Composite electrocatalyst for oxygen evolution reaction, water splitting device comprising same, and manufacturing method therefor

Abstract

The present invention relates to a composite electrocatalyst for oxygen evolution reaction (OER), a water splitting device (SPD) comprising same, and a manufacturing method therefor. The electrocatalyst comprises a composite including ceramic nanoparticles represented by chemical formula 1. [Chemical formula 1] Pb10-xCux[(PO4)6-y(SO4)6-y]OzSz' (x is a real number of 0.9 to 9.9, y is a real number of 10-10 to 5.9, each of z and z' is a real number of 10-10 to 4, and z+z' is a real number of 10-10 to 4.)

Description

Composite electrode catalyst for oxygen generation reaction, water electrolysis device including the same, and method for manufacturing the same

[0001] The present invention relates to a composite electrocatalyst for an oxygen evolution reaction (OER), a water splitting device (SPD) including the same, and a method for manufacturing the same.

[0002]

[0003] Efforts to explore sustainable, clean, and advantageously efficient energy generation to meet the energy demands of modern society continue unabated. Water electrolysis is a promising method for producing hydrogen, a clean energy source. Water electrolysis using electrode catalysts uses electricity to decompose water into hydrogen and oxygen at the cathode and anode, respectively. These are referred to as the Hydrogen Evolution Reaction (HER) and the Oxygen Evolution Reaction (OER), respectively.

[0004] Electrode catalysts for OER are a critical component of many cutting-edge technologies. However, the slow reaction rate of OER significantly hinders the practical application of these technologies, creating a need for the development of feasible, stable, and inexpensive catalyst systems.

[0005]

[0006] [Prior Art Literature]

[0007] [Patent Literature]

[0008] 1. Korean Registered Patent No. 10-1733492

[0009] 2. Korean Registered Patent No. 10-0785043

[0010] 3. Korean Published Patent No. 10-2011-0033212

[0011] 4. Korean Published Patent No. 10-2023-0030188

[0012] [Non-patent literature]

[0013] 1. Chemistry of Materials (2024), 36(1), 275-285

[0014]

[0015] The present invention aims to solve the technical problems of the existing technology described above, provide a composite that can be utilized as an electrode catalyst for water electrolysis with excellent performance, and a water electrolysis device including the same, thereby achieving the production of green hydrogen by water electrolysis.

[0016]

[0017] One aspect of the present invention relates to ceramic nanoparticles for electrode catalysts represented by the following chemical formula.

[0018] [Chemical Formula 1]

[0019] Pb 10-x Cu x [(PO4) 6-y (SO4) y ]O z S z'

[0020] x is a real number from 0.9 to 9.9, and y is 10 -10 It is a real number of up to 5.9, and

[0021] z and z' are 10 each -10 It is a real number between 4 and 10, and z+z' is 10 -10 It is a mistake of up to 4.

[0022] Another aspect of the present invention relates to a composite comprising (a) a substrate, (b) a nanostructure formed on the substrate, and (c) a plurality of ceramic nanoparticles located on the surface of the nanostructure, wherein the ceramic nanoparticles are represented by the chemical formula 1.

[0023] [Chemical Formula 1]

[0024] Pb 10-x Cu x [(PO4) 6-y (SO4) y ]Oz S z'

[0025] x is a real number from 0.9 to 9.9, and y is 10 -10 It is a real number of up to 5.9, and

[0026] z and z' are 10 each -10 It is a real number between 4 and 10, and z+z' is 10 -10 It is a mistake of up to 4.

[0027] Another aspect of the present invention relates to an electrode catalyst comprising a composite according to various embodiments of the present invention.

[0028] Another aspect of the present invention relates to an electrode for a water electrolysis device comprising a composite according to various embodiments of the present invention.

[0029] Another aspect of the present invention relates to a water splitting device (SPD) comprising (i) a working electrode, (ii) a counter electrode, and (iii) a reference electrode, wherein the working electrode is an electrode for water electrolysis according to various embodiments of the present invention.

[0030] Another aspect of the present invention relates to a method for manufacturing a composite comprising the steps of: (A) forming a plurality of nanostructures on a substrate by a hydrothermal method; and (B) forming a plurality of ceramic nanoparticles represented by Formula 1 on the nanostructures by a vacuum thermal evaporation method.

[0031]

[0032] According to various embodiments of the present invention, the technical problems of the existing technology described above are resolved, and a composite for an electrode catalyst having excellent OER performance, an OER electrode catalyst including the same, a water electrolysis device including the same, and a method for manufacturing the same are provided, and ultimately, green hydrogen production through water electrolysis can be achieved through the same.

[0033]

[0034] Figure 1 schematically illustrates the synthesis of a ceramic@Co(OH)F / CC electrode.

[0035] Figure 2 shows the XRD patterns of the Co(OH)F / CC electrode and the ceramic@Co(OH)F / CC electrode.

[0036] Figure 3 shows the Raman spectra of the ceramic powder and the ceramic @ / CC electrode.

