JP6434280B2 - Electrode for water electrolysis and method for producing the same - Google Patents

Description

  The present invention relates to an electrode for water electrolysis used for electrolyzing water to generate hydrogen. In particular, the present invention relates to an electrode for water electrolysis carrying a hydrogen generating enzyme.

  Conventionally, hydrogen generation technology by electrolysis using an alkaline or acidic aqueous solution as an electrolyte is known. Electrolysis requires a chemically stable electrode, such as a hydrogen generating electrode centered on noble metal Pt (see, for example, Patent Document 1), and alkaline water electrolysis using a Ni-P electrodeposited film. There is an electrode (for example, refer to Patent Document 2).

JP 2008-240001 A JP 2011-174162 A

  Conventionally used noble metal Pt is a scarce resource and is expensive. Further, the Ni—P electrodeposited film not using Pt has a high hydrogen generation voltage and low power efficiency.

  An object of the present invention is to provide an electrode for water electrolysis that is inexpensive and has high power efficiency, that is, a low hydrogen generation voltage.

  The electrode for water electrolysis according to the first aspect is the second electrodeposited in a neutral region on the rough surface of the first metal body using the first metal body blackened by surface fine structure as a base material. The first metal body, which is a base material, is removed from the metal body.

  In the electrode for water electrolysis according to the second aspect, in the first aspect, the second metal body may be a Ni-W alloy.

  In the electrode for water electrolysis according to a third aspect, in the first or second aspect, the second metal body has a surface area in the range of 2 to 1000 times the projected area and a rough surface exhibiting black. The rough surface may have a plurality of pores having a diameter in the range of 20 nm to 200 nm.

  The electrode for water electrolysis according to the fourth aspect may carry a biological enzyme on the rough surface of the second metal body in the third aspect.

  In the electrode for water electrolysis according to a fifth aspect, in the fourth aspect, the biological enzyme may be a hydrogenase.

A method for producing an electrode for water electrolysis according to a sixth aspect uses Cu as the first metal body, and a step of subjecting the first metal body to surface microstructure treatment with an acid or an alkali;
A step of electrodepositing Ni-W in a neutral region as a second metal body different from the first metal body using the first metal body subjected to the surface microstructure treatment as a base material;
Removing the first metal body, which is a base material, to obtain the second metal body having a surface to which at least a part of the surface of the first metal body that has been subjected to a surface microstructure treatment is transferred; ,
including.

  According to the electrode for water electrolysis according to the present invention, the first metal body that has been blackened by surface microstructuring is used as a base material, and the second metal body that is electrodeposited in a neutral region is used as the base material. By removing the first metal body, the black surface (rough surface) of the blackened first metal body can be transferred to the chemically stable second metal body. As a result, the chemically stable second metal body can be provided with a black surface including fine irregularities, and an electrode for water electrolysis that is inexpensive and has a low hydrogen generation voltage can be obtained.

