A hydrogen evolution catalyst, its preparation method and application

Abstract

The present invention discloses a hydrogen evolution catalyst, a preparation method thereof and an application thereof. The preparation method of the hydrogen evolution catalyst includes using a carrier electrode as a substrate, using an iron salt solution as an electrolyte, applying a commutation step current to the carrier electrode to pass a cathodic current, so as to deposit an iron metal layer on the carrier electrode, and then changing the current direction by the commutation step current and applying an anodic current to the carrier electrode to oxidize the surface of the iron metal layer to form an iron oxide layer. Repeating the above process for electrochemical deposition to obtain the hydrogen evolution catalyst. By the above method, electrochemical deposition is carried out using a commutation step current, which can realize the interactive combination of reduction deposition and surface oxidation of iron metal, and obtain an Fe / / Fe2O3 interactive hierarchical composite hydrogen evolution catalyst. The product catalyst has good conductivity and hydrogen evolution catalytic performance, and its process is simple, raw materials are easy to obtain, the cost is low, and it is suitable for large-scale industrial production.

Description

Technical Field

[0001] The present invention relates to the technical field of electrocatalytic chemistry, and in particular to a hydrogen evolution catalyst, a preparation method thereof, and an application thereof. Background Art

[0002] With the growth of global energy demand, while traditional fossil fuels have driven rapid economic development, they have also brought serious problems such as energy shortages and environmental pollution. In recent years, new energy industries marked by low energy consumption and low emissions have been developing day by day, alleviating the dependence on traditional fossil energy. Among many new energy industries, hydrogen energy is an ideal green energy carrier, with advantages such as rich resources, high combustion calorific value, and pollution-free combustion products, and is an ideal zero-emission fuel. Therefore, the development of highly efficient hydrogen production processes has become a research hotspot in recent years.

[0003] In existing hydrogen production processes, electrolytic water hydrogen production based on the hydrogen evolution reaction uses water, which is rich in resources, as a raw material, and no pollutants are released during the preparation process. It is considered a green, clean technology with great application prospects. However, the hydrogen evolution reaction (HER) of water decomposition itself has a relatively high reaction barrier and is not easy to occur thermodynamically. Using an efficient HER electrocatalyst to improve the sluggish reaction kinetics and reduce the overpotential can effectively solve the above problems. Currently, commonly used noble metal electrolytic water catalysts (such as Pt-based catalysts) although show excellent hydrogen evolution catalytic activity, they have problems of low resource reserves and high costs, which limit their large-scale application; while some catalysts have problems of insufficient conductivity and poor catalytic performance. Summary of the Invention

[0004] The present invention aims to solve at least one of the technical problems existing in the prior art. For this purpose, the present invention provides a hydrogen evolution catalyst, a preparation method thereof, and an application thereof.

[0005] In a first aspect of the present invention, a preparation method of a hydrogen evolution catalyst is provided, including the following steps: using a carrier electrode as a substrate, using an iron salt solution as an electrolyte, and performing electrochemical deposition with a commutation step current to obtain a hydrogen evolution catalyst; wherein, performing electrochemical deposition with a commutation step current includes: applying a cathode current to the carrier electrode to deposit an iron metal layer on the carrier electrode, and then changing the current direction to apply an anode current to the carrier electrode to oxidize the surface of the iron metal layer to form an iron oxide layer, and repeating this process to perform electrochemical deposition.

[0006] According to the preparation method of the hydrogen evolution catalyst of the embodiments of the present invention, it has at least the following beneficial effects: This preparation method uses a carrier electrode as the substrate, an iron salt solution as the electrolyte, and a commutating step current for electrochemical deposition to prepare the hydrogen evolution catalyst. Among them, in the electrochemical deposition process, a cathode current is applied to the carrier electrode through the commutating step current, so that iron ions in the electrolyte are reduced and deposited on the substrate carrier electrode to form an iron metal layer. Then, the current direction is changed through the commutating step current, and an anode current is applied to the carrier electrode, so that the surface of the iron metal layer deposited on the carrier electrode is oxidized to form an iron oxide layer. Taking this as a cycle, the commutating step current is used to continuously replace and alternate through the cycle, realizing the interactive compounding of the reduction deposition and surface oxidation of iron metal on the carrier electrode, and preparing the Fe / / Fe2O3 interactive hierarchical composite hydrogen evolution catalyst. The prepared hydrogen evolution catalyst has good electrical conductivity and hydrogen evolution catalytic performance, and its preparation process is simple, easy to operate, the raw materials are easy to obtain, the cost is low, and it is suitable for large-scale industrial production.

