.0 μL of the dispersion (catalytic ink) obtained above was coated on the glassy carbon rod, and dried at 60°C for 1 hour, thereby fabricating an functional electrode having a catalyst layer (hydrogen-generating catalyst layer) containing cobalt-doped molybdenum sulfide powder. The loading of cobalt-doped molybdenum sulfide on the glassy carbon rod was 1.0 mg / cm2.

[0337] <Evaluation of Hydrogen Generation Catalyst> Electrochemical measurements were performed using a three-electrode cell manufactured by MICLAB Corporation and a potentiostat manufactured by Oriental Technical Research Co., Ltd. The electrolyte used was 0.1 M H₂SO₄, and the measurement was conducted at 30°C. A reversible hydrogen electrode (RHE) was used as the reference electrode, and a glassy carbon plate was used as the counter electrode. As a pretreatment, cyclic voltammetry was performed for 300 cycles under nitrogen atmosphere at a scan rate of 150 mV / s and a range of 0.05 V to 0.9 V.

[0338] Therefore, low-speed scanning voltammetry (O2+4H++4e-→2H2O) was performed in oxygen and nitrogen environments, respectively, with a scanning speed of 5 mV / s and a scanning range of 0.2 V to 0.9 V.

[0339] The current density (i / mA·cm2) for the hydrogen production reaction (HER) was calculated based on the difference in current density between the oxygen and nitrogen environments. The current density at an overvoltage η of 300 mV was determined to be -6.4 mA / cm2. Furthermore, the overvoltage η at a current density of 1 mA / cm2 was -170.0 mV.

[0340] [Experimental Example 2] <<Evaluation of Hydrogen-Generating Catalyst>> <Preparation of Hydrogen-Generating Catalyst (Molybdenum Sulfide Powder)> In a magnetic crucible, 1.00 g of molybdenum trioxide powder obtained in Example 1 was mixed with 1.57 g of sulfur powder (manufactured by Kanto Chemical Co., Ltd.) using a stirring rod to homogenize the powder. The mixture was then calcined at 500°C for 4 hours under a nitrogen environment to obtain a black powder. Here, the amount of MoO3 in the molybdenum trioxide powder was 100 mol%, and the amount of S in the sulfur powder was 705 mol%. The X-ray diffraction (XRD) pattern of this black powder (molybdenum sulfide powder of Experimental Example 2) is shown in Figure 30 along with the diffraction patterns of the 3R crystal structure of molybdenum disulfide (MoS2), the 2H crystal structure of molybdenum disulfide (MoS2), and the diffraction pattern of molybdenum dioxide (MoO2) described in the Inorganic Crystal Structure Database (ICSD). Molybdenum dioxide (MoO2) is the reaction intermediate.

[0341] In the X-ray diffraction (XRD) pattern of Figure 30, only peaks belonging to molybdenum disulfide (MoS2) were detected, and no peaks not belonging to molybdenum disulfide (MoS2) were observed. That is, no peaks of reaction intermediates such as molybdenum dioxide (MoO2) as byproducts were observed, and only peaks belonging to molybdenum disulfide (MoS2) were observed. Based on this, it can be confirmed that the conversion rate RC of the molybdenum sulfide powder obtained above to MoS2 is above 99%, and the reaction with sulfur proceeds rapidly. The crystal structure analysis of the molybdenum sulfide powder of Experimental Example 2 by X-ray diffraction (XRD) confirmed that it contained 2H crystal structure and 3R crystal structure. The half-widths of the peaks near 39.5° and 49.5° were as wide as 2.36° and 3.71°, respectively.

[0342] The specific surface area of ​​the molybdenum sulfide powder in Example 2 was determined by the BET method, and the result was 70 m2 / g.

[0343] The particle size distribution of molybdenum sulfide powder in Test Example 2 was measured by a dynamic light scattering particle size distribution measuring device, and the median particle size D50 was determined to be 200 nm.

