Preparation method of high-entropy alloy catalyst for producing hydrogen by electrolyzing water

Abstract

The invention provides a preparation method of a high-entropy alloy catalyst for producing hydrogen by electrolyzing water, which is characterized by comprising the following steps: firstly, dissolving five, six, seven or eight of cerium salt, manganese salt, ferric salt, cobalt salt, nickel salt, zinc salt, copper salt and molybdate in water, and adjusting the pH value of the solution to obtain a stable electroplating solution; then, the foamed nickel serves as a cathode, a platinum sheet or a carbon sheet serves as an anode, a constant-current pulse or constant-potential pulse technology is adopted, and high-entropy alloy is obtained through electroplating; and finally, performing electrochemical activation on the prepared high-entropy alloy by adopting a cyclic voltammetry technology to obtain the high-entropy alloy catalyst. The catalyst can efficiently produce hydrogen by electrolyzing water under an alkaline condition.

Description

BACKGROUND

[0001] Hydrogen is a clean energy and a good substitute for traditional energy, which can alleviate environmental pollution. Water electrolysis is an environmentally friendly, easy and sustainable method for hydrogen production. Water electrolysis technology combined with renewable energy such as wind and solar energy can utilize surplus electricity to produce hydrogen, realizing sustainable utilization of energy.

[0002] There are a large number of high-activity catalyst materials for hydrogen production by acidic water electrolysis. However, these materials lack stability under strong acid and reducing conditions, which limits their application in water electrolysis for hydrogen production under acidic conditions. Therefore, catalysts for water electrolysis for hydrogen production under alkaline conditions have become a research hotspot. Under alkaline conditions, the concentration of H + is extremely low, so water electrolysis for hydrogen production is more difficult than under acidic conditions. Even platinum-based catalysts have difficulty in achieving efficient alkaline hydrogen evolution reaction. At present, there is an urgent need to develop catalysts that can efficiently electrolyze water for hydrogen production under alkaline conditions.

[0003] High-entropy alloys are composed of five or more metals in near-equi-molar ratios. The unique "high-entropy effect" can significantly inhibit the crystal plane preferred orientation of single metals, forming a highly disordered solid solution structure. This multi-element synergistic effect can expose more active sites and optimize the surface electron distribution, thereby enhancing the intrinsic catalytic activity of the hydrogen evolution reaction. Second, the lattice distortion effect of the multi-component system can induce local charge density rearrangement, enhance the adsorption / desorption capacity of the catalyst surface to reaction intermediates, and effectively reduce the hydrogen evolution overpotential by adjusting the hydrogen adsorption free energy. High-entropy alloys are prone to form nanocrystalline or amorphous structures. This high-density grain boundary and defect not only provides abundant active sites, but also accelerates the charge transport efficiency, and its porous characteristics is more conducive to electrolyte penetration and bubble desorption. In addition, the synergistic effect between elements can make up for the poor conductivity and weak corrosion resistance of single non-noble metals, significantly improving the long-term stability of the catalyst in acidic or alkaline electrolyte.

[0004] The present application provides a preparation method of a high-entropy alloy catalyst for water electrolysis for hydrogen production under alkaline conditions. The high-entropy alloy is obtained by electroplating using constant current pulse or constant potential pulse technology; and the prepared high-entropy alloy is electrochemically activated by cyclic voltammetry technology to obtain a high-entropy alloy catalyst. The catalyst can efficiently produce hydrogen by water electrolysis under alkaline conditions. SUMMARY

[0005] The application provides a preparation method of a high-entropy alloy catalyst for electrolytic water hydrogen evolution under alkaline conditions.

[0006] Further, the cerium salt includes one or more of cerium nitrate, cerium chloride, and cerium ammonium sulfate, the manganese salt includes one or more of manganese nitrate, manganese chloride, and manganese sulfate, the iron salt includes one or more of iron nitrate, iron chloride, iron sulfate, and ferrous sulfate, the nickel salt includes one or more of nickel nitrate, nickel chloride, and nickel sulfate, the cobalt salt includes one or more of cobalt nitrate, cobalt chloride, and cobalt sulfate, the zinc salt includes one or more of zinc chloride and zinc nitrate, the copper salt includes one or more of copper nitrate, copper chloride, and copper sulfate, and the molybdate salt includes one or more of sodium molybdate and potassium molybdate.

[0007] Further, the molar ratio of the cerium salt to the manganese salt is 1:1 to 8:1, the molar ratio of the manganese salt to the cobalt salt is 0.1:1 to 0.01:1, the molar ratio of the iron salt to the cobalt salt is 1:1 to 5:1, the molar ratio of the nickel salt to the cobalt salt is 1:1 to 5:1, the molar ratio of the cobalt salt to the molybdate salt is 5:1 to 10:1, the molar ratio of the molybdate salt to the zinc salt is 0.1:1 to 1:1, and the molar ratio of the zinc salt to the copper salt is 60:1 to 100:1.

[0008] Further, the pH value of the electroplating solution is adjusted to 4 to 10 by using ammonia water.

[0009] Further, in the electroplating process, the current density of the constant-current pulse is 0.2 to 5 A cm -2 .

[0010] Further, in the constant-current pulse electroplating process, the current duty cycle is 30 to 90%, and the electroplating time is 5 to 50 min.

[0011] Further, in the electroplating process, the potential of the constant-potential pulse is 0.5 to 25 V.

[0012] Further, in the constant-current pulse electroplating process, the current duty cycle is 30 to 90%, and the electroplating time is 5 to 50 min.

[0013] Further, in the electroplating process, the temperature of the plating solution is 20 to 70 DEG C.

