High-performance electro-catalysis oxygen evolution reaction electrode and preparation method thereof

Abstract

The invention discloses a preparation method of a high-performance electro-catalysis oxygen evolution reaction electrode, which comprises the following steps: preparing graphene oxide printing ink, injecting the graphene oxide printing ink into a DLP photocuring 3D printer, and performing 3D printing to obtain a reduced graphene oxide electrode; carrying out high-temperature sintering on the reduced graphene oxide electrode; performing acid pickling and chemical nickel plating on the sintered reduced graphene oxide electrode to obtain a reduced graphene oxide electrode of which the surface is modified with a nickel plating layer; coFe hydroxide is electrically deposited on the surface of the nickel plating layer, so that the surface of the nickel plating layer is loaded with a CoFe hydroxide outer layer, and then the high-performance electro-catalysis oxygen evolution reaction electrode is obtained through cleaning and drying. The electrode is printed through the DLP photocuring 3D printing technology, the electrode can be provided with an accurate and controllable three-dimensional porous structure substrate, and through chemical nickel plating and multi-step modification of electro-deposition of CoFe hydroxide, the conductivity of the electrode can be improved, and the catalytic performance can be enhanced. The invention further discloses a high-performance electro-catalysis oxygen evolution reaction electrode.

Description

Technical Field

[0001] This invention belongs to the field of electrochemical catalysis technology, specifically relating to a high-performance electrocatalytic oxygen evolution reaction electrode and its preparation method. Background Technology

[0002] Currently, common preparation methods for porous graphene-based electrodes include chemical vapor deposition, template method, freeze drying method, and chemical exfoliation-self-assembly method. Common modification strategies for porous graphene-based electrodes include heteroatom doping, metal oxide / hydroxide modification, bimetallic / multimetallic catalyst composite, pore structure optimization, heat treatment, and defect introduction. One method involves heteroatom doping, which introduces heteroatoms such as nitrogen, sulfur, or phosphorus into the graphene carbon framework using chemical methods. These heteroatoms alter the electronic structure of graphene, increasing the density of active sites and thus enhancing the adsorption capacity for OER (electrocatalytic oxygen evolution reaction) intermediates (such as *OH and *OOH), thereby improving catalytic performance. Another method involves metal oxide / hydroxide modification, where nanoparticles of transition metal oxides or hydroxides such as nickel, cobalt, and iron are loaded onto the surface of porous graphene. Metal compounds such as NiO provide OER catalytic active centers, synergistically interacting with the graphene substrate to promote electron transfer and catalytic reactions. A third method involves bimetallic / multimetallic catalyst composites, where transition metal hydroxides are deposited onto the porous graphene framework using chemical or electrochemical deposition methods. These metal hydroxides then act as OER catalysts, optimizing OER through intermetallic electronic coupling. The adsorption free energy of intermediates can be reduced, thereby lowering the reaction overpotential. Pore structure optimization methods adjust the pore structure of porous graphene using hard templates (such as SiO2) or chemical etching. The optimized pore structure increases specific surface area and active site exposure, while improving the mass transfer efficiency of reactants and products. Thermal treatment and defect introduction involve removing oxygen groups and introducing defects through thermal reduction of graphene oxide (rGO). These defect sites serve as catalytic active centers, enhancing OER reaction efficiency, while thermal treatment improves the material's conductivity. However, traditional methods for preparing and modifying porous graphene-based electrodes still suffer from limitations in precise pore structure control, insufficient uniform dispersion of modified components, and poor stability of modified components.

[0003] Existing technologies also include non-graphene-based OER electrodes prepared using existing methods, such as noble metal-based electrodes and transition metal-based electrodes. Noble metal-based electrodes rely on noble metals and their oxides; while exhibiting high catalytic activity, they are expensive and resource-scarce. Transition metal-based electrodes provide OER active sites through transition metal hydroxides, promoting catalytic reactions through synergistic effects. Their conductive substrate supports electron transfer, but their low specific surface area and limited number of exposed catalytic active sites restrict OER catalytic efficiency.

[0004] In summary, existing OER electrode preparation methods struggle to construct substrate structures with precise and uniform pore sizes and high specific surface areas, resulting in insufficient utilization of active materials. Furthermore, the poor conductivity and mass transfer properties of the electrode materials negatively impact the overall catalytic performance of the electrode. Summary of the Invention

[0005] To address the shortcomings of the prior art, this invention provides a method for preparing a high-performance electrocatalytic oxygen evolution reaction electrode. The electrode is printed using DLP photopolymerization 3D printing technology, resulting in a precisely controllable three-dimensional porous substrate that effectively increases the electrode's specific surface area, providing ample space for the effective loading of active materials. Through multi-step modification via electroless nickel plating and electrodeposition of CoFe hydroxide, the electrode's conductivity and catalytic performance are enhanced. This invention also provides a high-performance electrocatalytic oxygen evolution reaction electrode.

[0006] The technical effects to be achieved by this invention are realized through the following technical aspects: In a first aspect, the present invention provides a method for preparing a high-performance electrocatalytic oxygen evolution reaction (OER) electrode, comprising the following steps: S1. Add monolayer graphene oxide powder to deionized water, mix well, and then add photosensitive resin and photoinitiator in sequence to prepare graphene oxide printing ink. Inject the graphene oxide printing ink into a DLP photopolymerization 3D printer to obtain a reduced graphene oxide (rGO) electrode through 3D printing. S2. The reduced graphene oxide electrode is sintered at high temperature; S3. The sintered reduced graphene oxide electrode is acid-washed and then electroless nickel plating is performed to obtain a reduced graphene oxide electrode with a nickel plating layer on the surface. S4. Using the reduced graphene oxide electrode with a nickel coating as the working electrode, the Pt electrode as the counter electrode, and the Ag / AgCl electrode as the reference electrode, the three electrodes are arranged in a line with the working electrode in the middle and the counter and reference electrodes at both ends to form a three-electrode system. The system is then placed in a mixed solution of Co(NO3)2 and Fe(NO3)3 for electrodeposition, so that the surface of the nickel coating is loaded with CoFe hydroxide. After electrodeposition, the working electrode is removed, cleaned, and dried to obtain a high-performance electrocatalytic oxygen evolution reaction (OER) electrode.