[0037] Figures 4a and 4b show the Co 2p XPS spectra of the Co(OH)F / CC electrode and the ceramic@Co(OH)F / CC electrode, respectively.

[0038] Figures 5a and 5b, 5c and 5d, 5e and 5f are scanning electron microscope (SEM) images of the Co(OH)F / CC electrode, ceramic / CC electrode, and ceramic@Co(OH)F / CC electrode, respectively.

[0039] Figure 6 is an energy dispersive spectroscopy (EDS) elemental mapping image of ceramic@Co(OH)F / CC.

[0040] Figure 7 shows the oxygen evolution reaction (OER) activity of Co(OH)2 / CC, Co(OH)F / CC, and ceramic@Co(OH)F / CC electrodes. Linear sweep voltammetry (LSV) curve (a), 10 mAcm -2 , 50mAcm -2 and 100 mAcm -2 Comparison of overvoltage(??) at constant density (b), Tafel plot derived from LSV curve (c), and Nyquist plot derived from electrochemical impedance spectroscopy (EIS) measurement (d).

[0041]

[0042] Below, various aspects and embodiments of the present invention will be examined in more detail.

[0043] Expressions such as 'includes', 'has', 'is made up', and 'is composed' in this specification may have other parts added unless 'only' is used.

[0044] In addition, where a component is expressed in the singular in this specification, it may also be a plural component unless specifically stated otherwise.

[0045] In addition, numerical values ​​or numerical ranges described in this specification are interpreted to include a margin of error unless otherwise explicitly stated.

[0046] Additionally, the expression "X to Y" indicating a numerical range in this specification means "X or greater and Y or less."

[0047] Embodiments of the present invention will be described in detail below with reference to the drawings. However, detailed descriptions of known functions or configurations that may obscure the essence of the present invention in the following description and the attached drawings are omitted. Additionally, throughout the specification, the term 'comprising' a component means that, unless specifically stated otherwise, it does not exclude other components but may include additional components.

[0048] Unless specifically defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as generally understood by those skilled in the art to which the present invention pertains. Terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology, and should not be interpreted in an ideal or overly formal sense unless explicitly defined in this application.

[0049]

[0050] One aspect of the present invention relates to ceramic nanoparticles for electrode catalysts represented by the following chemical formula.

[0051] [Chemical Formula 1]

[0052] Pb 10-x Cu x [(PO4) 6-y (SO4) y ]O zS z'

[0053] x is a real number from 0.9 to 9.9, and y is 10 -10 It is a real number of up to 5.9, and

[0054] z and z' are 10 each -10 It is a real number between 4 and 10, and z+z' is 10 -10 It is a mistake of up to 4.

[0055] According to various aspects and embodiments of the present invention, the above ceramic may be used as an electrode catalyst, particularly an electrode catalyst for an oxygen evolution reaction (OER); a water electrolysis device including the same; and various other multifunctional materials by forming a composite with a semiconductor oxide.

[0056] If some of the components constituting the ceramic are omitted or fall outside the compositional range, it is undesirable in that the effects according to various aspects and embodiments of the present invention cannot be fully expressed.

[0057] In particular, if some of the components constituting the ceramic are omitted or fall outside the compositional range, unlike the ceramic of the composition according to the present invention, the improvement in electrical conductivity is not effective, and thus the synergistic effect between Co(OH)F and the ceramic may not be observed.

[0058]

[0059] Another aspect of the present invention relates to a composite comprising (a) a substrate, (b) a nanostructure formed on the substrate, and (c) a plurality of ceramic nanoparticles located on the surface of the nanostructure, wherein the ceramic nanoparticles are represented by the chemical formula 1.

[0060] In various aspects of the present invention, according to one embodiment, x in Formula 1 is 2.1 to 9.9. It is desirable that increasing the amount of Cu doping changes the band energy of the ceramic of Formula 1, thereby significantly improving conductivity. However, it is not desirable if the amount exceeds the upper and lower limits above, as the effect of improving conductivity or the effect of improving the electrochemical performance of the composite electrode containing it is negligible.

[0061] According to another embodiment, the above material is one or more selected from carbon cloth, nickel foam, copper foam, graphite paper, carbon fiber paper, stainless steel mesh, and titanium mesh.

[0062] The material of the electrode substrate used in electrochemical water splitting (OER or HER) can have a significant effect on the electrochemical behavior of the electrode catalyst formed thereon. Examples of materials that can be used as a substrate in the present invention may include, but are not limited to, one or more selected from carbon cloth, nickel foam, copper foam, graphite paper, carbon fiber paper, stainless steel mesh, and titanium mesh.

[0063] In the present invention, among the materials described above, carbon cloth or nickel foam is a preferred substrate material. When using carbon cloth or nickel foam, compared to when using other materials, it has a 3D structure, flexibility, excellent electrical conductivity, and a relatively high specific surface area, which has a positive effect on the surface morphology, orientation, and deposition of ceramic nanoparticles of nanostructures such as Co(OH)F, thereby increasing the electrocatalytic active sites.

