Preparation and application method of nickel-based electrode for hydrogen evolution by electrolyzing water

Abstract

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

Description

Technical Field

[0001] The invention relates to the technical field of nanomaterials and electrochemical technology, and in particular to a method for preparing a nickel-based electrode by electrocatalysis. Background Art

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

[0003] Water electrolysis is one of the cleanest ways to produce hydrogen, and water electrolysis is divided into two half reactions, namely the hydrogen evolution reaction (HER) at the cathode and the oxygen evolution reaction (OER) at the anode. In the electrolyte system, alkaline electrolytes are widely used in China because of their relatively low cost. The commercial electrode for HER is Pt / C, and its scarcity and high price limit the further commercialization of water electrolysis. Compared with the anode OER, the energy consumption of cathode HER has greater room for reduction. At the same time, it is extremely challenging and valuable to use cheap elements to prepare HER electrodes and achieve or even exceed the HER activity of precious metals through modification. Among them, transition metals are widely used in the preparation of water electrolysis materials because of their abundant reserves, low prices and easy modification; among them, nickel-based electrodes have been widely used as electrodes for commercial alkaline water electrolyzers since 1900 because of their low cost and excellent activity. However, due to factors such as the low intrinsic activity of nickel, limited active sites, and poor conductivity of nickel, the HER performance of nickel-based electrodes is still too high in energy consumption cost for commercialization.

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

[0005] In view of the above problems, the present invention proposes a method for preparing and applying a nickel-based electrode for hydrogen evolution by electrolysis of water. A three-dimensional self-supporting electrode NF is used as a substrate, combined with an in-situ grown In-doped Ni precursor and a catalytically active phase of the precious metal Pt. The electrode manufacturing is simplified, the interface resistance is reduced, and the overall stability of the electrode material is improved, thereby achieving excellent HER performance.

[0006] The technical solution of the present invention is: the nickel-based electrode is constructed by using Ni source and In source as precursor, Pt source as modification element, NaBH 4 As the electrode prepared by the chemical reducing agent, the nickel-based electrode is prepared according to the following steps:

[0007] Step 1, pre-treating NF;

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

[0009] Step 2, loading NiIn hydroxide on NF to prepare Ni5In1;

[0010] Take appropriate amounts of nickel salt, indium salt, urea, and ammonium fluoride and dissolve them in ultrapure water. After stirring evenly, immerse the NF obtained in step 1 in the above solution and transfer them to a hydrothermal reactor for hydrothermal reaction. After the reaction is completed and cooled to room temperature, take out the NF loaded with Ni5In1, wash it with clean water, and dry it to obtain Ni5In1.

[0011] Step 3, impregnating Ni5In1 with Pt, loading Pt, and preparing Ni5In1-Pt;

[0012] The Ni5In1 obtained in step 2 is placed in a solution of chloroplatinic acid at room temperature for soaking, the soaked material is taken out and placed in a vacuum oven, and Ni5In1-Pt is obtained after drying;

[0013] Step 4: Using NaBH 4 Perform secondary hydrothermal reaction treatment to prepare Ni5In1-Pt-B3;

[0014] Take NaBH 4 Dissolve in ultrapure water and stir evenly, immerse the Ni5In1-Pt obtained in step 3 in the above solution and transfer them to a hydrothermal reactor for hydrothermal reaction. After the reaction is completed, cool to room temperature, wash with ultrapure water and dry to obtain Ni5In1-Pt-B3.

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

[0016] Furthermore, the nickel salt in step 2 is Ni(NO 3 ) 2 6H 2 O, indium salt is In(NO 3 ) 3 , and the ratio of nickel salt, indium salt, urea and ammonium fluoride is 5:0.5 to 5:80:5;

[0017] The hydrothermal reaction kettle in step 2 is a polytetrafluoroethylene-lined high-pressure reactor placed in a constant temperature drying oven. The hydrothermal reaction temperature ranges from 150 to 200° C., and the hydrothermal reaction time ranges from 10 to 15 hours. The subsequent drying temperature is 50 to 80° C.

[0018] Further, the concentration of the chloroplatinic acid solution used in step 3 is: 6.4×10 -4 M, the soaking time is 2h, take out the soaked material and place it in a vacuum oven, dry it at 50-80℃ for 6h.

[0019] Furthermore, the hydrothermal reaction temperature in step 4 is in the range of 150 to 200°C, the hydrothermal reaction time is in the range of 1 to 5 hours, and the subsequent drying temperature is in the range of 50 to 80°C.

[0020] The application method of the nickel-based electrode is to process the prepared Ni5In1-Pt-B3 into a HER electrode for electrolyzing water to produce hydrogen.

