A nickel-based electrocatalyst, a preparation method and application thereof

Abstract

The application belongs to the technical field of hydrogen evolution electrocatalyst preparation, and particularly relates to a nickel-based electrocatalyst and a preparation method and application thereof; the nickel-based electrocatalyst takes a foamed nickel as a base material, obtains a nickel-based alloy film through a direct-current magnetron sputtering method, and then obtains the nickel-based electrocatalyst through liquid-phase reduction treatment of ruthenium; the application provides a design idea of a cheap, easily-obtained and high-activity hydrogen evolution electrocatalyst, the nickel-based electrocatalyst prepared by the application has high charge transfer efficiency and excellent hydrogen evolution activity, and shows good durability and low hydrogen evolution overpotential under long-term alkaline large-current conditions. The preparation method can synthesize different nickel-based alloy pre-catalysts, and has wide development prospect and large application space.

Description

TECHNICAL FIELD

[0001] The application relates to an electrocatalytic material, and belongs to the technical field of hydrogen evolution electrocatalysts, in particular to a nickel-based electrocatalyst and a preparation method and application thereof. BACKGROUND

[0002] Hydrogen is non-toxic, odorless, clean and pollution-free, and has a high calorific value (142 MJ / kg), which is more than three times that of oil, and is an ideal substitute for fossil fuels. In the future, hydrogen energy will play a key role in the transition from fossil energy to clean energy. Hydrogen is obtained from water, and water is generated after combustion, which can be recycled, achieving zero pollution and zero emission. At present, there are several ways to produce hydrogen, including fossil fuel hydrogen production, hydrogen-containing tail gas by-product hydrogen recovery, and water electrolysis hydrogen production. Water electrolysis hydrogen production accounts for only a small part, and fossil fuel hydrogen production and hydrogen-containing tail gas by-product hydrogen recovery account for about 96% of hydrogen production. This process consumes a large amount of fossil energy and emits excessive carbon dioxide, which is contrary to the national double carbon goal. Water electrolysis hydrogen production does not emit carbon dioxide, avoids the emission of methane greenhouse gases in the steam reforming process, and meets the principle of sustainable development, which is the trend of hydrogen production. Alkaline water electrolysis has attracted widespread attention due to its low equipment requirements and effective avoidance of acid mist and corrosion. However, in an alkaline medium, the additional water dissociation step leads to slow kinetics. In order to overcome the slow kinetics and reduce the overpotential of the hydrogen evolution reaction to the minimum, it is urgent to design an alkaline HER catalyst with high activity, high stability and durability.

[0003] In the current research, Pt-based catalysts are widely used due to their suitable hydrogen adsorption free energy, but they have high cost, while Ru-based catalysts have lower cost and similar Ru-H bond strength to Pt, and are considered as ideal substitutes for Pt-based catalysts. However, Ru-based catalysts also have certain disadvantages, such as poor water dissociation ability, which leads to insufficient proton supply; and the Ru-H bond strength is too strong, which hinders the desorption of H2. Therefore, a series of studies are devoted to combining Ru with suitable transition metal-based carriers to optimize the Ru-H adsorption energy and improve the water dissociation ability through electronic regulation and other means. In the current research, nickel-based catalysts have attracted widespread attention due to their high electrical conductivity and good water molecule adsorption / desorption performance. Alloying nickel with other transition metals can improve the inherent electrocatalytic activity and corrosion resistance of the catalyst, and also can adjust the electronic structure of the active site, thereby optimizing the hydrogen adsorption free energy, which is helpful to realize large current density hydrogen evolution and the development of efficient and low-cost water electrolysis hydrogen production technology. SUMMARY

[0004] The present application overcomes the shortcomings of the prior art and provides a nickel-based electrocatalyst to meet the needs of research and application in the field.

[0005] To solve the above technical problems, the technical scheme of the present application is as follows: a nickel-based electrocatalyst, taking foamed nickel as a base material, using a magnetron sputtering method to deposit a layer of nickel-based alloy film on the surface of the foamed nickel, and then using a liquid phase reduction method to obtain the nickel-based electrocatalyst.

