Nickel-based catalyst electrode for hydrogen production by electrolysis of water and preparation method thereof

Abstract

The application belongs to the field of electrolysis of water to produce hydrogen, and particularly relates to a nickel-based catalyst electrode for electrolysis of water to produce hydrogen and a preparation method thereof. A nickel salt and a buffer are dissolved in deionized water, an organic molecule regulator is added, an inorganic acid is used to adjust the pH of the solution, an electrolyte solution is obtained, a conductive substrate is placed in an electroplating device, a sulfuric acid aqueous solution is placed in an anode chamber, an Ag / AgCl electrode is used as a reference electrode, a titanium sheet coated with a mixed metal oxide (MMO) of IrO2 / RuO2 is used as an anode, the conductive substrate is electroplated at a cathode potential, and the electroplated sample is activated in an alkaline solution. The activity of the catalyst is improved by adding an organic additive and a cyclic voltammetry scanning technology, the prepared nickel-based catalyst electrode has high hydrogen production activity, and the overpotential is only 11 mV@10 mA / cm 2 The technology has the advantages of simple process, good stability of electrolyte, low cost, easy scaling up, and being conducive to reducing the cost of hydrogen production by electrolysis of water.

Description

Technical Field

[0001] This invention belongs to the field of hydrogen production through water electrolysis, specifically relating to a nickel-based catalyst electrode for hydrogen production through water electrolysis and its preparation method. Background Technology

[0002] Electrolysis of water to produce hydrogen is considered one of the most efficient ways to obtain green hydrogen energy. Using electricity generated from renewable energy sources for water electrolysis can convert intermittent energy sources such as wind and solar power into hydrogen gas for storage, which can then be stably output as electrical or chemical energy. Currently, the difficulties hindering the large-scale application of water electrolysis for hydrogen production lie in the low energy conversion efficiency from electricity to hydrogen and the challenges of hydrogen storage and transportation. The high cost of hydrogen production is primarily due to the lack of efficient and long-term stable electrocatalysts.

[0003] Hydrogen production through water electrolysis involves two half-reactions: the hydrogen evolution reaction (HER) at the cathode and the oxygen evolution reaction (OER) at the anode. To improve the conversion efficiency of hydrogen production through water electrolysis, it is necessary to develop HER and OER catalysts to reduce the overpotential of water electrolysis and thus reduce energy consumption. HER catalysts are mostly noble metal-based powders or single-atom structure catalysts. These catalysts are typically expensive, have complex preparation processes, and exhibit poor long-term stability, limiting their application in hydrogen production through water electrolysis. Developing non-noble metal-based catalysts is key to improving the efficiency of hydrogen production through water electrolysis and reducing the cost of catalyst-based hydrogen production. Among all materials, Ni-based catalysts have been proven to be the most effective hydrogen production catalysts. For example, Jinsong Wang et al. recently prepared Ni-based alloys on nickel foam using electrochemical deposition, and then prepared NiCu alloy HER catalysts via electrochemical oxidation (Jinsong Wang et al. Manipulating the Water Dissociation ElectrocatalyticSites of Bimetallic Nickel-Based Alloys for Highly Efficient Alkaline Hydrogen Evolution, Angew. Chem. Int. Ed. 2022, 61, e202202518), which achieved a performance of 10 mA cm⁻¹. -2The alkaline overpotential at the specified current density is 23 mV, and it can operate stably for over 100 hours. However, this low HER overpotential mainly stems from the introduction of Cu and O, which provide active sites for H adsorption and desorption. In actual preparation, precise adjustment of the solution composition is required. Furthermore, to control the Cu content in the catalyst, a low-concentration (<50 mM / L) nickel salt electrolyte solution is needed. This electrolyte solution cannot be reused, resulting in a complex preparation process, high cost, non-reproducible product quality, and difficulty in performance control. Chinese patent CN110479271 A discloses a method for preparing a two-dimensional nickel-carbon nanosheet catalyst for hydrogen production through water electrolysis. The method involves dissolving nickel nitrate, 2,6-naphthalenedicarboxylic acid, and triethylenediamine in an organic solvent, ultrasonically dispersing the mixture, and then solvothermically reacting it at 100–180°C for 10–48 h. After the reaction, the mixture is cooled to room temperature, filtered, and the product is washed with N,N-dimethylformamide and ethanol, then dried to obtain a Ni-containing metal-organic framework precursor powder (Ni-MOF). The Ni-MOF is then annealed under nitrogen protection to obtain the two-dimensional nickel-carbon nanosheet catalyst Ni@C. However, this preparation process is complex and not conducive to industrialization. Summary of the Invention

[0004] To address the aforementioned problems, this invention provides a nickel-based electrolytic water hydrogen production catalyst electrode, which is obtained by electroplating using nickel salt and buffer as electrolytes. Furthermore, this application also provides a specific preparation method that is simple and highly industrially feasible.

