OER catalyst for in-situ growth of layered transition metal sulfide on surface of metal substrate as well as preparation method and application of OER catalyst

Abstract

The invention relates to the technical field of catalysis, in particular to an OER catalyst for in-situ growth of layered transition metal sulfide on the surface of a metal substrate and a preparation method and application of the OER catalyst. The preparation method of the OER catalyst comprises the following steps: adding transition metal salt and thiourea into an organic solvent, and stirring to obtain a precursor solution; heating the metal substrate to a target temperature to obtain the metal substrate at the target temperature; and atomizing the precursor solution, and spraying the atomized precursor solution on a target surface of a metal substrate at a target temperature to obtain the OER catalyst for in-situ growth of layered transition metal sulfide on the surface of the metal substrate. The OER catalyst is obtained through in-situ growth of the layered transition metal sulfide on the surface of the metal substrate by adopting a spray pyrolysis method, the interface bonding strength between the layered transition metal sulfide OER catalyst and the metal substrate is enhanced, and the OER catalyst has the advantages of being excellent in oxygen evolution reaction catalytic activity, low in overpotential, low in Tafel slope, high in structural stability and the like.

Description

Technical Field

[0001] The present invention relates to the field of catalytic technology, and in particular to an OER catalyst having layered transition metal sulfide in situ grown on a metal substrate surface, and a preparation method and application thereof. Background Art

[0002] Water electrolysis is an efficient and sustainable pathway for hydrogen production and is considered an effective method for future renewable energy production, storage, and utilization. Water electrolysis consists of two half-reactions: the cathode hydrogen evolution reaction (HER) and the anode oxygen evolution reaction (OER). The OER involves a four-electron transfer process with slow reaction kinetics and a high energy barrier, which severely limits the efficiency of hydrogen production from water electrolysis. Studies have shown that the addition of catalysts to the OER process can significantly reduce the activation energy of the reaction, promote the reaction, and improve the efficiency of hydrogen production from water electrolysis.

[0003] Traditional OER catalysts are oxides of the precious metals iridium and ruthenium, such as iridium oxide (IrO2) and ruthenium oxide (RuO2), but their high cost and scarcity seriously hinder their large-scale application. Therefore, the development of low-cost non-precious metal-based OER catalysts is of great significance for the large-scale application of hydrogen production by water electrolysis. Transition metal sulfides are regarded as highly promising alternative materials due to their low cost, easy availability, excellent conductivity, and good intrinsic activity. However, the preparation of existing transition metal sulfide-based OER catalysts still faces some problems. For example, the existing technology usually adopts traditional methods (such as binder coating, solvothermal method, vapor deposition method, co-precipitation method, etc.) to arrange transition metal sulfides on the surface of metal substrates to prepare transition metal sulfide-based OER catalysts. The transition metal sulfides and the metal substrates are mostly physically attached, and the interfacial bonding strength is poor. When working in the oxygen evolution reaction, the transition metal sulfides are easily detached, thereby reducing the structural stability of the transition metal sulfide-based OER catalysts.

[0004] Therefore, developing a method to improve the structural stability of transition metal sulfide-based OER catalysts is an urgent issue to be addressed. Summary of the Invention

[0005] The present invention provides a method for preparing an OER catalyst having in-situ grown layered transition metal sulfides on the surface of a metal substrate. The method adopts a spray pyrolysis method to in-situ grow layered transition metal sulfides on the surface of the metal substrate to prepare an OER catalyst having in-situ grown layered transition metal sulfides on the surface of the metal substrate (hereinafter referred to as OER catalyst). The OER catalyst has the advantages of excellent catalytic activity for oxygen evolution reaction, low overpotential, low Tafel slope, high structural stability and excellent operational stability. The method is simple in process, easy to operate, and is conducive to industrial production.

[0006] The present invention also provides an OER catalyst having layered transition metal sulfides in situ grown on the surface of a metal substrate. The OER catalyst is prepared by the above-mentioned preparation method, so the OER catalyst has the advantages of excellent catalytic activity for oxygen evolution reaction, low overpotential, low Tafel slope, high structural stability and excellent operational stability.

[0007] The present invention also provides an OER catalyst prepared by the above-mentioned method for preparing an OER catalyst by in-situ growth of a layered transition metal sulfide on a metal substrate, or the use of the above-mentioned OER catalyst in electrocatalytic oxygen evolution. The inventors' research has shown that when the layered transition metal sulfide OER catalyst is used as a working electrode, its Tafel slope can be as low as 29 mV / dec in a 1 mol / L potassium hydroxide solution, and its current density can be as low as 10 mA / cm 2 The lowest overpotential is 208 mV, indicating that the OER catalyst has excellent catalytic activity for oxygen evolution reaction, and therefore has good application prospects in industrial water electrolysis.

[0008] A first aspect of the present invention provides a method for preparing an OER catalyst by in-situ growth of layered transition metal sulfides on a metal substrate, comprising the following steps:

[0009] adding a transition metal salt and thiourea into an organic solvent and stirring the mixture to obtain a precursor solution;

[0010] heating the metal substrate to a target temperature to obtain a metal substrate at the target temperature;

[0011] The precursor liquid is atomized and then sprayed onto the target surface of the metal substrate at the target temperature, thereby obtaining an OER catalyst with in-situ growth of layered transition metal sulfide on the surface of the metal substrate.