[0006] The present application also provides a preparation method of the above-mentioned nickel-based electrocatalyst, comprising the following steps:

[0007] (1) depositing a nickel-based alloy film on the foamed nickel by using a direct current magnetron sputtering method: first, install the target material, fix the treated foamed nickel in the sample area, and the working atmosphere during the deposition process is argon, and the pressure is selected according to different transition metals; before formal deposition, pre-sputter the nickel target and different transition metal targets in an argon atmosphere for five minutes to remove the surface oxide layer; then adjust the deposition power of the nickel to 50W, and the deposition power of the other transition metals is 20W; deposit on both the front and back surfaces for thirty minutes respectively to obtain a nickel-based alloy pre-catalyst;

[0008] (2) immerse the nickel-based alloy pre-catalyst obtained in step (1) in a ruthenium trichloride solution, and then reduce it by a sodium borohydride solution; then wash off the ruthenium attached to the surface of the foamed nickel with deionized water, wash with ethanol, and dry to obtain a nickel-based electrocatalyst.

[0009] As a further limitation of the technical scheme of the present application, the purity of the argon in step (1) is 99.999%, and the flow rate is 30sccm.

[0010] As a further limitation of the technical scheme of the present application, the pre-sputtering power of the nickel target and the different transition metal targets in step (1) is 70W.

[0011] As a further limitation of the technical scheme of the present application, the transition metal target in step (1) is cobalt, molybdenum, copper, tin or zinc, and the purity of the molybdenum target is 99.95%, and the purity of the remaining targets is 99.999%.

[0012] As a further limitation of the technical scheme of the present application, the corresponding pressures of the cobalt, molybdenum, copper, tin and zinc in step (1) are 0.5Pa, 0.7Pa, 0.7Pa, 0.7Pa and 0.8Pa respectively.

[0013] As a further limitation of the technical scheme of the present application, the size of the foamed nickel in step (1) is 1*1.2cm -2 , and the ruthenium trichloride solution in step (2) is a 20mL aqueous solution containing 25mg RuCl3•xH2O, and the immersion time is two hours.

[0014] As a further limitation of the technical scheme of the present application, the concentration of the sodium borohydride solution is 0.5mol / L, and the volume ratio of the ruthenium trichloride solution to the sodium borohydride solution used is 2:1.

[0015] As a further limitation of the technical scheme of the application, the drying condition of step (2) is drying in a 110℃ oven for three hours.

[0016] In addition, the application also provides the application of the above-mentioned nickel-based electrocatalyst in the cathode hydrogen evolution reaction of alkaline large current density. The nickel-based electrocatalyst prepared by the method has excellent hydrogen evolution activity and exhibits good durability and lower hydrogen evolution overpotential under long-term alkaline large current conditions.

[0017] Compared with the prior art, the application has the following beneficial effects:

[0018] 1. The nickel-based alloy pre-catalyst is in a film shape, and the cross section is in a closely arranged columnar structure, which is firmly connected with the foam nickel and can be used as an excellent carrier of the nickel-based electrocatalyst. Different nickel-based alloy pre-catalysts can be obtained by simultaneously depositing the nickel target and other transition metal targets in a direct current magnetron sputtering system.

[0019] 2. The Ru particles are loaded on the nickel-based alloy pre-catalyst by a liquid phase reduction method, which retains the dense film structure of the nickel-based alloy pre-catalyst, and the film structure can also make the Ru particles uniformly distributed, so that the catalyst has abundant active sites and high intrinsic activity. The interface between the Ru particles and the nickel-based alloy film is also conducive to charge transfer, thereby realizing electronic redistribution.

[0020] 3. The nickel-based electrocatalyst has excellent alkaline large current hydrogen evolution performance, and can drive long-term stable operation of large current density at a lower potential.

[0021] 4. The nickel-based electrocatalyst is easy to prepare, and the process is simple and easy to realize batch production.

[0022] The application has reasonable design, can prepare different nickel-based alloy electrocatalysts, and has broad development prospects and larger application space. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 The scanning electron microscope picture of NiCo obtained in Example 1 is shown.