It is a schematic sectional drawing which shows the fine uneven | corrugated shape of the surface of the metal which carried out the blackening process. It is a schematic sectional drawing which shows the electrodeposited film formed in the surface, using the blackened metal of FIG. 1 as a base material. It is a schematic sectional drawing which shows the fine uneven | corrugated shape of the surface of the electrodeposited film which removed the metal which blackened the base material from the electrodeposited film of FIG. (A) is a schematic sectional drawing which shows the composite structure containing the macro uneven | corrugated shape of the surface of the blackened metal of FIG. 1, and a micro fine uneven | corrugated shape, (b) was blackened. It is an example of the scanning electron micrograph of the surface of Cu. FIG. 5 is a schematic cross-sectional view showing an electrodeposited film formed on the surface of the blackened metal of FIG. 4 as a base material. (A) removes the blackened metal of the base material from the electrodeposited film of FIG. 5, the macro uneven shape of the transfer surface showing the black color of the extracted electrodeposited film, the micro fine uneven shape, FIG. 2B is an example of a scanning electron micrograph of the surface when the electrodeposited film is a Ni—W alloy. It is a schematic diagram which shows typically the surface structure of the black surface of the surface of Cu by which the blackening process of Fig.4 (a) was carried out. It is a schematic diagram which shows typically the surface structure of the transfer Ni-W electrodeposition film | membrane of Fig.6 (a). (A) is the laser micrograph of the black surface of the transfer Ni-W electrodeposition film | membrane of FIG. 8, (b) is a 3D image of (a). (A) is a laser micrograph of the silver white surface of the transfer Ni-W electrodeposited film of FIG. 8, and (b) is a 3D image of (a). (A)-(c) is a two-dimensional cross-sectional curve of the black surface of the transfer Ni-W electrodeposition film | membrane of Fig.9 (a). (A)-(c) is a two-dimensional cross-sectional curve of the silver white surface of the transfer Ni-W electrodeposition film | membrane of Fig.10 (a). It is a graph which shows the wavelength dependence of the reflectance of the black surface of a transfer Ni-W electrodeposition film, and the silver white surface, and the reflectance of the black surface of Cu of a base material. It is an enlarged view of FIG. 13, Comprising: It is a graph which shows the wavelength dependence of the reflectance of the black surface of a transfer Ni-W electrodeposition film, and the reflectance of the black surface of Cu of a base material. 6 is a graph showing the results of cyclic voltammetry of the Pt plate and the transferred Ni—W electrodeposited film according to Example 1. 4 is a graph showing the results of cyclic voltammetry between a Ni—W alloy without transfer and a Ni—W electrodeposited film having transferred a fine uneven shape according to Example 1. FIG. 4 is a graph showing the results of cyclic voltammetry of a Ni—W electrodeposited film to which fine irregularities according to Example 1 are transferred. 6 is a graph showing the results of cyclic voltammetry of a transferred Ni—W electrodeposited film carrying a biological enzyme according to Example 2. FIG.

<Background to the Present Invention>
In order to develop a water electrolysis electrode having a high specific surface area and a water electrolysis electrode carrying a hydrogen generating enzyme, surface treatment of a highly conductive metal substrate was investigated. When a metal substrate such as Cu is blackened by chemical treatment, nanofiber-like surface fine irregularities are formed, and a surface structure having a high specific surface area is formed.

  However, the nanoscale surface fine unevenness produced by such a blackening treatment is chemically unstable and unsuitable for use as an electrode material. For this reason, we attempted to develop a hydrogen generating electrode with a high specific surface area by electrodepositing a chemically stable metal on the surface of a blackened metal substrate and transferring the shape of nanoscale surface fine irregularities. Examples of metal electrodeposition materials for shape transfer include platinum and nickel. Since most of the conventional electrolytic solutions for metal plating are strong acid or strong alkaline aqueous solutions, the present inventors have a problem that the nanofiber-like surface fine irregularities are instantly dissolved during the electrolytic deposition process. I found.

As a result of studying various electrode materials, the present inventor has found that a Ni—W alloy is suitable. The Ni—W alloy has an amorphous or nanocrystalline structure within a predetermined W content range and is suitable for nanoscale shape transfer without being affected by anisotropy due to crystal orientation. Furthermore, since the electrodeposition bath of the Ni—W alloy is a neutral bath in the vicinity of pH 6 to pH 7, the Ni—W alloy can be electrodeposited without dissolving the nanofiber structure by the blackening treatment described above. it can. In addition, the Ni-W alloy has sufficient mechanical strength as an electrode material, is chemically stable, and does not dissolve even in concentrated nitric acid. Therefore, after the surface transfer, the Cu substrate as a base material is dissolved and removed. Is also easy.
The present inventor removed Cu, which is a base material, from a Ni—W electrodeposition film obtained by electrodepositing on a black surface (rough surface) of Cu that was blackened by surface microstructuring. A transferred Ni—W electrodeposited film having a black surface including fine irregularities transferred from the surface was obtained, and the present invention was achieved.