[0012] In the preparation method of the OER catalyst for in-situ growth of layered transition metal sulfide on the surface of a metal substrate as described above, the transition metal salt is at least one of nickel chloride, ferric chloride, and cobalt chloride.

[0013] The method for preparing an OER catalyst having an in-situ growth layered transition metal sulfide on the surface of a metal substrate as described above, wherein the transition metal salt is composed of nickel chloride and ferric chloride in a first molar ratio, the transition metal salt is composed of nickel chloride and cobalt chloride in a second molar ratio, or the transition metal salt is composed of ferric chloride and cobalt chloride in a third molar ratio;

[0014] The first molar ratio is (1-3): (1-2); the second molar ratio is (1-3): (1-2); and the third molar ratio is (1-3): (1-2).

[0015] The method for preparing the OER catalyst by in-situ growth of layered transition metal sulfide on the surface of the metal substrate as described above, wherein the method for heating the metal substrate to the target temperature comprises:

[0016] The metal substrate was heated to a target temperature of 300-500°C at a heating rate of 2-5°C / min and kept at this temperature for 20-30 minutes.

[0017] The method for preparing the OER catalyst for in-situ growth of layered transition metal sulfides on the surface of the metal substrate as described above, wherein the precursor liquid is atomized and then sprayed onto the target surface of the metal substrate at the target temperature, comprises:

[0018] The precursor liquid is atomized by ultrasonic atomization spraying technology and then sprayed on the target surface of the metal substrate at the target temperature in a field-shaped trajectory. During spraying, the spraying height is controlled to be 3-8 cm, the spraying speed is 1-3 mL / min, and the spraying spacing is 5-10 mm.

[0019] As described above, in the preparation method of the OER catalyst having layered transition metal sulfide in situ grown on the surface of a metal substrate, the thickness of the layered transition metal sulfide in the OER catalyst having layered transition metal sulfide in situ grown on the surface of the metal substrate is 3-5 μm.

[0020] In the preparation method of the OER catalyst for in-situ growth of layered transition metal sulfide on the surface of a metal substrate as described above, the concentration of the transition metal salt in the precursor solution is 0.2-0.8 mol / L, and the concentration of thiourea is 0.2-0.8 mol / L.

[0021] The method for preparing an OER catalyst for in-situ growth of layered transition metal sulfides on a metal substrate surface as described above, wherein the organic solvent comprises ethanol;

[0022] and / or, during the stirring process, the rotation speed is 200-400 rpm, the temperature is 20-30° C., and the time is 10-40 min;

[0023] And / or, the metal substrate is any one of nickel foam, nickel sheet, nickel mesh, iron foam, iron sheet, stainless steel mesh, and stainless steel sheet;

[0024] And / or, the step of heating the metal substrate to the target temperature further includes cleaning the metal substrate.

[0025] The second aspect of the present invention provides an OER catalyst having layered transition metal sulfides in situ grown on the surface of a metal substrate. The OER catalyst having layered transition metal sulfides in situ grown on the surface of a metal substrate is prepared by the preparation method of the OER catalyst having layered transition metal sulfides in situ grown on the surface of a metal substrate.

[0026] The third aspect of the present invention provides an OER catalyst with layered transition metal sulfide in situ grown on the surface of a metal substrate prepared by the preparation method of the OER catalyst with layered transition metal sulfide in situ grown on the surface of a metal substrate, or the use of the OER catalyst with layered transition metal sulfide in situ grown on the surface of a metal substrate in electrocatalytic oxygen evolution.

[0027] The solution of the present invention has at least the following effects:

[0028] The present invention provides a method for preparing an OER catalyst having layered transition metal sulfides in situ grown on a metal substrate surface. The method adopts a spray pyrolysis method to in situ grow layered transition metal sulfides on a metal substrate surface to prepare an OER catalyst having layered transition metal sulfides in situ grown on a metal substrate surface (hereinafter referred to as an OER catalyst). The interfacial bonding strength between the metal substrate and the layered transition metal sulfides is enhanced, and the structural stability of the OER catalyst is improved. The OER catalyst exhibits excellent catalytic activity for oxygen evolution reaction and has the advantages of low overpotential and low Tafel slope. The OER catalyst can stably operate for up to 1000 hours at a high current density and has excellent operational stability. The OER catalyst has a high current density of 25°C and 1 mol / L After running in KOH solution for 500h, layered transition metal sulfide is still firmly attached to the metal substrate surface, and the structure does not collapse, with excellent structural stability; In addition, after the precursor liquid is atomized by spray pyrolysis, it is directly sprayed on the metal substrate surface with a certain spraying height, spraying speed and spraying spacing, the precursor liquid after atomization and the metal substrate react rapidly at high temperature to obtain OER catalyst, and the distribution of OER catalyst can be controlled by controlling the flow velocity and the pace of the precursor liquid after atomization, in terms of large-scale preparation, there is excellent scalability. This method is simple in process, easy to operate, and is conducive to industrial production. The OER catalyst (abbreviation OER catalyst) of metal substrate surface in-situ growth layered transition metal sulfide prepared by the method provided by the present invention has the advantages of excellent oxygen evolution reaction catalytic activity, low overpotential, low Tafel slope, high structural stability and excellent operational stability. Compared with the traditional spraying method, the preparation method provided by the present invention allows layered transition metal sulfides to be in-situ grown on the surface of the metal substrate, which has excellent interface bonding strength and effectively prevents the problem of layered transition metal sulfides falling off due to high current bubble desorption. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0030] Figure 1 This is an optical photograph of the OER catalyst in Example 1 of the present invention;

