Preparation and application method of nickel-based electrode for electrolysis of water to produce hydrogen

Abstract

The application discloses a preparation and application method of a nickel-based electrode for electrolytic water hydrogen evolution, and relates to the technical field of nanomaterials and electrochemistry. The nickel-based electrode is prepared by using a three-dimensional self-supporting electrode NF as a substrate, combining an in-situ grown In-doped Ni precursor and a catalytic active phase of a noble metal Pt, simplifying electrode manufacturing, reducing interface resistance, improving the overall stability of the electrode material, and thus achieving excellent HER performance. The nickel-based electrode is prepared by using a Ni source and an In source to construct a precursor, a Pt source as a modification element, and NaBH4 as a chemical reducing agent. The electrode preparation method of low-temperature chemical reduction and catalytic interface construction provides a brand-new idea for the design of low-energy-consumption hydrogen production electrode materials.

Description

Technical Field

[0001] This invention relates to the fields of nanomaterials and electrochemistry, specifically to a method for electrocatalytic preparation of nickel-based electrodes. Background Technology

[0002] Hydrogen energy is a highly efficient, clean, and high-quality energy carrier with enormous potential in modern industry, transportation, construction, and other fields. Faced with the global energy and environmental crises, hydrogen energy, especially "green hydrogen," as a rare decarbonization resource in nature, is of great significance for promoting the long-term development of the clean energy market.

[0003] Electrolysis of water is one of the cleanest methods for hydrogen production. This electrolysis involves two half-reactions: the hydrogen evolution reaction (HER) at the cathode and the oxygen evolution reaction (OER) at the anode. Among electrolyte systems, alkaline electrolytes are widely used in China due to their relatively low cost. The commercially available electrode for HER is Pt / C, whose scarcity and high price limit further commercialization of water electrolysis. Compared to anode OER, cathode HER has greater potential for energy consumption reduction. Meanwhile, using inexpensive elements to prepare HER electrodes and achieving or even exceeding the HER activity of precious metals through modification is extremely challenging and valuable. Transition metals are widely used in the production of water electrolysis materials due to their abundant reserves, low price, and ease of modification; nickel-based electrodes, in particular, have been widely used as electrodes in commercial alkaline water electrolyzers since 1900 due to their low cost and excellent activity. However, due to nickel's low intrinsic activity, limited active sites, and poor conductivity, the energy cost of nickel-based electrodes for commercial HER performance remains too high.

[0004] Therefore, if inexpensive Ni-based electrodes can be modified to achieve performance comparable to that of precious metal electrodes, it would be of great significance for the application of water electrolysis. Summary of the Invention

[0005] To address the above problems, this invention proposes a method for preparing and applying a nickel-based electrode for hydrogen evolution by water electrolysis. Using a three-dimensional self-supporting electrode NF as a substrate, combined with an in-situ grown In-doped Ni precursor and a catalytically active phase of noble metal Pt, the method simplifies electrode manufacturing, reduces interfacial resistance, and improves the overall stability of the electrode material, thereby achieving excellent HER performance.

[0006] The technical solution of the present invention is as follows: the nickel-based electrode is prepared by using Ni and In sources as precursors, Pt source as a modifying element, and NaBH4 as a chemical reducing agent. The nickel-based electrode is prepared according to the following steps:

[0007] Step 1: Preprocess NF;

[0008] The three-dimensional self-supporting NF was cut out and ultrasonically cleaned with HCl solution, ethanol, and ultrapure water in sequence.

[0009] Step 2: Prepare Ni5In1 by loading NiIn hydroxide onto NF;

[0010] Take appropriate amounts of nickel salt, indium salt, urea, and ammonium fluoride and dissolve them in ultrapure water. After stirring evenly, NF obtained in step 1 is immersed in the above solution and then transferred to a hydrothermal reactor for hydrothermal reaction. After the reaction is completed and cooled to room temperature, the NF loaded with Ni5In1 is taken out, washed with water and dried to obtain Ni5In1.

[0011] Step 3: Impregnate Ni5In1 with Pt and load Pt to prepare Ni5In1-Pt;

[0012] The Ni5In1 obtained in step 2 was immersed in a solution of chloroplatinic acid at room temperature. The immersed material was then placed in a vacuum oven and dried to obtain Ni5In1-Pt.