[0005] The technical solution of the present invention is as follows:

[0006] A nickel-based catalyst electrode for hydrogen production by water electrolysis is obtained by electroplating nickel salt and buffer as electrolyte solution; then activated.

[0007] Preferably, the electrolyte solution is prepared by dissolving nickel salt and buffer in deionized water, adding an organic molecule that can provide negative charge and simultaneously coordinate unsaturated Ni ions, stirring evenly, and then adding an inorganic acid to adjust the pH of the solution to 2-4 to obtain the electrolyte solution.

[0008] Preferably, the nickel salt is nickel sulfate and / or nickel chloride.

[0009] Preferably, the buffer is boric acid and / or ammonium sulfate.

[0010] Preferably, the organic molecule that can provide a negative charge and simultaneously provide unsaturated coordination to Ni ions is histidine and / or tryptophan.

[0011] Preferably, the electroplating process is as follows: a bipolar electrolytic cell separated by anion exchange membrane is used as the electroplating device, the cathode chamber is injected with the electrolyte solution prepared in step (1), and the anode chamber is filled with sulfuric acid aqueous solution; an Ag / AgCl electrode is used as the reference electrode, and a titanium sheet coated with IrO2 / RuO2 mixed metal oxide MMO is used as the anode; the electroplating substrate and Ag / AgCl are placed in the cathode chamber, and the MMO anode is placed in the anode chamber; the electroplating substrate, reference electrode and MMO anode are respectively connected to the working electrode, reference electrode and counter electrode of the electrochemical workstation; the electrode potential is -1.0V to -3.0V; the electroplating time is 10s to 3000s; the sample is taken out, cleaned with deionized water and set aside for use.

[0012] Preferably, the electroplating substrate can be a copper mesh, a nickel mesh, copper foam, or nickel foam.

[0013] Preferably, the activation process is as follows: using an alkaline solution as the electrolyte solution, an Hg / HgO electrode as the reference electrode, and an MMO electrode as the counter electrode; activating by cyclic voltammetry, and completing the activation after multiple cycles.

[0014] Preferably, the alkaline solution is sodium hydroxide, potassium hydroxide, or tetramethylammonium hydroxide, with a concentration of 0.1–3.0 mol / L; the scanning potential range used in the cyclic voltammetry is -0.5 V to -1.2 V; and the number of scans is 50–1000.

[0015] Beneficial effects of the present invention

[0016] The bipolar chamber electrolyzer is used to prevent Ni from entering the electrolyte solution. 2+ The anodic oxidation produces a high-valence nickel compound precipitate to maintain the stability of the electrolyte solution, enabling repeated electroplating.

[0017] The activity of electroplated nickel-based hydrogen production catalysts is improved by using organic molecules that provide negative charges and unsaturated coordination. The method is simple and has strong applicability.

[0018] The high-concentration nickel-containing electrolyte solution used can be reused, the prepared product has stable quality, and the process is easy to control.

[0019] The prepared electrode exhibits good hydrogen production activity, with an alkaline hydrogen production overpotential reaching 11 mV @ 10 mA / cm. 2 Within. Attached Figure Description

[0020] Figure 1 This is a process route diagram for the preparation of active nickel-based electrolytic water hydrogen production catalyst;

[0021] Figure 2 This is the X-ray diffraction pattern of the nickel-based catalyst electrode electroplated on the copper mesh substrate in Example 1;

[0022] Figure 3 The activation voltammetry curves of the nickel-based catalyst electrode prepared in Example 1 are shown.