[0007] As a further description of the technical solution of the present invention, the specific steps of the electroless nickel plating are as follows: the acid-washed reduced graphene oxide electrode is sequentially immersed in SnCl2 solution and PdCl2 solution, then taken out for water washing and air drying, and then placed in nickel plating aqueous solution for reaction.

[0008] As a further description of the technical solution of the present invention, the concentration of the SnCl2 solution is 40~60mM, preferably 50mM; the concentration of the PdCl2 solution is 2~5mM, preferably 3mM; The nickel plating aqueous solution comprises the following components: NiSO4·6H2O 0.1~0.2M, C6H5Na3O7·3H2O 0.05~0.1M, NH4Cl 0.3~0.5M, and NaH2PO2·H2O 0.3~0.5M. Preferably, the nickel plating aqueous solution comprises the following components: NiSO4·6H2O 0.15M, C6H5Na3O7·3H2O 0.08M, NH4Cl 0.4M, and NaH2PO2·H2O 0.4M.

[0009] As a further description of the technical solution of the present invention, the pickling uses concentrated sulfuric acid with a concentration of 98% to remove impurities from the electrode surface.

[0010] As a further description of the technical solution of the present invention, in the mixed solution of Co(NO3)2 and Fe(NO3)3, the concentration of Co(NO3)2 is 2~5mM, preferably 3 mM; the concentration of Fe(NO3)3 is 2~5mM, preferably 3 mM.

[0011] As a further description of the technical solution of the present invention, the voltage condition for electrodeposition is -1.8±0.09V.

[0012] As a further description of the technical solution of the present invention, the high-temperature sintering heating process adopts a gradient heating method, specifically including the following steps: First, the temperature is increased to 180-220℃ at a rate of 0.5-1℃ / min and held for 5-15 min; then, the temperature is increased to 460-500℃ at a rate of 0.5-1℃ / min and held for 25-35 min; next, the temperature is increased to 530-570℃ at a rate of 0.5-1℃ / min and held for 25-35 min; finally, the temperature is increased to 600-1100℃ at a rate of 8-12℃ / min and held for 55-65 min. This gradient heating method for high-temperature sintering facilitates the formation of a highly crystalline catalytic phase, enhancing electron transport and the exposure of active sites in the electrode.

[0013] In a preferred embodiment, the high-temperature sintering process involves first increasing the temperature to 200°C at a rate of 1°C / min and holding for 10 min; then increasing the temperature to 480°C at a rate of 0.5°C / min and holding for 30 min; next, increasing the temperature to 550°C at a rate of 1°C / min and holding for 30 min; and finally increasing the temperature to 1000°C at a rate of 10°C / min and holding for 60 min. Using a sintering temperature of 1000°C significantly enhances catalytic activity and stability, providing high current density and low overpotential in the oxygen evolution reaction, ensuring long-term electrode stability and excellent electrochemical performance.

[0014] As a further description of the technical solution of the present invention, during the process of heating to 600~1100℃ at a rate of 8~12℃ / min, when the temperature reaches an integer multiple of 100℃ (e.g., 600℃, 700℃, 800℃, 900℃, 1000℃), the temperature is first held for 55~65 minutes before continuing to heat up.

[0015] As a further description of the technical solution of the present invention, in the graphene oxide printing ink, the mass ratio of single-layer graphene oxide powder, photosensitive resin and photoinitiator is 1:(2~3):(90~100), preferably 1:2:97.

[0016] Secondly, the present invention provides a high-performance electrocatalytic oxygen evolution reaction electrode, which is prepared by the method for preparing the high-performance electrocatalytic oxygen evolution reaction electrode.

[0017] In summary, the present invention has at least the following advantages: The present invention provides a method for preparing a high-performance electrocatalytic oxygen evolution reaction (OER) electrode. This method employs DLP photopolymerization 3D printing technology to cure graphene oxide printing ink layer by layer, achieving precise design and fabrication of the electrode's three-dimensional structure. It enables the bottom-up construction of a pore structure with precise pore size, porosity, and high interconnectivity, effectively increasing the electrode's specific surface area. This provides ample space for the effective loading of active materials and exposes more catalytic active sites, fully leveraging the catalytic potential of the active materials and improving the overall OER efficiency of the electrode. Simultaneously, it constructs efficient electrolyte transport channels, significantly improving the utilization efficiency and mass transfer efficiency of active sites. A uniform and dense nickel layer is then applied to the surface of the reduced graphene oxide (rGO) electrode using chemical plating technology, enhancing charge transport efficiency, improving the conductivity of the reduced graphene oxide substrate, and reducing the hydrophilicity of the rGO electrode surface. This provides an excellent conductive substrate for the subsequent uniform nucleation and growth of CoFe-LDH (cobalt-iron-based basal double hydroxide). Subsequently, CoFe hydroxide was uniformly loaded onto the nickel layer surface using electrodeposition technology, which effectively prevented the agglomeration of active materials, ensured its high dispersibility, and enhanced the electronic coupling and binding strength between CoFe-LDH and the reduced graphene oxide substrate. This fully leveraged the synergistic effect of each component and significantly improved the structural stability and catalytic activity persistence of the electrode.

[0018] This invention ingeniously utilizes abundant non-precious metal elements nickel, cobalt, and iron to form the catalytic active center, effectively avoiding dependence on expensive and rare precious metals and significantly reducing the electrode preparation cost, thus providing an effective solution for the low-cost development of OER electrodes. The introduction of nickel also generates a good synergistic effect with CoFe-LDH, optimizing the electronic structure of the catalyst and effectively lowering the energy barrier of the OER reaction, thereby achieving excellent OER catalytic activity based on non-precious metal catalysts.

