KR20230026606A - Multi-functional catalyst for water electrolysis in which transition metal-chalcogen compound is electrodeposited, catalyst electrode using same, and method for manufacturing the same. - Google Patents

Abstract

A catalyst applied to a water electrolysis system and a catalyst electrode using the same are disclosed. The catalyst has a transition metal chalcogen compound. The catalyst electrode is made of a hydrophilic coating film and a TMCs catalyst layer. As the hydrophilic coating film is formed, the TMCs catalyst layer can be easily formed. Hydrogen generation and oxygen generation operations may be simultaneously performed at one electrode.

Description

Multi-functional catalyst for water electrolysis in which transition metal-chalcogen compound is electrodeposited, catalyst electrode using same, and method for producing the same manufacturing the same.}

The present invention relates to a catalyst electrode for water electrolysis, and more particularly, to a catalyst electrode for water electrolysis prepared by electrodepositing a transition metal-chalcogen compound on a conductive substrate.

Recently, research to develop alternative energy sources has been actively conducted in response to energy crisis and environmental problems caused by fossil fuel consumption. In particular, water electrolysis (water electrolysis) is in the spotlight as an energy source that can replace fossil fuels in terms of producing energy without harm.

However, the oxygen evolution reaction (OER) of the water electrolysis reaction has a very slow reaction rate, so that a large amount of overvoltage must be supplied for normal operation of the water electrolysis system, resulting in a large loss in terms of energy. In addition, in the case of a catalyst for generating hydrogen, platinum is widely used, but it is acting as a factor in increasing the price of a water electrolysis system due to the problem of being a precious metal. These problems act as an obstacle to the commercialization of the system, and to solve the problem, it is necessary to develop a non-precious metal-based water electrolysis catalyst electrode with high activity and good durability.

In the case of the hydrogen evolution reaction (HER), the reaction rate is fast, but it is considered a problem in terms of commercialization of the system because a commonly used catalyst is based on platinum. Recently, studies on MoS, NiFe, and CoW as non-noble metal catalysts have been actively conducted, and alternative catalysts having better activity than platinum have been reported. there is.

Transition metal chalcogenides (TMCs) may be used as the catalyst, and it is simple and mass-produced when prepared using a solution phase synthesis process. However, in the solution phase synthesis process, it is not easy to control the structure of the transition metal chalcogen compound.

Therefore, for commercialization or large-scale water electrolysis system, there is a need for a catalytic electrode and a method for manufacturing the catalytic electrode capable of accurately controlling the composition by using a low-cost material as a catalytic material in a simple method.

Korean Patent Publication No. 10-2016-0127885

One embodiment of the present invention is a substrate having electrical conductivity; A hydrophilic coating layer formed on the substrate; and a TMCs catalyst layer formed on the coating layer.

Another embodiment of the present invention comprises preparing an electrolyte for electrodeposition in which a transition metal precursor and a chalcogen precursor are dispersed; and introducing the electrolyte into a two-electrode system using a conductive substrate as a working electrode and a counter electrode to perform electro-deposition.

The technical problem to be achieved by the present invention is not limited to the above-mentioned technical problem, and other technical problems not mentioned can be clearly understood by those skilled in the art from the description below. There will be.

In order to achieve the above technical problem, one embodiment of the present invention provides a multifunctional TMCs catalyst electrode for water electrolysis and a manufacturing method thereof. The TMCs multifunctional catalytic electrode for water electrolysis includes a substrate having electrical conductivity; a hydrophilic coating layer formed on the substrate; and a TMCs catalyst layer formed on the hydrophilic coating layer.

The electrically conductive substrate may be any one of nickel, copper, titanium, tungsten, aluminum, silver, stainless steel, carbon, iron, cobalt, molybdenum, and graphene.

The hydrophilic coating layer may be metal nitrate or carbon nitride.

The metal nitrate may be NiNO ₃ .

The TMCs catalyst layer is TiS, ZrS, HfS, VS, NbS, TaS, MoS, WS, TcS, ReS, CoS, RhS, IrS, NiS, PdS, PtS, FeS, TiSe, ZrSe, HfSe, VSe, NbSe, TaSe, MoSe, WSe, TcSe, ReSe, CoSe, RhSe, IrSe, NiSe, PdSe, PtSe, FeSe and NiS _0.5 Se _0.5 .

The TMCs catalyst layer may be any one of NiS, NiSe, FeSe, and NiS _0.5 Se _0.5 .

The manufacturing method of the TMCs multi-function catalyst electrode for water electrolysis includes preparing an electrolyte for electrodeposition in which a transition metal precursor and a chalcogen precursor are dispersed; and preparing a TMCs catalytic electrode by introducing the electrolyte for electrodeposition into a two-electrode system using the substrate having electrical conductivity as a working electrode and a counter electrode and performing electrodeposition to prepare a TMCs catalyst electrode, wherein the electrodeposition is performed from a power source. A positive current flowing in the direction of the working electrode may be applied for a predetermined period of time, and then a negative current, in which the positive current and the current flow in opposite directions, may be applied for a predetermined period of time.

Between the step of preparing the electrolyte for electrodeposition and the step of preparing the TMCs catalyst electrode by performing the electrodeposition, in order to remove the oxidized surface of the electroconductive substrate, it was washed with hydrochloric acid, distilled water, and ethanol in this order and then dried in an oven. A pre-processing process may be further included.

When the positive current is applied for a predetermined period of time, the hydrophilic coating layer may be formed on the electrically conductive substrate.

When the negative current is applied for a certain period of time, a TMCs catalyst layer may be formed on the hydrophilic coating layer.

The time for applying the positive current and negative current may be 10 minutes to 20 minutes.

The value of the positive current may be 40 to 60 mA/cm ² .

The value of the negative current may be 40 to 60 mA/cm ² .

The transition metal precursor is Co(NO ₃ ) ₂ 6H ₂ O, Fe(NO ₃ ) ₂ 9H ₂ O, Na ₂ MoO ₄ 2H ₂ O, Ni(NO ₃ ) ₂ 6H ₂ O and Na ₂ WO It may be any one of _{4.2H 2} O.