[0023] Figure 4 for Figure 3 A magnified view of part A in the image;

[0024] Figure 5 This is a hydrogen production stability test of the nickel-based catalyst electrode prepared in Example 1. Detailed Implementation

[0025] The following are preferred embodiments of the present invention. It should be noted that several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications are also considered to be within the protection scope of the present invention.

[0026] Example 1

[0027] like Figure 1 As shown, a highly active nickel-based electrolytic water electrolysis catalyst for hydrogen production and its preparation method are disclosed. The method includes the following steps:

[0028] (1) Preparation of electrolyte solution: Dissolve 0.5 mol / L nickel sulfate and 0.3 mol / L boric acid in deionized water, add 0.2 mol / L histidine, stir well, add sulfuric acid to adjust the pH of the solution to 4, and obtain electrolyte solution.

[0029] (2) Electroplating preparation: A bipolar cell electrolytic cell separated by anion exchange membrane is used as the electroplating device. The cathode chamber is injected with the electrolyte solution prepared in step (1), and the anode chamber is filled with an aqueous solution of sulfuric acid with pH=2. An Ag / AgCl electrode is used as the reference electrode, and a titanium sheet coated with MMO is used as the anode. A copper mesh and Ag / AgCl are placed in the cathode chamber, and the MMO anode is placed in the anode chamber. The working electrode, reference electrode and counter electrode of the electrochemical workstation are connected respectively.

[0030] (3) Electroplating of nickel-based catalyst electrode: Electroplating at an electrode potential of -1.0V for 1000s. After electroplating, the sample is taken out and cleaned with deionized water for later use.

[0031] (4) Activation of nickel-based catalyst electrode: The electrolyte solution used for activation is 1.0 mol / L potassium hydroxide solution, the reference electrode used for activation is Hg / HgO (1M KOH) electrode, and the counter electrode is MMO electrode; the hydrogen production catalyst electrode is obtained by cyclic voltammetry scanning between -0.5V and -1.2V for 50 cycles.

[0032] Comparing the structures of the hydrogen-producing catalyst electrodes obtained by electroplating before and after adding organic molecules to the electrolyte solution, as follows: Figure 2As shown in the figure. Comparison of X-ray diffraction patterns revealed that the nickel-based catalyst deposited after the addition of organic molecules became significantly amorphous, which is the main reason for its high activity. Cyclic voltammetry scans of the activation process... Figure 3 , Figure 4 It can be seen that cyclic voltammetry significantly activated the hydrogen production performance of the electrode, and the final hydrogen production overpotential obtained was 11 mV @ 10 mA / cm. 2 Moreover, the hydrogen production stability is relatively good. Figure 5 After 22 consecutive hours of 20mA / cm 2 Even after continuous hydrogen production, it still maintains good activity, and the hydrogen production overpotential does not worsen but even improves slightly.

[0033] Example 2

[0034] like Figure 1 As shown, a highly active nickel-based electrolytic water hydrogen production catalyst and its preparation method include the following steps:

[0035] (1) Preparation of electrolyte solution: Dissolve 0.1 mol / L nickel sulfate and 0.1 mol / L boric acid in deionized water, add 0.02 mol / L histidine, stir well, add sulfuric acid to adjust the pH of the solution to 4, and obtain electrolyte solution.

[0036] (2) Electroplating preparation: A bipolar cell electrolytic cell separated by anion exchange membrane is used as the electroplating device. The cathode chamber is injected with the electrolyte solution prepared in step (1), and the anode chamber is filled with an aqueous solution of sulfuric acid with pH=2. An Ag / AgCl electrode is used as the reference electrode, and a titanium sheet coated with MMO is used as the anode. A copper mesh and Ag / AgCl are placed in the cathode chamber, and the MMO anode is placed in the anode chamber. The working electrode, reference electrode and counter electrode of the electrochemical workstation are connected respectively.

[0037] (3) Electroplating of nickel-based catalyst electrode: Electroplating was performed at an electrode potential of -1.0V for 3000s. After the electroplated sample was taken out, it was cleaned with deionized water and ready for use.

[0038] (4) Activation of the nickel-based catalyst electrode: The electrolyte solution used for activation was 0.1 mol / L potassium hydroxide solution. The reference electrode used for activation was a Hg / HgO (1M KOH) electrode, and the counter electrode was an MMO electrode. The hydrogen production catalyst electrode was obtained by cyclic voltammetry scanning 50 times between -0.5 V and -1.2 V. The overpotential of the hydrogen production catalyst electrode tested in 1.0 mol / L sodium hydroxide solution was 40 mV @ 10 mA / cm. 2 .