  Hereinafter, an electrode for water electrolysis and a manufacturing method thereof according to an embodiment of the present invention will be described with reference to the accompanying drawings. In the drawings, substantially the same members are denoted by the same reference numerals.

(Embodiment 1)
FIG. 1 is a schematic cross-sectional view showing the fine irregularities on the surface of the metal 1 that has been blackened by surface microstructure formation. FIG. 2 is a schematic sectional view showing an electrodeposited film 2 formed on the surface of the blackened metal 1 shown in FIG. 1 as a base material. FIG. 3 is a schematic cross-sectional view showing the fine uneven shape of the surface of the electrodeposited film 2 obtained by removing the metal 1 subjected to the blackening treatment of the base material from the electrodeposited film 2 of FIG. FIG. 4A is a schematic cross-sectional view showing a macro uneven shape and a micro fine uneven shape on the surface of the blackened metal 1 of FIG. FIG. 4B is an example of a scanning electron micrograph of the blackened Cu surface. FIG. 5 is a schematic sectional view showing the electrodeposited film 2 formed on the surface of the blackened metal 1 shown in FIG. 4 as a base material. FIG. 6A shows a macro uneven shape and a micro fine uneven shape on the surface of the electrodeposited film obtained by removing the blackened metal 1 from the electrodeposited film 2 in FIG. It is a schematic sectional drawing. FIG. 6B is an example of a scanning electron micrograph of the surface when the electrodeposited film 2 is a Ni—W alloy.

The electrode according to Embodiment 1 is a base material from a second metal body electrodeposited in a neutral region on the rough surface of the first metal body using the blackened first metal body as a base material. It is obtained by removing the first metal body, and consists of the second metal body. The electrode has a surface area in the range of 2 to 1000 times, preferably in the range of 50 to 1000 times, more preferably in the range of 100 to 1000 times the projected area, and is a rough surface exhibiting a black color. Have This rough surface has a plurality of pores having a diameter in the range of 20 nm to 200 nm.
According to this electrode, the black surface (rough surface) of the blackened first metal body 1 can be transferred to the chemically stable second metal body. As a result, the chemically stable second metal body 2 can be provided with a black surface including the fine irregularities 4, and an electrode for water electrolysis with a low hydrogen generation voltage can be obtained.

  Below, the component which comprises this electrode is demonstrated.

<First metal body subjected to blackening treatment>
The black metal-treated first metal body 1 is, for example, the first metal body 1 obtained by surface-structuring (roughening) the surface of a metal substrate with an acidic or alkaline agent. The first metal body may be any metal that can be subjected to surface microstructuring (roughening) treatment with acid or alkali, and examples thereof include Cu, Fe, Co, and Ni, and Cu is preferred.
The first metal body 1 that performs the blackening treatment may be obtained by electrodepositing the same metal on the surface of a flat metal as it is as a flat metal. By depositing the same metal on the metal plate in this way, a concavo-convex shape having a sub-μm to μm order of macro structure can be formed on the surface.

  FIG. 7 is a schematic diagram schematically showing the surface structure of the black surface of the blackened Cu surface of FIG. As shown in FIG. 7, when the same metal is electrodeposited on a metal plate and subjected to blackening treatment, the surface of the metal blackened by surface microstructuring has a macro uneven shape and microscopic fineness. A composite structure including the concavo-convex shape is formed. The micro fine uneven shape has a nanofiber structure as shown in FIG. The surface of the blackened metal has a surface area in the range of 2 to 1000 times, preferably in the range of 50 to 1000 times, more preferably in the range of 100 to 1000 times the projected area. It is preferable that the rough metal fine concavo-convex shape is not larger than the wavelength of visible light exhibiting black, and is approximately 400 nm or less.