[0344] A TEM image of the molybdenum sulfide powder of Example 2 is shown in Figure 31. It can be observed that there are many band-like or sheet-like molybdenum sulfides with a length of about 200 nm and a width of about 10 nm.

[0345] <Manufacturing of Catalyst Ink, Manufacturing of Acting Electrode, and Evaluation of Hydrogen-Generating Catalyst> In manufacturing the catalyst ink, in addition to using 2.0 mg of cobalt-doped molybdenum sulfide powder, 2.0 mg of molybdenum sulfide powder obtained in Test Example 2 was also used. Otherwise, the catalyst ink and acting electrode were manufactured using the same method as in Test Example 1, and the hydrogen-generating catalyst was evaluated. In the acting electrode, the molybdenum sulfide loading on the glassy carbon rod was 1.0 mg / cm². The current density at an overvoltage η of 300 mV was calculated, and the result was -2.5 mA / cm². Furthermore, the overvoltage η at a current density of 1 mA / cm² was -231.7 mV.

[0346] [Experimental Example 3] <<Evaluation of Hydrogen-Generating Catalyst>> In the manufacture of the catalyst ink, in addition to using 2.0 mg of molybdenum sulfide powder obtained in Experimental Example 2, 0.2 mg of conductive carbon black (Ketjen Black (registered trademark), EC300J, median particle size D50: 40 nm) manufactured by Lion Specialty Chemicals Co., Ltd. was used. Apart from this, the hydrogen-generating catalyst, catalyst ink, and working electrode were manufactured using the same method as in Experimental Example 2, and the hydrogen-generating catalyst was evaluated. In the working electrode, the molybdenum sulfide loading on the glass carbon rod was 1.0 mg / cm². The current density at an overvoltage η of 300 mV was calculated, and the result was -16.1 mA / cm². Furthermore, the overvoltage η at a current density of 1 mA / cm² was -126.7 mV, and the overvoltage η at a current density of 10 mA / cm² was -245.2 mV.

[0347] [Experimental Example 4] Except for the absence of catalyst ink, electrochemical measurements were performed using the same method as in Experimental Example 1. The current density at an overvoltage η of 300 mV was determined to be -0.2 mA / cm².

[0348] [Experimental Example 5] In the manufacture of the catalyst ink, except that 2.0 mg of molybdenum sulfide powder manufactured by Kanto Chemical Co., Ltd. was used instead of 2.0 mg of cobalt-doped molybdenum sulfide powder, a comparative catalyst ink was manufactured using the same method as in Experimental Example 1, and the comparative hydrogen-generating catalyst (molybdenum sulfide powder) was evaluated. The specific surface area of ​​the comparative molybdenum sulfide powder was determined by the BET method, and the result was 3.0 m2 / g. The particle size distribution of the comparative molybdenum sulfide powder was measured by a dynamic light scattering particle size distribution measuring device, and the median particle size D50 was determined to be less than 30 μm. In the working electrode, the molybdenum sulfide loading on the glass carbon rod was 1.0 mg / cm2. The current density at an overvoltage η of 300 mV was determined to be -0.3 mA / cm2.

[0349] [Table 2] Types of hydrogen-producing catalysts Physical properties of powder MoS2 loading (mg / cm³) 2 ) Specific surface area (m²) 2 / g) Median particle size D 50 (nm) Experimental Example 1 Co-doped molybdenum sulfide powder containing MoS2 in 2H and 3R crystal structures 35.6 810 1.0 Experimental Example 2 Molybdenum sulfide powder containing 2H and 3R crystal structures of MoS2 70 200 1.0 Experimental Example 3 Molybdenum sulfide powder containing 2H and 3R crystal structures of MoS2 + carbon black 70 200 1.0 Test Example 4 - - - 0 Experimental Example 5 MoS2 containing a 2H crystal structure but lacking a 3R crystal structure 3.0 ≤30000 1.0