[0007] In some embodiments of the present invention, the cathode current of the commutating step current is 1 A to 4 A, and the anode current is 2 A to 4 A; within one cycle of the commutating step current, the deposition time for applying the cathode current to the carrier electrode is 0.3 to 0.7 s, and the deposition time for applying the cathode current to the carrier electrode is 0.3 to 0.7 s. In each cycle, first, a cathode current is applied to the carrier electrode, so that iron ions in the electrolyte are reduced and deposited on the substrate carrier electrode to form an iron metal layer. Then, the current direction is changed, and an anode current is applied to the carrier electrode, and by controlling the current magnitude and deposition time, the surface of the iron metal layer deposited on the carrier electrode is oxidized to form an iron oxide layer, rather than all of the iron metal layer being oxidized.

[0008] In some embodiments of the present invention, the iron salt in the iron salt solution is selected from at least one of ferric sulfate, ferric chloride, and ferric nitrate.

[0009] In some embodiments of the present invention, the iron salt in the iron salt solution is ferric sulfate and ferric chloride.

[0010] In some embodiments of the present invention, the iron salt in the iron salt solution is ferric sulfate and ferric chloride with a mass ratio of (3 - 5):(1 - 3).

[0011] In some embodiments of the present invention, the mass concentration of the iron salt solution is controlled at 8% - 16%. The iron salt solution can be specifically prepared by dissolving the iron salt in a solvent, and generally water is used as the solvent.

[0012] In some embodiments of the present invention, the carrier electrode is selected from a metal electrode or a non-metal electrode.

[0013] In some embodiments of the present invention, the carrier electrode is selected from any one of a copper plate, an aluminum plate, and a carbon cloth.

[0014] In some embodiments of the present invention, in the electrochemical deposition process, any one of a carbon rod and a platinum electrode is used in cooperation with a carrier electrode for electrochemical deposition.

[0015] In some embodiments of the present invention, the temperature of the electrochemical deposition is 40 - 70 °C, and for example, it can be 40 °C, 45 °C, 50 °C, 55 °C, 60 °C, 70 °C, etc.

[0016] In some embodiments of the present invention, after the electrochemical deposition, a drying treatment is further included.

[0017] In some embodiments of the present invention, the temperature of the drying treatment is 40 - 60 °C, and for example, it can be 40 °C, 50 °C, 55 °C, 60 °C, etc.; the drying time can be controlled within 3 - 5 h.

[0018] In the second aspect of the present invention, a hydrogen evolution catalyst is proposed, which is prepared by any one of the preparation methods of the hydrogen evolution catalysts proposed in the first aspect of the present invention. This hydrogen evolution catalyst is a composite catalyst formed by alternating several Fe layers and Fe₂O₃ layers, wherein the Fe layers and the Fe₂O₃ layers are stacked alternately. Among them, the Fe layer can enhance the electrical conductivity, but it is difficult to improve the catalytic performance of a single Fe layer. By forming an interaction between the Fe₂O₃ layer and the Fe layer, the Fe₂O₃ layer can increase the hydrogen adsorption performance through oxygen vacancies and improve the catalytic performance. Thus, this hydrogen evolution catalyst has good electrical conductivity and hydrogen evolution catalytic performance.

[0019] In the third aspect of the present invention, an application of the above hydrogen evolution catalyst in hydrogen production by electrolyzing water is proposed.

[0020] In the fourth aspect of the present invention, a hydrogen evolution reaction electrode is proposed, and this hydrogen evolution reaction electrode includes any one of the hydrogen evolution catalysts proposed in the second aspect of the present invention.