[0019] The high-performance electrocatalytic oxygen evolution reaction electrode provided by this invention has a precise and uniform pore size and a high specific surface area. It has a stable overall structure, high catalytic activity, strong conductivity, and excellent OER catalytic performance. Attached Figure Description

[0020] Figure 1 Comparison of OER catalytic performance of rGO electrodes at different sintering temperatures (ac); Figure 2 Digital image of the rGO electrode (a); optical micrographs of the rGO electrode before and after sintering (bc); digital image of the porous rGO electrode (d); optical micrographs of the sintered rGO electrode at X5 and X20 magnification (ef). Figure 3SEM images of rGO electrodes (ad): planar (ab), cross-section (cd); SEM images of rGO electrodes with nickel plating (eg): surface (e), cross-section (fg); SEM image of CoFe-LDH on the surface of a high-performance OER electrode (hi); SEM-EDS pattern of CoFe-LDH on the surface of a high-performance OER electrode (j). Figure 4 TGA curve (a); EPR spectrum of rGO electrode (b); Raman spectrum of rGO electrode (c); XPS spectra of rGO electrode before and after pickling (df); XRD spectrum of rGO electrode with nickel plating (g); XRD spectrum of high-performance OER electrode (rGO / Ni / CoFeOH) (h). Figure 5 The following are the electrochemical performance test results for the electrodes: (a) Comparison of linear sweep voltammetry (LSV) curves for different electrodes (rGO, rGO / Ni, rGO / Ni / CoFeOH); (b) Tafel slope plot calculated from (a); (c) Nyquist plot of electrochemical impedance spectroscopy (EIS); (d) Comparison of overpotentials of the high-performance OER electrode rGO / Ni / CoFeOH and the control group electrode with only Co(OH)2 or Fe(OH)3 deposited at different current densities; (e) Overpotential of the high-performance OER electrode at 50 mA / cm². 2 Comparison of overpotential performance of various transition metal-based OER catalysts with existing technologies at current densities; (f) shows the overpotential performance of the rGO / Ni / CoFe-LDH electrode at 10 mA / cm². 2 50mA / cm 2 100mA / cm 2 (g) is the LSV scan of the -0.4~1.0V (vs. Hg / HgO) range used to determine the non-reactive region; (h) is the fitting plot of the double layer capacitance (Cdl) calculated by cyclic voltammetry (CV); (i) is the comparison plot of the specific activity LSV curve after normalization by electrochemical active surface area (ECSA). Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. The described embodiments are some, but not all, of the embodiments of the present invention.

[0022] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0023] Example 1 This embodiment provides a high-performance electrocatalytic oxygen evolution reaction electrode, which is prepared by the following method: S1. Add monolayer graphene oxide powder (Suzhou Carbon-rich Graphene Technology Co., Ltd., monolayer, powder) to deionized water and ultrasonically disperse to obtain a uniformly dispersed graphene oxide suspension. Then, add photosensitive resin PEG(400)DA and photoinitiator TPO-L in sequence and mix thoroughly using a ball mill to prepare graphene oxide printing ink suitable for DLP photopolymerization 3D printing (monolayer graphene oxide powder: photosensitive resin: photoinitiator = 1:2:97). Graphene oxide printing ink is injected into the feed tank of a top-illuminated DLP photopolymerization 3D printer. The pre-designed 3D electrode model is imported into the printer control software, and printing is started. During printing, the forming tank rises to the focal length of the UV lamp, and the scraper drives the graphene oxide printing ink in the feed tank to spread evenly on the forming tank at a set speed. The UV lamp receives the image transmitted by DLP and exposes the corresponding pattern, causing the liquid printing ink to solidify. The printing is carried out layer by layer according to the set layer thickness until the electrode printing is completed. The printed electrode is removed from the printing platform, and the residual ink on the surface is removed to obtain the rGO electrode. S2. The rGO electrode was subjected to high-temperature sintering. First, the temperature was increased to 200℃ at a rate of 1℃ / min and held for 10 min; then increased to 480℃ at a rate of 0.5℃ / min and held for 30 min; next, the temperature was increased to 550℃ at a rate of 1℃ / min and held for 30 min; finally, the temperature was increased to 800℃ at a rate of 10℃ / min. During the final heating process, the temperature was held for 60 min at 600℃ and 700℃ before continuing the heating process, finally reaching 800℃ and holding for 60 min at the same time. The crystallinity, specific surface area, and exposure of catalytic active sites of the material were controlled. The OER catalytic performance of the sintered rGO electrode was as follows: Figure 1 As shown in (ac), its catalytic activity is low, indicating that the electrode material may still contain undecomposed precursors or have insufficient crystallinity. S3. The sintered rGO electrode was acid-washed with 98% concentrated sulfuric acid to remove impurities from the electrode surface. A 0.25M HCl solution was prepared as the base solution, and 50mM SnCl2 solution and 3mM PdCl2 solution were prepared respectively. The acid-washed rGO electrode was immersed in SnCl2 solution and PdCl2 solution in turn, then taken out, washed with water and air-dried. Then it was placed in a nickel plating aqueous solution (NiSO4·6H2O 0.15M, C6H5Na3O7·3H2O 0.08M, NH4Cl 0.4M, NaH2PO2·H2O 0.4M) for reaction to obtain an rGO electrode with a nickel plating layer on the surface. S4. Using an rGO electrode with a nickel plating layer as the working electrode, a Pt mesh as the counter electrode, and an Ag / AgCl electrode as the reference electrode, the three electrodes are arranged in a line, with the working electrode in the middle and the counter and reference electrodes at both ends, forming a three-electrode system. This system is placed in a mixed solution of Co(NO3)2 (3mM) and Fe(NO3)3 (3mM), and stirred at room temperature using a magnetic stirring hot stage (Aika). Electrodeposition is performed at -1.8V to load CoFe hydroxide onto the surface of the nickel plating layer. After electrodeposition, the working electrode is removed, washed with deionized water, and dried in a vacuum oven to obtain a high-performance OER electrode.