[0350] [Table 3] Evaluation results of hydrogen production catalyst Current density (mA / cm) when overvoltage η is 300 mV 2 ) Current density is 10 mA / cm 2 Overvoltage η (mV) at that time Current density is 1 mA / cm 2 Overvoltage η (mV) at that time Experimental Example 1 -6.4 - -170.0 Experimental Example 2 -2.5 - -231.7 Experimental Example 3 -16.1 -245.2 -126.7 Test Example 4 -0.2 - - Experimental Example 5 -0.3 - -

[0351] Based on the results of Test Examples 1 to 5, it was confirmed that the metal-doped molybdenum sulfide powder exhibited activity as a hydrogen production catalyst equal to or greater than that of the pure molybdenum sulfide powder. [Industrial Applicability]

[0352] The present invention can be used as an active material such as a catalyst for hydrogen production reaction and a semiconductor material. [Simplified Explanation of the Diagram]

[0023] Figure 1 is a schematic diagram of an example of the apparatus used in the manufacture of molybdenum trioxide powder as a raw material. Figure 2 is a diagram showing the results of the X-ray diffraction (XRD) pattern of the molybdenum trioxide powder as a raw material, together with the standard patterns of α-MoO3 and β-MoO3 crystals of molybdenum trioxide. Figure 3 is an extended X-ray absorption fine structure (EXAFS) spectrum of the K absorption end of molybdenum measured using the molybdenum trioxide powder as a raw material. Figure 4 is a magnified diagram of the region near 2θ / degree 14 in the X-ray diffraction (XRD) patterns of the metal-doped molybdenum sulfide powder of Example 1 and the molybdenum sulfide powder of Comparative Example 1. Figure 5 is a transmission electron microscope (TEM) image of the metal-doped molybdenum sulfide powder of Example 1. Figure 6 is an atomic force microscope (AFM) image of the metal-doped molybdenum sulfide powder of Example 1. Figure 7 is a diagram showing a cross-section of the metal-doped molybdenum sulfide powder shown in Figure 6. Figure 8 is a TEM image of the molybdenum sulfide powder of Comparative Example 1. Figure 9 is a magnified view of the region near 2θ / degree 14 in the X-ray diffraction (XRD) patterns of the metal-doped molybdenum sulfide powders of Examples 2 to 4 and the molybdenum sulfide powder of Comparative Example 2. Figure 10 is a TEM image of the metal-doped molybdenum sulfide powder of Example 2. Figure 11 is a SEM image of the metal-doped molybdenum sulfide powder of Example 2. Figure 12 is an energy dispersive spectrometer (EDS) image of the metal-doped molybdenum sulfide powder of Example 2. Figure 13 is a TEM image of the metal-doped molybdenum sulfide powder of Example 3. Figure 14 is a SEM image of the metal-doped molybdenum sulfide powder of Example 3. Figure 15 is an EDS image of the metal-doped molybdenum sulfide powder of Example 3. Figure 16 is a TEM image of the metal-doped molybdenum sulfide powder of Example 4. Figure 17 is a SEM image of the metal-doped molybdenum sulfide powder of Example 4. Figure 18 is an EDS image of the metal-doped molybdenum sulfide powder of Example 4. Figure 19 is a TEM image of the molybdenum sulfide powder of Comparative Example 2. Figure 20 is a SEM image of the molybdenum sulfide powder of Comparative Example 2. Figure 21 is a magnified view of the region near 2θ / degree 14 in the X-ray diffraction (XRD) patterns of the metal-doped molybdenum sulfide powders of Examples 5-7 and Comparative Example 3. Figure 22 is a TEM image of the metal-doped molybdenum sulfide powder of Example 5. Figure 23 is a SEM image of the metal-doped molybdenum sulfide powder of Example 5. Figure 24 is a TEM image of the metal-doped molybdenum sulfide powder of Example 6. Figure 25 is a SEM image of the metal-doped molybdenum sulfide powder of Example 6. Figure 26 is a TEM image of the metal-doped molybdenum sulfide powder of Example 7.Figure 27 is a SEM image of the metal-doped molybdenum sulfide powder of Example 7. Figure 28 is a TEM image of the molybdenum sulfide powder of Comparative Example 3. Figure 29 is a SEM image of the molybdenum sulfide powder of Comparative Example 3. Figure 30 shows the X-ray diffraction (XRD) pattern of the molybdenum sulfide powder of Experimental Example 2, along with the diffraction patterns of the 3R crystal structure of molybdenum disulfide (MoS2), the 2H crystal structure of molybdenum disulfide (MoS2), and the diffraction pattern of molybdenum dioxide (MoO2). Figure 31 is a TEM image of the molybdenum sulfide powder of Experimental Example 2.