[0013] Step 4: Ni5In1-Pt-B3 is prepared by secondary hydrothermal reaction treatment using NaBH4.

[0014] Dissolve NaBH4 in ultrapure water and stir until homogeneous. Immerse the Ni5In1-Pt obtained in step 3 into the above solution and transfer them together into a hydrothermal reactor for hydrothermal reaction. After the reaction is completed and cooled to room temperature, wash and dry with ultrapure water to obtain Ni5In1-Pt-B3.

[0015] Furthermore, the concentration range of the HCl solution in step 1 is 0.5–2 M; the ultrasonic time is 10–20 min.

[0016] Furthermore, in step 2, the nickel salt is Ni(NO3)2·6H2O, the indium salt is In(NO3)3, and the ratio of nickel salt, indium salt, urea, and ammonium fluoride used is 5:0.5 to 5:80:5;

[0017] In step 2, the hydrothermal reactor is a high-pressure reactor with a polytetrafluoroethylene liner placed in a constant temperature drying oven. The hydrothermal reaction temperature range is 150-200℃, and the hydrothermal reaction time range is 10-15h. The subsequent drying temperature is 50-80℃.

[0018] Furthermore, the concentration of the chloroplatinic acid solution used in step 3 is 6.4 × 10⁻⁶. -4 M, soaking time is 2h, after soaking the material is placed in a vacuum oven and dried at 50-80℃ for 6h.

[0019] Furthermore, the hydrothermal reaction temperature range in step 4 is 150–200℃, and the hydrothermal reaction time range is 1–5 h; the subsequent drying temperature is 50–80℃.

[0020] The application method of this nickel-based electrode is to process the prepared Ni5In1-Pt-B3 into a HER electrode for use in the electrolysis of water to generate hydrogen.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] This invention utilizes three-dimensional self-supporting nickel foam as a substrate. In-doped Ni(OH)2 is loaded onto the three-dimensional self-supporting nickel foam through a simple hydrothermal reaction, allowing over-In-doped Ni double hydroxide to grow in situ on the nickel foam. Then, it is impregnated to load the noble metal Pt onto the material. Finally, a second hydrothermal process is performed using sodium borohydride to reduce Pt ions and some Ni ions into a PtNi alloy, thus preparing a Ni5In1-Pt-B3 electrode with abundant active sites.

[0023] The introduction of Ni, In, and Pt elements endows the prepared electrode with excellent HER catalytic activity, reaching 10 mA·cm⁻¹. -2 The required overpotential for the current density is only 13mV. At 100mA cm⁻¹ -2 It maintained excellent stability for at least 188 hours under high current density. This low-temperature chemical reduction and catalytic interface construction electrode preparation method provides a novel approach for the design of low-energy hydrogen production electrode materials.

[0024] Compared with existing HER electrodes, the modified nickel-based HER electrode involved in this invention has superior performance, with multiple active sites that are fully exposed, exhibiting high catalytic activity and chemical stability. It can perform water electrolysis under simulated industrial electrolysis conditions and has promising industrial application prospects. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the preparation method of the nickel-based electrode described in this invention, as well as the structural model of the electrode material.

[0026] Figure 2 This is a TEM image of Ni5In1-Pt-B3 obtained in Example 1 of the present invention.

[0027] Figure 3 This is a SEM image of Ni5In1-Pt-B3 obtained in Example 1 of the present invention.

[0028] Figure 4 This is the X-ray diffraction pattern of Ni5In1-Pt-B3 obtained in Example 1 of the present invention.

[0029] Figure 5The Ni5In1-Pt-B3 obtained in Example 1 of this invention, compared with Comparative Examples 1, 2, and 3, and Pt / C under alkaline conditions of 1M KOH, exhibits: (a) a comparison of HER polarization curves; (b) current densities of 10, 100, and 200 mA·cm⁻¹. -2 The following is a comparison chart of HER bars.

[0030] Figure 6 The Ni5In1-Pt-B3 obtained in Example 1 of this invention is subjected to 100 mA·cm -2 HER stability test graph under current density. Detailed Implementation

[0031] To clearly illustrate the technical features of this patent, the following detailed description is provided through specific embodiments and in conjunction with the accompanying drawings.

[0032] All raw materials used in the following embodiments of the present invention are commercially available.

