Method for preparing porous nickel skeleton oxygen evolution electrode through two-step electrodeposition

Abstract

The invention discloses a method for preparing a porous nickel skeleton oxygen evolution electrode through two-step electrodeposition, and relates to the field of electrolyzed water oxygen evolution reaction, and the method is characterized by comprising the following steps: electrode pretreatment: carrying out ultrasonic cleaning on foamed nickel and a nickel sheet electrode substrate by using hydrochloric acid, absolute ethyl alcohol and deionized water in sequence; a nickel chloride hexahydrate solution and an ammonium chloride solution serve as electrodeposition liquid, a two-electrode system is used for electrodeposition, a pretreated nickel substrate serves as a working electrode, a graphite rod serves as a counter electrode, and the microstructure of an electrode framework is controlled by controlling electrodeposition time and current; a nickel nitrate hexahydrate solution and a ferric nitrate nonahydrate solution are used as electro-deposition liquid, a two-electrode system is used for electro-deposition, a working electrode is the porous nickel framework substrate prepared through electro-deposition in the first step, a counter electrode is a graphite rod, and the nickel-iron layered hydroxide nano-catalysis array is prepared through electro-deposition in the second step. And the surface microstructure of the electrode is controlled by controlling the electrodeposition time and current.

Description

Technical Field

[0001] The invention belongs to the field of water electrolysis oxygen evolution reaction, and designs a preparation method for a porous nickel skeleton oxygen evolution electrode by two-step electrodeposition which can be used for water electrolysis oxygen evolution reaction. Background Art

[0002] Water electrolysis technology is a new technology that uses electricity to decompose water into oxygen and hydrogen. The oxygen produced can be used in steel smelting, chemical synthesis, defense industry, medical breathing and other fields; the hydrogen produced can be used in petroleum, chemical industry, electronics, metallurgy, oil, aerospace, light industry and other fields. Water electrolysis hydrogen production technology is an ideal technology for converting unstable renewable electricity into hydrogen energy that can be stored for a long time. This technology includes two half reactions, hydrogen evolution reaction and oxygen evolution reaction. Any slow progress of any half reaction will reduce the energy efficiency of water electrolysis. Compared with the hydrogen evolution reaction, the oxygen evolution reaction involves a complex four-electron transfer process, which makes its kinetic process slower, thereby limiting the efficient operation of the water electrolysis system.

[0003] Alkaline water electrolysis is the most mature and widely used large-scale hydrogen production technology. Alkaline water electrolysis systems usually use porous asbestos as diaphragms and alkali-resistant nickel metals as electrode materials. Although this system has the advantage of high economic efficiency, the electrodes currently used for water electrolysis have problems such as low catalytic reaction activity and poor stability, resulting in low efficiency of the water electrolysis system.

[0004] In summary, it is crucial to develop oxygen evolution electrodes with high oxygen evolution reaction catalytic ability and high stability. Summary of the invention

[0005] The purpose of the present invention is to solve the problems of low catalytic ability and poor stability of oxygen evolution reaction in alkaline water electrolysis, and propose a method for preparing a porous nickel skeleton oxygen evolution electrode by two-step electrodeposition.

[0006] The present invention is based on a two-step electrodeposition method, and the specific preparation steps are divided into the following three steps.

[0007] Step 1 is nickel substrate pretreatment, immersing the nickel foam and nickel sheet electrode substrates in a hydrochloric acid solution for ultrasonic cleaning, and then using anhydrous ethanol and deionized water for ultrasonic cleaning, and after cleaning, taking them out and vacuum drying them.

[0008] Step 2 is the first step of electrodeposition, preparing a porous nickel skeleton substrate on the electrode substrate. The substrate skeleton microstructure is controlled by controlling the electrodeposition time and current. Prepare the electrodeposition solution: add nickel chloride hexahydrate and ammonium chloride to a deionized water solution, and then ultrasonically shake until the nickel chloride hexahydrate and ammonium chloride are fully dissolved in the solution. Use a two-electrode system for electrodeposition, the working electrode is the nickel substrate treated in step 1, and the counter electrode is a graphite rod. Electrodeposit for 150 seconds at a current of 1A in the above-prepared electrodeposition solution, rinse the prepared electrode with deionized water and ethanol several times, and vacuum dry.

[0009] Step three is the second step of electrodeposition, in which a nickel-iron layered hydroxide nanocatalytic array is prepared on the basis of the electrode prepared in the first step. The electrode surface microstructure is controlled by controlling the electrodeposition time and current. An electrodeposition solution is prepared, and nickel nitrate hexahydrate and ferric nitrate nonahydrate are added to the deionized water reaction solution, and then ultrasonically shaken until the nickel nitrate hexahydrate and ferric nitrate nonahydrate are fully dissolved in the deionized water solution. A two-electrode system is used for electrodeposition, the working electrode is the electrode prepared in step two, and the counter electrode is a graphite rod. A current of 20 mA is used to electrodeposit in the above-configured electrodeposition solution for 900 seconds.