Claims

1. A metal-doped molybdenum sulfide powder, doped with metals from Group 4 to Group 13, and containing a 3R crystal structure of molybdenum disulfide, wherein the primary particles of the molybdenum disulfide constituting the metal-doped molybdenum sulfide powder are rope-like, ribbon-like, or sheet-like in shape, and have a thickness in the range of 3 nm to 20 nm.

2. The metal-doped molybdenum sulfide powder as claimed in claim 1, wherein the metal-doped molybdenum sulfide powder comprises a 2H crystal structure and a 3R crystal structure of molybdenum disulfide.

3. The metal-doped molybdenum sulfide powder as claimed in claim 2, wherein in the spectrum obtained by powder X-ray diffraction using Cu-Kα rays as the X-ray source for the metal-doped molybdenum sulfide powder, the peaks near 39.5° and near 49.5° both contain the combined peaks of the 2H crystal structure and the 3R crystal structure, and the half-width is greater than 1°.

4. The metal-doped molybdenum sulfide powder as claimed in any one of claims 1 to 3, wherein the specific surface area determined by the Buerter method is 10 m² / g or more.

5. The metal-doped molybdenum sulfide powder as claimed in any one of claims 1 to 3, wherein the median particle size D50 determined by a dynamic light scattering particle size distribution measuring device is 10 nm to 2000 nm.

6. The metal-doped molybdenum sulfide powder as claimed in any one of claims 1 to 3, wherein the ratio (I / II) of the intensity I of the peak caused by Mo-S to the peak intensity II of Mo-Mo in the radial distribution function obtained from the extended X-ray absorption fine structure spectrum of the K-end of molybdenum is greater than 1.

0.

7. The metal-doped molybdenum sulfide powder as claimed in any one of claims 1 to 3, wherein the metal of group 4 to group 13 is one or more selected from the group consisting of cobalt, palladium, iridium, manganese, iron, nickel, zirconium, ruthenium, indium and zinc.

8. A method for manufacturing metal-doped molybdenum sulfide powder, comprising: After obtaining a mixed powder by dry mixing molybdenum trioxide powder containing an aggregate of primary particles with a β-crystal structure of molybdenum trioxide, a sulfur source, and metal salts from Group 4 to Group 13, the mixed powder is heated at a temperature of 200°C to 1000°C. The primary particles constituting the metal-doped molybdenum sulfide powder are rope-like, ribbon-like, or sheet-like, and have a thickness in the range of 3 nm to 20 nm.

9. A method for manufacturing metal-doped molybdenum sulfide powder, comprising: After obtaining a solid substance by removing the dispersion medium from a mixture of molybdenum trioxide powder containing a self-adjusted aggregate of primary particles with a β-crystal structure of molybdenum trioxide, a group 4 to 13 metal salt, and a dispersion medium, the solid substance is heated at a temperature of 200°C to 1000°C in the presence of a sulfur source. The primary particles constituting the metal-doped molybdenum sulfide powder are rope-like, ribbon-like, or sheet-like, and have a thickness in the range of 3 nm to 20 nm.

10. A method for manufacturing metal-doped molybdenum sulfide powder as claimed in claim 9, wherein the dispersion medium is removed from the mixture by freeze-drying the mixture.

11. A method for manufacturing metal-doped molybdenum sulfide powder as claimed in claim 9, wherein the dispersion medium is removed from the mixture by heating the mixture.

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