[0033] Example 1

[0034] Step 1, Pretreatment: Measure 41.4 mL of concentrated hydrochloric acid (mass fraction of 36-38%) and make up to 500 mL to prepare 1M hydrochloric acid for later use; cut a 1*5 cm piece of NF, put it in a beaker, and clean it by ultrasonication for 15 min in sequence with 30 mL of 1M HCl, sewage ethanol and ultrapure water to remove the influence of oxides on the surface of NF.

[0035] Step 2, Preparation of Ni5In1: 0.5 mmol nickel nitrate hexahydrate, 0.1 mmol indium nitrate, 8 mmol urea, and 0.5 mmol ammonium fluoride were dispersed in 30 mL of ultrapure water and magnetically stirred for about 5 min. The mixture was then transferred to a high-pressure reactor lined with polytetrafluoroethylene (PTFE). Pretreated 1*5 cm NF (nitrogen fluoride) was added, and the reactor was placed in a constant-temperature drying oven and heated to 160 °C for 12 h. After the reaction, the high-pressure reactor was allowed to cool naturally to room temperature. The loaded NF was removed, and excess Ni and In compounds on the surface were washed away with a slow flow of water. The product was then placed in a vacuum oven and dried at 60 °C for 6 h to obtain Ni5In1.

[0036] Step 3, Preparation of Ni5In1-Pt: Pipette 10 μL of chloroplatinic acid solution (0.64 M) into a centrifuge tube, dilute to 10 mL, then immerse Ni5In1 in it and soak at room temperature for 2 h. Remove the soaked material and place it in a vacuum oven to dry at 60 °C for 6 h to obtain Ni5In1-Pt.

[0037] Step 4: Preparation of Ni5In1-Pt-B3: Cut the obtained Ni5In1-Pt into 1*1.5cm pieces for later use. Weigh 0.1g of sodium borohydride and disperse it in 17mL of ultrapure water. Stir magnetically for about 5 minutes, then transfer it to a high-pressure reactor lined with polytetrafluoroethylene. Add the 1*1.5cm Ni5In1-Pt pieces and place the reactor in a constant temperature drying oven. Heat the oven to 180℃ and react for 3 hours. After the reaction is complete, allow the high-pressure reactor to cool naturally to room temperature. Remove the Ni5In1-Pt pieces and gently wash the surface with clean water. Finally, place the product in a vacuum oven and dry at 60℃ for 6 hours to obtain Ni5In1-Pt-B3.

[0038] The schematic diagram and microstructure of the Ni5In1-Pt-B3 prepared on a three-dimensional nickel foam substrate in this embodiment are shown in the attached figure. Figure 1 , 2 As shown in Figures 3 and 4.

[0039] Comparative Example 1

[0040] The only difference from Example 1 is that the NaBH4 was not chemically reduced in step 4, and it is denoted as Ni5In1-Pt.

[0041] Comparative Example 2

[0042] The only difference from Example 1 is that the Pt ion exchange in step 3 is not performed, and it is denoted as Ni5In1-B3.

[0043] Comparative Example 3

[0044] The only difference from Example 1 is that NiIn is not loaded on NF, but NF is directly impregnated with Pt and then borated, denoted as Pt-B3.

[0045] Application Example 1

[0046] The specific implementation process of the Ni5In1-Pt-B3 water electrolysis hydrogen evolution (HER) experiment is as follows:

[0047] To prepare the 1M KOH electrolyte: Weigh 29.5315g of KOH and dissolve it in a beaker. After cooling to room temperature, transfer it to a 500mL volumetric flask and make up to volume.

[0048] Electrochemical testing: Tests were conducted using a standard three-electrode system on a CHI660E electrochemical workstation. A dual-salt-bridged Hg / Hg₂Cl₂ electrode was used as the reference electrode, and a Pt sheet as the counter electrode. The prepared Ni₅In₁-Pt-B₃ electrode material was directly used as the working electrode. The working electrode size immersed in the electrolyte was 1 cm × 1 cm, and the electrolyte was 1 M KOH. Approximately 60 mL of electrolyte was used per test. When using this electrode material for the first time, a CV test should be performed to activate the active sites. HER testing was performed with 85% IR compensation, and all measured potentials were converted to reversible hydrogen electrode polarization for comparison. The HER polarization curves are shown below. Figure 5 As shown in (a), the figure demonstrates that at the same current density, the overpotential required for Ni5In1-Pt-B3 is significantly lower than that of other electrodes, exhibiting superior performance even compared to Pt / C under high current conditions. Figure 5 (b) It can be seen that at a current density of 10 mA·cm -2 100mA·cm -2、 200mA·cm -2 At that time, the overpotentials of Ni5In1-Pt-B3 were 13mV, 61mV, and 82mV, respectively;