[0024] Example 2 This embodiment provides a high-performance electrocatalytic oxygen evolution reaction electrode, which is prepared by the following method: S1. Add monolayer graphene oxide powder (Suzhou Carbon-rich Graphene Technology Co., Ltd., monolayer, powder) to deionized water and ultrasonically disperse to obtain a uniformly dispersed graphene oxide suspension. Then, add photosensitive resin PEG(400)DA and photoinitiator TPO-L in sequence and mix thoroughly using a ball mill to prepare graphene oxide printing ink suitable for DLP photopolymerization 3D printing (monolayer graphene oxide powder: photosensitive resin: photoinitiator = 1:2:97). Graphene oxide printing ink is injected into the feed tank of a top-illuminated DLP photopolymerization 3D printer. The pre-designed 3D electrode model is imported into the printer control software, and printing is started. During printing, the forming tank rises to the focal length of the UV lamp, and the scraper drives the graphene oxide printing ink in the feed tank to spread evenly on the forming tank at a set speed. The UV lamp receives the image transmitted by DLP and exposes the corresponding pattern, causing the liquid printing ink to solidify. The printing is carried out layer by layer according to the set layer thickness until the electrode printing is completed. The printed electrode is removed from the printing platform, and the residual ink on the surface is removed to obtain the rGO electrode. S2. The rGO electrode was subjected to high-temperature sintering. First, the temperature was increased to 200℃ at a rate of 1℃ / min and held for 10 min; then increased to 480℃ at a rate of 0.5℃ / min and held for 30 min; next, the temperature was increased to 550℃ at a rate of 1℃ / min and held for 30 min; finally, the temperature was increased to 900℃ at a rate of 10℃ / min. During the final heating process, the temperature was held for 60 min at 600℃, 700℃, and 800℃ before continuing the heating process, finally reaching 900℃ and holding for 60 min. The crystallinity, specific surface area, and exposure of catalytic active sites of the material were controlled. The OER catalytic performance of the sintered rGO electrode was as follows: Figure 1 As shown in (ac), due to the formation of a highly crystalline catalytic phase, the electron transport and active site exposure of the rGO electrode are enhanced, resulting in a significant improvement in catalytic activity; S3. The sintered rGO electrode was acid-washed with 98% concentrated sulfuric acid to remove impurities from the electrode surface. A 0.25M HCl solution was prepared as the base solution, and 50mM SnCl2 solution and 3mM PdCl2 solution were prepared respectively. The acid-washed rGO electrode was immersed in SnCl2 solution and PdCl2 solution in turn, then taken out, washed with water and air-dried. Then it was placed in a nickel plating aqueous solution (NiSO4·6H2O 0.15M, C6H5Na3O7·3H2O 0.08M, NH4Cl 0.4M, NaH2PO2·H2O 0.4M) for reaction to obtain an rGO electrode with a nickel plating layer on the surface. S4. Using an rGO electrode with a nickel plating layer as the working electrode, a Pt mesh as the counter electrode, and an Ag / AgCl electrode as the reference electrode, the three electrodes are arranged in a line, with the working electrode in the middle and the counter and reference electrodes at both ends, forming a three-electrode system. This system is placed in a mixed solution of Co(NO3)2 (3mM) and Fe(NO3)3 (3mM), and stirred at room temperature using a magnetic stirring hot stage (Aika). Electrodeposition is performed at -1.8V to load CoFe hydroxide onto the surface of the nickel plating layer. After electrodeposition, the working electrode is removed, washed with deionized water, and dried in a vacuum oven to obtain a high-performance OER electrode.

[0025] Example 3 This embodiment provides a high-performance electrocatalytic oxygen evolution reaction electrode, which is prepared by the following method: S1. Add monolayer graphene oxide powder (Suzhou Carbon-rich Graphene Technology Co., Ltd., monolayer, powder) to deionized water and ultrasonically disperse to obtain a uniformly dispersed graphene oxide suspension. Then, add photosensitive resin PEG(400)DA and photoinitiator TPO-L in sequence and mix thoroughly using a ball mill to prepare graphene oxide printing ink suitable for DLP photopolymerization 3D printing (monolayer graphene oxide powder: photosensitive resin: photoinitiator = 1:2:97). Graphene oxide printing ink is injected into the feed tank of a top-illuminated DLP photopolymerization 3D printer. The pre-designed 3D electrode model is imported into the printer control software, and printing is started. During printing, the forming tank rises to the focal length of the UV lamp, and the scraper drives the graphene oxide printing ink in the feed tank to spread evenly on the forming tank at a set speed. The UV lamp receives the image transmitted by DLP and exposes the corresponding pattern, causing the liquid printing ink to solidify. The printing is carried out layer by layer according to the set layer thickness until the electrode printing is completed. The printed electrode is removed from the printing platform, and the residual ink on the surface is removed to obtain the rGO electrode. S2. The rGO electrode was subjected to high-temperature sintering. First, the temperature was increased to 200℃ at a rate of 1℃ / min and held for 10 min; then increased to 480℃ at a rate of 0.5℃ / min and held for 30 min; next, the temperature was increased to 550℃ at a rate of 1℃ / min and held for 30 min; finally, the temperature was increased to 1000℃ at a rate of 10℃ / min. During the final heating process, the temperature was held for 60 min at each of the 600℃, 700℃, 800℃, and 900℃ levels before continuing the heating process, finally reaching 1000℃ and holding for 60 min at the same time. The crystallinity, specific surface area, and exposure of catalytic active sites of the material were controlled. The OER catalytic performance of the sintered rGO electrode was as follows: Figure 1 As shown in (ac), at 50 mA / cm 2 After 100 hours of operation, the overpotential increased by only 16mV, indicating stronger catalytic stability and relatively higher catalytic activity. S3. The sintered rGO electrode was acid-washed with 98% concentrated sulfuric acid to remove impurities from the electrode surface. A 0.25M HCl solution was prepared as the base solution, and 50mM SnCl2 solution and 3mM PdCl2 solution were prepared respectively. The acid-washed rGO electrode was immersed in SnCl2 solution and PdCl2 solution in turn, then taken out, washed with water and air-dried. Then it was placed in a nickel plating aqueous solution (NiSO4·6H2O 0.15M, C6H5Na3O7·3H2O 0.08M, NH4Cl 0.4M, NaH2PO2·H2O 0.4M) for reaction to obtain an rGO electrode with a nickel plating layer on the surface. S4. Using an rGO electrode with a nickel plating layer as the working electrode, a Pt mesh as the counter electrode, and an Ag / AgCl electrode as the reference electrode, the three electrodes are arranged in a line, with the working electrode in the middle and the counter and reference electrodes at both ends, forming a three-electrode system. This system is placed in a mixed solution of Co(NO3)2 (3mM) and Fe(NO3)3 (3mM), and stirred at room temperature using a magnetic stirring hot stage (Aika). Electrodeposition is performed at -1.8V to load CoFe hydroxide onto the surface of the nickel plating layer. After electrodeposition, the working electrode is removed, washed with deionized water, and dried in a vacuum oven to obtain a high-performance OER electrode.