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

[0022] The present invention uses a three-dimensional self-supporting nickel foam as a substrate, and loads In-doped Ni(OH) on the three-dimensional self-supporting nickel foam through a simple hydrothermal reaction. 2 , In-doped Ni double hydroxide is grown in situ on nickel foam, which is then impregnated to load the precious metal Pt on the material. Finally, sodium borohydride is used for secondary hydrothermal reduction to reduce Pt ions and part of Ni ions into PtNi alloy, thereby preparing a Ni5In1-Pt-B3 electrode with rich active sites.

[0023] The introduction of Ni, In, and Pt elements makes the prepared electrode have excellent HER catalytic activity, reaching 10 mA cm -2 The overpotential required for the current density is only 13 mV. -2 Under high current density, it was maintained for at least 188 hours, showing excellent stability. This electrode preparation method of low-temperature chemical reduction and construction of catalytic interface provides a new idea for the design of low-energy hydrogen production electrode materials.

[0024] Compared with the existing HER electrodes, the modified nickel-based HER electrode involved in the present invention has excellent performance, many active sites and sufficient exposure, high catalytic activity and chemical stability, can carry out water electrolysis reaction under simulated industrial electrolysis conditions, and has industrial application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 The figure is a schematic diagram of the preparation method of the nickel-based electrode of the present invention and the structural model of the electrode material.

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

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

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

[0029] Figure 5 Comparison of the HER polarization curves of Ni5In1-Pt-B3 obtained in Example 1 of the present invention and those of Comparative Examples 1, 2, 3 and Pt / C under 1 M KOH alkaline conditions: (a) HER polarization curves; (b) current densities of 10, 100 and 200 mA cm -2 The HER bar chart below.

[0030] Figure 6 The Ni5In1-Pt-B3 obtained in Example 1 of the present invention is 100mA·cm -2 HER stability test diagram under current density. DETAILED DESCRIPTION

[0031] In order to clearly illustrate the technical features of this patent, this patent is elaborated in detail below through a specific implementation method and in combination with its accompanying drawings.

[0032] The raw materials used in the following examples of the present invention are all commercially available.

[0033] Example 1

[0034] Step 1, pretreatment: 41.4 mL of concentrated hydrochloric acid (mass fraction of 36-38%) was measured and made up to 500 mL, and 1 M hydrochloric acid was prepared for use; a 1*5 cm section of NF was cut and placed in a beaker, and then ultrasonically cleaned with 30 mL 1 M HCl, sewage ethanol and ultrapure water for 15 min in sequence to remove the influence of oxides on the NF surface.

[0035] Step 2, preparation of Ni5In1: 0.5mmol nickel nitrate hexahydrate, 0.1mmol indium nitrate, 8mmol urea, and 0.5mmol ammonium fluoride are dispersed in 30mL ultrapure water, magnetically stirred for about 5min, and then transferred to a polytetrafluoroethylene-lined autoclave, and then the pretreated 1*5cm NF is placed in it, and the temperature is raised to 160°C in a constant temperature drying oven for 12h. After the reaction is completed, wait for the autoclave to cool naturally to room temperature, take out the loaded NF, and wash the excess Ni and In compounds on the surface with a slow flow of clean water. The product is placed in a vacuum oven and dried at 60°C for 6h to obtain Ni5In1.

[0036] Step 3, preparation of Ni5In1-Pt: Use a pipette to measure 10 μL of chloroplatinic acid solution (0.64 M) into a centrifuge tube, dilute to 10 mL, then immerse Ni5In1 therein, soak at room temperature for 2 h, take out the soaked material and place it in a vacuum oven, 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 small pieces of 1*1.5cm for later use. Weigh 0.1g of sodium borohydride and disperse it in 17mL of ultrapure water, stir it magnetically for about 5min, then transfer it to a polytetrafluoroethylene-lined autoclave, and then put the cut 1*1.5cm Ni5In1-Pt into it, put it in a constant temperature drying oven and heat it to 180℃, and react for 3h. After the reaction is completed, wait for the autoclave to cool naturally to room temperature, take out the Ni5In1-Pt, and slowly wash the surface with clean water. Finally, place the product in a vacuum oven and dry it at 60℃ for 6h to obtain Ni5In1-Pt-B3.

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

[0039] Comparative Example 1

[0040] The only difference from Example 1 is that the NaBH 4 After chemical reduction treatment, it is recorded 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 recorded as Ni5In1-B3.

[0043] Comparative Example 3

[0044] The only difference from Example 1 is that NiIn is not loaded on the NF, and the NF is directly impregnated with Pt and then borated, which is recorded 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] Prepare 1M KOH electrolyte: weigh 29.5315 g KOH and dissolve it in a beaker. After cooling to room temperature, transfer it to a 500 mL volumetric flask and make up to volume.