[0064] In the present invention, carbon cloth is the most preferred substrate material among the above-mentioned materials. In particular, using carbon cloth is most preferable because, unlike when using other substrate materials mentioned above, it is possible to grow nanostructures such as Co(OH)F on the surface of the substrate without using a binder and to deposit multiple ceramic nanoparticles with a uniform distribution thereon.

[0065] According to another embodiment, examples of the nanostructures include, but are not limited to, one or more selected from metal hydroxides such as Co(OH)F, Ni(OH)F, Co(OH)2, and Ni(OH)2; metal oxides such as CoO, Co3O4, and NiO; and metal fluorides such as CoF2, CoF3, and NiF2.

[0066] According to another embodiment, the nanostructure is a metal hydroxide selected from Co(OH)F, Ni(OH)F, Co(OH)2, and Ni(OH)2; or a metal oxide selected from CoO, Co3O4, and NiO; or one or more of these. Nanostructures of these materials are preferred in that they not only have a higher surface area and conductivity, but also can be converted into a highly active metal oxyhydroxide (MOOH, M=metal) intermediate during the OER reaction to exhibit higher OER reaction activity.

[0067] According to another embodiment, the nanostructure is Co(OH)F, Ni(OH)F, Co(OH)2, Ni(OH) 2,The nanostructures of these materials are one or more metal hydroxides selected from among them. The nanostructures of these materials have an electronic structure favorable for charge transfer, exhibiting high OER activity, and have hydroxyl active sites for intermediate adsorption, resulting in a low overpotential for OER. In addition to having stability in alkaline media, they can be easily converted into highly active catalytic phases such as MOOH or MO under OER operating conditions (M=metal), exhibiting high catalytic activity, and can show better interaction with aqueous electrolytes due to their high hydrophilicity, making them even more desirable.

[0068] According to another embodiment, the nanostructure is a plurality of nanosheets.

[0069] According to another embodiment, the plurality of nanostructures are each structurally connected to adjacent nanosheets.

[0070] According to another embodiment, most of the plurality of nanosheets may be formed perpendicular to the surface of the substrate.

[0071] In the present invention, the term 'most' of the plurality of nanosheets refers to 60% or more, preferably 70% or more, more preferably 80% or more, and most preferably 90% or more of the plurality of nanosheets. This vertically formed structure can be confirmed by observing a common structure when morphologically analyzing at least two partial regions of the entire composite.

[0072] According to another embodiment, the preferred average diameter of the plurality of ceramic nanoparticles is 13-35 nm, and the more preferred average diameter is 20-30 nm. Within the preferred range, a satisfactory level of active site density and structural stability can be obtained, and it is particularly more desirable to maximize both the density of active sites and structural stability simultaneously within the preferred range. Outside the preferred range, it is undesirable because sufficient active site density cannot be obtained, or structural stability may be reduced due to aggregation over time caused by high surface energy.

[0073] According to another embodiment, the plurality of ceramic nanoparticles are a unit area (cm²) of the substrate. 2 It is included in an amount of 0.1-1 mg based on ). If it is below the lower limit, the entire surface of the carbon cloth is not sufficiently utilized, which may limit performance and is undesirable; if it exceeds the upper limit, the ceramic nanoparticles are not sufficiently dispersed, which may cause clumping and result in a loss of active surface area and is also undesirable.

[0074] According to another embodiment, the composite is characterized by exhibiting effective peaks at 2θ in the range of 7° to 80° when X-ray diffraction (XRD) is analyzed at 2θ of 24.83°±0.05°, 25.0°±0.05°, 25.18°±0.05°, 29.35°±0.05°, 29.58°±0.05°, 30.02°±0.05°, 35.09°±0.05°, 36.32°±0.05°, 44.30°±0.05°, 51.27°±0.05°, and 66.07°±0.05°. These effective peaks include those caused by ceramic nanoparticles.

[0075] According to another embodiment, the composite exhibits XRD characteristics in which the effective peak for the nanostructure is shifted toward a higher 2θ value than the known effective peak for the nanostructure when X-ray diffraction (XRD) is analyzed at 2θ in the range of 7° to 80°.

[0076] For example, when the material of the nanostructure is Co(OH)F, it is known that the XRD effective peaks of Co(OH)F / CC are observed at 2θ values ​​of 14.44°, 17.25°, 18.90°, 23.94°, 34.52°, and 64.86°; however, in the present invention, effective peaks are observed at 2θ values ​​of 14.48°, 17.32°, 23.99°, and 34.55°, so the XRD effective peaks for the nanostructure can be shifted toward higher 2θ values ​​than the known effective peaks. This may be due to chemical interactions between the ceramic nanoparticles and the nanostructure / substrate, such as Co(OH)F / CC.

[0077] According to another embodiment, the nanostructure comprises a material of Co(OH)F, and the composite, as a result of X-ray photoelectron spectroscopy (XPS) analysis, Co 3+ The binding energy of and Co 2+ The ratio of the bond energies of (Co 3+ / Co 2+ ) is 2.5 to 3.5.