The transition metal precursor may be added at a concentration of 0.01 mM to 0.05 mM compared to the electrolyte for electrodeposition.

The chalcogen precursor may be any one of CH ₄ N ₂ S and SeO ₂ .

The chalcogen precursor may be added at a concentration of 0.01 mM to 0.05 mM compared to the electrolyte for electrodeposition.

The electrolyte for electrodeposition may further include a pH adjusting agent.

The pH adjusting agent may be ethanol amine.

According to an embodiment of the present invention, a hydrophilic coating layer and a TMCs catalyst layer are formed in a double layer structure on a substrate having electrical conductivity, and the TMCs catalyst layer is easily formed by the hydrophilic coating layer, which saves time compared to conventional manufacturing processes. It can be, and it can be large-area.

According to an embodiment of the present invention, the TMCs catalyst layer is formed by electrodeposition on the substrate using an electrolyte containing a transition metal precursor and a chalcogen precursor, thereby more accurately controlling the composition of the catalyst and applying it to a water electrolysis system. stability can be maintained.

The effects of the present invention are not limited to the above effects, and should be understood to include all effects that can be inferred from the detailed description of the present invention or the configuration of the invention described in the claims.

1 is a view for explaining the structure of a catalyst electrode including a TMCs catalyst layer according to an embodiment of the present invention.
2 is a schematic explanatory view of an apparatus for manufacturing a catalyst electrode using a galvanostatic method according to an embodiment of the present invention.
3 is a flow chart showing a method of manufacturing a catalyst electrode including a TMCs catalyst layer according to an embodiment of the present invention.
4 is an XPS spectrum of TMCs catalytic electrodes according to an embodiment of the present invention.
5 is SEM and EDS images of TMCs catalytic electrodes according to an embodiment of the present invention.
6 is a graph evaluating HER performance of TMCs catalytic electrodes according to an embodiment of the present invention.
7 is a graph evaluating the OER performance of TMCs catalyst electrodes according to an embodiment of the present invention.
8 is a graph synthesizing HER performance and OER performance of TMCs catalytic electrodes according to an embodiment of the present invention.
9 is a graph evaluating HER performance and OER performance of a TMCs catalyst electrode whose composition is controlled according to an embodiment of the present invention.
10 is a graph evaluating the catalytic stability of a TMCs catalyst electrode having a controlled composition according to an embodiment of the present invention.
11 is a graph evaluating the performance and stability of both cells of the TMCs catalyst electrode according to an embodiment of the present invention.

Since the present inventive concept described below may be applied with various transformations and may have various embodiments, specific embodiments are exemplified in the drawings, and the detailed description will be described in detail. However, this is not intended to limit the present creative idea to a specific embodiment, and should be understood to include all transformations, equivalents, or substitutes included in the technical scope of the present creative idea.

Terms used below are only used to describe specific embodiments, and are not intended to limit the present inventive idea. Singular expressions include plural expressions unless the context clearly dictates otherwise. Hereinafter, the terms “include” or “have” are intended to indicate that there is a feature, number, step, operation, component, part, component, material, or combination thereof described in the specification, but one or the other It should be understood that the presence or addition of the above other features, numbers, steps, operations, components, parts, components, materials, or combinations thereof is not precluded.

In the drawings, the thickness is enlarged or reduced to clearly express various layers and regions. Like reference numerals have been assigned to like parts throughout the specification. Throughout the specification, when a part such as a layer, film, region, plate, etc. is said to be “on” or “on” another part, this includes not only the case directly above the other part, but also the case where another part is in the middle. . Throughout the specification, terms such as first and second may be used to describe various components, but the components should not be limited by the terms. Terms are used only to distinguish one component from another.

Although the terms first, second, etc. may be used to describe various elements, components, regions, layers and/or regions, these elements, parts, regions, layers and/or regions It will be understood that one should not be limited by these terms.

In one embodiment of the present invention, a catalyst capable of generating oxygen gas and/or hydrogen gas from water and an electrode using the same are provided. The electrode works like a catalyst. That is, the electrode can catalytically produce oxygen gas or hydrogen gas from water, but the electrode does not necessarily participate in the chemical reaction involved, and thus is consumed to any appreciable degree.

The catalyst used in one embodiment of the present invention is related to and increases the rate of the chemical electrolysis reaction (or other electrochemical reaction), and participates in the reaction as part of the electrolysis itself, but by the reaction itself. It refers to a substance that is largely non-consumable and thus capable of participating in multiple chemical transformations. A catalytic material may also refer to a catalyst and/or a catalytic composition. The catalytic material is not simply a bulk current collector material that either donates or accepts electrons from an electrolysis reaction, but is a material that changes the chemical state of one or more ions during the catalytic process. For example, the catalytic material is given its usual meaning in one oxidation state during a catalytic process. It will be appreciated from other descriptions herein that the catalytic material of the present invention may be consumed in small amounts during a particular use and, in many embodiments, may be regenerated to its original chemical state.

The catalyst electrode used in the present invention is an electrode coated on a substrate having electrical conductivity with a catalyst material having excellent HER performance and OER performance at the same time. The catalytic material may include a transition metal and a chalcogen.

Hereinafter, a catalyst for water electrolysis according to exemplary embodiments, an electrode to which the same is applied, and a manufacturing method thereof will be described in more detail with reference to the drawings.

1 is a view for explaining the structure of a catalyst electrode including a TMCs catalyst layer according to an embodiment of the present invention.

Referring to FIG. 1 , the catalytic electrode 100 may have a structure in which a double layer composed of a hydrophilic coating layer 20 and a TMCs catalyst layer 30 is deposited on an electrically conductive substrate 10 .