[0024] Figure 2 The scanning electron microscope picture of Ru / NiCo obtained in Example 1 is shown.

[0025] Figure 3 The Raman spectrum of Ru / NiCo and NiCo obtained in Example 1 is shown.

[0026] Figure 4 The picture of the mass percentage of each element of Ru / NiCo obtained in Example 1 tested by ICP is shown.

[0027] Figure 5 Linear voltammetry curve of Ru / NiCo obtained in Example 1 for hydrogen evolution performance test (1 mol / L potassium hydroxide).

[0028] Figure 6 Stability test curve of Ru / NiCo obtained in Example 1 at -10 mA cm -2

[0029] Figure 7 Stability test curve of Ru / NiCo obtained in Example 1 at -1000 mA cm -2

[0030] Figure 8 Linear voltammetry curve of Ru / NiMo obtained in Example 2 for hydrogen evolution performance test (1 mol / L potassium hydroxide).

[0031] Figure 9 Linear voltammetry curve of Ru / NiCu obtained in Example 3 for hydrogen evolution performance test (1 mol / L potassium hydroxide).

[0032] Figure 10 Linear voltammetry curve of Ru / NiSn obtained in Example 4 for hydrogen evolution performance test (1 mol / L potassium hydroxide).

[0033] Figure 11 Linear voltammetry curve of Ru / NiZn obtained in Example 5 for hydrogen evolution performance test (1 mol / L potassium hydroxide). DETAILED DESCRIPTION

[0034] The application will be further described below in conjunction with specific examples. Example 1

[0035] A preparation method of a nickel-based electrocatalyst for alkaline large-current hydrogen evolution, comprising the following steps:

[0036] (1) A nickel-cobalt film was deposited on the nickel foam by using a direct current magnetron sputtering system. First, the target material was installed, and the treated nickel foam was fixed in the sample area. The working atmosphere during the deposition process was high-purity argon, and the thin film rule vacuum degree was 0.5 Pa. Before the formal deposition, the nickel target with a purity of 99.999% and the cobalt target with a purity of 99.999% were pre-sputtered under an argon atmosphere at 70 W for five minutes to remove the surface oxide layer. Then, the deposition power of nickel was adjusted to 50 W, and the deposition power of cobalt was adjusted to 20 W. Each side was deposited for thirty minutes to obtain a nickel-cobalt alloy pre-catalyst (denoted as NiCo).

[0037] ​​(2) The NiCo obtained in step (1) was immersed in 20 mL of aqueous solution containing 25 mg of ruthenium trichloride hydrate for two hours. Then, 10 mL of 0.5 mol / L sodium borohydride solution was added dropwise to the ruthenium trichloride solution. The whole process was controlled within 15 minutes. When all the sodium borohydride solution was added and no obvious bubbles were generated, the mixture was allowed to stand for three hours to allow the system to react fully. Finally, the foamed nickel was removed, washed several times with deionized water and ethanol to remove the loosely attached ruthenium particles, and dried in an oven at 110 °C for three hours to obtain the nickel-based electrocatalyst (denoted as Ru / NiCo).

[0038] The scanning electron microscope image of the NiCo alloy precatalyst prepared in Example 1 is shown below. Figure 1 As shown, by Figure 1 It can be seen that the prepared NiCo alloy precatalyst is attached to the surface of nickel foam in the form of a thin film, and its cross-section has a tightly packed columnar structure. The thickness is approximately 172.5 nm.

[0039] The scanning electron microscope image of the Ru / NiCo electrocatalyst prepared in Example 1 is shown below. Figure 2 As shown, by Figure 2 This demonstrates that Ru particles successfully adhered to the surface of the NiCo alloy film and were distributed relatively uniformly.