[0031] Figure 2 This is a scanning electron microscope (SEM) image of the OER catalyst in Example 1 of the present invention;

[0032] Figure 3 This is a cross-sectional SEM image of the OER catalyst in Example 1 of the present invention;

[0033] Figure 4 LSV curves of the OER catalysts in Examples 1-6 of the present invention;

[0034] Figure 5 LSV curves of the OER catalysts in Examples 7-9 of the present invention;

[0035] Figure 6 LSV curves of the OER catalyst in Example 1 of the present invention at 40°C, 60°C, and 80°C;

[0036] Figure 7 The OER catalyst in Example 1 of the present invention is at 500mA / cm 2 Operation stability test diagram under current density;

[0037] Figure 8 The OER catalyst in Example 1 of the present invention is at 500mA / cm 2 Cross-sectional SEM image after running in 1 mol / L KOH solution at 25°C for 500 h at a current density of . DETAILED DESCRIPTION

[0038] In order to make the purpose, technical solutions and advantages of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with embodiments of the present invention. Obviously, the described embodiments are part of embodiments of the present invention, rather than all embodiments. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative work are within the scope of protection of the present invention. If specific techniques or conditions are not indicated in the embodiments, they are carried out according to the techniques or conditions described in the literature in this area or according to the product specifications. Reagents or instruments used that do not indicate manufacturers are conventional products that can be obtained commercially.

[0039] It should be noted that the descriptions involving "first", "second", "third", etc. in the present invention are used to distinguish similar objects, and are not used to describe a specific order or sequence, and therefore cannot be understood as a limitation of the present invention.

[0040] In addition, in the specification and claims, "and / or" means at least one of the connected objects, and the character " / " generally indicates that the previous and subsequent related objects are in an "or" relationship.

[0041] A first aspect of the present invention provides a method for preparing an OER catalyst by in-situ growth of layered transition metal sulfides on a metal substrate, comprising the following steps:

[0042] adding a transition metal salt and thiourea into an organic solvent and stirring the mixture to obtain a precursor solution;

[0043] heating the metal substrate to a target temperature to obtain a metal substrate at the target temperature;

[0044] The precursor liquid is atomized and then sprayed onto the target surface of the metal substrate at the target temperature, thereby obtaining an OER catalyst with in-situ growth of layered transition metal sulfide on the surface of the metal substrate.

[0045] In the present invention, the metal substrate has two surfaces, an upper surface and a lower surface, and the target surface is the surface of the metal substrate on which layered transition metal sulfide needs to be grown in situ.

[0046] In the present invention, the OER catalyst refers to a catalyst that can promote the oxygen evolution reaction (OER).

[0047] The present invention does not limit the shape, size, and thickness of the metal substrate, which can be selected according to actual needs.

[0048] The present invention does not impose any particular limitation on the specific amount of the precursor solution, and the amount can be selected according to actual needs.

[0049] The present invention does not impose any particular restrictions on the order in which the transition metal salt and thiourea are added to the organic solvent, and the order can be adjusted according to actual needs. For example, the transition metal salt can be first added to the organic solvent and stirred to obtain a transition metal salt solution, and then the thiourea can be added to the transition metal salt solution and stirred. Alternatively, the thiourea can be first added to the organic solvent and stirred to obtain a thiourea solution, and then the transition metal salt can be added to the thiourea solution and stirred. Alternatively, the transition metal salt and thiourea can be added to the organic solvent together and stirred.

[0050] The present invention does not specifically limit the specific heating device used to heat the metal substrate to the target temperature, and any heating device known to those skilled in the art can be used. For example, a heating plate can be used to heat the metal substrate to the target temperature.

[0051] The object prepared by the present invention is an OER catalyst for in-situ growth of layered transition metal sulfides on the surface of a metal substrate. Specifically, a transition metal salt and thiourea are added to an organic solvent to obtain a mixture solution, and then the mixture solution is stirred to uniformly mix the transition metal salt and thiourea in the mixture solution to obtain a precursor solution; the metal substrate is heated to a target temperature to obtain a metal substrate at the target temperature. The purpose of heating the metal substrate to the target temperature is to allow the thiourea in the precursor solution to decompose at the target temperature when the precursor solution is subsequently sprayed to generate hydrogen sulfide with strong reducing properties. The hydrogen sulfide reacts not only with the metal substrate but also with metal ions in the transition metal salt; the precursor solution is atomized and sprayed on the target surface of the metal substrate at the target temperature to obtain the OER catalyst for in-situ growth of layered transition metal sulfides on the surface of the metal substrate.