The electrically conductive substrate 10 is not limited as long as it is a metal substrate having excellent conductivity, and specifically, any one of nickel, copper, titanium, tungsten, aluminum, silver, stainless steel, carbon, iron, cobalt, molybdenum, and graphene. can be

The nickel is a non-noble metal catalyst and is economical because its price is lower than that of a noble metal catalyst generally used in a water electrolysis system. According to one embodiment, the nickel may include at least one selected from nickel foam, a nickel plate, a nickel wire, and a nickel rod, and specifically may be nickel foam or nickel metal. .

The nickel foam may be provided in a state in which pores having a size of several hundred um to several mm are formed therein.

When nickel is used as the electrically conductive substrate 10, the size of the nickel substrate is not particularly limited and may be determined according to needs such as electrode size, and the nickel substrate has a surface of a nanoporous structure including nanopores. can have

The hydrophilic coating layer 20 is a material having an amorphous bulk structure in which an anion layer that balances charge is interposed and weakly bonded to the surface of the electrically conductive substrate 10 carrying positive charges. According to one embodiment, the formation of the hydrophilic coating layer 20 is carried out using any one of nitric acid, hydrochloric acid, sulfuric acid, and a BOE (Buffered Oxide Etchant) solution in which hydrogen fluoride (HF) and ammonium fluoride (NH ₄ F) are mixed. It may be carried out using nitric acid.

The hydrophilic coating layer 20 may vary depending on the type of electrically conductive substrate 10 used. When a substrate containing a metal is used as the electrically conductive substrate 10, it may be metal nitrate [M _x (NO ₃ ) _y ], and when a substrate containing carbon is used, it may be carbon nitride (C ₃ N ₄ ) there is. Specifically, when a nickel substrate is used as the electrically conductive substrate 10, the hydrophilic coating layer 20 formed may be NiNO ₃ . The NiNO ₃ layer is formed by positioning an anion such as NO ₃ ⁻ , which is a reactant, on the surface of a nickel substrate, and can increase activity and widen a reaction area by reducing surface energy of the substrate. Accordingly, the formation of the catalyst layer on the hydrophilic coating layer 20 structure may be further facilitated.

The catalyst layer may be transition metal chalcogen compounds (TMCs) formed on the hydrophilic coating layer 20 having a negative charge, and may be provided in a single layer or multiple layers. The TMCs catalyst layer 30 may be formed in a single layer or a multilayer structure of 2 to 4 layers.

The TMCs catalyst layer 30 may include a transition metal and chalcogen, and the performance of the water electrolysis system can be improved by increasing the activity and durability of the catalyst due to the TMCs catalyst layer 30.

The TMCs catalyst layer 30 may be used as a HER catalyst. As shown in Chemical Formulas (2) and (3) below, during HER operation at the reduction electrode using the TMCs catalyst layer 30 as a catalyst in a basic atmosphere, hydrogen gas may be generated from the reduction electrode through a reduction reaction. At this time, electrons (e ⁻ ) in the reduction reaction may be transferred from the oxidation electrode, which is the counter electrode, through the circuit.

M(*) + H ₂ O + e ^- →MH(*) + OH ^- (2)

MH(*) + H ₂ O + e ^- → M + H ₂ + OH ^- (3)

However, '*' shown in Chemical Formulas (2) and (3) represents a catalytically active site.

The TMCs catalyst layer 30 may be used as an OER catalyst. As shown in Chemical Formulas (4) to (7) below, during OER operation at the anode using the TMCs catalyst layer 30 as a catalyst in a basic atmosphere, oxygen may be generated from the anode through an oxidation reaction.

OH ^- + M → M - OH (*) + e ^- (4)

M-OH(*) + OH ^- →MO(*) + H ₂ O + e ^- (5)

MO(*) + OH ^- → M-OOH(*) + e ^- (6)

M-OOH(*) + OH ^- → O ₂ + H ₂ O + e ^- + M (7)

However, '*' shown in Chemical Formulas (4) to (7) represents a catalytically active site.

The TMCs catalyst layer 30 can be manufactured by a simple electrochemical treatment method applicable to a large area, and is a multifunctional electrode catalyst with improved oxygen generation performance as well as hydrogen generation performance. ) and the electrode (cathode) where HER occurs, or both.

In addition, the TMCs catalyst layer 30 may be a compound represented by Formula 1 below:

[Formula 1]

MX _a X _b

In Formula 1, M is Ti, Zr, Hf, V, Nb, Ta, Mo, W, Tc, Re, Co, Rh, Ir, Ni, Pd, Pt or Fe, X _a and X _b is S, Se or Te.

In addition, X _a and X _b may be selected from the same or different elements, and may satisfy all of 0 <a ≤ 1, 0 <b ≤ 1, and a+b = 1.

The transition metal is Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Zr, Nb, Mo, Ru, Rh, Pd, Ag, Ta, W, Re, Os, Ir, Pt and Hg. It may be selected from the group consisting of, and may be specifically Ni. The chalcogen may be selected from the group consisting of S, Se and Te.

The TMCs catalyst layer 30 is TiS, VS, CrS, MnS, FeS, CoS, NiS, CuS, ZnS, ZrS, NbS, MoS, RuS, RhS, PdS, AgS, TaS, WS, ReS, OsS, IrS, PtS , HgS, TiSe, VSe, CrSe, MnSe, FeSe, CoSe, NiSe, NiS _0.5 Se _0.5, CuSe, ZnSe, ZrSe, NbSe, MoSe, RuSe, RhSe, PdSe, AgSe, TaSe, WSe, ReSe, OsSe, IrSe, Of PtSe, HgSe, TiTe, VTe, CrTe, MnTe, FeTe, CoTe, NiTe, CuTe, ZnTe, ZrTe, NbTe, MoTe, RuTe, RhTe, PdTe, AgTe, TaTe, WTe, ReTe, OsTe, IrTe, PtTe and HgTe It may be at least one, but is not limited thereto.

2 is a schematic explanatory view of an apparatus for manufacturing a catalyst electrode using a galvanostatic method according to an embodiment of the present invention. The galvanostatic method may measure a change in voltage over time by applying a constant current (galvanostatic).

