Method for Preparing Large-area Catalyst Electrode

Abstract

A method for preparing a large-area catalyst electrode includes the following steps: (A) providing an iron compound, a cobalt compound and a nickel compound, and dissolving these metal compounds in a solvent to form a mixed metal compound solution, and (B) providing a cathode and an anode, and performing a cathodic electrochemical deposition to the cathode, the anode and the mixed metal compound solution in a condition of constant voltage or constant current through a two-electrode method, followed by obtaining a catalyst electrode from the cathode. In the method for preparing the large-area catalyst electrode of the present invention, the large-area catalyst electrode having good dual-function water electrolysis catalytic property can be prepared by the steps of preparing the electrolyte, the electrochemical deposition, and the like. The process is simple and energy-saving.

Claims

1. A method for preparing a large-area catalyst electrode, comprising following steps: (A) providing an iron compound, a cobalt compound and a nickel compound, and dissolving the iron compound, the cobalt compound and the nickel compound in a solvent to form a mixed metal compound solution, and (B) providing a cathode and an anode, and performing a cathodic electrochemical deposition to the cathode, the anode and the mixed metal compound solution through a two-electrode method in a condition of constant voltage or constant current, followed by obtaining a catalyst electrode from the cathode.

2. The method for preparing the large-area catalyst electrode of claim 1, wherein the iron compound is ammonium iron sulfate, iron chloride, iron nitrate, iron sulfate or iron-containing coordination compound.

3. The method for preparing the large-area catalyst electrode of claim 1, wherein the cobalt compound is cobalt chloride, cobalt nitrate, cobalt sulfate or cobalt-containing coordination compound.

4. The method for preparing the large-area catalyst electrode of claim 1, wherein the nickel compound is nickel chloride, nickel nitrate, nickel sulfate or nickel-containing coordination compound.

5. The method for preparing the large-area catalyst electrode of claim 1, wherein the solvent is selected from water, methanol, ethanol, isopropanol, 1-butanol, acetone solution or combinations thereof.

6. The method for preparing the large-area catalyst electrode of claim 1, wherein a material of the cathode or the anode is selected from graphite, nickel, copper or stainless steel, and an area of the anode is greater than or equal to an area of the cathode.

7. The method for preparing the large-area catalyst electrode of claim 1, wherein a structure of the cathode or the anode is foam, plate or mesh.

8. The method for preparing the large-area catalyst electrode of claim 1, wherein a concentration of the iron compound, the cobalt compound or the nickel compound ranges from 0.01M to 0.5M.

9. The method for preparing the large-area catalyst electrode of claim 1, wherein the constant current ranges from 0.1 A to 1 A, and an electrochemical deposition time ranges from 1 min to 20 min in the step (B).

10. The method for preparing the large-area catalyst electrode of claim 1, wherein the constant voltage ranges from 0.1V to 1V and an electrochemical deposition time ranges from 1 min to 20 min in the step (B).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0016] FIG. 1 schematically illustrates a flow chart of a method for preparing a large-area catalyst electrode according to the present invention.

[0017] FIG. 2 schematically illustrates a cathode and an anode after the electrochemical deposition according to an embodiment of the present invention.

[0018] FIG. 3 schematically illustrates a cathodic catalyst electrode and an anodic catalyst electrode of a catalyst electrode after electrochemical electrolysis of water according to an embodiment of the present invention.

[0019] FIG. 4 is a scanning electron microscope diagram of the cathodic catalyst electrode of the catalyst electrode after electrochemical electrolysis of water according to an embodiment of the present invention.

[0020] FIG. 5 is an energy dispersive X-ray spectroscopy diagram of the cathodic catalyst electrode of the catalyst electrode after electrochemical electrolysis of water according to an embodiment of the present invention.

[0021] FIG. 6 is a scanning electron microscope diagram of the anodic catalyst electrode of the catalyst electrode after electrochemical electrolysis of water according to an embodiment of the present invention.

[0022] FIG. 7 is an energy dispersive X-ray spectroscopy diagram of the anodic catalyst electrode of the catalyst electrode after electrochemical electrolysis of water according to an embodiment of the present invention.