[0010] Compared with the prior art, the advantages of the present invention are: the porous nickel skeleton oxygen evolution electrode prepared by the two-step electrodeposition method has good catalytic ability and stability for oxygen evolution reaction. The integrated structure of the catalytic array and the porous skeleton is formed by electrodeposition growth, which eliminates the use of binders in the traditional electrode preparation process, is conducive to improving the electrode conductivity, improving the electrode reaction efficiency, and increasing the electrode stability, improving the electrode's tolerance to stress changes caused by periodic bubble generation, growth, desorption and transmission during the oxygen evolution reaction, and improving the stability of the electrode in long-term use. Therefore, the present invention has significant scientific significance and application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 It is a two-step electrodeposition process for preparing porous nickel skeleton oxygen evolution electrodes;

[0012] Figure 2 This is the polarization curve of oxygen evolution reaction of porous nickel skeleton oxygen evolution electrode on nickel foam substrate;

[0013] Figure 3 This is the polarization curve of oxygen evolution reaction of porous nickel skeleton oxygen evolution electrode on nickel sheet substrate. DETAILED DESCRIPTION

[0014] The present invention is further described in detail below in conjunction with examples, but the embodiments of the present invention are not limited thereto.

[0015] Implementation case 1, preparation process as follows Figure 1 As shown, a porous nickel skeleton oxygen evolution electrode is prepared by using nickel foam as the electrode substrate.

[0016] Step 1: Pretreatment of the electrode substrate: immerse the 2 cm long and 1 cm wide nickel foam in a 1 mol / L hydrochloric acid solution for ultrasonic cleaning. After waiting for 30 minutes, use anhydrous ethanol and deionized water for ultrasonic cleaning for 20 minutes. After cleaning, take it out and vacuum dry it for 8 hours.

[0017] Step 2: Prepare a porous nickel skeleton substrate on the electrode substrate. Prepare an electrodeposition solution, add 1.782g nickel chloride hexahydrate and 5.349g ammonium chloride to 30mL of deionized water solution, and then ultrasonically shake until the nickel chloride hexahydrate and ammonium chloride are fully dissolved in the solution. Use a two-electrode system for electrodeposition, the working electrode is the nickel foam treated in step 1, and the counter electrode is a graphite rod. Electrodeposit for 150s in the above-prepared electrodeposition solution with a current of 1A. Rinse the above-prepared porous nickel skeleton substrate with deionized water and ethanol several times, and vacuum dry.

[0018] Step 3: Prepare nickel-iron layered hydroxide nanocatalytic array. Prepare an electrodeposition solution, add 14.539g nickel nitrate hexahydrate and 5.050g ferric nitrate nonahydrate to 30mL of deionized water reaction solution, and then ultrasonically shake until the nickel nitrate hexahydrate and ferric nitrate nonahydrate are fully dissolved in the deionized water solution. Use a two-electrode system for electrodeposition, the working electrode is the electrode prepared in step 2, the counter electrode is a graphite rod, and use a current of 20mA to electrodeposit in the above-configured electrodeposition solution for 900s.

[0019] Electrochemical performance test performance: The electrode prepared by the present invention is used as the working electrode, the Hg / HgO electrode is used as the reference electrode, and the graphite rod is used as the counter electrode. All potentials are converted to relative to the reversible hydrogen electrode. Linear sweep voltammetry test, the voltage sweep range is 1.2V to 1.8V, and the sweep rate is 10mV / s. Stability test, using cyclic voltammetry, the voltage sweep range is 1.2V to 1.8V, the cycle test is 500 cycles, and the sweep rate is 100mV / s. Before the test, nitrogen is passed into the reactor to saturation, the cyclic voltammetry is swept to clean the electrode surface, and the nitrogen atmosphere of the test environment is maintained during the test.

[0020] The test results are as follows Figure 2 As shown, when the oxygen evolution current density is 100mA / cm 2 When the sample was subjected to cyclic test for 500 cycles, the overpotential of the oxygen evolution reaction was only 360 mV; after 500 cycles of cyclic test, the overpotential of the oxygen evolution reaction was 370 mV, which was only 10 mV higher than that of the initial sample.

[0021] Implementation case 2, preparation process as follows Figure 1 As shown, a porous nickel skeleton oxygen evolution electrode was prepared by using a nickel sheet as an electrode substrate.

[0022] Step 1: Electrode substrate pretreatment: Immerse a 2 cm long and 1 cm wide nickel sheet in 1 mol / L hydrochloric acid solution for ultrasonic cleaning, wait for 30 minutes, then use anhydrous ethanol and deionized water for ultrasonic cleaning for 20 minutes, and then take it out and vacuum dry it for 8 hours.