Referring to FIG. 2, an apparatus for manufacturing a catalytic electrode includes a container 1 for containing an electrolyte 3, a working electrode 5 providing a substrate on which a hydrophilic coating layer 20 and a TMCs catalyst layer 30 are deposited. ; and a counter electrode (7). The working electrode 5 and the counter electrode 7 are connected to a power supply. At this time, the working electrode 5 and the counter electrode 7 are not limited as long as they are metal substrates having excellent conductivity as described above, and specifically, nickel, copper, titanium, tungsten, aluminum, silver, stainless steel, carbon, iron, cobalt , molybdenum and graphene.

First, a direct current flowing in the direction of the working electrode 5 from the power source is defined as a positive current. The current supplied from the power source may be continuous or pulsed. When a positive current is supplied from the power source, the nickel substrate used as the working electrode 5 becomes a (+) electrode, and the anion dissolved in the electrolyte solution causes an oxidation reaction on the nickel substrate to cause the hydrophilic coating layer. (20) can be formed.

On the other hand, a direct current flowing from the power source to the counter electrode 7 is defined as a negative current. The positive current and the negative current may flow in opposite directions. When a negative current is supplied from the power source, the working electrode 5 may become an electron-rich (-) electrode. At this time, the cations dissolved in the electrolyte 3 solution cause a reduction reaction on the hydrophilic coating layer 20 to form the TMCs catalyst layer 30.

3 is a flow chart showing a method for manufacturing a catalyst electrode including a TMCs catalyst layer 30 according to an embodiment of the present invention. Referring to FIG. 3 , the method of manufacturing the catalyst electrode 100 for water electrolysis includes the steps of preparing an electrolyte for electrodeposition (S100); and preparing a TMCs electrode through electrodeposition (S200).

Between the step of preparing the electrolyte for electrodeposition (S100) and the step of preparing the TMCs electrode through the electrodeposition (S200), hydrochloric acid, distilled water, and ethanol are used to remove the oxidized surface of the electroconductive substrate 10. A pretreatment process of washing in order and then drying in an oven may be included.

According to an embodiment of the present invention, in the manufacturing method of the catalyst electrode 100 for water electrolysis, first, an electrolyte for electrodeposition may be manufactured (S100). The electrolyte for electrodeposition may be one in which a transition metal precursor and a chalcogen precursor are dispersed in a solvent, and a pH adjusting agent may be added.

The transition metal precursors are Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Zr, Nb, Mo, Ru, Rh, Pd, Ag, Ta, W, Re, Os, Ir, Pt and Hg Hydroxide, nitrate, sulfate, acetate, chloride, acetylacetonate, formate or oxide containing at least one element selected from the group consisting of, but is not necessarily limited thereto.

According to one embodiment of the present invention, the concentration of the transition metal cation in the electrolyte may be in the range of 0.001M to 0.1M. Specifically, the concentration of the transition metal cation in the electrolyte may be in the range of 0.01M to 0.05M.

The chalcogen precursor may include at least one element selected from the group consisting of S, Se, and Te, and for example, sulfur, hydrogen sulfide (H ₂ S), diethyl sulfide, dimethyl dimethyl disulfide, ethylmethyl sulfide, (Et ₃ Si) ₂ S, hydrogen selenide (H ₂ Se), diethyl selenide, dimethyl deselenide, ethyl Ethyl methyl selenide, (Et ₃ Si) ₂ Se, hydrogen telluride (H ₂ Te), dimethyl telluride, diethyl telluride, ethyl methyl telluride telluride) and (Et ₃ Si) ₂ It may include at least one selected from the group consisting of Te, but is not limited thereto.

According to one embodiment of the present invention, the concentration of the chalcogen ion in the electrolyte may be in the range of 0.001M to 0.1M. Specifically, the concentration of the chalcogen ion in the electrolyte may be in the range of 0.01M to 0.05M. In the above range, when the TMCs catalyst layer 30 is formed on the hydrophilic coating layer 20, the electrochemical catalytic activity of the nickel substrate can be more effectively increased.

The transition metal and the chalcogen element included in the electrolyte may be obtained by dissolving different types of precursor compounds, respectively, or may be obtained by dissolving one type of precursor compound including both of them. Specifically, when Ni as the transition metal and S as the chalcogen are selected, Ni-containing precursors and S-containing precursors may be dissolved and used at appropriate concentrations, or NiS single precursor compounds may be dissolved and used, , but is not limited thereto.

A solvent for dispersing the transition metal and chalcogen ion is not particularly limited, but a solvent capable of uniformly dissolving and mixing the precursor compound and then easily removing the solvent may be used. As the usable solvent, for example, water, alcohol-based, carbonate-based, glycol-based, thiol-based, amine-based, acetone, or mixed solvents thereof may be used. Non-limiting examples of such a solvent include alcohols such as purified water, ethanol, and methanol; Acetone, tetrahydrofuran, methylene chloride, chloroform, dimethylformamide, N-methyl-2-pyrrolidone (NMP) ), cyclohexane, dichloromethane, dimethyl sulfoxide (DMSO), acetonitrile, pyridine, amines, or mixtures thereof.

As the pH adjusting agent, any one of sodium carbonate, triethanolamine (TEA), diethanolamine (DEA) and ethanolamine may be used, but is not limited thereto.

After the preparation of the electrolyte for electrodeposition (S100), an electrochemical treatment (S200) is performed using the electrolyte. Through such a simple electrochemical treatment, it is possible to form a double layer including a hydrophilic coating layer 20 containing nickel and a TMCs catalyst layer 30 on the surface of the nickel substrate.

The electrochemical treatment may be performed using at least one selected from cyclic voltammetry, constant voltage, constant current, pulse voltage, and pulse current. Specifically, it may be performed using Chrono Potentiometry (CP) using the constant current.