<Second metal body>
The electrode is made of a second metal body. The second metal body is obtained by electrodepositing in a neutral region on the rough surface of the first metal body using the blackened first metal body as a base material. Moreover, the 1st metal body which is a base material is removed, and the transfer surface (black surface) which exhibits the black which transferred the blackened rough surface (black surface) of the 1st metal body is obtained. The second metal body may be selected from metals having activity as an electrode for water electrolysis and capable of being electrodeposited in a neutral region.
Examples of the second metal body include a Ni—W alloy and a Ni—Co alloy, and a Ni—W alloy is preferable.
The Ni—W alloy contains W in the range of 14 to 25 atomic%. This Ni—W alloy preferably contains 15 to 20 atomic% of W. The Ni—W alloy takes a nanocrystalline structure when the W content is 12 atomic% or less, and becomes amorphous when the content exceeds 20 atomic%. When the content of W is in the above range, a composite structure in which a nanocrystalline structure is included in an amorphous matrix is obtained. When the W content is 12 atomic% or less, a grain boundary is generated. Therefore, when the electrode is used as an anode, the grain boundary part may be corroded and eluted, which is not preferable.
FIG. 8 is a schematic view schematically showing the surface structure of the Ni—W electrodeposited film in FIG. As shown in FIG. 8, this electrode has a black transfer surface (black surface) obtained by transferring the black surface (rough surface) of the first metal body, and a silver white surface. On the black surface, as shown in the schematic cross-sectional view of FIG. 6 (a), the scanning electron micrograph of FIG. 6 (b), and the schematic diagram of FIG. 8, the rough surface of the first metal body subjected to blackening treatment In the same manner as the above, it has a composite structure including a macro uneven shape and a micro fine uneven shape.

FIG. 9A is a laser micrograph of the black surface of the Ni—W electrodeposited film of FIG. 8, and FIG. 9B is a 3D image of FIG. 9A. FIG. 10A is a laser micrograph of the silver white surface of the Ni—W electrodeposited film of FIG. 8, and FIG. 10B is a 3D image of FIG. FIGS. 11A to 11C are two-dimensional cross-sectional curves of the black surface of the Ni—W electrodeposited film in FIG. 12A to 12C are two-dimensional cross-sectional curves of the silver white surface of the Ni—W electrodeposited film in FIG.
As shown in FIGS. 9A and 9B and FIGS. 11A to 11C, on the black surface, a macro uneven shape on the order of sub-μm to μm and a nano-sized micro fine uneven shape. It can be seen that it has a composite structure. In addition, this fine uneven | corrugated shape is considered to be the pore by which the unevenness | corrugation was reversed by the transcription | transfer process unlike the nanofiber structure seen in the Cu board by which the blackening process of the base material was carried out.
Further, as shown in FIGS. 10A and 10B and FIGS. 12A to 12C, only a macro uneven shape of sub-μm to μm order exists on the silver white surface. I understand.
In addition, the thickness from a silver white surface to a black surface is 0.5 micrometer or more, and is exhibiting silver white.

FIG. 13 shows the wavelength dependence of the reflectance (solid line) and the reflectance of the silver white surface (dashed line) of the transfer Ni—W electrodeposited film and the reflectance of the black surface of the base material Cu (dotted line). It is a graph which shows sex. FIG. 14 is an enlarged view of FIG. 13, and shows the wavelength dependence of the reflectance (solid line) of the black surface of the transferred Ni—W electrodeposited film and the reflectance (dotted line) of the black surface of the base material Cu. It is a graph to show.
The wavelength dependence of the reflectance of the black surface and the silver white surface of the transferred Ni—W electrodeposited film will be examined with reference to FIGS. 13 and 14. The black surface (solid line) of the transferred Ni—W electrodeposited film has almost no wavelength dependence in a very wide wavelength range from 250 nm to 1200 nm as shown in FIG. 13 and an enlarged view of FIG. % Reflectivity is shown. Further, as shown in FIG. 13, the silver white surface (alternate-dotted line) of the transferred Ni—W electrodeposited film is almost independent of the wavelength in the wavelength range of 250 nm to 1200 nm, and has a substantially constant reflectance of about 60%. Show.
On the other hand, the black surface (dotted line) of Cu as the base material shows a very low reflectance of 2% or less in the wavelength range of 250 nm to 700 nm as shown in FIG. 13 and its enlarged view of FIG. From 1 to 1200 nm, the reflectance increases monotonously to nearly 10%.