[0040] The Raman spectra of the NiCo and Ru / NiCo electrocatalysts prepared in Example 1 are as follows: Figure 3 As shown, by Figure 3 It can be seen that the peaks of Ru / NiCo and NiCo are basically the same, at 185 cm⁻¹. -1 and 615cm -1 The peak at 510 cm⁻¹ corresponds to the Co-O bond. -1 The peak at 963 cm⁻¹ corresponds to the Ni-O bond. The Ru / NiCo peak at 963 cm⁻¹ corresponds to the Ni-O bond. -1 The weak peak at the point corresponds to the Ru-O bond on the surface, indicating that there is slight oxidation on both Ru / NiCo and NiCo surfaces.

[0041] The mass percentages of each element in the Ru / NiCo electrocatalyst prepared in Example 1 are as follows: Figure 4 As shown, by Figure 4 It can be seen that the mass ratio of Ru is 2.35 wt%, the mass ratio of Ni is 90.15 wt%, and the mass ratio of Co is 7.49 wt%.

[0042] The alkaline hydrogen evolution performance test curve of the Ru / NiCo electrocatalyst prepared in Example 1 is shown below. Figure 5 As shown, by Figure 5 It can be seen that the prepared nickel-based electrocatalyst can achieve -10 mA cm⁻¹ with only 15 mV and 94 mV. -2 and -100mA cm -2The current density is such that it can drive a -500mA cm at 178mV and 234mV. -2 and -1000mA cm -2 High current density.

[0043] The Ru / NiCo electrocatalyst prepared in Example 1 was subjected to an energy density of -10 mA cm⁻¹. -2 The stability test curve is as follows Figure 6 As shown, by Figure 6 It can be seen that the prepared nickel-based electrocatalyst can operate at -10 mA cm⁻¹ -2 It operates stably for 100 hours at the specified current density.

[0044] The Ru / NiCo electrocatalyst prepared in Example 1 was tested at -1000 mA cm⁻¹. -2 The stability test curves are as follows: Figure 7 As shown, by Figure 7 It can be seen that the prepared nickel-based electrocatalyst can operate at -1000 mA cm⁻¹ -2 It operated stably for 100 hours at a high current density, indicating that it can stably drive the hydrogen evolution reaction at a high current density over a long period. Example 2

[0045] A method for preparing a nickel-based electrocatalyst for alkaline high-current hydrogen evolution includes the following steps:

[0046] (1) A nickel-molybdenum thin film was deposited on nickel foam using a DC magnetron sputtering system. First, the target material was installed and the treated nickel foam was fixed in the sample area. The working atmosphere during the deposition process was high-purity argon, and the vacuum degree of the thin film was 0.7 Pa. Before the formal deposition, the nickel target material with a purity of 99.999% and the molybdenum target material with a purity of 99.95% were pre-sputtered at 70W in an argon atmosphere for five minutes to remove the surface oxide layer. Then, the deposition power of nickel was adjusted to 50W and the deposition power of molybdenum was 20W. The two sides were deposited for 30 minutes each to obtain the nickel-molybdenum alloy pre-catalyst (denoted as NiMo).

[0047] (2) The NiMo obtained in step (1) was immersed in 20 mL of aqueous solution containing 25 mg of ruthenium trichloride hydrate for two hours. Then, 10 mL of 0.5 mol / L sodium borohydride solution was added dropwise to the ruthenium trichloride solution. The whole process was controlled within 15 minutes. When all the sodium borohydride solution was added and no obvious bubbles were generated, the mixture was allowed to stand for three hours to allow the system to react fully. Finally, the nickel foam was removed, washed several times with deionized water and ethanol to remove the loosely attached ruthenium particles, and dried in an oven at 110 °C for three hours to obtain the nickel-based electrocatalyst (denoted as Ru / NiMo).

[0048] The alkaline hydrogen evolution performance test curve of the Ru / NiMo electrocatalyst prepared in Example 2 is shown below.Figure 8 As shown in Figure 8 It can be seen that the prepared nickel-based electrocatalyst only needs 473 mV to reach a large current density of -1000 mA cm -2 . Example 3

[0049] A method for preparing a nickel-based electrocatalyst for alkaline large current hydrogen evolution, comprising the following steps:

[0050] (1) A nickel-copper film was deposited on the nickel foam using a direct current magnetron sputtering system. First, the target material was installed, and the treated nickel foam was fixed in the sample area. The working atmosphere during deposition was high-purity argon, and the thin film rule vacuum degree was 0.7 Pa. Before formal deposition, the nickel target with a purity of 99.999% and the copper target with a purity of 99.999% were pre-sputtered under an argon atmosphere at 70 W for five minutes to remove the surface oxide layer. Then the deposition power of nickel was adjusted to 50 W, and the deposition power of copper was 20 W. Each side was deposited for thirty minutes to obtain a nickel-copper alloy pre-catalyst (denoted as NiCu).