According to one embodiment of the present invention, first, when the nickel substrate used as the working electrode 5 is placed in the electrolyte and the positive current applied in the direction of the working electrode 5 from the power source is applied, the transition metal is formed on the surface of the nickel substrate Nitrate anion (NO ₃ ^- ) generated from ethanolamine added as a precursor or pH adjusting agent is deposited to form a hydrophilic coating layer 20, nickel nitrate foam.

The nickel nitrate foam may have a nickel nitrate [Ni(NO ₃ ) ₂ ] layer formed on a nickel metal surface of the nickel foam. The nickel nitrate layer may have an amorphous bulk structure.

The electrochemical treatment using the Chrono Potentiometry (CP) may be performed by applying the positive current of 40 to 60 mA/cm ² for 10 seconds to 60 minutes, specifically, for 10 minutes to 20 minutes. Within the current range, the structure of the hydrophilic coating layer 20 may be formed on the surface of the nickel substrate without destroying the structure of the nickel substrate. If the range of the current is exceeded, the electric deposition is insufficient or excessive, and the surface of the nickel substrate on which the hydrophilic coating layer 20 is formed may be shaved, and the nickel substrate is not uniformly coated and exists in the form of small particles separated from each other resulting in an electrochemically unstable product.

After the nickel nitrate layer, which is the hydrophilic coating layer 20, is formed, when a negative current in the opposite direction of the positive current and current mutual flow is applied to the working electrode 5, the TMCs dissolved in the electrolyte undergo a reduction and adsorption reaction As this happens, an amorphous TMCs catalyst layer 30 may be formed. Specifically, transition metal ions and chalcogen ions dissolved in the electrolyte may be adsorbed onto the hydrophilic coating layer 20 due to a reduction reaction under the negative current. For example, nickel (Ni) ions, which are transition metal ions, exist in the form of Ni ⁴⁺ and Ni ⁶⁺ and are reduced to Ni ²⁺ , and sulfur (S) ions, which are chalcogen ions, are S ⁴⁺ and S ⁶⁺ It exists in the form of S ^2- and is reduced to form a NiS catalyst layer on the hydrophilic coating layer 20.

In the preparation of the TMCs catalyst electrode through electrodeposition according to an embodiment of the present invention (S200), after the electrodeposition, washing and drying the TMCs catalyst electrode with purified water may be additionally performed.

Exemplary embodiments are described in more detail through the following Examples and Comparative Examples. However, Examples and Comparative Examples are intended to illustrate the technical idea, and the scope of the present invention is not limited only to them.

Preparation Example 1: Preparation of Electrolyte for Electrodeposition

2 mM Ni(NO ₃ ) ₂ ·6H ₂ O was used as a transition metal precursor, 2 mM CH ₄ N ₂ S was used as a chalcogen precursor, and 50 ml of purified water was used as a solvent. 2mM of ethanolamine is used to adjust the pH of the mixed solution. Stir for 30 minutes to form a homogeneous mixed solution. Through this, an electrolyte for electrodeposition is formed.

Preparation Example 2

An electrolyte for electrodeposition was prepared in the same manner as in Preparation Example 1, except that Co(NO ₃ ) ₂ 6H ₂ O was used instead of Ni(NO ₃ ) ₂ 6H ₂ O as the transition metal precursor in Preparation Example 1. .

Preparation Example 3

An electrolyte for electrodeposition was prepared in the same manner as in Preparation Example 1, except that Fe(NO ₃ ) ₂ .9H ₂ O was used instead of Ni(NO ₃ ) ₂ 6H ₂ O as the transition metal precursor in Preparation Example 1. .

Production Example 4

An electrolyte for electrodeposition was prepared in the same manner as in Preparation Example 1, except that Na ₂ MoO ₄ .2H ₂ O was used instead of Ni(NO ₃ ) ₂ 6H ₂ O as the transition metal precursor in Preparation Example 1.

Preparation Example 5

An electrolyte for electrodeposition was prepared in the same manner as in Preparation Example 1, except that Na ₂ WO ₄ ·2H ₂ O was used instead of Ni(NO ₃ ) ₂ 6H ₂ O as the transition metal precursor in Preparation Example 1.

Preparation Example 6

An electrolyte for electrodeposition was prepared in the same manner as in Preparation Example 1, except that SeO ₂ was used instead of CH ₄ N ₂ S as a chalcogen precursor in Preparation Example 1.

Preparation Example 7

An electrolyte for electrodeposition was prepared in the same manner as in Preparation Example 1, except that SeO ₂ was used instead of CH ₄ N ₂ S as a chalcogen precursor in Preparation Example 2.

Preparation Example 8

An electrolyte for electrodeposition was prepared in the same manner as in Preparation Example 1, except that SeO ₂ was used instead of CH ₄ N ₂ S as a chalcogen precursor in Preparation Example 3.

Preparation Example 9

An electrolyte for electrodeposition was prepared in the same manner as in Preparation Example 1, except that SeO ₂ was used instead of CH ₄ N ₂ S as a chalcogen precursor in Preparation Example 4.

Preparation Example 10

An electrolyte for electrodeposition was prepared in the same manner as in Preparation Example 1, except that SeO ₂ was used instead of CH ₄ N ₂ S as a chalcogen precursor in Preparation Example 5.

Preparation Example 11

2 mM Ni(NO ₃ ) ₂ ·6H ₂ O was used as a transition metal precursor, 1 mM SeO ₂ was used as a chalcogen precursor, and 50 ml of purified water was used as a solvent. 2 mM ethanolamine was used to adjust the pH of the mixed solution. It was stirred for 30 minutes to form a homogeneous mixed solution. 1 mM of CH ₄ N ₂ S was added to the obtained homogeneous mixed solution and stirred for another 30 minutes. Through this, an electrolyte for electrodeposition is formed.

Example 1: Preparation of catalytic electrode through electrochemical treatment of nickel foam using electrolyte solution

After washing with hydrochloric acid, distilled water, and ethanol in order to remove the oxidized surface of the nickel foam used as the electrically conductive substrate, it was dried in an oven. The dried nickel foam was cut into a size of 2X2 cm ² and used as a working electrode for a two-electrode system. Meanwhile, the nickel foam subjected to the same process as above was used as the counter electrode of the two-electrode system.