[0026] Example 4 S1. Add monolayer graphene oxide powder (Suzhou Carbon-rich Graphene Technology Co., Ltd., monolayer, powder) to deionized water and ultrasonically disperse to obtain a uniformly dispersed graphene oxide suspension. Then, add photosensitive resin PEG(400)DA and photoinitiator TPO-L in sequence and mix thoroughly using a ball mill to prepare graphene oxide printing ink suitable for DLP photopolymerization 3D printing (monolayer graphene oxide powder: photosensitive resin: photoinitiator = 1:2:97). Graphene oxide printing ink is injected into the feed tank of a top-illuminated DLP photopolymerization 3D printer. The pre-designed 3D electrode model is imported into the printer control software, and printing is started. During printing, the forming tank rises to the focal length of the UV lamp, and the scraper drives the graphene oxide printing ink in the feed tank to spread evenly on the forming tank at a set speed. The UV lamp receives the image transmitted by DLP and exposes the corresponding pattern, causing the liquid printing ink to solidify. The printing is carried out layer by layer according to the set layer thickness until the electrode printing is completed. The printed electrode is removed from the printing platform, and the residual ink on the surface is removed to obtain the rGO electrode. S2. The rGO electrode was subjected to high-temperature sintering. First, the temperature was increased to 200℃ at a rate of 1℃ / min and held for 10 min; then increased to 480℃ at a rate of 0.5℃ / min and held for 30 min; next, the temperature was increased to 550℃ at a rate of 1℃ / min and held for 30 min; finally, the temperature was increased to 1100℃ at a rate of 10℃ / min. During the final heating process, the temperature was held for 60 min at each of the following stages: 600℃, 700℃, 800℃, 900℃, and 1000℃, before continuing the heating until reaching 1100℃, where it was held for another 60 min. The crystallinity, specific surface area, and exposure of catalytic active sites of the material were controlled. The OER catalytic performance of the sintered rGO electrode was as follows: Figure 1 As shown in (ac), the current density is further increased, but excessively high sintering temperature will cause the pore structure of the rGO electrode to collapse or the specific surface area to decrease, affecting the catalytic stability. S3. The sintered rGO electrode was acid-washed with 98% concentrated sulfuric acid to remove impurities from the electrode surface. A 0.25M HCl solution was prepared as the base solution, and 50mM SnCl2 solution and 3mM PdCl2 solution were prepared respectively. The acid-washed rGO electrode was immersed in SnCl2 solution and PdCl2 solution in turn, then taken out, washed with water and air-dried. Then it was placed in a nickel plating aqueous solution (NiSO4·6H2O 0.15M, C6H5Na3O7·3H2O 0.08M, NH4Cl 0.4M, NaH2PO2·H2O 0.4M) for reaction to obtain an rGO electrode with a nickel plating layer on the surface. S4. Using an rGO electrode with a nickel plating layer as the working electrode, a Pt mesh as the counter electrode, and an Ag / AgCl electrode as the reference electrode, the three electrodes are arranged in a line, with the working electrode in the middle and the counter and reference electrodes at both ends, forming a three-electrode system. This system is placed in a mixed solution of Co(NO3)2 (3mM) and Fe(NO3)3 (3mM), and stirred at room temperature using a magnetic stirring hot stage (Aika). Electrodeposition is performed at -1.8V to load CoFe hydroxide onto the surface of the nickel plating layer. After electrodeposition, the working electrode is removed, washed with deionized water, and dried in a vacuum oven to obtain a high-performance OER electrode.

[0027] Comparative Example 1 This comparative example provides an electrocatalytic oxygen evolution reaction electrode, which is prepared by the following method: S1. Add monolayer graphene oxide powder (Suzhou Carbon-rich Graphene Technology Co., Ltd., monolayer, powder) to deionized water and ultrasonically disperse to obtain a uniformly dispersed graphene oxide suspension. Then, add photosensitive resin PEG(400)DA and photoinitiator TPO-L in sequence and mix thoroughly using a ball mill to prepare graphene oxide printing ink suitable for DLP photopolymerization 3D printing (monolayer graphene oxide powder: photosensitive resin: photoinitiator = 1:2:97). Graphene oxide printing ink is injected into the feed tank of a top-illuminated DLP photopolymerization 3D printer. The pre-designed 3D electrode model is imported into the printer control software, and printing is started. During printing, the forming tank rises to the focal length of the UV lamp, and the scraper drives the graphene oxide printing ink in the feed tank to spread evenly on the forming tank at a set speed. The UV lamp receives the image transmitted by DLP and exposes the corresponding pattern, causing the liquid printing ink to solidify. The printing is carried out layer by layer according to the set layer thickness until the electrode printing is completed. The printed electrode is removed from the printing platform, and the residual ink on the surface is removed to obtain the rGO electrode. S2. The rGO electrode was subjected to high-temperature sintering. First, the temperature was increased to 200℃ at 1℃ / min and held for 10 min; then increased to 480℃ at 0.5℃ / min and held for 30 min; then increased to 550℃ at 1℃ / min and held for 30 min; finally, the temperature was increased to 1000℃ at 10℃ / min. During the final heating process, when the temperature reached 600℃, 700℃, 800℃ and 900℃, it was held for 60 min before continuing to heat up. Finally, when the temperature reached 1000℃, it was held for 60 min. The crystallinity, specific surface area and exposure of catalytic active sites of the material were controlled to obtain the OER electrode.

