In-situ construction of six-element high-entropy alloy mesoporous films based on one-step electrodeposition and its application

Abstract

This invention relates to the field of electrocatalyst preparation technology, specifically to the in-situ construction of hexa-membered high-entropy alloy mesoporous membrane electrocatalysts based on a one-step electrodeposition method and their applications. This invention utilizes a soft-template-assisted one-step electrodeposition method under mild conditions to prepare high-entropy alloy mesoporous membrane electrocatalysts with high specific surface area and multiple exposed active sites. This solves the problems of existing electrodeposition methods, which can only prepare flat films or particulate catalysts, and the resulting electrocatalysts have small specific surface areas, low metal utilization, and few exposed active sites. This invention reduces the amount of precious metals used and further improves catalyst performance by controlling the electronic structure distribution of the catalyst and introducing multiple active sites, possessing significant potential for widespread application.

Description

Technical Field

[0001] This invention relates to the field of electrocatalyst preparation technology, specifically to the in-situ construction of hexa-element high-entropy alloy mesoporous membranes based on a one-step electrodeposition method and their applications. Background Technology

[0002] With global population growth and technological advancements, non-renewable energy sources such as fossil fuels will gradually be phased out of modern society. Hydrogen (H2), as a crucial component of renewable and clean energy, is an ideal alternative to fossil fuels, potentially alleviating the global energy crisis and contributing to global carbon neutrality. Utilizing renewable energy sources like wind and solar power to power electrochemical whole water splitting (OWS) to achieve high-purity H2 production with oxygen (O2) as the only byproduct is an ideal green hydrogen production method. This method combines two half-pool reactions—cathode hydrogen evolution reaction (HER) and anodic oxygen evolution reaction (OER)—to achieve the conversion of water into H2 and O2 at a theoretical potential of 1.23V (vs. RHE). However, in actual production, the slow kinetics of OER require higher energy consumption and expensive precious metal catalysts to overcome the reaction energy barrier. Furthermore, the produced O2 is not only of low value but also poses a potential safety hazard of mixing with H2 and exploding, significantly reducing the economic efficiency of traditional OWS H2 production. To address this issue, researchers developed an innovative method that replaces the OER with alternative anodic reactions coupled with HER, thereby simultaneously solving the problems of high energy consumption and low-value products, and greatly improving the economic efficiency of the production process.

[0003] In recent years, nucleophilic electro-oxidation (NOR) has attracted widespread attention from researchers due to its ability to effectively replace OER in H2 production. 5-Hydroxymethylfurfural (HMF), containing both aldehyde and hydroxyl groups, is a typical nucleophile. Furthermore, it is a biomass-derived molecule, widely available and relatively inexpensive. Its oxidation products, such as 5-hydroxymethyl-2-furanic acid (HMFCA), 2,5-dicarboxyfuran (DFF), 2-formyl-5-furanic acid (FFCA), and 2,5-furandicarboxylic acid (FDCA), are high-value products that can be used to synthesize polymers and other chemicals. Therefore, coupling HMF oxidation (HMFOR) with HER is a potentially industrially valuable H2 production method. Consequently, highly efficient electrocatalysts related to HMFOR have also received considerable attention, with nickel (Ni)-based materials exhibiting the best performance. Researchers have mainly classified the mechanisms of Ni-based catalysts catalyzing HMFOR into two categories: one involving Ni(III) lattice oxygen Ni in the catalyst. 3+(OH)O serves as the main active site, utilizing the electrophilic lattice oxygen obtained from the electro-oxidation and deprotonation of hydroxyl groups in the catalyst's own structure to capture the aldehyde group and hydrogen atom in the hydroxyl group of the HMF molecule, thereby oxidizing it to FDCA; another type is hydroxyl oxygen adsorbed on Ni(III) Ni 3+ O(OH) ads As a medium for capturing hydrogen atoms in HMF molecules, it oxidizes them to FDCA. The former requires the catalyst itself to have protons that can be oxidized and removed, while the latter requires the Ni element in the catalyst to reasonably balance the HMF molecules and hydroxide ions (OH-). - The competitive adsorption relationship between Ni(OH)₂ and NiO was investigated, with Ni(OH)₂ and NiO serving as model catalysts, respectively. Catalysts using electrophilic lattice oxygen as a proton-capturing medium have been extensively studied, while catalysts adsorbing electrophilic oxygen as a proton-capturing medium require further development.