[0039] Example 3

[0040] like Figure 1As shown, a highly active nickel-based electrolytic water electrolysis catalyst for hydrogen production and its preparation method include the following steps:

[0041] (1) Preparation of electrolyte solution: Dissolve 2.0 mol / L nickel sulfate and 1.0 mol / L boric acid in deionized water, add 0.8 mol / L tryptophan, stir evenly, and then add inorganic acid to adjust the pH of the solution to 2.0 to obtain electrolyte solution.

[0042] (2) Electroplating preparation: A bipolar cell electrolytic cell separated by anion exchange membrane is used as the electroplating device. The cathode chamber is injected with the electrolyte solution prepared in step (1), and the anode chamber is filled with an aqueous solution of sulfuric acid with pH=2.0. An Ag / AgCl electrode is used as the electrode, and a titanium sheet with IrO2 / RuO2 mixed metal oxide (MMO) coating is used as the anode. The electroplating substrate and Ag / AgCl are placed in the cathode chamber, and the MMO anode is placed in the anode chamber. The foamed nickel substrate, the reference electrode and the anode are connected to the working electrode, the reference electrode and the counter electrode of the electrochemical workstation, respectively.

[0043] (3) Electroplating of nickel-based catalyst electrode: Electroplating was performed at an electrode potential of -3.0V for 10s. After the electroplated sample was taken out, it was cleaned with deionized water and then ready for use.

[0044] (4) Activation of nickel-based catalyst electrode: The electrolyte solution used for activation is 2.0 mol / L potassium hydroxide solution, the reference electrode used for activation is Hg / HgO (1M KOH) electrode, and the counter electrode is MMO electrode; the hydrogen production catalyst electrode is obtained by cyclic voltammetry scanning between -0.5V and -1.2V for 1000 cycles.

[0045] The overpotential of the hydrogen production catalyst electrode tested in a 1.0 mol / L potassium hydroxide solution was 24 mV @ 10 mA / cm. 2 .

[0046] Example 4

[0047] like Figure 1 As shown, a highly active nickel-based electrolytic water electrolysis catalyst for hydrogen production and its preparation method include the following steps:

[0048] (1) Preparation of electrolyte solution: Dissolve 1.0 mol / L nickel sulfate and 0.4 mol / L boric acid in deionized water, add 0.3 mol / L tryptophan, stir evenly, and then add inorganic acid to adjust the pH of the solution to 3.0 to obtain electrolyte solution.

[0049] (2) Electroplating preparation: A bipolar cell electrolytic cell separated by anion exchange membrane is used as the electroplating device. The cathode chamber is injected with the electrolyte solution prepared in step (1), and the anode chamber is filled with an aqueous solution of sulfuric acid with pH=2.0. An Ag / AgCl electrode is used as the electrode, and a titanium sheet with IrO2 / RuO2 mixed metal oxide (MMO) coating is used as the anode. The electroplating substrate and Ag / AgCl are placed in the cathode chamber, and the MMO anode is placed in the anode chamber. The foamed copper substrate, the reference electrode and the anode are connected to the working electrode, the reference electrode and the counter electrode of the electrochemical workstation, respectively.

[0050] (3) Electroplating of nickel-based catalyst electrode: Electroplating was performed at an electrode potential of -2.0V for 200s. The electroplated sample was then removed, cleaned with deionized water, and set aside for use.

[0051] (4) Activation of nickel-based catalyst electrode: The electrolyte solution used for activation is 1.5 mol / L potassium hydroxide solution, the reference electrode used for activation is Hg / HgO (1M KOH) electrode, and the counter electrode is MMO electrode; the hydrogen production catalyst electrode is obtained by cyclic voltammetry scanning 500 times between -0.5V and -1.2V.

[0052] The overpotential of the hydrogen production catalyst electrode tested in a 1.0 mol / L potassium hydroxide solution was 25 mV @ 10 mA / cm. 2 .