  According to the electrode made of the second metal body, a chemically stable second metal body can be provided with a black surface including fine irregularities, and an electrode for water electrolysis with a low hydrogen generation voltage can be obtained. It is done. The characteristics of the electrode made of the second metal body will be described in Example 1.

<Biological enzyme>
The bioenzyme is supported on the rough surface (black surface) of the second metal body that exhibits black color. This biological enzyme is, for example, a hydrogenase. In particular, [Ni-Fe] hydrogenase is preferable. Hydrogenase plays an important role in smoothly promoting the energy metabolism system in many bacteria, and is an enzyme that regulates the proton concentration gradient inside and outside the cell membrane.
Hydrogenase, a biological enzyme, has a size of about 10 nm. The black surface of the second metal body has a plurality of pores in the range of 20 nm to 200 nm, and the pores are optimally sized to carry hydrogenase. Therefore, by supporting hydrogenase, which is a biological enzyme, on the black surface of the second metal body, it can be used as a hydrogen generating electrode using the biological enzyme. The characteristics of the electrode carrying the biological enzyme will be described in Example 2.

  As described above, this electrode is inexpensive and has a low hydrogen generation voltage and is useful as an electrode for water electrolysis. Furthermore, this electrode is not limited to the electrode for water electrolysis, and may be used as an electrode for a fuel cell, for example.

<Manufacturing method>
This electrode manufacturing method includes the following steps.
(A) The first metal body 1 is blackened by surface fine structure (surface roughening, surface roughening) with acid or alkali (FIG. 1, FIG. 4 (a)). As the alkali, for example, a mixed solution of a strong oxidizing agent such as a sodium hydroxide solution and sodium sulfite can be used. This surface microstructuring treatment with acid or alkali is called blackening treatment. The fine uneven shape 3 is formed as a microstructure by the blackening treatment. The fine uneven shape 3 has, for example, a nanofiber structure as shown in the scanning electron micrograph of FIG. For example, Cu can be used for the first metal body. In addition, since the 1st metal body 1 needs to be removed after that, the metal which can be removed with an acid or an alkali is selected, for example.
(B) Electrodepositing the second metal body 2 different from the first metal body in the neutral region using the first metal body 1 subjected to the surface microstructure treatment as a base material (FIGS. 2 and 5) . The second metal body 2 has an activity as an electrode for water electrolysis, and can select a metal that can be electrodeposited in a neutral region. For example, a Ni—W alloy can be used.
(C) A second transfer surface having a black transfer surface obtained by removing the first metal body 1 as a base material and transferring at least a part of the surface of the first metal body 1 that has been subjected to the surface microstructure treatment. A metal body is obtained (FIG. 3, FIG. 6 (a)). The transfer surface exhibiting black has a plurality of pores having a diameter in the range of 20 nm to 200 nm.
By the above, the electrode which consists of a 2nd metal body which has the transfer surface which exhibits black can be obtained.

Example 1
Below, the manufacturing method of the electrode which consists of a Ni-W electrodeposition film | membrane which has the transfer surface which exhibits the black which transferred the black surface of Cu board blackened by surface microstructuring is demonstrated.
(1) First, for a pure copper plate for a commercial printed circuit board, a Cu plate having a surface microstructured by a blackening treatment using a mixed solution of a sodium hydroxide solution and sodium sulfite was prepared. . The blackened Cu plate has a composite structure including a macro uneven shape and a micro fine uneven shape as shown in the example of the scanning electron micrograph of FIG.
(2) Ni-W electrodeposition was performed in a neutral region using a Cu plate blackened by surface microstructuring as a base material. Ni-W electrodeposition conditions include, for example, an electrodeposition bath based on nickel sulfate and trisodium tungstate (Patent No. 4243281 “High-strength alloy and a metal material coated with the high-strength alloy and its high-strength alloy. The microstructure used "may be used as described in the application filed on March 23, 2001 (registered on January 9, 2009).
(3) Thereafter, the Cu plate was dissolved and removed to obtain a Ni-W electrodeposited film. The Cu plate was removed by dipping in a 50% nitric acid aqueous solution. The obtained Ni—W electrodeposited film is macroscopically formed on the black transfer surface of the obtained Ni—W electrodeposited film, as shown in the example of the scanning electron micrograph of FIG. It has a composite structure including an uneven shape and a micro fine uneven shape.
Thus, an electrode made of a Ni—W electrodeposited film having a black transfer surface was obtained.