[0078] When the binding energy ratio within the above range is excellent, charge separation and transfer are facilitated more easily, and as a result, the electrocatalytic activity of the composite can be significantly enhanced.

[0079] Another aspect of the present invention relates to an electrode catalyst comprising a composite according to various embodiments of the present invention.

[0080] According to one embodiment, the electrode catalyst is for an oxygen evolution reaction (OER).

[0081] Another aspect of the present invention relates to an electrode for a water electrolysis device comprising a composite according to various embodiments of the present invention.

[0082] According to one embodiment, the electrode for water electrolysis is for an oxygen generation reaction.

[0083] Another aspect of the present invention relates to a water splitting device (SPD) comprising (i) a working electrode, (ii) a counter electrode, and (iii) a reference electrode, wherein the working electrode is an electrode for water electrolysis according to various embodiments of the present invention.

[0084] Another aspect of the present invention relates to a method for manufacturing a composite comprising the following steps.

[0085] (A) A step of forming a plurality of nanostructures on a substrate by a hydrothermal method, and

[0086] (B) A step of forming a plurality of ceramic nanoparticles represented by Chemical Formula 1 on the nanostructure by vacuum thermal evaporation.

[0087] The above-described manufacturing method of the present invention is considered to have a distinctive advantage in that it enables the production of a composite composed of (ceramic nanoparticles)@nanostructures / substrates or an electrode containing the same without using a separate binder. While strong adhesion between the components is secured without the use of a separate binder, conductivity and accessibility to the active site can be significantly improved due to the absence of a separate binder.

[0088] Furthermore, according to the method of the present invention, the ceramic powder is evaporated in a vacuum state through a thermal evaporation system due to high-temperature heating, and the vapor particles move to reach the substrate directly and are converted back into a solid state. Therefore, not only is the structural integrity of the material guaranteed during this solidification process, but it also has the advantage of allowing active components to be uniformly distributed across the entire substrate.

[0089] In addition, the high vacuum environment adopted in the method of the present invention not only minimizes the incorporation of impurities into the substrate, but also adopts a thermal evaporation method that does not use any solvent, thereby eliminating the problem of damage to the lower part of the substrate caused by the use of solvents in existing technologies, which is of great significance to the method of the present invention.

[0090] According to one embodiment, the vacuum thermal evaporation method is performed by evaporating the ball-milled powder of the ceramic nanoparticles in a reduced pressure chamber in which the nanostructure is located.

[0091] According to one embodiment, the substrate is one or more selected from carbon cloth, nickel foam, copper foam, graphite paper, carbon fiber paper, stainless steel mesh, and titanium mesh.

[0092] According to another embodiment, the nanostructure is Co(OH)F, Co(OH)2, CoO, Co3O4, CoF2, CoF3, NiO, NiF 2, It is one or more selected from Ni(OH)2 and Ni(OH)F.

[0093] According to another embodiment, the nanostructure is a plurality of nanosheets.

[0094] According to another embodiment, the plurality of nanostructures are each structurally connected to adjacent nanosheets.

[0095] According to another embodiment, at least 60%, preferably at least 70%, more preferably at least 80%, and most preferably at least 90% of the plurality of nanosheets are formed perpendicular to the surface of the substrate.

[0096] According to another embodiment, the nanostructure is Co(OH)F, and the amount of F precursor added to form Co(OH)F by a hydrothermal method in step (a) is 1-10 g based on 100 g of Co precursor added, preferably 4-6 g. When added within the preferred range, the Co(OH)F nanostructure formed is excellent in terms of structural and surface morphology, and thus has electrochemical properties and OH - It exhibits the effect of simultaneously improving water solubility, ion transportability, electronic conductivity, and electrochemical activity.

[0097] According to another embodiment, the plurality of ceramic nanoparticles have an average diameter of 13-35 nm.

[0098] According to another embodiment, the plurality of ceramic nanoparticles are a unit area (cm²) of the substrate. 2 It is included in an amount of 0.1-1 mg based on ). If it is below the lower limit, the entire surface of the carbon cloth is not sufficiently utilized, which may limit performance and is undesirable; if it exceeds the upper limit, the ceramic nanoparticles are not sufficiently dispersed, which may cause clumping and result in a loss of active surface area and is also undesirable.

[0099] According to another embodiment, x is 2.1 to 9.9.

[0100] Increasing the amount of Cu doping is desirable because it changes the band energy of the ceramic of Formula 1, which can significantly improve conductivity. However, if it deviates from the upper and lower limits, it is not desirable because the effect of improving conductivity or the effect of improving the electrochemical performance of the composite electrode containing it is negligible.

[0101]

[0102] The present invention is to be explained in more detail below through examples, etc.; however, the scope and content of the present invention shall not be interpreted as being narrowed or limited by the examples, etc. below. Furthermore, based on the disclosure of the present invention including the examples below, it is evident that a person skilled in the art can easily practice the present invention even without specific experimental results presented, and it is natural that such variations and modifications fall within the scope of the appended claims.