The electrolyte prepared in Preparation Example 1 in which TMCs were dissolved was introduced into the electrolyte of the two-electrode system. Then, a positive current of 50 mA/cm ² was applied to the working electrode for 15 minutes using chrono potentiometry.

When the reaction time was over, a negative current of -50 mA/cm ² was applied to the working electrode for 15 minutes using chrono potentiometry.

After the reaction time was over, the electrode on which the TMCs layer was deposited on the nickel foam was washed with purified water and then dried.

Example 2

A catalyst electrode was prepared in the same manner as in Example 1, except that Preparation Example 2 was used instead of Preparation Example 1 as the electrolyte in which TMCs were dissolved.

Example 3

A catalyst electrode was prepared in the same manner as in Example 1, except that Preparation Example 3 was used instead of Preparation Example 1 as the electrolyte in which TMCs were dissolved.

Example 4

A catalyst electrode was prepared in the same manner as in Example 1, except that Preparation Example 4 was used instead of Preparation Example 1 as the electrolyte in which TMCs were dissolved.

Example 5

A catalyst electrode was prepared in the same manner as in Example 1, except that Preparation Example 5 was used instead of Preparation Example 1 as an electrolyte in which TMCs were dissolved.

Example 6

A catalyst electrode was prepared in the same manner as in Example 1, except that Preparation Example 6 was used instead of Preparation Example 1 as the electrolyte in which TMCs were dissolved.

Example 7

A catalyst electrode was prepared in the same manner as in Example 1, except that Preparation Example 7 was used instead of Preparation Example 1 as the electrolyte in which TMCs were dissolved.

Example 8

A catalyst electrode was prepared in the same manner as in Example 1, except that Preparation Example 8 was used instead of Preparation Example 1 as the electrolyte in which TMCs were dissolved.

Example 9

A catalyst electrode was prepared in the same manner as in Example 1, except that Preparation Example 9 was used instead of Preparation Example 1 as the electrolyte in which TMCs were dissolved.

Example 10

A catalyst electrode was prepared in the same manner as in Example 1, except that Preparation Example 10 was used instead of Preparation Example 1 as the electrolyte in which TMCs were dissolved.

Comparative Example 1

A catalyst electrode was prepared in the same manner as in Example 1, except that Preparation Example 11 was used instead of Preparation Example 1 as the electrolyte in which TMCs were dissolved.

4 is an XPS spectrum of TMCs catalytic electrodes according to an embodiment of the present invention.

Referring to FIG. 4, the transition metals have 2p _1/2 , 2p _3/2 , 3d _3/2 , 3d _5/2 , 4f _5/2 4f _7/2 , and 5p _3/2 spectra showing oxidation numbers higher than zero. may appear in a mixed state. said 2p _1/2 and 2p _3/2 appear in Co, Fe and Ni; 3d _3/2 and 3d _5/2 can appear in Mo, 4f _5/2 , 4f _7/2 and 5p _3/2 in W, respectively. Chalcogen may show a mixed pattern of 2p _1/2 , 2p _3/2 , 3d _3/2 , and 3d _5/2 spectra showing an oxidation number lower than zero. 2p _1/2 and 2p _3/2 are in S, 3d _3/2 and 3d _5/2 can respectively appear in Se. The spectra may be binding energies indicating that the transition metal and the chalcogen are present on the surface of the nickel foam and bonded in the form of TMCs.

5 is SEM and EDS images of TMCs catalytic electrodes according to an embodiment of the present invention. Referring to FIG. 5, the scale bar is 50 μm, and it can be seen that the transition metal and chalcogen are applied on the surface of the nickel foam.

Evaluation Example 1: Hydrogen evolution reactivity (HER) evaluation

A half-cell was fabricated using the TMCs catalytic electrode prepared according to an embodiment of the present invention, and HER was evaluated.

6 is a graph evaluating HER performance of TMCs catalytic electrodes according to an embodiment of the present invention. Referring to FIG. 6, the HER performance of TMCs catalyst electrodes prepared in Examples 1 to 10 by combining any one of the transition metals Co, Fe, Mo, Ni and W and any one of the chalcogens S and Se evaluated.

The performance of HER in water electrolysis is determined by overpotential, and the overpotential required to obtain an arbitrary current density value can be determined by the difference between the theoretical HER reaction potential of 0 V and the potential value at a specific current density value. If the overvoltage value required to obtain a certain current density value is high, it can be determined that the HER performance is relatively low. At this time, commercially available Pt/C electrodes may be used to compare HER performance.

Evaluation Example 2: Oxygen evolution reactivity (OER) evaluation

A half-cell was fabricated using the TMCs catalytic electrode fabricated according to an embodiment of the present invention, and OER was evaluated.

7 is a graph evaluating the OER performance of TMCs catalyst electrodes according to an embodiment of the present invention. Referring to FIG. 7, the HER performance of TMCs catalyst electrodes prepared in Examples 1 to 10 by combining any one of the transition metals Co, Fe, Mo, Ni and W and any one of the chalcogens S and Se evaluated.

The performance of OER in water electrolysis is determined by overpotential like the performance of HER, and the overpotential required to obtain an arbitrary density value is the difference between the theoretical OER reaction potential of 1.23V and the potential value at a specific current density value. It is decided. If the overvoltage value required to obtain an arbitrary current density value is high, it can be determined that the OER performance is relatively low. At this time, commercially available IrO ₂ electrodes may be used to compare the performance of the OER.

8 is a graph synthesizing HER performance and OER performance of TMCs catalytic electrodes according to an embodiment of the present invention. Referring to FIG. 8, the HER and OER performances of the TMCs catalytic electrodes of Examples 1 to 10 evaluated in the graphs of FIGS. 6 and 7 are disclosed, and current densities of 10, 50 and 100 mA/cm ² in HER and OER reactions The overpotentials required to obtain are shown in orange, yellow and green, respectively. As a comparative example of the catalyst electrode, the HER performance of Pt/C and the OER performance of IrO ₂ are shown together.