DETAILED DESCRIPTION

[0023] The implementation methods of the present invention will be described by the specific embodiment in the following contents. It should be noted that for those of ordinary skill in the art, the advantages and effects of the present invention can be easily understood after reading the disclosed contents of the present specification.

[0024] In a method for preparing a large-area catalyst electrode according to the present invention, a cathodic electrochemical deposition is adopted, in which a cathodic electrodeposition is performed to a mixed solution containing metal raw materials through the two-electrode method in a condition of constant voltage or constant current provided by the direct current stabilized power supply, such that a uniform thin layer of the catalyst electrode can be formed on the surface of the cathode. That is, the dual-function water electrolysis catalyst electrode can be prepared in only one step. The catalyst electrode prepared by the present invention can exhibit dual-function catalytic activity of hydrogen evolution and oxygen evolution through an electrochemical test under a 1M KOH alkaline condition.

[0025] Referring to FIG. 1, FIG. 1 schematically illustrates a flow chart of a method for preparing a large-area catalyst electrode according to the present invention. As shown in FIG. 1, a method for preparing a large-area catalyst electrode according to the present invention includes: (A) providing an iron compound, a cobalt compound and a nickel compound, and dissolving the above-mentioned metal compounds in a solvent to form a mixed metal compound solution 5101, and (B) providing a cathode and an anode, and performing a cathodic electrochemical deposition to the cathode, the anode and the mixed metal compound solution through the two-electrode method in a condition of constant voltage or constant current, followed by taking the cathode to obtain a catalyst electrode 5102, i.e., obtaining a catalyst electrode 5102 by taking the cathode.

[0026] The iron compound may be selected from ammonium iron sulfate, iron chloride, iron nitrate, iron sulfate or iron-containing coordination compound, the cobalt compound may be selected from cobalt chloride, cobalt nitrate, cobalt sulfate or cobalt-containing coordination compound, and the nickel compound may be selected from nickel chloride, nickel nitrate, nickel sulfate or nickel-containing coordination compound. The cathode or the anode is selected from graphite, nickel, copper or stainless steel, and an area of the anode is greater than or equal to an area of the cathode. The solvent may be selected from water, methanol, ethanol, isopropanol, 1-butanol, acetone solution or combinations thereof.

[0027] Example 1: A 0.05M FeCl.sub.3 aqueous solution, a 0.05M FeSO.sub.4 aqueous solution, a 0.1M Co(NO.sub.3).sub.2 aqueous solution and a 0.1M Ni(NO.sub.3).sub.2 aqueous solution are respectively prepared, and the above-mentioned metal compound solution are mixed by stirring, followed by performing the cathodic electrodeposition experiment through the two-electrode system, wherein the working electrode and the auxiliary electrode are both Ni foam (5 cm*5 cm), a constant current of 0.2 A is applied, the deposition time is 10 min, and an oxygen evolution catalyst electrode (as shown in FIG. 2) having an area of 25 cm.sup.2 is formed. After that, a catalyst electrode with a small area (0.08 cm.sup.2) is cut out of the prepared large-area catalyst electrode (25 cm.sup.2) for catalytic activity measurement of hydrogen/oxygen evolution reactions (HER/OER), in which the catalyst electrode with the small area is put in aqueous solution of 1M KOH electrolyte, and a linear sweep voltammetry (LSV) test of the electrochemistry is performed. It is found that the deposited thin film has the catalytic activities for the hydrogen evolution reaction and the oxygen evolution reaction, and the release of gas on the surface of the electrode plate is also observed during the process. It can be seen from the experimental data of the hydrogen evolution reaction that the overpotential η is 181 mV when the current density reaches 100 mA/cm.sup.2, and it can be seen from the experimental data of the oxygen evolution reaction that the overpotential η is 259 mV when the current density reaches 100 mA/cm.sup.2. Referring to FIG. 2, FIG. 2 schematically illustrates a cathode and an anode after the electrochemical deposition according to an embodiment of the present invention. Referring to FIG. 3, FIG. 3 schematically illustrates a cathodic catalyst electrode and an anodic catalyst electrode of a catalyst electrode after electrochemical electrolysis of water according to an embodiment of the present invention. Referring to FIG. 4, FIG. 4 is a scanning electron microscope diagram of the cathodic catalyst electrode of the catalyst electrode after electrochemical electrolysis of water according to an embodiment of the present invention. As shown in FIG. 4, the cathodic catalyst after electrochemical electrolysis of water presents a sub-micron plate shape. Referring to FIG. 5, FIG. 5 is an energy dispersive X-ray spectroscopy diagram of the cathodic catalyst electrode of the catalyst electrode after electrochemical electrolysis of water according to an embodiment of the present invention. As shown in FIG. 5, the cathodic catalyst electrode after electrochemical electrolysis of water contains three metal elements including iron, cobalt and nickel. Referring to FIG. 6, FIG. 6 is a scanning electron microscope diagram of the anodic catalyst electrode of the catalyst electrode after electrochemical electrolysis of water according to an embodiment of the present invention. As shown in FIG. 6, the anodic catalyst after electrochemical electrolysis of water presents a micron plate shape. Referring to FIG. 7, FIG. 7 is an energy dispersive X-ray spectroscopy diagram of the anodic catalyst electrode of the catalyst electrode after electrochemical electrolysis of water according to an embodiment of the present invention. As shown in FIG. 7, the anodic catalyst electrode after electrochemical electrolysis of water contains three metal elements including iron, cobalt and nickel.