Below, the manufacturing conditions of this Ni-W electrodeposition film are demonstrated.
<Ni-W electrodeposition bath>
The composition of the electrodeposition bath is, for example, nickel sulfate (NiSO ₄ ) having a concentration of 0.06 mol / L and sodium citrate (Na ₃ C) having a concentration changed in the range of 0.14 to 0.5 mol / L. ₆ H ₅ O ₇ -2H ₂ O), sodium tungstate (Na ₂ WO ₄ -2H ₂ O) at a concentration of 0.14 mol / L, and ammonium chloride (NH ₄ Cl) at a concentration of 0.5 mol / L It may be an electrodeposition bath containing as a main component.

<Electrodeposition conditions>
In this case, electrodeposition was performed using a platinum anode plate having a size of 0.5 mm × 30 mm × 40 mm and a blackened cathode plate having a size of 0.2 mm × 30 mm × 40 mm. Moreover, the electrodeposition current density was changed in the range of 5 to ²⁰ A / dm ² , thereby changing the W content of the alloy. Note that masking was performed on one side (non-black surface) of the Cu cathode plate, and the alloy was deposited only on one side (black surface) without masking. During the electrodeposition, the electrodeposition bath is constantly stirred using a hot stirrer so that the bath temperature during each experiment shown below is constant, and at the same time, the pH during electrodeposition is adjusted using a pH controller. It was kept constant (about 6.2-6.3). The electrodeposition time was 0.5 hours.

<Microstructure>
The obtained transfer Ni—W electrodeposited film has a black transfer surface (black surface) obtained by transferring the black surface (rough surface) of the first metal body, and a silver white surface. The black surface has a composite structure of a macro uneven shape on the order of sub μm to μm and a nano-sized micro fine uneven shape (FIGS. 6B and 9A). In addition, unlike the fibrous structure (nanofiber structure) seen in the blackened Cu plate of the base material, this fine uneven shape is considered to be a shape (pores) in which the unevenness is reversed by the transfer process. . In addition, on the silver-white surface, there are only macro uneven shapes on the order of sub-μm to μm (FIG. 10A).

<Cyclic voltammetry (CV) characteristics>
Next, cyclic voltammetry (CV) characteristics of the obtained transferred Ni—W electrodeposited film were evaluated together with the Pt plate.
FIG. 15 is a graph showing cyclic voltammetry (CV) characteristics of the Pt plate and the transferred Ni—W electrodeposited film obtained in Example 1. In the measurement of cyclic voltammetry (CV) characteristics, 0.1 mol of potassium phosphate was used as a buffer, and the pH was adjusted to 7.
As shown in FIG. 15, the hydrogen generation current starts to flow from about −0.9 V on the Pt plate, whereas the hydrogen generation current starts to flow from about −0.7 V on the transfer Ni—W electrodeposition film. It can be seen that the Ni-W electrodeposited film has a lower hydrogen generation voltage than the Pt plate. That is, the power required to obtain the same hydrogen generation indicates that the transferred Ni—W electrodeposited film is smaller than the Pt plate. From this, it is considered that the transfer Ni—W electrodeposited film having a black surface may have a catalytic ability close to or higher than Pt.