[0021] In the fifth aspect of the present invention, an electrochemical device is proposed, which includes an anode and a cathode, and the cathode is any one of the hydrogen evolution reaction electrodes proposed in the fourth aspect of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The following further describes the present invention in conjunction with the drawings and embodiments, wherein:

[0023] Figure 1 It is the SEM diagram of the hydrogen evolution catalyst prepared in Example 1;

[0024] Figure 2 It is the hydrogen evolution performance test result diagram of the hydrogen evolution catalyst prepared in Example 1;

[0025] Figure 3 It is the hydrogen evolution performance test result diagram of the hydrogen evolution catalyst prepared in Example 2;

[0026] Figure 4 Hydrogen evolution performance test result graph of the hydrogen evolution catalyst prepared in Example 3;

[0027] Figure 5 Hydrogen evolution performance test result graph of the hydrogen evolution catalyst prepared in Comparative Example 1;

[0028] Figure 6 Hydrogen evolution performance test result graph of the hydrogen evolution catalyst prepared in Comparative Example 2. Detailed implementation manners

[0029] The concept of the present invention and the resulting technical effects will be clearly and completely described below in conjunction with the embodiments to fully understand the purpose, features and effects of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, other embodiments obtained by those skilled in the art without creative efforts shall fall within the scope of protection of the present invention.

[0030] Example 1

[0031] In this example, a hydrogen evolution catalyst was prepared, and its preparation method included the following steps:

[0032] S1. Dissolve 3 g of ferric sulfate and 1 g of ferric chloride in 50 mL of ultrapure water to obtain an electrolyte solution;

[0033] S2. Use a carbon rod as the anode and a carrier electrode copper plate as the cathode, control the temperature of the electrolyte solution at 40 °C, and connect a commutating step current to perform electrochemical deposition in the electrolyte solution. Specifically, first apply a cathode current to the carrier electrode copper plate, the cathode current is 1 A, the deposition time is 0.5 s, and an iron metal layer is deposited on the carrier electrode copper plate. Then, change the current direction through the commutating step current, apply an anode current to the carrier electrode copper plate, the anode current is 2 A, and the deposition time is 0.5 s, so that the surface of the iron metal layer is oxidized to iron oxide, which is used as one cycle. Repeat the above process through the commutating step current, and the total duration of electrochemical deposition is 1 min to form a Fe / / Fe2O3 interactive hierarchical composite hydrogen evolution catalyst on the carrier electrode copper plate;

[0034] S3. Place the Fe / / Fe2O3 interactive hierarchical composite hydrogen evolution catalyst prepared in step S2 together with the carrier electrode copper plate in a vacuum furnace, and perform a drying treatment at 50 °C for 3 h to obtain the hydrogen evolution catalyst.

[0035] The hydrogen evolution catalyst prepared above was observed by a scanning electron microscope (SEM), and the obtained SEM image is as shown in Figure 1 shown.

[0036] Example 2

[0037] In this embodiment, a hydrogen evolution catalyst was prepared, and its preparation method includes the following steps:

[0038] S1. Dissolve 4 g of ferric sulfate and 2 g of ferric chloride in 50 mL of ultrapure water to obtain an electrolyte solution;

[0039] S2. Use a carbon rod as the anode and a carrier electrode copper plate as the cathode. Control the temperature of the electrolyte solution at 50 °C, and connect a commutating step current to perform electrochemical deposition in the electrolyte solution. Specifically, first apply a cathode current of 3 A to the carrier electrode copper plate for a deposition time of 0.5 s to deposit a layer of iron metal on the carrier electrode copper plate. Then, change the current direction through the commutating step current, apply an anode current of 3 A to the carrier electrode copper plate for a deposition time of 0.5 s to oxidize the surface of the iron metal layer to iron oxide. Taking this as one cycle, repeat the above process through the commutating step current to form a Fe / / Fe2O3 interactive hierarchical composite hydrogen evolution catalyst on the carrier electrode copper plate;

[0040] S3. Place the Fe / / Fe2O3 interactive hierarchical composite hydrogen evolution catalyst obtained in step S2 together with the carrier electrode copper plate in a vacuum furnace and dry it at 50 °C for 4 h to obtain the hydrogen evolution catalyst.