[0049] like Figure 6 As shown, at 100mA·cm -2 At current density, the voltage of Ni5In1@NiBO@Pt / NF as the working electrode shows almost no fluctuation and remains stable within 0.02V. It can operate stably for at least 188 hours, indicating that this electrode has excellent stability for HER and is very promising for industrial applications.

[0050] There are many specific ways to implement this invention. The above description is only a preferred embodiment of this invention. It should be noted that for those skilled in the art, several improvements can be made without departing from the principle of this invention, and these improvements should also be considered within the scope of protection of this invention.

Claims

1. A method for preparing a nickel-based electrode for hydrogen evolution through water electrolysis, characterized in that, The nickel-based electrode is prepared by using Ni and In sources as precursors, Pt source as a modifying element, and NaBH4 as a chemical reducing agent. The nickel-based electrode is prepared according to the following steps: Step 1: Preprocess NF; The three-dimensional self-supporting NF was cut out and ultrasonically cleaned with HCl solution, ethanol, and ultrapure water in sequence. Step 2: Prepare Ni5In1 by loading NiIn hydroxide onto NF; Take appropriate amounts of nickel salt, indium salt, urea, and ammonium fluoride and dissolve them in ultrapure water. After stirring evenly, NF obtained in step 1 is immersed in the above solution and then transferred to a hydrothermal reactor for hydrothermal reaction. After the reaction is completed and cooled to room temperature, the NF loaded with Ni5In1 is taken out, washed with water and dried to obtain Ni5In1. Step 3: Impregnate Ni5In1 with Pt and load Pt to prepare Ni5In1-Pt; The Ni5In1 obtained in step 2 was immersed in a solution of chloroplatinic acid at room temperature. The immersed material was then placed in a vacuum oven and dried to obtain Ni5In1-Pt. Step 4: Ni5In1-Pt-B3 is prepared by secondary hydrothermal reaction treatment using NaBH4. Dissolve NaBH4 in ultrapure water and stir until homogeneous. Immerse the Ni5In1-Pt obtained in step 3 into the above solution and transfer them together into a hydrothermal reactor for hydrothermal reaction. After the reaction is completed and cooled to room temperature, wash and dry with ultrapure water to obtain Ni5In1-Pt-B3.

2. The method for preparing a nickel-based electrode for hydrogen evolution by water electrolysis according to claim 1, characterized in that, The concentration range of the HCl solution in step 1 is 0.5~2M; the ultrasonic time is 10~20min.

3. The method for preparing a nickel-based electrode for hydrogen evolution by water electrolysis according to claim 1, characterized in that, In step 2, the nickel salt is Ni(NO3)2∙6H2O, the indium salt is In(NO3)3, and the ratio of nickel salt, indium salt, urea, and ammonium fluoride used is 5:0.5~5:80:5; In step 2, the hydrothermal reactor is a high-pressure reactor with a polytetrafluoroethylene liner placed in a constant temperature drying oven. The hydrothermal reaction temperature range is 150~200℃, and the hydrothermal reaction time range is 10~15h. The subsequent drying temperature is 50~80℃.

4. The method for preparing a nickel-based electrode for hydrogen evolution by water electrolysis according to claim 1, characterized in that, The concentration of the chloroplatinic acid solution used in step 3 is 6.4 × 10⁻⁶. -4 M, soaking time is 2h, after soaking the material is placed in a vacuum oven and dried at 50~80℃ for 6h.

5. The method for preparing a nickel-based electrode for hydrogen evolution by water electrolysis according to claim 1, characterized in that, The hydrothermal reaction temperature range for step 4 is 150~200℃, and the hydrothermal reaction time range is 1~5h; the subsequent drying temperature is 50~80℃.

6. A method for applying the nickel-based electrode for hydrogen evolution in water electrolysis prepared according to claim 1, characterized in that, The prepared Ni5In1-Pt-B3 was processed into a HER electrode for use in water electrolysis to generate hydrogen.

Images