  FIG. 16 shows the result of cyclic voltammetry between the non-transferred Ni—W alloy plate electrodeposited on a smooth Cu plate, not the black surface, and the Ni—W electrodeposited film transferred with the fine irregularities according to Example 1. It is a graph which shows. In the case of the Ni-W alloy plate without transfer, the hydrogen generation current starts to flow from around -0.9V, whereas in the Ni-W electrodeposited film to which the blackened Cu plate is transferred, around -0.6V. The hydrogen generation current begins to flow. That is, the transferred Ni—W electrodeposited film obtained in Example 1 is a water electrolysis electrode having a lower hydrogen generation voltage than a Ni—W alloy plate having no fine unevenness.

(Example 2)
In Example 2, a biological enzyme was supported on the black transfer surface of the transferred Ni—W electrodeposited film obtained in Example 1. This biological enzyme is [Ni-Fe] hydrogenase. Methyl viologen was also added as a mediator when carrying the enzyme on the transferred Ni-W electrodeposited film. The supporting method is a physical adsorption method in which an aqueous solution of a biological enzyme and methyl viologen is dropped onto a transfer Ni—W electrodeposition film and dried to be supported. Regarding the enzyme-carrying transfer Ni-W electrodeposition film, the cyclic voltammetry (CV) characteristic was evaluated together with the enzyme-carrying transfer Ni-W electrodeposition film.
18 is a graph showing the results of cyclic voltammetry (CV) of the transferred Ni—W electrodeposited film carrying the biological enzyme according to Example 2. FIG. FIG. 17 is a graph showing the results of cyclic voltammetry (CV) of the transferred Ni—W electrodeposited film according to Example 1.

Cyclic voltammetry (CV) characteristics were measured using 0.1 molar potassium phosphate as the buffer and adjusting to pH 6 or 7. In addition, MV (methyl viologen) was added in order to smoothly transfer electrons when carrying hydrogenase.
From the comparison between FIG. 18 and FIG. 17, at the beginning of the flow of the hydrogen generation current, the transfer Ni—W electrodeposition film without enzyme support has a low voltage, but the current gradient of the transfer Ni—W electrodeposition film with enzyme support is low. It is sharper and hydrogen generation at low power can be confirmed.
Thus, there is no precedent for realizing the catalytic ability of a biological enzyme with a metal electrode, and there is a high possibility as a highly efficient enzyme-carrying electrode.

  According to the electrode for water electrolysis according to the present invention, it is possible to provide an electrode for water electrolysis that is inexpensive and has high power efficiency without using rare resources and expensive noble metal Pt.

1 1st metal body (Cu)
2 Second metal body (transfer Ni-W electrodeposited film)
3 Nanofiber-like fine irregularities 4 Pore

Claims (6)

Using a first metal body blackened by surface microstructure formation as a base material , a nickel-W alloy containing W in a neutral region in a range of 15 to 20 atomic% on the rough surface of the first metal body is electrically charged. It had a black surface with a reflectance of 10% or less, including chemically stable nano-sized fine irregularities , obtained by removing the first metal body as a base material from the analyzed second metal body . A water electrolysis electrode comprising a second metal body and having a low hydrogen generation voltage . 2. The electrode for water electrolysis according to claim 1, wherein the second metal body has a transfer surface onto which the blackened rough surface of the first metal body is transferred .   The second metal body has a surface area in the range of 2 to 1000 times the projected area and a rough surface exhibiting black, and the rough surface has a plurality of pores having a diameter in the range of 20 nm to 200 nm. The electrode for water electrolysis of Claim 1 or 2 which has these.   The electrode for water electrolysis according to claim 3, wherein a biological enzyme is supported on the rough surface of the second metal body.   The electrode for water electrolysis according to claim 4, wherein the biological enzyme is a hydrogenase.   Using Cu as the first metal body, the step of subjecting the first metal body to surface microstructure treatment with an acid or alkali, and using the first metal body subjected to the surface microstructure treatment as a base material, A step of electrodepositing Ni-W in a neutral region as a second metal body different from the first metal body, and removing the first metal body as a base material, Obtaining the second metal body having a surface to which at least a part of the surface microstructured surface is transferred. A method for producing an electrode for water electrolysis.