[0048] Electrochemical test: The test was carried out in a standard three-electrode system of CHI660E electrochemical workstation, using Hg / Hg 2 Cl 2The electrode was used as the reference electrode, the Pt sheet was used as the counter electrode, and the prepared Ni5In1-Pt-B3 electrode material was directly used as the working electrode. The size of the working electrode immersed in the electrolyte was 1cm×1cm, and the electrolyte was 1M KOH. About 60mL of electrolyte was used for each test. When using the electrode material for the first time, a CV test should be performed to activate the active sites. When testing HER, 85% IR compensation was performed, and the measured potentials were converted to reversible hydrogen electrodes for comparison. The polarization curve of HER is shown in Figure 2. Figure 5 As shown in (a), it can be seen from the figure that at the same current density, the overpotential required by Ni5In1-Pt-B3 is much lower than that of other electrodes. Even compared with Pt / C, it also shows excellent performance at high current. Figure 5 (b) It can be seen that at a current density of 10 mA cm -2 , 100mA·cm -2、 200mA·cm -2 When , the overpotentials of Ni5In1-Pt-B3 are 13mV, 61mV, and 82mV respectively;

[0049] like Figure 6 As shown, at 100mA·cm -2 Under the current density, the voltage of Ni5In1@NiBO@Pt / NF as the working electrode has almost no fluctuation and is stably maintained within 0.02V. It can operate stably for at least 188 hours, indicating that the electrode has super stability for HER and has great industrial application prospects.

[0050] There are many specific implementation ways of the present invention. The above is only the preferred implementation mode of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements can be made without departing from the principle of the present invention. These improvements should also be regarded as the protection scope of the present invention.

Claims

1. A method for preparing a nickel-based electrode for electrolyzing water to generate hydrogen, characterized in that: The nickel-based electrode is prepared by using a Ni source and an In source as precursors, a 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, pre-treating NF; The three-dimensional self-supporting NF was cut and ultrasonically cleaned with HCl solution, ethanol, and ultrapure water; Step 2, loading NiIn hydroxide on NF to prepare Ni5In1; Take appropriate amounts of nickel salt, indium salt, urea, and ammonium fluoride and dissolve them in ultrapure water. After stirring evenly, immerse the NF obtained in step 1 in the above solution and transfer them to a hydrothermal reactor for hydrothermal reaction. After the reaction is completed and cooled to room temperature, take out the NF loaded with Ni5In1, wash it with clean water, and dry it to obtain Ni5In1. Step 3, impregnating Ni5In1 with Pt, loading Pt, and preparing Ni5In1-Pt; The Ni5In1 obtained in step 2 is placed in a solution of chloroplatinic acid at room temperature for soaking, the soaked material is taken out and placed in a vacuum oven, and Ni5In1-Pt is obtained after drying; Step 4, using NaBH4 to perform a secondary hydrothermal reaction treatment to prepare Ni5In1-Pt-B3; Take NaBH4 and dissolve it in ultrapure water. After stirring evenly, immerse the Ni5In1-Pt obtained in step 3 in the above solution and transfer it to a hydrothermal reactor for hydrothermal reaction. After the reaction is completed, cool to room temperature, wash with ultrapure water and dry to obtain Ni5In1-Pt-B3.

2. The method for preparing a nickel-based electrode for electrolyzing water to produce hydrogen 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 electrolyzing water to produce hydrogen according to claim 1, characterized in that: The nickel salt in step 2 is Ni(NO3)2·6H2O, the indium salt is In(NO3)3, and the ratio of the nickel salt, the indium salt, the urea, and the ammonium fluoride is 5:0.5 to 5:80:5; The hydrothermal reaction kettle in step 2 is a polytetrafluoroethylene-lined high-pressure reactor placed in a constant temperature drying oven. The hydrothermal reaction temperature ranges from 150 to 200° C., and the hydrothermal reaction time ranges from 10 to 15 hours. The subsequent drying temperature is 50 to 80° C.

4. The method for preparing a nickel-based electrode for electrolyzing water to produce hydrogen according to claim 1, characterized in that: The concentration of chloroplatinic acid solution used in step 3 is: 6.4×10 -4 M, the soaking time is 2h, take out the soaked material and place it in a vacuum oven, dry it at 50-80℃ for 6h.

5. The method for preparing a nickel-based electrode for electrolyzing water to produce hydrogen according to claim 1, characterized in that: The hydrothermal reaction temperature range of step 4 is: 150-200°C, the hydrothermal reaction time range is: 1-5h; the subsequent drying temperature is 50-80°C.

6. The application method of the nickel-based electrode for electrolyzing water to generate hydrogen according to claim 1, characterized in that: The prepared Ni5In1-Pt-B3 is processed into HER electrode for hydrogen evolution by electrolysis of water.

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