[0028] Example 2: A 0.075M FeCl.sub.3 aqueous solution, a 0.025M FeSO.sub.4 aqueous solution, a 0.1M Co(NO.sub.3).sub.2 aqueous solution and a 0.1M NiSO.sub.4 aqueous solution are respectively prepared, and the above-mentioned metal compound solution are mixed by stirring, followed by performing the cathodic electrodeposition experiment through the two-electrode system, wherein the working electrode and the auxiliary electrode are both Ti mesh (5 cm*5 cm), a constant current of 0.6 A is applied, the deposition time is 5 min, and an oxygen evolution catalyst electrode having an area of 25 cm.sup.2 is formed. After that, a catalyst electrode with a small area (0.08 cm.sup.2) is cut out of the prepared large-area catalyst electrode (25 cm.sup.2) for catalytic activity measurement of the hydrogen/oxygen evolution reaction (HER/OER), in which the catalyst electrode with the small area is put in aqueous solution of 1M KOH electrolyte, and a LSV test of the electrochemistry is performed. It is found that the deposited thin film has the catalytic activities of the hydrogen evolution reaction and the oxygen evolution reaction, and the release of gas on the surface of the electrode plate is also observed during the process. It can be seen from the experimental data of the hydrogen evolution reaction that the overpotential η is 169 mV when the current density reaches 100 mA/cm.sup.2, and it can be seen from the experimental data of the oxygen evolution reaction that the overpotential η is 243 mV when the current density reaches 100 mA/cm.sup.2.

[0029] Compared with the high-temperature and high-pressure method in the prior art literature, the non-noble metals having low costs are adopted as the raw materials in the preparing method of the present invention, and the traditional noble metal catalysts for electrolysis of water are replaced. The mixed metal solution is prepared, and the large-area cathodic electrochemical deposition is performed through the two-electrode method in a condition of constant current or constant voltage, such that a uniform thin film of the catalyst can be formed on the surface of the electrode plate. In the method of the present invention, the processes of mixing the raw materials and the electrochemical deposition are fast, the equipment is simple, and the large-area catalyst electrode applied to electrolysis of water for hydrogen evolution and oxygen evolution under an alkaline condition can be mass produced in only one step. In addition, the catalyst electrode prepared by the present invention can contain three metal elements including iron, cobalt and nickel, which can help the subsequent water electrolysis process to have dual-function hydrogen evolution and oxygen evolution effect, and the efficiency of water electrolysis and the amount of gas produced can be effectively improved. Therefore, in the preparation method of the present invention, the process is simple, the strict conditions such as high temperature, high pressure and high specification equipment are not required, the production cost is low, and the economic and energy-saving benefits are included.

[0030] Those skilled in the art will readily observe that numerous modifications and alterations of the device and method may be made while retaining the teachings of the invention. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims.