Preparation method of oxygen evolution electrode for synergistically promoting bubble removal by double Laplace forces

Abstract

The invention relates to the field of electrolyzed water oxygen evolution reaction, and particularly discloses a preparation method of an oxygen evolution electrode for promoting bubble removal through cooperation of double Laplacian forces. A microscopic nanocone catalyst layer structure is grown on foamed nickel in an electro-deposition mode, a discontinuous three-phase interface is formed by means of the morphology to reduce bubble adhesive force, and under the simultaneous action of Laplace force generated by a microscopic V-shaped structure, microbubbles are promoted to be desorbed from the surface of a catalyst layer and leave a reaction area. A macroscopic gradient hole array is constructed on foamed nickel, and hydrophobic coatings are coated in holes, so that a hydrophobic and aerophilic effect is presented in the holes, gas in a reaction area is induced to gather towards a hydrophobic and aerophilic hole area under the action of surface tension, and the Laplace force generated by a gradient hole macroscopic V-shaped structure is utilized to promote rapid and directional transmission and removal of bubbles.

Description

Technical Field

[0001] The invention relates to the field of oxygen evolution reaction by electrolysis of water, and in particular to a method for preparing an oxygen evolution electrode capable of synergistically promoting bubble removal by dual Laplace forces. Background Art

[0002] Wind power and photovoltaic power are subject to natural conditions, resulting in intermittent and unstable generation, making it difficult to maintain stable power generation. However, water electrolysis technology can be coupled with wind power and photovoltaic power to convert excess electricity generated by wind and photovoltaic power into hydrogen for storage. When needed, this hydrogen can be burned or used to generate electricity using hydrogen fuel cells, enabling energy transfer across time and space. This effectively addresses the storage challenges of renewable energy and improves the stability and reliability of energy supply.

[0003] Water electrolysis consists of two half-reactions: the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER). As one of the half-reactions in the electrolysis process, the efficiency of the OER directly impacts the overall efficiency of hydrogen production. The OER is accompanied by the formation of gas molecules on the electrode surface, rapidly reaching a state of gas supersaturation. This causes bubbles to nucleate, grow, and detach from the electrode. Due to their non-conductivity, the bubbles' growth can cover the active sites on the electrode surface, hindering the reaction. Furthermore, due to the bubbles' adhesion to the electrode surface, repeated growth, prolonged detachment cycles, and high stress can also mechanically damage the catalyst layer, impacting its efficiency and service life.

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

[0005] The purpose of the present invention is to solve the problems of difficulty in removing bubbles, poor stability and durability in alkaline water electrolysis oxygen evolution reaction.

[0006] Based on the above objectives, the present invention proposes a method for preparing an oxygen evolution electrode that synergistically promotes bubble removal by dual Laplace forces, comprising the following steps:

[0007] (1) A gradient pore array was constructed on the surface of nickel foam, which was then ultrasonically cleaned with hydrochloric acid, anhydrous ethanol, and deionized water, and finally dried by vacuum heating.

[0008] (2) preparing a hydrophobic slurry by dissolving polydimethylsiloxane and a silicone rubber curing agent in n-hexane, followed by ultrasonic oscillation until fully mixed, then adding hydrophobic gas-phase nano-SiO2 particles, and ultrasonic oscillation again until uniformly dispersed; spraying the prepared hydrophobic slurry into the gradient pores of the nickel foam prepared in step (1), and then heating and drying under vacuum;

[0009] (3) Prepare a nanocone array catalytic layer on the nickel foam substrate prepared in step (2) using an electrodeposition method. Prepare an electrodeposition solution, add nickel chloride hexahydrate, ferrous chloride tetrahydrate, boric acid and ammonium chloride to the deionized water reaction solution, and then ultrasonically vibrate until fully dissolved. 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 a 30 mA cm -2 The electrodeposition was carried out in the above-configured electrodeposition solution at a current density of 100 nm for 20 min.

[0010] Compared with the existing technology, the advantages of the present invention are: utilizing the discontinuous three-phase interface and Laplace force formed by the V-shaped structure composed of the microscopic nanocone array to promote the desorption of microbubbles and leave the surface of the catalytic layer; utilizing the surface tension generated by the designed hydrophobic and air-philic pore areas to induce bubbles in the surrounding reaction zone to enter the interior of the macroscopic gradient pores and utilizing the Laplace force generated by the V-shaped structure of the macroscopic gradient pores to promote the rapid and directional transmission of bubbles within the 3D structure of the foam nickel electrode and timely discharge the electrode; under the above synergistic effect, the rapid removal of bubbles is promoted.

[0011] Therefore, the present invention has significant scientific significance and application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is an oxygen evolution electrode preparation process in which dual Laplace forces synergistically promote bubble removal.

[0013] Figure 2 These are SEM images of NiFe / HBNF in Example 1 and NF in Comparative Example 2: Figure a is the SEM image of NF, and Figure b is the SEM image of NiFe / HBNF.

[0014] Figure 3 1 and 2 are oxygen evolution performance curves of NiFe / HBNF, NiFe / NF, and NF in Example 1, Comparative Example 1, and Comparative Example 2.

[0015] Figure 4 This is the polarization curve of NiFe / HBNF at a constant current density in Example 1. DETAILED DESCRIPTION

[0016] The present invention will be further described in detail below with reference to the examples, but the embodiments of the present invention are not limited thereto.

[0017] Example 1

[0018] Preparation method of oxygen evolution electrode with dual Laplace forces synergistically promoting bubble removal

[0019] (1) Nickel foam substrate treatment: 1 cm*1 cm nickel foam was used to construct 4*4 equally spaced gradient holes on its surface. The nickel foam with gradient holes was immersed in 1 mol / L hydrochloric acid solution for ultrasonic cleaning for 10 min, and then ultrasonic cleaning was performed with anhydrous ethanol and deionized water for 10 min. After cleaning, it was placed in a vacuum drying oven for drying.

[0020] (2) Prepare a hydrophobic slurry by adding 44 mL of n-hexane to a 100 mL beaker, followed by 4 g of polydimethylsiloxane and 0.4 g of silicone rubber curing agent, and ultrasonically vibrate for 30 minutes to fully mix. Then, add 1.6 g of hydrophobic gas-phase nano-SiO2 particles and continue ultrasonically vibrating for 30 minutes until uniformly dispersed. Spray the prepared hydrophobic slurry into the gradient pores of the nickel foam prepared in step (1), and then heat and dry in a vacuum.

[0021] (3) Growth of nanocone array catalytic layer: Prepare electrodeposition solution: add 38g nickel chloride hexahydrate, 7.95g ferrous chloride tetrahydrate, 7.42g boric acid and 15g ammonium chloride to 200mL deionized water and ultrasonically shake until fully dissolved. Electrodeposition was performed using a two-electrode system, with the working electrode being the nickel foam prepared in step (2) and the counter electrode being a graphite rod. A 30mA cm -2 The electrode was electroplated in the above-configured electroplating solution at a current density of 100 nm for 20 min, and then washed with deionized water and dried in a vacuum drying oven. The obtained electrode was named NiFe / HBNF.

[0022] Example 2

[0023] The electrode preparation method of this embodiment is the same as that of Example 1. In this embodiment, the purpose is to measure the stability of the oxygen evolution electrode prepared by double Laplace force synergistically promoting bubble desorption at industrial current density. The steps are as follows:

[0024] The stability test was carried out using a three-electrode system, with the electrode prepared in Example 1 as the working electrode, the Hg / HgO electrode as the reference electrode, and the graphite rod as the counter electrode. -2 The test was continued under a constant current density, and the test environment and working conditions were the same as those in Example 1.

[0025] Comparative Example 1

[0026] The electrode preparation method of this comparative example differs from that of Example 1 in that the nickel foam used does not have gradient pores or a hydrophobic coating. The steps are as follows:

[0027] (1) Treatment of nickel foam substrate: 1 cm*1 cm nickel foam was immersed in 1 mol / L hydrochloric acid solution for ultrasonic cleaning for 10 min, followed by ultrasonic cleaning with anhydrous ethanol and deionized water for 10 min. After cleaning, it was placed in a vacuum drying oven for drying.

[0028] (2) Growth of nanocone array catalytic layer: Prepare electrodeposition solution: add 38g nickel chloride hexahydrate, 7.95g ferrous chloride tetrahydrate, 7.42g boric acid and 15g ammonium chloride to 200mL deionized water and ultrasonically shake until fully dissolved. Electrodeposition was performed using a two-electrode system: the working electrode was the nickel foam prepared in step (1), the counter electrode was a graphite rod, and a 30mA cm -2 The electrode was electroplated in the above-configured electroplating solution at a current density of 100 nm for 20 min, and then washed with deionized water and dried in a vacuum drying oven. The obtained electrode was named NiFe / NF.

[0029] Comparative Example 2

[0030] In this comparative example, only the nickel foam was cleaned with hydrochloric acid, anhydrous ethanol and deionized water and dried in a vacuum drying oven. The obtained electrode was named NF.

[0031] from Figure 1 It can be seen that compared with the smooth skeleton of ordinary nickel foam, a nanocone array catalytic layer grows uniformly on the surface of NiFe / HBNF. These nanostructures significantly increase the catalytic active sites and form a discontinuous three-phase interface to reduce the adhesion of bubbles.

[0032] Performance was tested using an electrochemical workstation, using the electrodes prepared in Example 1 / Comparative Example 1 / Comparative Example 2 as the working electrode, a Hg / HgO electrode as the reference electrode, and a graphite rod as the counter electrode. All potentials were converted relative to a reversible hydrogen electrode. Linear sweep voltammetry was performed over a voltage sweep range of 1.1 V to 1.8 V at a scan rate of 5 mV / s. Prior to testing, nitrogen was purged into the reactor to clean the electrode surfaces during cyclic voltammetry. A nitrogen atmosphere was maintained throughout the test.

[0033] from Figure 2 It can be seen that when the oxygen evolution current density is 100 mA cm -2 When the NiFe / HBNF reaction overpotential is 335mV, the oxygen evolution current density is 500mA cm -2 When the NiFe / HBNF reaction overpotential is 404mV; when the oxygen evolution current density is 1000mAcm -2 When the reaction overpotential of NiFe / HBNF is 459mV, by comparing NiFe / HBNF with NiFe / NF, it is effectively proved that the desorption of bubbles is promoted under the synergistic action of the dual Laplace force, which further improves the oxygen evolution performance.

[0034] from Figure 3 It can be seen that the NiFe / HBNF in Example 1 is -2The present invention can be stably operated for 25 hours at a current of , which further proves the effectiveness of the present invention.

[0035] Based on Example 1, Example 2, Comparative Example 1 and Comparative Example 2, the present invention proposes a method for preparing an oxygen evolution electrode that synergistically promotes bubble removal using dual Laplace forces. The prepared electrode has excellent catalytic performance and rapid bubble desorption effect, and also has good stability under industrial current density.

[0036] While 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 invention, and that the scope of the invention is defined by the claims and their equivalents.

Claims

1. A method for preparing an oxygen evolution electrode that promotes bubble removal by synergistically utilizing dual Laplace forces, characterized in that: The method comprises the following steps: (1) Construction of a macroscopic gradient pore array: A gradient pore array was constructed on the surface of nickel foam, followed by ultrasonic cleaning with hydrochloric acid, anhydrous ethanol, and deionized water, and finally vacuum heating and drying; (2) spraying a hydrophobic coating: preparing a hydrophobic slurry, spraying the hydrophobic slurry into the gradient pores of the nickel foam prepared in step (1), and then heating and drying in vacuum; (3) Growth of nanocone array catalytic layer: Prepare electrodeposition solution, use two-electrode system for electrodeposition, and grow microscopic nanocone array structure on the electrode surface by controlling electrodeposition time and current.

2. The method for preparing an oxygen evolution electrode with dual Laplace forces synergistically promoting bubble removal according to claim 1, characterized in that: The hydrophobic slurry prepared in step (2) is composed of n-hexane, polydimethylsiloxane, silicone rubber curing agent, and hydrophobic gas-phase nano-SiO2 particles.

3. The method for preparing an oxygen evolution electrode with dual Laplace forces synergistically promoting bubble removal according to claim 1, characterized in that: The electrodeposition solution prepared in step (3) consists of nickel chloride hexahydrate, ferrous chloride tetrahydrate, boric acid and ammonium chloride.

4. The method for preparing an oxygen evolution electrode with dual Laplace forces synergistically promoting bubble removal according to claim 1, characterized in that: In step (3), a two-electrode system was used for electrodeposition. The working electrode was the nickel foam prepared in step (2), and the counter electrode was a graphite rod. The reaction was carried out at 60°C and 30 mA cm -2 The electrodeposition was carried out for 20 min at a current density of 1.5 Å.

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