[0051] (2) The NiCu obtained in step (1) was immersed in a 20 mL aqueous solution containing 25 mg of ruthenium trichloride hydrate for two hours. Then 10 mL of 0.5 mol / L sodium borohydride solution was added dropwise to the ruthenium trichloride solution. The whole process was controlled within fifteen minutes. When all the sodium borohydride solution was added and no obvious bubbles were generated, the system was allowed to stand for three hours for full reaction. Finally, the nickel foam was taken out, washed with deionized water and ethanol several times to remove the loose ruthenium particles attached to the surface, and dried in a 110°C oven for three hours to obtain a nickel-based electrocatalyst (denoted as Ru / NiCu).

[0052] The alkaline hydrogen evolution performance test curve of the Ru / NiCu electrocatalyst prepared in this example 3 is shown in Figure 9 As shown in Figure 9 It can be seen that the prepared nickel-based electrocatalyst only needs 399 mV to reach a large current density of -1000 mA cm -2 . Example 4

[0053] A method for preparing a nickel-based electrocatalyst for alkaline large current hydrogen evolution, comprising the following steps:

[0054] (1) Using a direct current magnetron sputtering system, a nickel-tin film was deposited on the nickel foam. First, the target material was installed, and the treated nickel foam was fixed in the sample area. During the deposition process, the working atmosphere was high-purity argon, and the film rule vacuum degree was 0.7 Pa. Before formal deposition, the nickel target with a purity of 99.999% and the tin target with a purity of 99.999% were pre-sputtered under an argon atmosphere at 70 W for five minutes to remove the surface oxide layer. Then, the deposition power of nickel was adjusted to 50 W, and the deposition power of tin was adjusted to 20 W. Each side was deposited for thirty minutes to obtain a nickel-tin alloy pre-catalyst (denoted as NiSn).

[0055] (2) The NiSn obtained in step (1) was immersed in a 20 mL aqueous solution containing 25 mg of ruthenium trichloride hydrate for two hours. Then, 10 mL of a 0.5 mol / L sodium borohydride solution was added dropwise to the ruthenium trichloride solution. The entire process was controlled within fifteen minutes. When all the sodium borohydride solution was added and no obvious bubbles were generated, the system was allowed to react for three hours. Finally, the nickel foam was taken out, washed several times with deionized water and ethanol to remove the loosely attached ruthenium particles, and dried in a 110°C oven for three hours to obtain a nickel-based electrocatalyst (denoted as Ru / NiSn).

[0056] The basic hydrogen evolution performance test curve of the Ru / NiSn electrocatalyst prepared in Example 4 is shown in Figure 10 , and it can be seen from Figure 10 that the prepared nickel-based electrocatalyst only needs 432 mV to reach a large current density of -1000 mA cm -2 . Example 5

[0057] A method for preparing a nickel-based electrocatalyst for alkaline large-current hydrogen evolution includes the following steps:

[0058] (1) Using a direct current magnetron sputtering system, a nickel-zinc film was deposited on the nickel foam. First, the target material was installed, and the treated nickel foam was fixed in the sample area. During the deposition process, the working atmosphere was high-purity argon, and the film rule vacuum degree was 0.8 Pa. Before formal deposition, the nickel target with a purity of 99.999% and the zinc target with a purity of 99.999% were pre-sputtered under an argon atmosphere at 70 W for five minutes to remove the surface oxide layer. Then, the deposition power of nickel was adjusted to 50 W, and the deposition power of zinc was adjusted to 20 W. Each side was deposited for thirty minutes to obtain a nickel-zinc alloy pre-catalyst (denoted as NiZn).