[0004] Alloying is a commonly used method to control OH groups. - The adsorption process mainly involves adjusting the electronic structure of the catalyst surface to regulate the OH groups. - The strength of adsorption increases with the number of metal elements involved in the alloy, and the configurational entropy of the alloy also increases accordingly. Therefore, alloys can be classified into low-entropy alloys, medium-entropy alloys, and high-entropy alloys (HEAs). HEAs, due to their composition of five or more elements, possess a rich variety of surface sites when used as electrocatalysts. For tandem reactions with multiple intermediates, they can effectively selectively adsorb reactants and intermediates, achieving synergistic effects at multiple sites, thus exhibiting catalytic activity and selectivity that are difficult to achieve with conventional catalysts. By controlling the types and amounts of components in high-entropy alloys, it is possible to achieve the desired adsorption of surface adsorbed species such as OH-. - The adsorption energy of HMF and other compounds can be modulated to balance the competitive adsorption relationship between them, thereby improving catalytic activity and active site utilization. However, traditional high-entropy alloy electrocatalysts typically utilize high temperatures to overcome the enthalpy effect, requiring conditions much higher than room temperature to achieve uniform mixing of elements and rapid cooling to preserve the phase structure. This usually involves complex heating and cooling control processes and consumes a large amount of energy. Electrodeposition can achieve rapid synthesis of high-entropy alloys at room temperature, significantly reducing preparation costs. Furthermore, the composition and morphology of high-entropy alloys can be controlled by adjusting the electrode potential, making it an ideal method for preparing high-entropy alloys. Conventional electrodeposition methods typically only produce flat high-entropy alloy films with relatively small specific surface areas and limited exposed active sites, resulting in the waste of active elements encapsulated within.

[0005] Based on this, the present invention employs a soft template-assisted one-step electrodeposition technique to transform a flat high-entropy alloy film into a morphology rich in uniform and ordered mesopores of 8-15 nm, thereby preparing a hexa-element high-entropy alloy mesoporous membrane electrocatalyst. The aim is to increase its specific surface area, improve metal utilization, and further enhance the catalytic activity of the prepared catalyst. Summary of the Invention

[0006] The purpose of this invention is to provide a hexa-element high-entropy alloy mesoporous membrane electrocatalyst, its preparation method, and its application.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows: The preparation method of the hexa-element high-entropy alloy mesoporous membrane electrocatalyst of the present invention includes the following steps: S1, Apply template agent PEO 10500 -b-PMMA 18000 The sample was ultrasonically dissolved in THF, and anhydrous ethanol, deionized water, and HCl solution were added to form a micelle solution. RuCl3, K3RhCl6, CuSO4, CoCl2, and LaCl3 solutions were added dropwise to the micelle solution to obtain a metal precursor solution. The molar ratio of RuCl3, K3RhCl6, CuSO4, CoCl2, and LaCl3 was 1~6:1~4:1~6:1:1. S2. Soak and wash the nickel foam, and fix it on the platinum electrode clip as the working electrode; S3. Platinum wire and Ag / AgCl in 3MKCl were used as the counter electrode and reference electrode, respectively. The metal precursor solution prepared in S1 was used as the electrolyte. Electrodeposition was carried out at room temperature in a three-electrode system with a deposition potential of -0.5V to -3.0V and a deposition time of 1200 to 4000s. S4. After deposition, immerse the working electrode in THF and store it at room temperature for 6-24 hours to remove micelles. Then, thoroughly clean it with deionized water and ethanol to obtain the final product.

[0008] Preferably, in the preparation method of the hexa-element high-entropy alloy mesoporous membrane electrocatalyst of the present invention, the molar ratio of RuCl3, K3RhCl6, CuSO4, CoCl2 and LaCl3 in step S1 is 6:1:1:1:1.

[0009] In a further preferred embodiment, in the preparation method of the hexa-element high-entropy alloy mesoporous membrane electrocatalyst of the present invention, step S1 specifically comprises: weighing 4.5 mg of template agent PEO. 10500 -b-PMMA 18000The solution was ultrasonically dissolved in 0.6 mL of THF, and then 0.5 mL of anhydrous ethanol, 2.35 mL of deionized water and 0.053 mL of 3M HCl were added to form a micelle solution. Then, 0.3 mL of RuCl3, 0.05 mL of K3RhCl6, 0.05 mL of CuSO4, 0.05 mL of CoCl2 and 0.05 mL of LaCl3 (all with a concentration of 40 mM) were added dropwise to the prepared micelle solution to obtain the metal precursor solution.