[0028] The OER electrode in this comparative example only underwent sintering treatment and did not undergo chemical nickel plating and electrodeposition steps. The overpotential of the OER electrode in this comparative example is much higher than 500mV, while the high-performance OER electrode in Example 3 has an overpotential of only 340mV. The high-performance OER electrode in Example 3 has a higher catalytic efficiency than that in Comparative Example 1 and a smaller Tafel slope, indicating that it has a higher electron transfer efficiency.

[0029] Test case The test objects for the following test items are electrodes from different preparation stages in Example 3.

[0030] (1) Macroscopic and optical microscopic morphology of rGO electrode Figure 2 (a, d) show the overall size changes of the rGO electrode before and after sintering. It can be seen that the size of the rGO electrode shrinks significantly after sintering, mainly due to solvent evaporation and densification of the graphene sheets. Figure 2 (b, c) Further magnification reveals the dimensional changes of the rGO electrode mesh structure. The diameter of the holes is marked in red. It can be seen that the mesh pore size is significantly reduced after sintering, and the edges tend to be rounded, indicating that the sintering process has a significant impact on the morphology of the electrode. Figure 2 (e) and (f) are optical microscope images of the rGO electrode at X5 and X20 magnification, respectively, which more clearly show the microstructural features of the electrode. It can be observed that the surface of the mesh skeleton is uniform and the overall structure maintains good integrity, which is crucial for subsequent electrocatalytic performance.

[0031] (2) The morphology of electrode materials at different preparation stages was observed using a scanning electron microscope. Figure 3 (a) The overall surface morphology of the sintered rGO electrode is shown, which shows that the graphene framework has a uniform mesh structure and obvious irregular wrinkles and layered features on the surface. This is the typical morphology of reduced graphene oxide (rGO), proving that the graphene oxide was effectively reduced during the sintering process. Figure 3 (b) is Figure 3 (a) The magnified image shows the microstructure of the graphene framework more clearly. The surface wrinkles and layered structure of the framework are significant, which increases the specific surface area of ​​the electrode and provides more adhesion sites for subsequent nickel plating and CoFe-LDH deposition. Figure 3 (c) shows a cross-sectional SEM image of the sintered rGO electrode, which clearly shows the layered structure formed by the 3D printing process. Each layer has significant wrinkle features in the cross section, further confirming the reduction of graphene oxide and the formation of a porous structure. Figure 3 (d) is a high-resolution SEM image of the rGO electrode surface, showing that the graphene sheets overlap to form a rich porous structure. This interconnected and wrinkled porous structure effectively improves the specific surface area and stability of the electrode, providing an ideal carrier for subsequent functionalization modification. Figure 3 (e) shows the morphology of the rGO electrode surface after electroless nickel plating. It can be observed that many fine particulate materials are uniformly distributed on the graphene sheet surface. The average size of these particles is about 500 nanometers. Combined with EDS energy dispersive spectroscopy analysis, it can be confirmed that these particles are deposited nickel metal. These uniformly distributed nickel particles provide a good foundation for the subsequent uniform deposition of CoFe-LDH. Figure 3 (f) is a SEM image of the cross section of the rGO electrode with a nickel coating. It can be observed that nickel particles are uniformly covered on the surface of the graphene layer, forming a relatively dense coating with a thickness of about 2.62 micrometers. This shows that the chemical plating method can effectively deposit a uniform nickel layer on the porous graphene framework. Figure 3 (g) shows the interfacial connection between the rGO electrode substrate and the nickel plating. It can be seen that the nickel layer and the graphene layer are closely bonded and connected, with no obvious delamination or peeling. This indicates that the nickel plating and the rGO electrode substrate have good adhesion, which provides a guarantee for subsequent electrochemical stability. Figure 3 (h) shows the morphology of CoFe-LDH after electrodeposition on the surface of an rGO electrode (rGO / Ni) with a nickel coating. It can be observed that many flower-like or plate-like nanostructures grow on the surface covered by nickel particles, which are typical morphological features of CoFe-LDH. Figure 3(i) The image at a higher magnification shows more clearly that the flower-like CoFe-LDH is assembled from many nanosheets that are interwoven to form a porous structure, which helps to increase the contact area between the electrode and the solution, making the reaction more complete; like Figure 3 As shown in (j), the distribution of Fe (red), Co (green) and Ni (blue) elements on the electrode surface can be clearly observed through SEM-EDS elemental spectrum analysis. The results show that Fe and Co elements are highly overlapping with Ni elements in space, indicating that CoFe-LDH is successfully and uniformly attached to the nickel plating surface, forming an rGO / Ni / CoFe-LDH composite structure.

[0032] (3) Thermogravimetric analysis (TGA) Thermogravimetric analysis (TGA) of the electrode materials was performed using a thermogravimetric analyzer (TG4000, nitrogen atmosphere, heating rate 5℃ / min). Figure 4 As shown in (a), the TGA curves indicate that the electrode quality decreases in stages before 600℃, which is attributed to the thermal evaporation or thermal decomposition of adsorbed moisture and residual polymers (such as photosensitive resin) on the surface of graphene oxide, which is beneficial to electrocatalysis. After 600℃, the quality tends to stabilize, indicating that the organic components have been completely removed and the electrode material is mainly composed of reduced graphene oxide (rGO). This process not only verifies the rationality of the sintering temperature, but also provides an important reference for subsequent electrode performance optimization.