[0041] Example 3

[0042] In this embodiment, a hydrogen evolution catalyst was prepared, and its preparation method includes the following steps:

[0043] S1. Dissolve 5 g of ferric sulfate and 3 g of ferric chloride in 50 mL of ultrapure water to obtain an electrolyte solution;

[0044] S2. Use a carbon rod as the anode and a carrier electrode copper plate as the cathode. Control the temperature of the electrolyte solution at 70 °C, and connect a commutating step current to perform electrochemical deposition in the electrolyte solution. Specifically, first apply a cathode current of 4 A to the carrier electrode copper plate for a deposition time of 0.5 s to deposit a layer of iron metal on the carrier electrode copper plate. Then, change the current direction through the commutating step current, apply an anode current of 4 A to the carrier electrode copper plate for a deposition time of 0.5 s to oxidize the surface of the iron metal layer to iron oxide. Taking this as one cycle, repeat the above process through the commutating step current to form a Fe / / Fe2O3 interactive hierarchical composite hydrogen evolution catalyst on the carrier electrode copper plate;

[0045] S3. Place the Fe / / Fe2O3 interactive hierarchical composite hydrogen evolution catalyst obtained in step S2 together with the carrier electrode copper plate in a vacuum furnace and dry it at 50 °C for 5 h to obtain the hydrogen evolution catalyst.

[0046] Comparative Example 1

[0047] A hydrogen evolution catalyst was prepared in this comparative example. The difference between this comparative example and Example 1 is that in step S2 of this comparative example, a step current was used instead of the commutation step current used in Example 1 for electrochemical deposition. During the electrochemical deposition process, the cathode current applied to the carrier electrode copper plate by the step current was 1 A, and the deposition time was 0.5 s. Then, the current application was stopped for 0.5 s. Other operations were the same as those in Example 1. The specific preparation method includes the following steps:

[0048] S1. Dissolve 3 g of ferric sulfate and 1 g of ferric chloride in 50 mL of ultrapure water to obtain an electrolyte solution;

[0049] S2. Use a carbon rod as the anode and a carrier electrode copper plate as the cathode. Control the temperature of the electrolyte solution at 40 °C and turn on the step current to perform electrochemical deposition in the electrolyte solution. Specifically, first apply a cathode current to the carrier electrode copper plate. The cathode current is 1 A, and the deposition time is 0.5 s. A ferrous metal layer is deposited on the carrier electrode copper plate. Then, stop applying the current for 0.5 s. Taking this as a cycle, repeat the above process through the step current to form an Fe layer hydrogen evolution catalyst on the carrier electrode copper plate;

[0050] S3. Place the Fe layer hydrogen evolution catalyst obtained in step S2 together with the carrier electrode copper plate in a vacuum furnace and perform drying treatment at 50 °C for 3 h to obtain a hydrogen evolution catalyst.

[0051] Comparative Example 2

[0052] A hydrogen evolution catalyst was prepared in this comparative example. The specific preparation method includes the following steps:

[0053] S1. Dissolve 3 g of ferric sulfate and 1 g of ferric chloride in 50 mL of ultrapure water to obtain an electrolyte solution;

[0054] S2. Use a carbon rod as the anode and a carrier electrode copper plate as the cathode. Control the temperature of the electrolyte solution at 40 °C and turn on the current to perform electrochemical deposition in the electrolyte solution. Specifically, first apply a cathode current to the carrier electrode copper plate. The cathode current is 1 A, and the deposition time is 100 s. A ferrous metal layer is formed on the carrier electrode copper plate. Then, change the current direction and apply an anode current to the carrier electrode copper plate. The anode current is 4 A, and the deposition time is 100 s. Oxidize the ferrous metal layer to iron oxide, and then form an Fe2O3 layer hydrogen evolution catalyst on the carrier electrode copper plate;

[0055] S3. Place the Fe2O3 layer hydrogen evolution catalyst obtained in step S2 together with the carrier electrode copper plate in a vacuum furnace and perform drying treatment at 50 °C for 3 h to obtain a hydrogen evolution catalyst.