[0010] Preferably, in the preparation method of the hexa-element high-entropy alloy mesoporous membrane electrocatalyst of the present invention, step S2 specifically involves: soaking nickel foam in 3M HCl for 20 minutes, then washing it three times alternately with water and ethanol, and then fixing it on a platinum electrode holder as a working electrode.

[0011] Preferably, in the preparation method of the hexa-element high-entropy alloy mesoporous membrane electrocatalyst of the present invention, in step S2: the area of ​​the nickel foam is 1cm × 1.5cm; the deposition area of ​​the nickel foam exposed after being fixed to the platinum electrode clamp is 1cm × 1cm.

[0012] Preferably, in the preparation method of the hexa-element high-entropy alloy mesoporous membrane electrocatalyst of the present invention, in step S3: the room temperature is 24°C; the deposition potential is -2.0V to -3.0V; and the deposition time is 4000s.

[0013] In a further preferred embodiment, in the preparation method of the hexa-element high-entropy alloy mesoporous membrane electrocatalyst of the present invention, the deposition potential in step S3 is -2.5V.

[0014] Preferably, in the preparation method of the hexa-component high-entropy alloy mesoporous membrane electrocatalyst of the present invention, step S4 specifically involves: after deposition, immersing the working electrode in THF, storing it at room temperature for 24 hours to remove micelles, and then rinsing it three times alternately with deionized water and ethanol to obtain the hexa-component high-entropy alloy mesoporous membrane electrocatalyst.

[0015] The hexa-element high-entropy alloy mesoporous membrane electrocatalyst of the present invention was prepared by the above method.

[0016] The application of the hexa-component high-entropy alloy mesoporous membrane electrocatalyst described in this invention in the electrocatalytic oxidation of 5-hydroxymethylfurfural.

[0017] The beneficial effects of this invention are: This invention employs a soft-template-assisted one-step electrodeposition method to prepare a hexa-membered high-entropy alloy mesoporous membrane electrocatalyst with high specific surface area and multiple exposed active sites. By controlling the electronic structure distribution of the catalyst and introducing multiple active sites, this invention further enhances catalyst performance. The hexa-membered high-entropy alloy mesoporous membrane electrocatalyst prepared by this invention significantly improves the reaction efficiency in the electrocatalytic oxidation of HMF. Furthermore, the preparation method of this electrocatalyst requires mild conditions, reduces the amount of precious metals used, and ensures uniform metal deposition without segregation during the preparation process. It also boasts advantages such as simple operation and environmental friendliness. This invention solves the problems of existing electrodeposition methods, which can only prepare flat films or particulate catalysts, and the resulting electrocatalysts have small specific surface areas, low metal utilization, and few exposed active sites, thus possessing significant potential for widespread application. Attached Figure Description