[0033] (4) Electron paramagnetic resonance (EPR) like Figure 4 As shown in (b), the EPR results indicate that oxygen vacancies exist in the electrode in the range of 600 to 1000 °C, decrease sharply in the range of 600 to 700 °C, and then gradually recover.

[0034] (5) Raman spectroscopy The experiment used green laser rays as the light source to perform Raman spectroscopy characterization on the electrode material to analyze its carbon defect degree and surface characteristics. The gradual easing of this phenomenon after 700℃ was considered to indicate defect repair, followed by partial deoxygenation and reduction of the graphene oxide. Figure 4 As shown in (c), the Raman spectrum shows the D and G peaks of rGO, and the ID / IG ratio increases with increasing temperature, indicating that the graphene defects are being gradually repaired.

[0035] (6) X-ray photoelectron spectroscopy (XPS) The chemical composition of the electrode surface was analyzed using an Escalab Xi+ type photoelectron spectrometer (monochromatic Al Kα rays, energy 1486.6 eV). XPS full spectrum revealed the main elemental composition of the electrode surface, including C, O, Ni, Co, and Fe. Fine spectral analysis of C 1s and O 1s further indicated that the electrode surface contains abundant oxygen-containing functional groups (such as -COO-), which provides active sites for subsequent wet chemical deposition. In addition, high-resolution spectra of Ni 2p and Co 2p confirmed the chemical states of nickel and cobalt, respectively, indicating that they were successfully loaded onto the electrode surface. The experiment used X-ray photoelectron spectroscopy (XPS) to analyze the chemical composition of the electrode surface. For example... Figure 4 As shown in (df), the sintered rGO electrode underwent acid washing to improve its surface chemical properties. A comparison of the high-resolution XPS spectra before and after acid washing is presented. Figure 4 The C 1s spectrum in (e) shows that CC sp 3 The proportion of hybrid carbon increased from 71.81% to 73.23%; meanwhile, Figure 4 The O 1s spectrum in (f) shows a shift of 0.4 eV in the binding energy of the CO bond peak, while the peak area ratio representing the C=O bond significantly decreased from 27.19%. These changes indicate that the pickling process effectively adjusted the distribution of oxygen-containing functional groups on the electrode surface, enriching it with active sites conducive to subsequent wet chemical deposition, and significantly improving the hydrophilicity of the electrode surface, thus providing a good foundation for the uniform loading of the subsequent metal coating.

[0036] (7) X-ray diffraction (XRD) Figure 4 (g) shows the XRD patterns of the rGO electrode with nickel coating before (rGO / Ni) and after (rGO / Ni-100h) stability test. By comparing the XRD patterns of rGO / Ni and rGO / Ni-100h, it was found that the position, intensity and full width at half maximum of the diffraction peaks did not change significantly, indicating that the nickel coating still maintained a good crystal structure and phase after 100 hours of testing, and has good structural stability. Figure 4 (h) shows the XRD pattern of the high-performance OER electrode (rGO / Ni / CoFeOH) after CoFe hydroxide deposition, and... Figure 4 By comparing the rGO / Ni spectra of (g), it can be clearly seen that the characteristic diffraction peaks of CoFe hydroxide are newly added, which further verifies the successful loading of CoFe hydroxide.

[0037] (8) Electrochemical testing Electrochemical tests were performed on a CHI760E electrochemical workstation (Shanghai Chenhua). 1M KOH was used as the electrolyte, and a 6.5*5.5 mm dense mesh (high-performance OER electrode) was used as the working electrode. A three-electrode system was used with a Pt mesh and Hg / HgO as the counter and reference electrodes, respectively. The OER catalytic performance was studied using linear sweep voltammetry (LSV), and the overpotential η was obtained. The LSV test results and Tafel slope were adjusted with 85% iR compensation, and the double-layer capacitance (C0) was also calculated. dl The active surface area (ECSA) was obtained using cyclic voltammetry (CV) at different scan rates (20-120 mV / s) in the non-Radial region of 1 M KOH (-0.1~0 V vs. Hg / HgO) and calculated.

[0038] For OER, due to the potential E of the reversible hydrogen electrode RHE，Reversible Hydrogen Electrode = 0V, Nernst potential E in the electrochemical system vs. RHE The relationship needs to be calibrated (as shown in Equation 1-1 below), and the potential E of the reversible oxygen electrode ROE，Reversible Oxygen Electrode =1.23V, corresponding to the overpotential calculation (as shown in Equation 1-2 below). The calculated Tafel slope (as shown in Equation 1-3 below, where R is the ideal gas constant, T is the Kelvin temperature, F is the Faraday constant, and n is the number of transferred electrons) represents the magnitude of the electron transport capability. Finally, the active surface area is calculated using the double-layer capacitance (as shown in Equation 1-4 below) (C s The series capacitance introduced by the solution corresponds to a parameter of 60 μF / cm for 1M KOH. 2 ); (1-1); (1-2); (1-3); (1-4).

[0039] Therefore, if the electrode still has a large current density and a relatively vigorous Faraday reaction occurs under a low overpotential, it indicates that the catalytic ability of OER is excellent. According to the definition of Tafel slope, the smaller the value, the higher the electron transfer ability.

[0040] Linear sweep voltammetry (LSV): such as Figure 5 As shown in (a), the LSV curves indicate that the OER catalytic performance of the electrode is significantly improved after modification by electroless nickel plating and CoFe hydroxide deposition. The rGO / Ni / CoFe-LDH electrode exhibits the lowest overpotential and the highest current density.

[0041] Tafel curve: as shown Figure 5As shown in (b), Tafel slope analysis indicates that the rGO / Ni / CoFe-LDH electrode has the lowest Tafel slope, indicating that it has the fastest OER kinetics.

[0042] Electrochemical impedance spectroscopy (EIS): such as Figure 5 As shown in (c), the EIS results show that the modified electrode (rGO / Ni / CoFe-LDH) has a smaller charge transfer resistance, indicating that its charge transport performance is significantly improved.