[0052] The present invention uses the above-mentioned method to in situ grow layered transition metal sulfides on the surface of a metal substrate to prepare an OER catalyst (hereinafter referred to as OER catalyst) with in situ growth of layered transition metal sulfides on the surface of a metal substrate, thereby enhancing the interfacial bonding strength between the metal substrate and the layered transition metal sulfides and improving the structural stability of the OER catalyst. The OER catalyst prepared by this method exhibits excellent catalytic activity for oxygen evolution reaction, has the advantages of low overpotential, low Tafel slope and high structural stability, and the OER catalyst can operate stably for more than 500 hours at a high current density, showing excellent operational stability. In addition, the precursor liquid is atomized by spray pyrolysis and then directly sprayed onto the surface of the metal substrate at a certain spraying height, spraying speed and spraying spacing. The atomized precursor liquid reacts rapidly with the metal substrate at high temperature to obtain the OER catalyst. The distribution of the OER catalyst can be controlled by controlling the flow rate and pace of the atomized precursor liquid, and has excellent scalability in large-area preparation. The method is simple in process, easy to operate, and conducive to industrial production.

[0053] The principle of the present invention for preparing an OER catalyst by in-situ growth of layered transition metal sulfides on a metal substrate surface is explained:

[0054] First, during the spraying process, thiourea in the precursor solution decomposes at the target temperature to generate hydrogen sulfide, a strong reducing substance. The hydrogen sulfide not only reacts with the metal substrate (such as the nickel foam in this embodiment 1), but also reacts with the metal ions in the transition metal salt (such as the Ni in this embodiment 1). 2+ and Fe 3+) reacts, and in situ grows layered transition metal sulfide on the target surface of the metal substrate, enhancing the interface bonding strength between the layered transition metal sulfide and the metal substrate. At this time, the metal substrate acts as a conductive carrier and a metal ion source at the same time. Therefore, the OER catalyst has excellent structural stability; secondly, the spraying process is carried out at a high temperature (300-400 ° C), and the layered transition metal sulfide reacts and grows rapidly on the surface of the metal substrate. During the rapid heating / cooling process, rich defects are formed inside the layered transition metal sulfide, which optimizes its electronic structure while effectively reducing The intermediate adsorption energy barrier is reduced; thirdly, during the spraying process, the thiourea in the precursor solution decomposes at the target temperature to generate hydrogen sulfide, a strongly reducing substance, and also decomposes to generate NH3, HCl, CO2 and other substances. NH3, HCl, CO2 and other substances evaporate in the form of gas. Due to the significant difference in the diffusion rate between layered transition metal sulfides and gases such as NH3, HCl, CO2, a Turing structure with a spatial periodic distribution is generated. This structure provides additional reaction active sites and accelerates the transport of ions and bubbles. Therefore, the OER catalyst has excellent catalytic activity.

[0055] In a specific embodiment, the transition metal salt is at least one of nickel chloride, ferric chloride, and cobalt chloride.

[0056] When the transition metal salt is the above-mentioned substance, it is beneficial to prepare an OER catalyst with excellent catalytic activity for oxygen evolution reaction, low overpotential, low Tafel slope and high structural stability.

[0057] In a specific embodiment, the transition metal salt is composed of nickel chloride and ferric chloride in a first molar ratio, the transition metal salt is composed of nickel chloride and cobalt chloride in a second molar ratio, or the transition metal salt is composed of ferric chloride and cobalt chloride in a third molar ratio.

[0058] When the transition metal salt is composed of nickel chloride and ferric chloride in a first molar ratio, or the transition metal salt is composed of nickel chloride and cobalt chloride in a second molar ratio, or the transition metal salt is composed of ferric chloride and cobalt chloride in a third molar ratio, it is beneficial to prepare an OER catalyst with better oxygen evolution reaction catalytic activity, lower overpotential and lower Tafel slope.

[0059] In a specific embodiment, the first molar ratio is (1-3): (1-2), for example, the first molar ratio is 1:1, 2:1, 3:1, 1:2, etc.; the second molar ratio is (1-3): (1-2), for example, the second molar ratio is 1:1, 2:1, 3:1, 1:2, etc.; the third molar ratio is (1-3): (1-2), for example, the second molar ratio is 1:1, 2:1, 3:1, 1:2, etc.

[0060] In a specific embodiment, the method of heating the metal substrate to the target temperature includes heating the metal substrate to the target temperature of 300-500° C. at a heating rate of 2-5° C. / min and keeping the temperature for 20-30 minutes.

[0061] After the metal substrate is treated according to the above method, a metal substrate at 300-500° C. is obtained. The precursor liquid needs to react with the high-temperature (300-500° C.) metal substrate to in-situ grow layered transition metal sulfide on the surface of the metal substrate.

[0062] For example, the heating rate may be in the range of any one of 2°C / min, 3°C / min, 4°C / min, and 5°C / min, or any two thereof;

[0063] The temperature may be any one of 300°C, 350°C, 400°C, 450°C, and 500°C, or a range consisting of any two of them.

[0064] In a specific embodiment, the above-mentioned method of atomizing the precursor liquid and spraying it on the target surface of the metal substrate at the target temperature includes: using ultrasonic atomization spraying technology to atomize the precursor liquid and spraying it on the target surface of the metal substrate at the target temperature according to a zigzag trajectory. During spraying, the spraying height is controlled to be 3-8 cm, the spraying speed is 1-3 mL / min, and the spraying spacing is 5-10 mm.