[0053] Example 5

[0054] like Figure 1 As shown, a highly active nickel-based electrolytic water electrolysis catalyst for hydrogen production and its preparation method include the following steps:

[0055] (1) Preparation of electrolyte solution: Dissolve 1.5 mol / L nickel sulfate and 1.0 mol / L boric acid in deionized water, add 0.6 mol / L histidine, stir evenly, and then add inorganic acid to adjust the pH of the solution to 3.0 to obtain electrolyte solution.

[0056] (2) Electroplating preparation: A bipolar cell electrolytic cell separated by anion exchange membrane is used as the electroplating device. The cathode chamber is injected with the electrolyte solution prepared in step (1), and the anode chamber is filled with an aqueous solution of sulfuric acid with pH=2.0. An Ag / AgCl electrode is used as the electrode, and a titanium sheet with IrO2 / RuO2 mixed metal oxide (MMO) coating is used as the anode. The electroplating substrate and Ag / AgCl are placed in the cathode chamber, and the MMO anode is placed in the anode chamber. The nickel mesh substrate, reference electrode and anode are connected to the working electrode, reference electrode and counter electrode of the electrochemical workstation, respectively.

[0057] (3) Electroplating of nickel-based catalyst electrode: Electroplating was performed at an electrode potential of -2.0V for 200s. The electroplated sample was then cleaned with deionized water and ready for use.

[0058] (4) Activation of nickel-based catalyst electrode: The electrolyte solution used for activation is 1.0 mol / L potassium hydroxide solution, the reference electrode used for activation is Hg / HgO (1M KOH) electrode, and the counter electrode is MMO electrode; the hydrogen production catalyst electrode is obtained by cyclic voltammetry scanning between -0.5V and -1.2V for 500 cycles.

[0059] The overpotential of the hydrogen production catalyst electrode tested in a 1.0 mol / L tetramethylammonium hydroxide solution was 36 mV @ 10 mA / cm. 2 .

Claims

1. A nickel-based electrolytic water electrolysis catalyst electrode for hydrogen production, characterized in that, A nickel-based catalyst electrode was obtained by electroplating using nickel salt and buffer as electrolyte solutions; then activated to obtain the final product. The electrolyte solution is prepared by dissolving nickel salt and buffer in deionized water, adding an organic molecule that can provide negative charge and simultaneously coordinate unsaturated Ni ions, stirring evenly, and then adding an inorganic acid to adjust the pH of the solution to 2-4 to obtain the electrolyte solution. The buffer is boric acid and / or ammonium sulfate; The organic molecules that can provide negative charge and simultaneously provide unsaturated coordination to Ni ions are histidine and / or tryptophan; The electroplating process is as follows: a bipolar electrolytic cell separated by anion exchange membrane is used as the electroplating device, with the electrolyte solution injected into the cathode chamber and sulfuric acid aqueous solution placed in the anode chamber; an Ag / AgCl electrode is used as the reference electrode, and a titanium sheet coated with IrO2 / RuO2 mixed metal oxide MMO is used as the anode; the electroplating substrate and Ag / AgCl are placed in the cathode chamber, and the MMO anode is placed in the anode chamber; the electroplating substrate, reference electrode, and MMO anode are respectively connected to the working electrode, reference electrode, and counter electrode of the electrochemical workstation; the electrode potential is -1.0V to -3.0V; the electroplating time is 10s to 3000s; the sample is removed, rinsed with deionized water, and then ready for use. The activation process is as follows: an alkaline solution is used as the electrolyte solution, an Hg / HgO electrode is used as the reference electrode, and an MMO electrode is used as the counter electrode; Activation is performed using a cyclic voltammetric scan method, which is completed after multiple cycles. The scanning potential range used in the cyclic voltammetric method is -0.5V to -1.2V.

2. The nickel-based electrolytic water electrolysis hydrogen production catalyst electrode according to claim 1, characterized in that, The nickel salt is nickel sulfate and / or nickel chloride.

3. The nickel-based electrolytic water electrolysis hydrogen production catalyst electrode according to claim 1, characterized in that, The electroplating substrate is a copper mesh, nickel mesh, copper foam, or nickel foam.

4. The nickel-based electrolytic water electrolysis hydrogen production catalyst electrode according to claim 1, characterized in that, The alkaline solution is sodium hydroxide, potassium hydroxide, or tetramethylammonium hydroxide, with a concentration of 0.1~3.0 mol / L; the number of scans is 50~1000.

Images