[0023] Step 2: Prepare a porous nickel skeleton substrate on the electrode substrate. Prepare the electrodeposition solution: add 1.782g nickel chloride hexahydrate and 5.349g ammonium chloride to 30mL deionized water solution, and then ultrasonically shake until the nickel chloride hexahydrate and ammonium chloride are fully dissolved in the solution. Use a two-electrode system for electrodeposition, the working electrode is the nickel sheet treated in step 1, and the counter electrode is a graphite rod. Electrodeposit in the above-prepared electrodeposition solution at a current of 1A for 150s, rinse the prepared electrode with deionized water and ethanol several times, and vacuum dry.

[0024] Step 3: Prepare nickel-iron layered hydroxide nanocatalytic array. Prepare electrodeposition solution: add 14.539g nickel nitrate hexahydrate and 5.050g ferric nitrate nonahydrate to 30mL deionized water reaction solution, and then ultrasonically shake until nickel nitrate hexahydrate and ferric nitrate nonahydrate are fully dissolved in the deionized water solution. Use a two-electrode system for electrodeposition, the working electrode is the electrode prepared in step 2, the counter electrode is a graphite rod, and use a current of 20mA to electrodeposit in the above-configured electrodeposition solution for 900s.

[0025] Electrochemical performance test performance: The electrode prepared by the present invention is used as the working electrode, the Hg / HgO electrode is used as the reference electrode, and the graphite rod is used as the counter electrode. All potentials are converted to relative to the reversible hydrogen electrode. Linear sweep voltammetry test, the voltage sweep range is 1.2V to 1.8V, and the sweep rate is 10mV / s. Stability test, using cyclic voltammetry, the voltage sweep range is 1.2V to 1.8V, the cycle test is 500 cycles, and the sweep rate is 100mV / s. Before the test, nitrogen is passed into the reactor to saturation, the cyclic voltammetry is swept to clean the electrode surface, and the nitrogen atmosphere of the test environment is maintained during the test.

[0026] The test results are as follows Figure 3 As shown, when the current density is 100mA / cm 2 When the sample was subjected to 500 cycles of cyclic testing, the overpotential of the oxygen evolution reaction was only 340 mV; after 500 cycles of cyclic testing, the overpotential of the oxygen evolution reaction was 380 mV, which was only 40 mV higher than that of the initial sample.

[0027] Combining Case 1 and Case 2, it can be concluded that the porous nickel skeleton oxygen evolution electrode prepared by the two-step electrodeposition proposed in the present invention has excellent catalytic ability and good stability.

[0028] Although the embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the claims and their equivalents.

Claims

1. A method for preparing a porous nickel skeleton oxygen evolution electrode by two-step electrodeposition, characterized in that: A method for preparing a porous nickel skeleton oxygen evolution electrode comprises the following steps: Step 1 is to pretreat the electrode substrate: the foam nickel and nickel sheet electrode substrates are cleaned with hydrochloric acid, anhydrous ethanol, and deionized water ultrasonically in sequence, and finally dried; Step 2 is to prepare a porous nickel skeleton substrate by electrodeposition in the first step: prepare an electrodeposition solution, use a two-electrode system for electrodeposition, and control the electrodeposition time and current to control the electrode skeleton microstructure; Step three is to prepare the nickel-iron layered hydroxide nanocatalytic array by the second step of electrodeposition: prepare an electrodeposition solution, use a two-electrode system for electrodeposition, and control the electrode surface microstructure by controlling the electrodeposition time and current.

2. The method for preparing a porous nickel skeleton oxygen evolution electrode by two-step electrodeposition according to claim 1, characterized in that: The first step is to prepare a porous nickel skeleton substrate by electrodeposition. The electrodeposition solution is prepared by adding nickel chloride hexahydrate and ammonium chloride into a deionized water solution, and then ultrasonically vibrating the solution until the nickel chloride hexahydrate and ammonium chloride are fully dissolved in the deionized water solution.

3. The method for preparing a porous nickel skeleton oxygen evolution electrode by two-step electrodeposition according to claim 1, characterized in that: The second step is to prepare the nickel-iron layered hydroxide nanocatalytic array by electrodeposition. The method for preparing the electrodeposition solution is to add nickel nitrate hexahydrate and iron nitrate nonahydrate into a deionized water solution, and then ultrasonically vibrate until the nickel nitrate hexahydrate and iron nitrate nonahydrate are fully dissolved in the deionized water solution.

4. The method for preparing a porous nickel skeleton oxygen evolution electrode by two-step electrodeposition according to claim 1, characterized in that: In the first step, a porous nickel skeleton substrate was prepared by electrodeposition using a two-electrode system. The working electrode was a pretreated nickel substrate, and the counter electrode was a graphite rod. The electrodeposition was performed at a current of 1 A for 150 s.

5. The method for preparing a porous nickel skeleton oxygen evolution electrode by two-step electrodeposition according to claim 1, characterized in that: The second step was to prepare nickel-iron layered hydroxide nanocatalytic arrays by electrodeposition. A two-electrode system was used for electrodeposition. The working electrode was the porous nickel skeleton substrate prepared by the first step of electrodeposition, and the counter electrode was a graphite rod. Electrodeposition was performed at a current of 20 mA for 900 s.

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