[0065] The present invention adopts the spray pyrolysis method to atomize the precursor liquid and then spray it directly on the surface of the metal substrate at a certain spraying height, spraying speed and spraying spacing. The atomized precursor liquid and the metal substrate react rapidly at high temperature to obtain the OER catalyst. The distribution of the OER catalyst can be controlled by controlling the flow rate and pace of the atomized precursor liquid. In terms of large-area preparation, it has excellent scalability.

[0066] For example, the spraying height may be any one of 3 cm, 4 cm, 5 cm, 6 cm, 7 cm, and 8 cm, or any two thereof;

[0067] The spraying speed may be any one of 1 mL / min, 2 mL / min, 3 mL / min, or a range consisting of any two thereof;

[0068] The spraying interval is any one of 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, and 10 mm, or a range consisting of any two of them.

[0069] In a specific embodiment, in the OER catalyst having layered transition metal sulfide in situ grown on the surface of the metal substrate, the thickness of the layered transition metal sulfide is 3-5 μm.

[0070] When the thickness of the layered transition metal sulfide in the OER catalyst grown in situ on the surface of the metal substrate is within the above range, the layered transition metal sulfide in situ grown on the surface of the metal substrate exhibits excellent catalytic activity for oxygen evolution reaction and has the advantages of low overpotential and low Tafel slope.

[0071] In a specific embodiment, in the above-mentioned precursor solution, the concentration of the transition metal salt is 0.2-0.8 mol / L, for example, the concentration of the transition metal salt is 0.2 mol / L, 0.3 mol / L, 0.4 mol / L, 0.5 mol / L, 0.6 mol / L, 0.7 mol / L or 0.8 mol / L, etc.; the concentration of thiourea is 0.2-0.8 mol / L, for example, the concentration of thiourea is 0.2 mol / L, 0.3 mol / L, 0.4 mol / L, 0.5 mol / L, 0.6 mol / L, 0.7 mol / L or 0.8 mol / L, etc.

[0072] In one embodiment, the organic solvent includes ethanol.

[0073] In a specific embodiment, during the above stirring process, the rotation speed is 200-400 rpm, the temperature is 20-30° C., and the time is 10-40 min.

[0074] When the parameters of rotation speed, temperature and time during the stirring process are each within the above ranges, the transition metal salt and thiourea can be completely dissolved in the organic solvent and the transition metal salt and thiourea can be uniformly mixed in the organic solvent, which is conducive to the subsequent preparation of an OER catalyst with excellent catalytic activity for oxygen evolution reaction, low overpotential, low Tafel slope and high structural stability.

[0075] For example, during the stirring process, the rotation speed may be any one of 200 rpm, 250 rpm, 300 rpm, 350 rpm, and 400 rpm, or any two thereof;

[0076] The temperature may be any one of 20°C, 25°C, 30°C, or any two of them;

[0077] The time can be any one of 10 min, 12 min, 14 min, 16 min, 18 min, 20 min, or a range consisting of any two of them.

[0078] In a specific embodiment, the metal substrate is any one of nickel foam, nickel sheet, nickel mesh, iron foam, iron sheet, stainless steel mesh, and stainless steel sheet.

[0079] When the above materials are selected as the metal substrate, the high-temperature (300-500°C) metal substrate can react with the precursor liquid, thereby in situ growing layered transition metal sulfides on the surface of the metal substrate to prepare an OER catalyst (OER catalyst) with in situ growth of layered transition metal sulfides on the surface of the metal substrate.

[0080] In a specific embodiment, the step of heating the metal substrate to the target temperature further includes cleaning the metal substrate.

[0081] The present invention does not impose any particular restrictions on the specific operation and reagents for the cleaning process, and the cleaning process is conventional. For example, the metal substrate is cleaned using hydrochloric acid and water in sequence to obtain a clean metal substrate.

[0082] The present invention does not impose any particular limitation on the specific amounts of hydrochloric acid and water used, and they can be selected according to actual needs.

[0083] A second aspect of the present invention provides an OER catalyst comprising a layered transition metal sulfide in situ grown on a metal substrate. The OER catalyst is prepared using the above-described method for preparing an OER catalyst comprising a layered transition metal sulfide in situ grown on a metal substrate. Consequently, the OER catalyst exhibits excellent catalytic activity for the oxygen evolution reaction, a low overpotential, a low Tafel slope, high structural stability, and excellent operational stability.

[0084] A third aspect of the present invention provides an OER catalyst comprising layered transition metal sulfide in situ grown on a metal substrate surface, prepared by the above-described method for preparing an OER catalyst comprising layered transition metal sulfide in situ grown on a metal substrate surface, or the use of the above-described OER catalyst comprising layered transition metal sulfide in situ grown on a metal substrate surface in electrocatalytic oxygen evolution. The inventors' research has shown that when the layered transition metal sulfide OER catalyst is used as a working electrode, its Tafel slope can be as low as 29 mV / dec in a 1 mol / L potassium hydroxide solution, and its current density can be as low as 10 mA / cm 2 The lowest overpotential is 208 mV, indicating that the OER catalyst has excellent catalytic activity for oxygen evolution reaction, and therefore has good application prospects in industrial water electrolysis.