[0014] Further, the electrochemical activation process adopts cyclic voltammetry technology, the scanning potential range is-0.5-0.2V relative to reversible hydrogen electrode, the scanning rate is 10-200mV s -1 , and the cycle number is 50-200 times. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 is an x-ray diffraction pattern of the MnCoNiZnMo high-entropy alloy catalyst. DETAILED DESCRIPTION

[0016] EMBODIMENT

[0017] Dissolve 2.94g Na3C6H5O7·2H2O, 0.02g MnCl2·4H2O, 1.02g ZnCl2, 1.82g Co(NO3)2·6H2O, 1.97g NiCl2·6H2O and 0.27g Na2MoO4·2H2O in 25ml deionized water, and after fully stirring and dissolving, adjust the pH value of the electrolyte to 8 with concentrated ammonia water.

[0018] Adopt constant current pulse technology, use foamed nickel as cathode, and use platinum sheet electrode as anode. Set the pulse current density to 2A cm -2 , and electroplate for 30min under 40% current duty cycle, with the plating solution temperature being 50℃ and the stirring speed being 300rpm.

[0019] Adopt cyclic voltammetry technology to electrochemically activate the prepared high-entropy alloy, to obtain a high-entropy alloy catalyst. The activation process is carried out in an H-type electrolytic cell, adopts a three-electrode system, the high-entropy alloy electrode is the working electrode, the platinum sheet electrode is the counter electrode, and the Hg / HgO electrode is the reference electrode. Perform cyclic voltammetry scanning in 1M KOH electrolyte, the potential window is-0.5-0.2V relative to reversible hydrogen electrode, the scanning rate is 100mV s -1 , and the cycle number is 100 times, to obtain the high-entropy alloy catalyst.

[0020] The catalyst exhibits excellent hydrogen evolution activity in 1M KOH electrolyte, and the overpotential is-22mV under-100mA cm -2 current density.

Claims

1. A method for preparing a high entropy alloy catalyst for producing hydrogen by electrolysis of water under alkaline conditions, characterized in that: Dissolving five, six, seven, or eight of cerium salts, manganese salts, iron salts, cobalt salts, nickel salts, zinc salts, copper salts, and molybdates in water and adjusting the pH value of the solution to obtain a stable electroplating solution; using nickel foam as a cathode and a platinum sheet or a carbon sheet as an anode, electroplating to obtain a high entropy alloy using a constant current pulse or constant potential pulse technique; The prepared high entropy alloy is electrochemically activated using cyclic voltammetry technology to obtain a high entropy alloy catalyst.

2. The method for preparing a high entropy alloy catalyst for producing hydrogen by electrolysis of water under alkaline conditions according to claim 1, characterized in that: The cerium salt includes one or more of cerium nitrate, cerium chloride, and ammonium cerium sulfate; the manganese salt includes one or more of manganese nitrate, manganese chloride, and manganese sulfate; the iron salt includes one or more of ferric nitrate, ferric chloride, ferric sulfate, and ferrous sulfate; the nickel salt includes one or more of nickel nitrate, nickel chloride, and nickel sulfate; the cobalt salt includes one or more of cobalt nitrate, cobalt chloride, and cobalt sulfate; the zinc salt is one or more of zinc chloride and zinc nitrate; the copper salt includes one or more of copper nitrate, copper chloride, or copper sulfate; and the molybdate includes one or more of sodium molybdate and potassium molybdate.

3. The method for preparing a high entropy alloy catalyst for producing hydrogen by electrolysis of water under alkaline conditions according to claim 1, characterized in that: The molar ratio of cerium salt to manganese salt is 1:1 to 8:1; the molar ratio of manganese salt to cobalt salt is 0.1:1 to 0.01:1; the molar ratio of iron salt to cobalt salt is 1:1 to 5:1; the molar ratio of nickel salt to cobalt salt is 1:1 to 5:1; the molar ratio of cobalt salt to molybdenum salt is 5:1 to 10:1; the molar ratio of molybdenum salt to zinc salt is 0.1:1 to 1:1; and the molar ratio of zinc salt to copper salt is 60:1 to 100:

1.

4. The method for preparing a high entropy alloy catalyst for producing hydrogen by electrolysis of water under alkaline conditions according to claim 1, characterized in that: The pH value of the plating solution is adjusted to 4-10 with ammonia water.

5. The method for preparing a high entropy alloy catalyst for producing hydrogen by electrolysis of water under alkaline conditions according to claim 1, characterized in that: During the electroplating process, the current density of the constant current pulse is 0.2~5Acm -2 .

6. The method for preparing a high entropy alloy catalyst for producing hydrogen by electrolysis of water under alkaline conditions according to claim 1, characterized in that: During the constant current pulse electroplating process, the current duty cycle is 30 to 90%, and the electroplating time is 5 to 50 minutes.

7. The method for preparing a high entropy alloy catalyst for producing hydrogen by electrolysis of water under alkaline conditions according to claim 1, characterized in that: During the electroplating process, the potential of the constant potential pulse is 0.5~25V.

8. The method for preparing a high entropy alloy catalyst for producing hydrogen by electrolysis of water under alkaline conditions according to claim 1, characterized in that: During the constant current pulse electroplating process, the current duty cycle is 30 to 90%, and the electroplating time is 5 to 50 minutes.

9. The method for preparing a high entropy alloy catalyst for producing hydrogen by electrolysis of water under alkaline conditions according to claim 1, characterized in that: During the electroplating process, the bath temperature is 20-70°C.

10. The method for preparing a high entropy alloy catalyst for producing hydrogen by electrolysis of water under alkaline conditions according to claim 1, characterized in that: The electrochemical activation process was carried out using cyclic voltammetry with a scanning potential range of -0.5 to 0.2 V relative to the reversible hydrogen electrode and a scanning rate of 10 to 200 mV s -1 , the number of cycles is 50 to 200 times.

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