[0103] Furthermore, the experimental results presented below describe only the representative experimental results of the above examples and comparative examples, and the respective effects of various embodiments of the present invention not explicitly presented below will be described in detail in the relevant sections.

[0104] Examples

[0105] chemical substances

[0106] Cobalt (II) nitrate hexahydrate (Co(NO3)2·6H2O), urea (CO(NH2)2), ammonium fluoride (NH4F), and ceramic powder were used as precursors, and deionized water (DI) and ethanol (C2H5OH) were used as solvents. All chemicals used were AR grade and used without further purification.

[0107] Preparation Example 1: Ceramic Preparation

[0108] Powders of PbO, PbSO4, Cu, and P were prepared in the molar ratio of the molecule to be synthesized and uniformly mixed. The mixture was placed in a reaction tube (quartz or copper tube), vacuum was created, and the tube was sealed. The reaction was carried out by heating at 770 °C for 12 hours in the first stage. After the reaction was completed, the granules formed in the reaction tube were powdered, and the pressure was reduced to a near-vacuum state and heated at 550 °C for 5 hours in the second stage. Through this process, solid sulfur was sublimated, and the ceramic was manufactured by removing the sublimated sulfur in the molar ratio through an evacuation process.

[0109] For example, when synthesizing a ceramic with a Cu doping amount controlled to 2 moles, the raw materials are mixed with a molar ratio of PbO : PbSO4 : Cu : P = 2 : 6 : 2 : 6, and as another example, the composition is Pb 7.38 Cu 2.62 (PO4) 5.46 (SO4) 0.54 O 0.66 S 0.84 When synthesizing phosphorus ceramics, the raw materials are mixed with a molar ratio of PbO : PbSO4 : Cu : P = 1.38 : 6 : 2.62 : 6.

[0110] Preparation Example 2: Preparation of Ceramic Ball Milling Powder

[0111] Pb 7.38 Cu 2.62 (PO4) 5.46 (SO4) 0.54 O 0.66 S 0.84 A ceramic (structure confirmed via XPS and XRD, average molecular weight 2,303) was ball-milled at 500 rpm for 6 hours to obtain ball-milled powder of the ceramic of Formula 1.

[0112] Comparative Manufacturing Example 1: Ceramic Manufacturing

[0113] Pb9Cu(PO4)6O (CAS No. 2972464-09-6) was prepared according to a known method, such as Chemistry of Materials (2024), 36(1), 275-285.

[0114] Comparative Manufacturing Example 2: Ceramic Manufacturing

[0115] Pb9Cu(PO4) according to the method disclosed in Korean Published Patent No. 10-2023-0030188 (Patent Application No. 10-2021-0112104) 5.5 (SO4) 0.5 S 3.5 Manufactured.

[0116]

[0117] Example: Ceramic@Co(OH)F / CC Electrode Synthesis

[0118] (1) Co(OH)F was grown hydrothermally in situ on a CC substrate without a binder as follows.

[0119] Specifically, 2 mmol of cobalt precursor Co(NO3) 2· 6H2O, 4 mmol of CO(NH2)2, and 1, 2, 5, 6, 8, and 10 wt% of NH4F based on the weight of the cobalt precursor were dispersed in 35 mL of DI H2O. Then, the homogeneous solution was transferred to a Teflon-lined autoclave, and activated CC pieces were immersed in the homogeneous solution. The mixture was placed in the autoclave and heated at 140°C for 12 hours. After the hydrothermal reaction, the CC pieces were removed, washed several times with DI H2O and C2H5OH, and vacuum dried for 12 hours.

[0120] (2) After that, ① ceramic / CC and ② ceramic@Co(OH)F / CC electrodes were prepared using the vacuum thermal evaporation method as follows.

[0121] Specifically, a specific amount of the ceramic ball-milled powder prepared in Preparation Example 2 above was filled into a tungsten metal boat, a carbon cloth substrate was placed in a substrate holder facing the material source, and then the chamber was closed using a vacuum. After tightly closing the chamber lid, a rotary pump was operated so that the pressure was 5×10 -5 It was operated until Torr was reached. After reaching the target pressure, the current source (16-19A) was operated for various deposition times. Then, the filament current was turned off to stop the deposition process.

[0122] Comparative Examples 1 and 2: Ceramic@Co(OH)F / CC Electrode Synthesis

[0123] Ceramic@Co(OH)F / CC electrodes were prepared in the same manner as in the example, except that the ceramics prepared in Comparative Examples 1 and 2 were used instead of the ceramic prepared in Example 1 (Comparative Examples 1 and 2, respectively).