[0043] Stability testing: such as Figure 5 As shown in (f), the rGO / Ni / CoFe-LDH electrode is subjected to a current of 10 mA / cm. 2 50mA / cm 2 100mA / cm 2 A continuous 30-hour test was conducted at different current densities, and the rGO / Ni / CoFe-LDH electrode showed good stability at all current densities.

[0044] To further verify the synergistic catalytic effect between Co and Fe, electrodes loaded only with Co(OH)₂ and Fe(OH)₃ were prepared as control groups in this test example. Figure 5 As shown in (d), at 10, 50, and 100 mA / cm 2 At different current densities, the CoFe hydroxide-loaded electrode (high-performance OER electrode rGO / Ni / CoFeOH) showed much lower overpotentials than the two control group electrodes, proving that the combination of Co and Fe can effectively enhance the OER catalytic activity.

[0045] like Figure 5 As shown in (e), at 50 mA / cm 2 At a current density of 289 mV, the overpotential required for the high-performance OER electrode is significantly higher than that of various transition metal-based OER catalysts in the prior art, demonstrating its excellent catalytic performance.

[0046] To standardize the comparison of the intrinsic activity of the catalysts, the electrochemical active surface area (ECSA) and specific activity of the electrode were calculated. First, through... Figure 5 (g) LSV scans in the voltage range of -0.4 to 1.0 V were used to determine the non-Radida reaction region (-0.1 to 0 V vs. Hg / HgO). Subsequently, cyclic voltammetry (CV) tests were performed within this range at different scan rates to obtain... Figure 5 (h), whose linear fit slope is proportional to the double-layer capacitance (Cdl), can be used to calculate ECSA. The final specific activity curve is as follows: Figure 5As shown in (i), after ECSA normalization, the rGO / Ni / CoFeOH electrode exhibits the highest intrinsic catalytic activity, further confirming its efficient oxygen evolution performance.

[0047] Although the description of the invention has been given in conjunction with the specific embodiments described above, it will be apparent to those skilled in the art that many substitutions, modifications, and variations can be made based on the foregoing. Therefore, all such substitutions, modifications, and variations are included within the spirit and scope of the appended claims.

Claims

1. A method for preparing a high-performance electrocatalytic oxygen evolution reaction electrode, characterized in that, The method comprises the following steps: S1, adding single-layer graphene oxide powder into deionized water, mixing, then adding photosensitive resin and photoinitiator in sequence to prepare graphene oxide printing ink, injecting the graphene oxide printing ink into a DLP photocuring 3D printer, and obtaining reduced graphene oxide electrode through 3D printing; S2, high-temperature sintering the reduced graphene oxide electrode; S3, acid washing the sintered reduced graphene oxide electrode, then chemical nickel plating to obtain a reduced graphene oxide electrode with a nickel plating layer on the surface; S4, using the reduced graphene oxide electrode with the nickel plating layer as a working electrode, using a Pt electrode as a counter electrode, and using an Ag / AgCl electrode as a reference electrode, forming a three-electrode system and placing it in a mixed solution of Co(NO3)2 and Fe(NO3)3 for electrodeposition, so that the surface of the nickel plating layer is loaded with CoFe hydroxide, and then taking out the working electrode after electrodeposition, washing and drying to obtain a high-performance electrocatalytic oxygen evolution reaction electrode.

2. The method for preparing the high-performance electrocatalytic oxygen evolution reaction electrode according to claim 1, characterized in that, The specific steps of the chemical nickel plating are as follows: immersing the acid-washed reduced graphene oxide electrode into SnCl2 solution and PdCl2 solution in sequence, then taking it out for water washing, air drying, and then placing it in a nickel plating aqueous solution for reaction.

3. The method of claim 2, wherein the method further comprises the step of: The concentration of the SnCl2 solution is 40-60 mM, and the concentration of the PdCl2 solution is 2-5 mM. The nickel plating aqueous solution comprises the following components: NiSO4·6H2O 0.1-0.2 M, C6H5Na3O7·3H2O 0.05-0.1 M, NH4Cl 0.3-0.5 M, and NaH2PO2·H2O 0.3-0.5 M.

4. The method of claim 1, wherein the high performance electrocatalytic oxygen evolution reaction electrode is prepared by the steps of: The acid washing uses concentrated sulfuric acid with a concentration of 98%.

5. The method for preparing the high-performance electrocatalytic oxygen evolution reaction electrode according to claim 1, characterized in that, In the mixed solution of Co(NO3)2 and Fe(NO3)3, the concentration of Co(NO3)2 is 2-5 mM, and the concentration of Fe(NO3)3 is 2-5 mM.

6. The method of claim 1, wherein the high performance electrocatalytic oxygen evolution reaction electrode is prepared by the steps of: The voltage condition of the electrodeposition is -1.8±0.09 V.

7. The method for preparing the high-performance electrocatalytic oxygen evolution reaction electrode according to claim 1, characterized in that, The temperature rising process of the high-temperature sintering adopts gradient rising, specifically comprising the following steps: firstly rising at 0.5-1 ℃ / min to 180-220 ℃, keeping for 5-15 min; then rising at 0.5-1 ℃ / min to 460-500 ℃, keeping for 25-35 min; then rising at 0.5-1 ℃ / min to 530-570 ℃, keeping for 25-35 min; finally rising at 8-12 ℃ / min to 600-1100 ℃, keeping for 55-65 min.

8. The method of claim 7, wherein the method further comprises the step of: During the process of rising at 8-12 ℃ / min to 600-1100 ℃, the temperature is kept for 55-65 min every time when it reaches an integer multiple of 100 ℃, and then the temperature continues to rise.

9. The method for preparing the high-performance electrocatalytic oxygen evolution reaction electrode according to claim 1, characterized in that, In the graphene oxide printing ink, the mass ratio of single-layer graphene oxide powder, photosensitive resin and photoinitiator is 1:(2-3):(90-100).

10. A high performance electrocatalytic oxygen evolution reaction electrode, characterized in that, The high-performance electrocatalytic oxygen evolution reaction electrode is prepared by the method of any one of claims 1-9.

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