[0085] The present invention is further described below through specific examples.

[0086] Example 1 (transition metal salts are nickel chloride and ferric chloride)

[0087] This embodiment provides a method for preparing an OER catalyst by in-situ growing a layered transition metal sulfide on a metal substrate, comprising the following steps:

[0088] (1) adding a transition metal salt (the transition metal salt is composed of nickel chloride and ferric chloride in a molar ratio of 3:1) and thiourea to ethanol, stirring at 300 rpm and 25°C for 30 minutes to completely dissolve the transition metal salt and thiourea to obtain a precursor solution; the concentration of the transition metal salt in the precursor solution is 0.5 mol / L, and the concentration of the thiourea is 0.5 mol / L;

[0089] (2) Using a nickel foam with a thickness of 0.5 mm as a metal substrate, the nickel foam was cleaned with hydrochloric acid and water in sequence to obtain a clean metal substrate; the clean metal substrate was heated to 400°C at a heating rate of 5°C / min using a hot plate and kept at this temperature for 30 minutes to ensure that the metal substrate was heated evenly, thereby obtaining a metal substrate at 400°C;

[0090] (3) The precursor liquid is atomized by ultrasonic atomization spraying technology and then evenly sprayed on the upper surface of the metal substrate at 400°C in (2). During spraying, the spraying height is controlled to be 5 cm, the spraying speed is 2 mL / min, and the spraying spacing is 8 mm, thereby obtaining an OER catalyst (hereinafter referred to as OER catalyst) with in situ growth of layered transition metal sulfide on the surface of the metal substrate, wherein the thickness of the layered transition metal sulfide is 4 μm.

[0091] Example 2 (transition metal salt is nickel chloride)

[0092] The preparation method of the OER catalyst provided in this embodiment for in-situ growth of layered transition metal sulfides on the surface of a metal substrate is basically the same as that in Example 1, except that:

[0093] (1) Add nickel chloride and thiourea to ethanol, stir at 300 rpm and 25° C. for 30 min to completely dissolve the nickel chloride and thiourea to obtain a precursor solution; the concentration of nickel chloride in the precursor solution is 0.5 mol / L, and the concentration of thiourea is 0.5 mol / L.

[0094] Example 3 (transition metal salt is ferric chloride)

[0095] The preparation method of the OER catalyst provided in this embodiment for in-situ growth of layered transition metal sulfides on the surface of a metal substrate is basically the same as that in Example 1, except that:

[0096] (1) Add ferric chloride and thiourea to ethanol and stir at 300 rpm and 25°C for 30 min to completely dissolve the ferric chloride and thiourea to obtain a precursor solution; the concentration of ferric chloride in the precursor solution is 0.5 mol / L, and the concentration of thiourea is 0.5 mol / L.

[0097] Example 4 (transition metal salt is cobalt chloride)

[0098] The preparation method of the OER catalyst provided in this embodiment for in-situ growth of layered transition metal sulfides on the surface of a metal substrate is basically the same as that in Example 1, except that:

[0099] (1) Cobalt chloride and thiourea were added to ethanol and stirred at 300 rpm and 25° C. for 30 min to completely dissolve the cobalt chloride and thiourea to obtain a precursor solution; the concentration of cobalt chloride in the precursor solution was 0.5 mol / L, and the concentration of thiourea was 0.5 mol / L.

[0100] Example 5 (transition metal salts are nickel chloride and cobalt chloride)

[0101] The preparation method of the OER catalyst provided in this embodiment for in-situ growth of layered transition metal sulfides on the surface of a metal substrate is basically the same as that in Example 1, except that:

[0102] (1) A transition metal salt (the transition metal salt is composed of nickel chloride and cobalt chloride in a molar ratio of 3:1) and thiourea are added to ethanol, and stirred at 300 rpm and 25°C for 30 minutes to completely dissolve the transition metal salt and thiourea to obtain a precursor solution; the concentration of the transition metal salt in the precursor solution is 0.5 mol / L, and the concentration of the thiourea is 0.5 mol / L.

[0103] Example 6 (transition metal salts are ferric chloride and cobalt chloride)

[0104] The preparation method of the OER catalyst provided in this embodiment for in-situ growth of layered transition metal sulfides on the surface of a metal substrate is basically the same as that in Example 1, except that:

[0105] (1) A transition metal salt (the transition metal salt is composed of ferric chloride and cobalt chloride in a molar ratio of 3:1) and thiourea are added to ethanol, and stirred at 300 rpm and 25°C for 30 minutes to completely dissolve the transition metal salt and thiourea to obtain a precursor solution; the concentration of the transition metal salt in the precursor solution is 0.5 mol / L, and the concentration of the thiourea is 0.5 mol / L.

[0106] Example 7 (transition metal salts are nickel chloride and ferric chloride)

[0107] The preparation method of the OER catalyst provided in this embodiment for in-situ growth of layered transition metal sulfides on the surface of a metal substrate is basically the same as that in Example 1, except that:

[0108] The transition metal salt is composed of nickel chloride and ferric chloride in a molar ratio of 2:1.