[0124]

[0125] Test Example: Measurement of Electrode Catalyst OER Performance

[0126] (1) Test method

[0127] The electrode catalyst OER test was measured using a BioLogic VSP-3e Potentiostat with a standard three-electrode setup. The CC-phase electrode catalyst, Pt wire, and saturated Ag / AgCl prepared in the above example were used as the working electrode, counter electrode, and reference electrode, respectively. The measured potential was converted to the reversible hydrogen electrode (RHE) using the equation E(vs. RHE) = E(vs. Ag / AgCl) + 0.197 + 0.0591 × pH. The linear sweep voltammetry (LSV) plot was 5 mVs -1 Measurements were taken in a 1M KOH aqueous electrolyte (pH 14) at a scan rate. Electrochemical impedance spectroscopy (EIS) was performed in a frequency range of 0.01 Hz to 100 kHz.

[0128] (2) XRD analysis results

[0129] As shown in Figure 1, ceramic / CC, Co(OH)F / CC, and ceramic@Co(OH)F / CC electrodes were synthesized and confirmed through XRD crystal structure analysis.

[0130] As shown in Fig. 2, the two peaks at 25.5° and 42.9° are peaks associated with the graphite carbon lattice planes (002) and (100) of the CC substrate (JCPDS No. 012-0212), and the XRD peaks with 2θ of 14.46°, 17.25°, 18.90°, 23.94°, 34.52°, and 64.86° are all attributed to Co(OH)F, which confirms that the hydrothermal reaction played a role in growing the material on the CC substrate. Additionally, new peaks appeared as the vacuum thermal evaporation system deposited the ceramic material onto the Co(OH)F / CC electrode, and it was confirmed that the main Co(OH)F peak of the composite material shifted slightly to a higher diffraction angle.

[0131] (3) Raman spectroscopic analysis results

[0132] Raman measurement results confirmed that ceramic was successfully deposited on the CC substrate via vacuum thermal evaporation, as shown in Fig. 3. Observations revealed that the vacuum-deposited ceramic on the CC exhibited a spectrum similar to the known LK-99 powder, and at 400-600 cm⁻¹ -1 and 800-950cm -1 The spectral peak in the range is the phosphate group (PO4 3- It corresponds to ), which means that the deposition process preserves the structural integrity of LK-99. In addition, the presence of these peaks indicates that important chemical properties capable of playing a significant role in the material's potential applications have been maintained.

[0133] (4) XPS analysis results

[0134] XPS studies were performed on Co(OH)F / CC and ceramic@Co(OH)F / CC electrodes to investigate in more detail the effect of the deposited ceramic material on the surface of Co(OH)F / CC nanosheets.

[0135] Figures 4a and 4b are high-resolution spectra of Co 2p, Co 2p 3 / 2 and Co 2p 1 / 2 It shows two spin-orbital doublets and two shakeup satellite peaks called "Sat". This indicates that Co for all samples 3+ and Co 2+ Indicates that species are included. Co2p XPS spectrum of Co(OH)F / CC Co 3+ In the case of 780.15 / 796.20 eV, Co 2+ In this case, it can be deconvolved into two spin-orbital doublets of 782.16 / 797.88 eV. In contrast to Co(OH)F / CC, the Co2p spectrum of ceramic@Co(OH)F / CC can be confirmed to have shifted to high binding energies.

[0136] Also, ceramic@Co(OH)F / CC is Co3+ / Co 2+ It was confirmed that the value was 3, exhibiting a higher Co3+ / Co2+ value than Co(OH)F / CC with a value of 1.2, indicating that interfacial polarization was improved after the ceramic was deposited on Co(OH)F / CC. This enhancement in interfacial polarization is due to the intrinsic electronic structure of the ceramic, which facilitates better charge separation and transfer. Consequently, the improved Co 3+ / Co 2+ The ratio represents an environment more favorable for catalytic reactions, which can increase the overall efficiency of materials in OER applications.

[0137] (5) Results of morphological analysis

[0138] Morphological studies analyzed the characteristics of Co(OH)F nanostructures grown in situ on CC substrates. Figures 5a and 5b illustrate the process of uniformly fabricating thin Co(OH)F nanosheets on CC via a hydrothermal method. The nanosheets are interconnected and are confirmed to be mostly perpendicular to the CC. Meanwhile, the ceramic material was successfully and firmly loaded onto the framework of the CC substrate via vacuum evaporation (Figures 5c and 5d). Notably, even after bonding, Co(OH)F and the ceramic maintain similar morphological structures, as shown in Figures 5e and 5f. The ceramic@Co(OH)F consists of many 20-30 nm ceramic nanoparticles embedded within the Co(OH)F nanosheets on the CC surface.

[0139] (6) Element mapping analysis results

[0140] The elemental mapping image (Fig. 6) further confirms the presence of all elements of the ceramic@Co(OH)F / CC electrode, showing that the ceramic was successfully deposited on the Co(OH)F surface.

[0141] (7) OER electrode catalyst activity evaluation results

[0142] The catalytic activity of three types of electrodes—Co(OH)2 / CC, Co(OH)F / CC, and ceramic@Co(OH)F / CC—for OER in an alkaline medium (1 M KOH, pH 14) was evaluated using a 3-electrode system with iR compensation. As a result, the ceramic@Co(OH)F / CC electrode exhibited superior catalytic performance compared to other electrodes, with reduced overpotential and lower starting potential, which demonstrates that ceramics significantly improve the overall efficiency of the OER process under alkaline conditions.