6 to 8, it can be seen that the TMCs catalyst electrode prepared according to an embodiment of the present invention shows the following characteristics and trends. First, as a result of comparing the HER performance of the TMCs catalyst electrode, all of them showed inferior performance to the comparative Pt / C electrode, and when the same transition metal was used, the electrode using S as the chalcogen element showed better HER performance than the electrode using Se visibility can be seen. In particular, the electrode with the best HER performance was found to be the NiS electrode, and it can be seen that the performance is comparable to that of Pt/C, which is a comparative example, toward a potential corresponding to a high current density.

On the other hand, the OER performance of the catalytic electrodes was superior to that of the IrO ₂ electrode, which is a comparative example, except for the electrode using Mo. In particular, it was found that the electrode using Se as the chalcogen element showed better OER performance than the electrode using S. can Also, this tendency was greatly observed when Ni was used. In particular, the FeSe electrode showing the best OER performance showed the most inferior performance in HER performance, so it can be seen that it is difficult to use it as a multifunctional catalyst.

Evaluation Example 3: Evaluation of composition control capability of electrodeposition method

Half-cells were fabricated using a NiS electrode, a NiSe electrode, and a NiS _0.5 Se _0.5 electrode prepared according to Comparative Example 1 among TMCs catalyst electrodes prepared according to an embodiment of the present invention, and their HER and OER performances were evaluated.

9 is a graph evaluating HER performance and OER performance of a TMCs catalyst electrode whose composition is controlled according to an embodiment of the present invention. Referring to (a) of FIG. 9 , the polarization curve of the NiS _0.5 Se _0.5 electrode in the HER potential region is more negative than that of NiS, but more positive than that of NiSe. The aspect of the polarization curve shows that the HER performance of the NiS _0.5 Se _0.5 electrode is always inferior to NiS but superior to NiSe at any potential below 0 V.

Referring to (b) of FIG. 9, the polarization curve by the NiS _0.5 Se _0.5 electrode in the OER potential region is biased in a negative direction rather than that by NiS, as in the HER potential region, but in a positive direction than by NiSe It can be seen that it is biased toward In addition, it can be seen from the above polarization curves that the performance of the NiS _0.5 Se _0.5 electrode is always inferior to NiSe and superior to NiS at any potential above 1.23 V.

Referring to FIG. 9 , it can be seen that the HER performance and OER performance of the electrodeposited NiS _0.5 Se _0.5 electrode are between those of the NiS electrode and those of the NiSe electrode. When the composition of a material is controlled for the purpose of controlling the catalytic activity of TMCs constituting the catalyst layer of the electrode, it is difficult to control complex variables and obtain high reproducibility in a long and complex synthesis process. Therefore, the results of Evaluation Example 3 using Comparative Example 1 may be meaningful in that the composition of the catalytic electrode fabricated through the above example was controlled with high accuracy.

Evaluation Example 4: Stability Evaluation of Electrodeposited Catalytic Electrode

A half-cell was fabricated using a NiS electrode, a NiSe electrode, and a NiS _0.5 Se _0.5 electrode prepared in Comparative Example 1 among catalytic electrodes prepared according to an embodiment of the present invention, and HER and OER stability were evaluated.

10 is a graph evaluating the catalytic stability of a TMCs catalyst electrode having a controlled composition according to an embodiment of the present invention. Referring to FIG. 9, the NiS _0.5 Se _0.5 electrode maintains the catalytic action for 24 hours at -50mA/cm 2 which is a negative current (a) and 50mA/cm ² which is a positive current (b) together with the NiS electrode and the NiSe electrode ^. The size of the required overpotential was measured. In general, in the case of measuring catalytic stability using a galvanostatic method, the size of the required overpotential may increase due to deformation of the catalyst or degradation of performance caused by separation from the electrode. However, no appreciable increase in overpotential was observed for all three measured electrodes.

Thereafter, HER performance (c) and OER performance (d) of the three electrodes were measured to compare catalytic activity before and after the constant current experiment. The polarization curve before the constant current experiment is shown as a translucent line, and the polarization curve after the constant current experiment is shown as a bubble shape. The NiS _0.5 Se _0.5 electrode did not show significant performance degradation in HER and OER, as did the NiS and NiSe electrodes.

It can be seen from Evaluation Example 4 that the tendency of the catalytic activity of the electrodes is maintained even after the stability test is over. In general, deformation of TMCs catalysts can arise from variations in composition during successive catalysis. Therefore, it can be seen from Evaluation Example 4 that the composition of the catalytic electrode prepared through the above example maintains stability, showing high catalytic stability.

Evaluation Example 5: Performance and stability evaluation of both batteries

Both batteries were constructed using NiS electrode and FeSe electrode, which have the best HER performance and OER performance among catalyst electrodes manufactured according to an embodiment of the present invention, and water electrolysis performance and stability were evaluated.

11 is a graph evaluating the performance and stability of both cells of the TMCs catalyst electrode according to an embodiment of the present invention.

Referring to FIG. 11(a), the water electrolysis performance of both batteries was shown in which the NiS electrode, which showed the best HER performance, was used as the cathode, and the FeSe electrode, which showed the best OER performance, was used as the anode. The polarization curves of both cells constructed above are biased in a negative direction compared to the polarization curves of both cells based on noble metal catalysts shown together. As for the polarization curve, at any potential of 1.23 V or more, it can be seen that the performance of the NiS ? cell is always superior to that of the Pt/C ? ₂ cell used as a comparative example.

Referring to FIG. 11 (b), the water electrolysis performance before and after the constant current experiment using both the NiS ? battery and the Pt/C ? ₂ battery is shown. At this time, the performance before the constant current experiment is shown as a translucent line, and the performance after the constant current experiment is shown as a bubble shape. The NiS ? cell showed little change in water electrolysis performance before and after the constant current test, whereas the Pt/C ?rO ₂ cell showed a sharp decrease in performance as the required overpotential value increased significantly after the constant current test. there is. From Evaluation Example 5, it can be seen that the NiS ? both batteries have excellent water electrolysis performance and high stability compared to the noble metal-based Pt/C ? ₂ both batteries.