[0109] Example 8 (transition metal salts are nickel chloride and ferric chloride)

[0110] The preparation method of the OER catalyst provided in this embodiment for in-situ growth of layered transition metal sulfides on the surface of a metal substrate is basically the same as that in Example 1, except that:

[0111] The transition metal salt is composed of nickel chloride and ferric chloride in a molar ratio of 1:1.

[0112] Example 9 (transition metal salts are nickel chloride and ferric chloride)

[0113] The preparation method of the OER catalyst provided in this embodiment for in-situ growth of layered transition metal sulfides on the surface of a metal substrate is basically the same as that in Example 1, except that:

[0114] The transition metal salt is composed of nickel chloride and ferric chloride in a molar ratio of 1:2.

[0115] Performance Testing

[0116] 1. Morphology test

[0117] The OER catalyst in Example 1 of the present invention was subjected to morphology testing; Figure 1 This is an optical photograph of the OER catalyst in Example 1 of the present invention; Figure 2 This is a scanning electron microscope (SEM) image of the OER catalyst in Example 1 of the present invention; Figure 3 This is a cross-sectional SEM image of the OER catalyst in Example 1 of the present invention.

[0118] Depend on Figure 1-Figure 3 It can be seen that the structure of the layered transition metal sulfide (i.e., the transition metal sulfide layer) in the OER catalyst is dense, and there is good interface bonding strength between the layered transition metal sulfide and the nickel foam (i.e., the nickel foam layer).

[0119] 2. Catalytic activity of oxygen evolution reaction

[0120] The OER catalysts (hereinafter referred to as OER catalysts) in situ grown on the metal substrate surface in Examples 1-9 of the present invention were used as working electrodes, platinum sheets as counter electrodes, and mercury / mercuric oxide electrodes as reference electrodes to perform three-electrode system tests. The electrolyte was a 1 mol / L potassium hydroxide (KOH) solution. The system was subjected to linear sweep voltammetry (LSV) at 25°C. The results are shown in FIG. Figure 4 and Figure 5 As shown; Figure 4 LSV curves of the OER catalysts in Examples 1-6 of the present invention; Figure 5 These are the LSV curves of the OER catalysts in Examples 7-9 of the present invention.

[0121] Depend on Figure 4It can be seen that the Tafel slope of the OER catalyst in Example 1 is 29 mV / dec, and at 10 mA / cm 2 The overpotential at 10 mA / cm2 is 208 mV; the Tafel slope of the OER catalyst in Example 2 is 64 mV / dec. 2 The overpotential at 10 mA / cm2 is 302 mV; the Tafel slope of the OER catalyst in Example 3 is 126 mV / dec. 2 The overpotential at 10 mA / cm2 is 347 mV; the Tafel slope of the OER catalyst in Example 4 is 102 mV / dec. 2 The overpotential at 10 mA / cm2 is 305 mV; the Tafel slope of the OER catalyst in Example 5 is 45 mV / dec. 2 The overpotential at 10 mA / cm2 is 262 mV; the Tafel slope of the OER catalyst in Example 6 is 39 mV / dec. 2 The overpotential is 245mV.

[0122] Depend on Figure 5 It can be seen that the OER catalyst in Example 7 is at 10 mA / cm 2 The overpotential of the OER catalyst in Example 8 is 212 mV at 10 mA / cm 2 The overpotential of the OER catalyst in Example 9 is 219 mV at 10 mA / cm 2 The overpotential is 224 mV.

[0123] The above results show that the OER catalyst provided by the embodiment of the present invention exhibits excellent catalytic activity for oxygen evolution reaction, and has the advantages of low overpotential and low Tafel slope.

[0124] 3. The OER catalyst (hereinafter referred to as OER catalyst) of the in situ grown layered transition metal sulfide on the surface of the metal substrate in Example 1 of the present invention was used as the working electrode, the platinum sheet was used as the counter electrode, and the mercury / mercuric oxide electrode was used as the reference electrode. The three-electrode system was tested, and the electrolyte was a 1 mol / L potassium hydroxide (KOH) solution. The system was subjected to linear sweep voltammetry (LSV) tests at 40°C, 60°C, and 80°C, respectively. The results are as follows: Figure 6 As shown; Figure 6 These are the LSV curves of the OER catalyst in Example 1 of the present invention at 40°C, 60°C, and 80°C.

[0125] Depend on Figure 6 It can be seen that at 40 °C, the OER catalyst in Example 1 is 2The overpotential of the OER catalyst in Example 1 is 170mV at 60℃ and 10mA / cm 2 The overpotential of the OER catalyst in Example 1 is 154 mV at 80 °C and 10 mA / cm 2 The overpotential is 140mV.

[0126] These results indicate that the OER catalyst provided in Example 1 of the present invention has the advantage of low overpotential, further illustrating that the OER catalyst provided in the present invention has excellent catalytic activity for oxygen evolution reaction.