[0056] The hydrogen evolution catalysts prepared in the above embodiments and comparative examples can be used for hydrogen production by electrolysis of water. Specifically, the hydrogen evolution catalyst prepared above is used to prepare a hydrogen evolution reaction electrode, and then the hydrogen evolution reaction electrode includes the above hydrogen evolution catalyst. Since the above hydrogen evolution catalyst is prepared by an electrochemical deposition method, wherein the hydrogen evolution catalyst is attached to the surface of the carrier electrode, then the carrier electrode and the hydrogen evolution catalyst attached to the surface of the carrier electrode can be combined to form a hydrogen evolution reaction electrode; alternatively, the layered hydrogen evolution catalyst attached to the carrier electrode can be stripped off to form a hydrogen evolution reaction electrode alone or in combination with other carrier electrodes.

[0057] Based on the above hydrogen evolution reaction electrode, an electrochemical device can be further constructed for electrolysis of water to produce hydrogen, the electrochemical device includes an anode and a cathode, and the cathode can specifically adopt the above hydrogen evolution reaction electrode. The hydrogen produced by electrolysis of water to produce hydrogen by the electrochemical device can be used as a clean energy source in fuel cells, such as proton exchange membrane fuel cells.

[0058] In order to verify the hydrogen evolution catalytic activity of the hydrogen evolution catalyst prepared above, the inventors conducted specific verification experiments, including preparing a hydrogen evolution reaction electrode similar to the above method, and constructing an electrochemical device to conduct a water electrolysis hydrogen production experiment. Specifically including:

[0059] The electrochemical performance testing instrument of Shanghai Chenhua CHI760E electrochemical workstation was used, and the performance of the hydrogen evolution catalyst was tested using a three-electrode system, wherein the carrier electrode in the above embodiments and comparative examples and the hydrogen evolution catalyst attached to the surface of the carrier electrode were used as a hydrogen evolution reaction electrode, the hydrogen evolution reaction electrode was used as a working electrode, a graphite rod electrode was used as a counter electrode, a mercuric oxide electrode was used as a reference electrode, and a 1M KOH solution was used as an electrolyte. In order to ensure the stability of the test environment, N2 was continuously introduced into the electrolyte for about 30 minutes before the hydrogen evolution performance test to ensure that the electrolyte was a nitrogen saturated solution, and then the electrolyte was placed in a water bath, and the hydrogen evolution performance test was carried out at a constant temperature (30°C).

[0060] The hydrogen evolution catalysts prepared in Examples 1 to 3 and Comparative Examples 1 to 2 (specifically, the carrier electrode copper plate and the hydrogen evolution catalyst attached thereto as a whole are used as the hydrogen evolution catalyst) were used to test the hydrogen evolution performance according to the above method. The results are as follows: Figures 2 to 6 shown.

[0061] After testing, such as Figure 2 As shown, the hydrogen evolution performance test was carried out using the hydrogen evolution catalyst prepared in Example 1 according to the above method. 2 The overpotential at the current density is -121mV. Figure 2 The negative sign in the horizontal and vertical axes only means that the direction of the current is opposite to the original one. It can be understood that at 10mA / cm 2The overpotential at a current density of 121 mV. As Figure 3 shown, using the hydrogen evolution catalyst prepared in Example 2, the overpotential at a current density of 10 mA / cm 2 is 125 mV. As Figure 4 shown, using the hydrogen evolution catalyst prepared in Example 3, the overpotential at a current density of 10 mA / cm 2 is 127 mV.

[0062] And as Figure 5 shown, the hydrogen evolution performance of the hydrogen evolution catalyst prepared in Comparative Example 1 was tested according to the above method. The overpotential at a current density of 10 mA / cm 2 is 142 mV; as Figure 6 shown, using the hydrogen evolution catalyst prepared in Comparative Example 2, the overpotential at a current density of 10 mA / cm 2 is 138 mV.