From the results of the above evaluation examples, it can be seen that the TMCs catalyst electrode for water electrolysis according to an embodiment exhibits high performance due to the increase in catalytic activity due to the TMCs layer used as the catalyst layer. In addition, both HER performance and OER performance are excellent, and when used as a cathode and an anode applied to a water electrolysis system, it can have high stability.

In addition, the TMCs catalyst electrode prepared according to an embodiment of the present invention can increase the electrode area by using the electrodeposition method using an electrolyte, and when using the electrodeposition method, the composition control is easy by adjusting the positive current and the negative current. , HER performance and OER performance are both excellent, so it may be practically applicable to water electrolysis systems.

In the above, preferred embodiments according to the present invention have been described with reference to drawings and embodiments, but this is only exemplary, and those skilled in the art can make various modifications and equivalent other implementations therefrom. will be able to understand Therefore, the scope of protection of the present invention should be defined by the appended claims.

container(1)
Electrolytes(3)
Working electrode (5)
counter electrode (7)
Electrically conductive substrate (10)
Hydrophilic coating layer (20)
TMCs catalyst layer (30)
Catalyst Electrode (100)

Claims (19)

a substrate having electrical conductivity;
a hydrophilic coating layer formed on the substrate; and
A multifunctional TMCs catalyst electrode for water electrolysis comprising a TMCs catalyst layer formed on the hydrophilic coating layer. According to claim 1,
The substrate having electrical conductivity is any one of nickel, copper, titanium, tungsten, aluminum, silver, stainless steel, carbon, iron, cobalt, molybdenum and graphene multifunctional TMCs catalyst electrode for water electrolysis. According to claim 1,
The hydrophilic coating layer is a metal nitrate or carbon nitride multi-function TMCs catalyst electrode for water electrolysis. According to claim 3,
The metal nitrate is NiNO ₃ Multifunctional TMCs catalyst electrode for water electrolysis. According to claim 1,
The TMCs catalyst layer is TiS, ZrS, HfS, VS, NbS, TaS, MoS, WS, TcS, ReS, CoS, RhS, IrS, NiS, PdS, PtS, FeS, TiSe, ZrSe, HfSe, VSe, NbSe, TaSe, A multifunctional TMCs catalytic electrode for water electrolysis that is any one of MoSe, WSe, TcSe, ReSe, CoSe, RhSe, IrSe, NiSe, PdSe, PtSe, FeSe and NiS _0.5 Se _0.5 . According to claim 1,
The TMCs catalyst layer is any one of NiS, NiSe, FeSe, and NiS _0.5 Se _0.5 TMCs multifunctional catalyst electrode for water electrolysis. preparing an electrolyte for electrodeposition in which a transition metal precursor and a chalcogen precursor are dispersed;
Preparing a TMCs catalytic electrode by introducing the electrolyte for electrodeposition into a two-electrode system using the substrate having electrical conductivity as a working electrode and a counter electrode to perform electrodeposition,
The electrodeposition is characterized in that, after applying a positive current supplied from a power source flowing in the direction of the working electrode for a predetermined time, a negative current in which the mutual flow of the positive current and the current flows in the opposite direction is applied for a predetermined time Manufacturing method of TMCs multifunctional catalytic electrode for water electrolysis. According to claim 7,
Between the step of preparing the electrolyte for electrodeposition and the step of preparing the TMCs catalyst electrode by performing the electrodeposition, in order to remove the oxidized surface of the electroconductive substrate, it was washed with hydrochloric acid, distilled water, and ethanol in this order and then dried in an oven. Method for producing a TMCs multi-functional catalyst electrode for water electrolysis, characterized in that it further comprises a pretreatment process through the process. According to claim 7,
When the positive current is applied for a certain period of time, the hydrophilic coating layer is formed on the electrically conductive substrate. According to claim 7,
When the negative current is applied for a certain period of time, a TMCs catalyst layer is formed on the hydrophilic coating layer. According to claim 7,
Method for producing a TMCs multi-functional catalyst electrode for water electrolysis in which the time for applying the positive current and negative current is 10 to 20 minutes. According to claim 7,
The value of the positive current is 40 to 60 mA / cm ² Method for producing a TMCs multi-function catalyst electrode for water electrolysis. According to claim 7,
The value of the negative current is 40 to 60 mA / cm ² Method for producing a TMCs multi-function catalyst electrode for water electrolysis. According to claim 7,
The transition metal precursor is Co(NO ₃ ) ₂ 6H ₂ O, Fe(NO ₃ ) ₂ 9H ₂ O, Na ₂ MoO ₄ 2H ₂ O, Ni(NO ₃ ) ₂ 6H ₂ O and Na ₂ WO A method for preparing a multifunctional catalyst electrode of TMCs for water electrolysis of any one of ₄ 2H ₂ O. According to claim 7,
The transition metal precursor is a method for producing a TMCs multi-function catalyst electrode for water electrolysis, characterized in that added at a concentration of 0.01mM to 0.05mM compared to the electrolyte for electrodeposition. According to claim 7,
The chalcogen precursor is any one of CH ₄ N ₂ S and SeO ₂ Method for producing a TMCs multi-function catalyst electrode for water electrolysis. According to claim 7,
The chalcogen precursor is a method for producing a TMCs multi-function catalyst electrode for water electrolysis, characterized in that added at a concentration of 0.01mM to 0.05mM compared to the electrolyte for electrodeposition. According to claim 7,
The method for producing a TMCs multi-function catalyst electrode for water electrolysis, characterized in that the electrolyte for electrodeposition further comprises a pH adjusting agent. According to claim 18,
The pH adjusting agent is ethanol amine, a method for producing a TMCs multi-function catalyst electrode for water electrolysis.

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