[0059] (2) The NiZn obtained in step (1) was immersed in 20 mL of aqueous solution containing 25 mg of ruthenium trichloride hydrate for two hours. Then, 10 mL of 0.5 mol / L sodium borohydride solution was added dropwise to the ruthenium trichloride solution. The whole process was controlled within 15 minutes. When all the sodium borohydride solution was added and no obvious bubbles were generated, the mixture was allowed to stand for three hours to allow the system to react fully. Finally, the foamed nickel was removed, washed several times with deionized water and ethanol to remove the loosely attached ruthenium particles, and dried in an oven at 110 °C for three hours to obtain the nickel-based electrocatalyst (denoted as Ru / NiZn).

[0060] The alkaline hydrogen evolution performance test curve of the Ru / NiZn electrocatalyst prepared in Example 5 is shown below. Figure 11 As shown, by Figure 11 It can be seen that the prepared nickel-based electrocatalyst only requires 381mV to reach -1000mA cm⁻¹. -2 High current density.

[0061] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the embodiments of the present invention have been described in detail, those skilled in the art should understand that modifications or equivalent substitutions to the technical solutions of the present invention do not depart from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of protection of the claims of the present invention.

Claims

1. A method for preparing a nickel-based electrocatalyst, characterized by, The method comprises the following steps: (1) depositing a nickel-based alloy film on the nickel foam by a direct current magnetron sputtering method: first, installing the target material, fixing the treated nickel foam in the sample area, and depositing in an argon atmosphere during the process; the pressure is selected according to different transition metals; before formal deposition, the nickel target and different transition metal targets are pre-sputtered in an argon atmosphere for five minutes to remove the surface oxide layer; then the deposition power of the nickel is adjusted to 50W, and the deposition power of the other transition metals is 20W; the front and back surfaces are each deposited for thirty minutes to obtain a nickel-based alloy pre-catalyst; the transition metal target is one of cobalt, molybdenum, copper, tin or zinc; except that the purity of the molybdenum target is 99.95%, the purity of the other targets is 99.999%; (2) immersing the nickel-based alloy pre-catalyst obtained in step (1) in a ruthenium trichloride solution, and then reducing it with a sodium borohydride solution; then washing the ruthenium attached to the surface of the nickel foam with deionized water, and then washing with ethanol and drying to obtain a nickel-based electrocatalyst.

2. The method for preparing a nickel-based electrocatalyst according to claim 1, characterized in that, The purity of the argon in step (1) is 99.999%, and the flow rate is 30sccm.

3. The method of claim 1, wherein the nickel-based electrocatalyst is prepared by the steps of: The pre-sputtering power of the nickel target and the different transition metal targets in step (1) is 70W.

4. The method for preparing a nickel-based electrocatalyst according to claim 1, characterized in that, The corresponding pressures of the cobalt, molybdenum, copper, tin and zinc in step (1) are 0.5Pa, 0.7Pa, 0.7Pa, 0.7Pa and 0.8Pa, respectively.

5. The method for preparing a nickel-based electrocatalyst according to claim 1, characterized in that, The size of the foamed nickel in step (1) was 1*1.2 cm -2 The solution of ruthenium trichloride in step (2) was 20 mL of an aqueous solution containing 25 mg of RuCl3xH2O, and the impregnation time was two hours.

6. The method for preparing a nickel-based electrocatalyst according to claim 1, characterized in that, The concentration of the sodium borohydride solution is 0.5mol / L, and the volume ratio of the ruthenium trichloride solution to the sodium borohydride solution used is 2:

1.

7. The method for preparing a nickel-based electrocatalyst according to claim 2, characterized in that, The drying condition of step (2) is drying in a 110°C oven for three hours.

8. The nickel-based electrocatalyst prepared by the preparation method according to any one of claims 1-7.

9. The use of the nickel-based electrocatalyst prepared by the preparation method according to any one of claims 1-7 in the cathodic hydrogen evolution reaction of alkaline high-current density.

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