[0143] Linear sweep voltammetry (LSV) curves (Figs. 7a and 7b) show that the Co(OH)2 / CC electrode at a current density of 10 mA cm⁻¹ -2 At [time], a high overpotential (η) of 412 mV was observed, and the Co(OH)F / CC electrode showed an η value of 239.4 mV. Interestingly, however, the ceramic@Co(OH)F / CC showed an η value of 141.3 mV, confirming that it has a significantly lower η value than the Co(OH)2 / CC and Co(OH)F / CC electrodes. This implies that it exhibits excellent catalytic activity for OER applications. Furthermore, the η value (141.3 mV) of the ceramic@Co(OH)F / CC is significant in that it can be evaluated as having superior performance compared to most previously reported synthetic catalysts for OER.

[0144] Also, as can be seen in Fig. 7c, the ceramic@Co(OH)F / CC electrode has a Tafel slope (105.6 mV / dec) of the Co(OH)2 / CC electrode. -1 ) and Tafel slope of Co(OH)F / CC electrode (91.5 mV dec -1 A relatively very low Tafel slope (83.9 mVdec) compared to ) -1 It was confirmed that it exhibits ), which means it has the best response speed for OER.

[0145] In addition, electrical conductivity and charge mobility were improved by depositing ceramic on the Co(OH)F / CC electrode, which can be confirmed in the EIS Nyquist plot of Fig. 7d. Specifically, the charge transfer resistance (R) measured in the high-frequency region ct The ceramic@Co(OH)F / CC electrode has a resistance of 0.6Ω, the Co(OH)2 / CC electrode has a resistance of 16.4Ω, and the Co(OH)F / CC electrode has a resistance of 3.5Ω, which shows that the LK-99 embedded in the ceramic@Co(OH)F / CC electrode induces faster electrode / electrolyte surface kinetics in the OER. This improvement in kinetics implies that the interaction between the ceramic and electrode materials significantly improves the efficiency of the OER.

[0146]

[0147] As seen above, in an embodiment of the present invention, a composite that can be used as an electrode catalyst for OER in the field of water electrolysis was prepared by vacuum deposition of a ceramic material of Formula 1 using a thermal evaporation system on cobalt hydroxyfluoride (Co(OH)F) grown hydrothermally on a carbon cloth (CC) substrate.

[0148] In addition, the present invention analyzed the fabricated electrodes using various structural and morphological techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS).

[0149] Raman spectroscopy analysis confirmed that the ceramic material was successfully deposited on the CC substrate using vacuum thermal evaporation. Additionally, SEM / EDS analysis confirmed the presence of all elements (Pb, P, O, Cu, S, Co, and F) of the ceramic@Co(OH)F on the CC substrate. Furthermore, XPS analysis confirmed that the ceramic material and Co(OH)F engage in strong electronic interactions capable of altering interfacial charges by enhancing electron transfer.

[0150] In addition, electrode catalyst activity tests for OER of ceramic@Co(OH)F / CC were performed in an alkaline medium (1M KOH aqueous electrolyte). It was confirmed that the ceramic@Co(OH)F / CC electrode exhibited superior performance compared to Co(OH)2 / CC and Co(OH)F / CC catalysts.

[0151] Due to distinct oxygen generation accompanied by high current density at low positive potential, the current density increases rapidly after the initial stabilization region to 10 mA cm -2 (η 10 At ), the overvoltage is 141.3mV and the Tafel slope is 83.9mVdec -1 It showed distinct electrochemical OER activity.

[0152] As such, the present invention has confirmed that the synergistic interaction between the ceramic material and Co(OH)F improves electrical conductivity and facilitates rapid alkaline water decomposition, thereby providing excellent OER performance.

[0153] In addition, although drawings and the like were not presented, it was confirmed that the ceramic@Co(OH)F / CC electrodes prepared in Comparative Examples 1 and 2, respectively, not only showed significantly lower overall electrode catalyst activity, including final water decomposition performance, compared to the ceramic@Co(OH)F / CC electrode of the example, but also did not show effective improvement in electrical conductivity, unlike the ceramic@Co(OH)F / CC electrode of the example, and thus no synergistic effect between Co(OH)F and ceramic was observed.

Claims

1. Ceramic nanoparticles for electrode catalysts represented by the following chemical formula: [Chemical Formula 1] Pb 10-x With x [(PO4) 6-y (SO4) y ]A z S z' x is a real number from 0.9 to 9.9, and y is 10 -10 It is a real number of up to 5.9, and z and z' are 10 each -10 It is a real number between 4 and 10, and z+z' is 10 -10 It is a mistake of 4.