[0063] As can be seen from the above, in Examples 1 to 3, the carrier electrode is used as the substrate, the iron salt solution is used as the electrolyte, and the cathodic current is passed through the carrier electrode by a commutation step current to deposit an iron metal layer on the substrate carrier electrode. Then, the current direction is changed by the commutation step current, and the anodic current is passed through the carrier electrode to oxidize the surface of the iron metal layer to form an iron oxide layer. This is repeated, and through the periodic and continuous replacement and interaction of electrochemical deposition, the reduction deposition of iron metal and the interactive composite of surface oxidation are realized on the carrier electrode, and the Fe / / Fe2O3 interactive hierarchical composite hydrogen evolution catalyst is prepared. Compared with the Fe layer hydrogen evolution catalyst prepared in Comparative Example 1 and the Fe2O3 layer hydrogen evolution catalyst prepared in Comparative Example 2, it has higher hydrogen evolution catalytic activity.

[0064] The above embodiments only represent several implementation manners of the present invention. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the patent of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several deformations and improvements can still be made, and these all belong to the protection scope of the present invention.

Claims

1. A preparation method of a hydrogen evolution catalyst, characterized in that, It includes the following steps: using a carrier electrode as a substrate, using an iron salt solution as an electrolyte, and performing electrochemical deposition with a commutation step current to obtain a hydrogen evolution catalyst, and the hydrogen evolution catalyst is an Fe / / Fe2O3 interactive hierarchical composite hydrogen evolution catalyst; Among them, the process of performing electrochemical deposition with a commutation step current includes: passing a cathode current through the carrier electrode to deposit an iron metal layer on the carrier electrode, and then changing the current direction and passing an anode current through the carrier electrode to oxidize the surface of the iron metal layer to form an iron oxide layer, and repeating this process to perform electrochemical deposition.

2. The preparation method of the hydrogen evolution catalyst according to claim 1, characterized in that The cathode current is 1 A to 4 A, and the anode current is 2 A to 4 A; within one cycle of the commutation step current, the deposition time for passing the cathode current through the carrier electrode is 0.3 to 0.7 s, and the deposition time for passing the anode current through the carrier electrode is 0.3 to 0.7 s.

3. The preparation method of the hydrogen evolution catalyst according to claim 1, wherein, The iron salt in the iron salt solution is selected from at least one of ferric sulfate, ferric chloride, and ferric nitrate.

4. The preparation method of the hydrogen evolution catalyst according to claim 3, characterized in that, The iron salt in the iron salt solution is ferric sulfate and ferric chloride.

5. The preparation method of the hydrogen evolution catalyst according to claim 4, characterized in that, The iron salts in the iron salt solution are ferric sulfate and ferric chloride with a mass ratio of (3 to 5):(1 to 3).

6. The preparation method of the hydrogen evolution catalyst according to claim 1, characterized in that, The carrier electrode is selected from a metal electrode or a non-metal electrode.

7. The preparation method of the hydrogen evolution catalyst according to claim 6, characterized in that, The carrier electrode is selected from any one of a copper plate, an aluminum plate, and a carbon cloth.

8. The preparation method of the hydrogen evolution catalyst according to any one of claims 1 to 7, characterized in that, The temperature of the electrochemical deposition is 40 to 70 °C.

9. The preparation method of the hydrogen evolution catalyst according to claim 8, characterized in that, After the electrochemical deposition, a drying treatment is further included.

10. The preparation method of the hydrogen evolution catalyst according to claim 9, wherein, The temperature of the drying treatment is 40 to 60 °C.

11. A hydrogen evolution catalyst, characterized in that, Prepared by the preparation method of the hydrogen evolution catalyst according to any one of claims 1 to 10.

12. Use of the hydrogen evolution catalyst according to claim 11 in hydrogen production by electrolyzing water.

13. A hydrogen evolution reaction electrode, characterized in that, The hydrogen evolution reaction electrode includes the hydrogen evolution catalyst according to claim 11.

14. An electrochemical device, characterized in that, It includes an anode and a cathode, and the cathode is the hydrogen evolution reaction electrode according to claim 13.

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