[0127] 4. The OER catalyst (hereinafter referred to as OER catalyst) of the in situ grown layered transition metal sulfide on the surface of the metal substrate in Example 1 of the present invention was used as the working electrode, the platinum sheet was used as the counter electrode, and the mercury / mercuric oxide electrode was used as the reference electrode to test the three-electrode system. The electrolyte was a 1 mol / L potassium hydroxide (KOH) solution. The system was tested for operational stability at 25°C. The results are as follows: Figure 7 The system was operated at 25 ° C for 500 h, and the OER catalyst was taken out after 500 h of operation and subjected to morphology testing. The results are shown in Figure 8 As shown; Figure 7 The OER catalyst in Example 1 of the present invention is at 500mA / cm 2 Operation stability test diagram under current density; Figure 8 The OER catalyst in Example 1 of the present invention is at 500mA / cm 2 Cross-sectional SEM image after running in 1 mol / L KOH solution at 25°C for 500 h at a current density of .

[0128] Depend on Figure 7 It can be seen that the OER catalyst provided by the present invention is 2 The stable operation time under high current density conditions can reach 1000 hours (h), indicating that the OER catalyst has excellent operation stability.

[0129] Depend on Figure 8 It can be seen that the OER catalyst provided by the present invention is 2 At a current density of 1.5 wt % and 25 °C, after running in a 1 mol / L KOH solution for 500 h, the layered transition metal sulfide was still firmly attached to the surface of the metal substrate and the structure did not collapse, indicating that the OER catalyst has excellent structural stability.

[0130] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing an OER catalyst by in-situ growth of layered transition metal sulfides on a metal substrate, characterized in that: The following steps are involved: adding a transition metal salt and thiourea into an organic solvent and stirring the mixture to obtain a precursor solution; heating the metal substrate to a target temperature to obtain a metal substrate at the target temperature; The precursor liquid is atomized and then sprayed onto the target surface of the metal substrate at the target temperature, thereby obtaining an OER catalyst with in-situ growth of layered transition metal sulfide on the surface of the metal substrate.

2. The method for preparing an OER catalyst by in-situ growth of layered transition metal sulfides on a metal substrate according to claim 1, characterized in that: The transition metal salt is at least one of nickel chloride, ferric chloride and cobalt chloride.

3. The method for preparing an OER catalyst comprising in-situ growth of layered transition metal sulfides on a metal substrate according to claim 2, wherein: The transition metal salt is composed of nickel chloride and ferric chloride in a first molar ratio, the transition metal salt is composed of nickel chloride and cobalt chloride in a second molar ratio, or the transition metal salt is composed of ferric chloride and cobalt chloride in a third molar ratio; The first molar ratio is (1-3): (1-2); the second molar ratio is (1-3): (1-2); and the third molar ratio is (1-3): (1-2).

4. The method for preparing an OER catalyst by in-situ growth of layered transition metal sulfides on a metal substrate surface according to claim 1, characterized in that: Methods for raising the metal substrate to a target temperature include: The metal substrate was heated to a target temperature of 300-500°C at a heating rate of 2-5°C / min and kept at this temperature for 20-30 minutes.

5. The method for preparing an OER catalyst by in-situ growth of layered transition metal sulfides on a metal substrate surface according to claim 1, characterized in that: The method of atomizing the precursor liquid and spraying it onto the target surface of the metal substrate at the target temperature comprises: The precursor liquid is atomized by ultrasonic atomization spraying technology and then sprayed on the target surface of the metal substrate at the target temperature. During spraying, the spraying height is controlled to be 3-8 cm, the spraying speed is 1-3 mL / min, and the spraying spacing is 5-10 mm.

6. The method for preparing an OER catalyst by in-situ growth of layered transition metal sulfides on a metal substrate surface according to claim 1, characterized in that: In the OER catalyst in which layered transition metal sulfide is in situ grown on the surface of the metal substrate, the thickness of the layered transition metal sulfide is 3-5 μm.

7. The method for preparing an OER catalyst by in-situ growth of layered transition metal sulfides on a metal substrate surface according to claim 1, characterized in that: In the precursor solution, the concentration of the transition metal salt is 0.2-0.8 mol / L, and the concentration of thiourea is 0.2-0.8 mol / L.

8. The method for preparing an OER catalyst comprising in-situ growth of layered transition metal sulfides on a metal substrate according to claim 1, wherein: The organic solvent includes ethanol; and / or, during the stirring process, the rotation speed is 200-400 rpm, the temperature is 20-30° C., and the time is 10-40 min; And / or, the metal substrate is any one of nickel foam, nickel sheet, nickel mesh, iron foam, iron sheet, stainless steel mesh, and stainless steel sheet; And / or, the step of heating the metal substrate to the target temperature further includes cleaning the metal substrate.

9. An OER catalyst comprising an in-situ growth layered transition metal sulfide on a metal substrate, characterized in that: The OER catalyst having layered transition metal sulfides in situ grown on the surface of a metal substrate is prepared by the preparation method of the OER catalyst having layered transition metal sulfides in situ grown on the surface of a metal substrate according to any one of claims 1 to 8.

10. Use of an OER catalyst having layered transition metal sulfide in situ grown on a metal substrate surface prepared by the method for preparing an OER catalyst having layered transition metal sulfide in situ grown on a metal substrate surface according to any one of claims 1 to 8, or an OER catalyst having layered transition metal sulfide in situ grown on a metal substrate surface according to claim 9 in electrocatalytic oxygen evolution.

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