2. A composite comprising (a) a substrate, (b) a nanostructure formed on the substrate, and (c) a plurality of ceramic nanoparticles located on the surface of the nanostructure; A composite characterized by the above ceramic nanoparticles being represented by the following chemical formula: [Chemical Formula 1] Pb 10-x With x [(PO4) 6-y (SO4) y ]A z S z' x is a real number from 0.9 to 9.9, and y is 10 -10 It is a real number of up to 5.9, and z and z' are 10 each -10 It is a real number between 4 and 10, and z+z' is 10 -10 It is a mistake of 4.

3. A composite according to paragraph 2, characterized in that the above-mentioned material is one or more selected from carbon cloth, nickel foam, copper foam, graphite paper, carbon fiber paper, stainless steel mesh, and titanium mesh.

4. In paragraph 2, the nanostructures are Co(OH)F, Co(OH)2, CoO, Co3O4, CoF2, CoF3, NiO, NiF 2, A composite characterized by being one or more selected from Ni(OH)2 and Ni(OH)F.

5. A composite according to paragraph 2, characterized in that the nanostructure is a plurality of nanosheets.

6. In paragraph 5, the plurality of nanostructures are each structurally connected to adjacent nanosheets, and A composite characterized in that at least 60% of the plurality of nanosheets are formed perpendicular to the surface of the substrate.

7. A composite according to claim 2, characterized in that the plurality of ceramic nanoparticles have an average diameter of 13-35 nm.

8. In paragraph 2, the plurality of ceramic nanoparticles are a unit area (cm²) of the substrate. 2 A complex characterized by containing 0.1-1 mg based on ).

9. A composite according to paragraph 2, characterized in that x is 2.1 to 9.

9.

10. In paragraph 2, the above complex, based on the X-ray diffraction (XRD) analysis results, 2θ shows an effective peak at 7° to 80°, and A composite characterized in that the effective peak for the above nanostructure is shifted in the direction of a higher 2θ value than the known effective peak for the above nanostructure.

11. In paragraph 2, the nanostructure comprises a material of Co(OH)F, and The above complex, as a result of X-ray photoelectron spectroscopy (XPS) analysis, Co 3+ The binding energy of and Co 2+ The ratio of the bond energies of (Co 3+ / Co 2+ A complex characterized by ) being 2.5 to 3.

5.

12. An electrode catalyst characterized by comprising a complex according to any one of claims 2 to 11.

13. An electrode catalyst according to claim 12, characterized in that the electrode catalyst is for an oxygen evolution reaction (OER).

14. An electrode for a water electrolysis device characterized by comprising a composite according to any one of claims 2 to 11.

15. An electrode for water electrolysis according to claim 14, characterized in that the electrode for water electrolysis is for an oxygen generation reaction.

16. A water splitting device (SPD) comprising (i) a working electrode, (ii) a counter electrode, and (iii) a reference electrode, wherein A water electrolysis device characterized in that the above-mentioned working electrode is an electrode for water electrolysis according to claim 15.

17. A method for manufacturing a composite comprising the following steps: (A) A step of forming a plurality of nanostructures on a substrate by a hydrothermal method, and (B) A step of forming a plurality of ceramic nanoparticles on the above nanostructure by vacuum thermal evaporation; A method for preparing a composite characterized in that the ceramic nanoparticles are represented by the following chemical formula 1: [Chemical Formula 1] Pb 10-x With x [(PO4) 6-y (SO4) y ]A z S z' x is a real number from 0.9 to 9.9, and y is 10 -10 It is a real number of up to 5.9, and z and z' are 10 each -10 It is a real number between 4 and 10, and z+z' is 10 -10 It is a mistake of 4.

18. A method for manufacturing a composite according to claim 17, wherein the vacuum thermal evaporation method is performed by evaporating the ball-milled powder of the ceramic nanoparticles in a reduced pressure chamber in which the nanostructure is located.

19. In paragraph 17, the above description is one or more selected from carbon cloth, nickel foam, copper foam, graphite paper, carbon fiber paper, stainless steel mesh, and titanium mesh, and The above nanostructures are Co(OH)F, Co(OH)2, CoO, Co3O4, CoF2, CoF3, NiO, NiF 2, A method for manufacturing a composite characterized by having one or more selected from Ni(OH)2 and Ni(OH)F.

20. In paragraph 17, the nanostructure is a plurality of nanosheets, and Each of the above multiple nanostructures is structurally connected to an adjacent nanosheet, and A method for manufacturing a composite, characterized in that at least 60% of the plurality of nanosheets are formed perpendicular to the surface of the substrate.

21. In paragraph 17, the plurality of ceramic nanoparticles have an average diameter of 13-35 nm, and The plurality of ceramic nanoparticles above are based on a unit area (cm²) of the above-mentioned substrate. 2 A method for manufacturing a complex characterized by containing 0.1-1 mg based on ).

22. A method for manufacturing a composite according to claim 17, wherein x is 2.1 to 9.

9.

23. In paragraph 17, the nanostructure is Co(OH)F, and A method for manufacturing a composite, characterized in that the amount of F precursor introduced for the formation of Co(OH)F in step (a) above is 1-10 g based on the amount of Co precursor introduced, which is 100 g.

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