[0018] Figure 1 XRD patterns of m-HEA / NF, HEA / NF, and m-RhNi / NF; Figure 2 Electron micrographs of m-HEA / NF and their corresponding elemental mappings (in the figures: a is low-magnification SEM, b is high-magnification SEM, c is TEM, d is HRTEM, and e is HAADF-STEM). Figure 3 Electron micrographs of HEA / NF and their corresponding elemental mappings (in the figures: a is low-magnification SEM, b is high-magnification SEM, c is TEM, d is HRTEM, e is HAADF-STEM). Figure 4 Electron microscopy images of m-RhNi / NF and their corresponding elemental mappings (in the figures: a is low-magnification SEM, b is high-magnification SEM, c is TEM, d is HRTEM, and e is HAADF-STEM). Figure 5 XPS high-resolution images of the elemental orbitals m-HEA / NF, HEA / NF, and m-RhNi / NF (in the image: a is Rh3d orbital, b is Ru3p orbital, c is Cu2p orbital, d is Co2p orbital, e is La3d orbital, and f is Ni2p orbital). Figure 6 The morphology of m-HEA / NF under different deposition voltages (vs. Ag / AgCl) is shown in the figure (a is -0.5V, b is -1.0V, c is -1.5V, d is -2.0V, e is -2.5V, f is -3.0V). Figure 7The morphology of m-HEA / NF under different metal precursor ratios is shown in the figure (Ru:Rh:Cu:Co:La=a is 3:4:1:1:1, b is 4:3:1:1:1, c is 5:2:1:1:1, d is 3:1:4:1:1, e is 2:1:5:1:1, f is 1:1:6:1:1). Figure 8 The morphology of m-HEA prepared on different supports (in the figure: a and b are supported by titanium foam, and c and d are supported by carbon cloth). Figure 9 Mesoporous high-entropy alloy films prepared by constant potential deposition for 1200 s on NF with different metal combinations are shown in the figure (a: Ru:Co:Ni:Cu:Mn=1:1:1:1:1, -0.5V; b: Ru:Co:Ni:Cu:Zn=1:1:1:1:1, -0.45V; c: Ru:Co:Ni:Fe:Cr=1:1:1:1:1, -0.55V; d: Ru:Co:Ni:Cu:Fe=1:1:1:1:1, -0.45V). ; e is Ru:Co:Ni:Cu:Cr=1:1:1:1:1, -0.45V; f is Ru:Co:Ni:Fe:Mn=1:1:1:1:1, -0.55V; g is Ru:Co:Ni:Cr:M n=1:1:1:1:1, -0.6V; h is Ru:Co:Ni:Mn:Zn=1:1:1:1:1, -0.6V; i is Ru:Co:Ni:Fe:Cr=1:1:1:1:1, -0.6V); Figure 10 Mesoporous alloy films prepared using PS-b-PEO for different metal combinations are shown in the figure (a: Ru:Rh:Pt:Pd:Cu=1:1:1:1:1, -0.2V, 1200s, carbon cloth as support; b: Ru:Rh:Cu=6:1:1, -2.5V, 4000s, nickel foam as support; c: Ru:Rh:Cu:Co:La:Pt:Pd=6:1:1:1:1:1:1, -2.5V). d = Ru:Rh:Cu:Sb:Mo = 6:1:1:1:1, -2.5V, 4000s, nickel foam support; e = Ru:Rh:Cu:Sb:Te = 6:1:1:1:1, -2.5V, 4000s, nickel foam support; f = Ru:Rh:Cu:Sn:In = 6:1:1:1:1, -2.5V, 4000s, nickel foam support. Figure 11The performance test results for m-HEA / NF are shown in the figure (a is a comparison of OER and HMFORLSV of m-HEA / NF; b is a comparison of HMFORLSV curves of m-HEA / NF with HEA / NF, m-RhNi / NF and NF; c is a Tafel slope plot; d is the C of m-HEA / NF, HEA / NF and m-RhNi / NF). dl The fitting values ​​are compared; d is the electrochemical impedance comparison between m-HEA / NF and HEA / NF, m-RhNi / NF and NF; f is the open circuit potential test result; g is the cycle stability test result of m-HEA / NF). Detailed Implementation

[0019] The technical solution of the present invention will be described in detail below with reference to specific embodiments. The following embodiments are for explanation and illustration only, and do not constitute a limitation on the technical solution of the present invention. Example 1

[0020] The preparation method of a hexa-membered high-entropy alloy mesoporous membrane electrocatalyst is as follows: Weigh 4.5 mg of the template agent PEO 10500 -b-PMMA 18000 The nickel foam was ultrasonically dissolved in 0.6 mL THF, and then 0.5 mL anhydrous ethanol, 2.35 mL deionized water, and 0.053 mL 3 M HCl were added to form a micelle solution. Then, 0.3 mL RuCl3, 0.05 mL K3RhCl6, 0.05 mL CuSO4, 0.05 mL CoCl2, and 0.05 mL LaCl3 solutions (all at 40 mM) were added dropwise to the prepared micelle solution to obtain a metal precursor solution. The nickel foam (1 cm × 1.5 cm) was first soaked in 3 M HCl for 20 min, then rinsed three times alternately with water and ethanol, and then fixed on a platinum electrode holder (the exposed deposition area of ​​the nickel foam was 1 cm × 1 cm) as the working electrode. Platinum wire and Ag / AgCl (3 M KCl) were used as the counter and reference electrodes, respectively, with the metal precursor solution as the electrolyte. Electrodeposition was performed at room temperature in a three-electrode system with a deposition potential of -2.5 V and a deposition time of 4000 seconds. After deposition, the working electrode was immersed in THF and stored at room temperature for 24 h to remove micelles. Then, it was rinsed three times alternately with deionized water and ethanol to obtain a hexa-membered high-entropy alloy mesoporous membrane electrocatalyst. Example 2

[0021] The preparation method of a hexa-membered high-entropy alloy mesoporous membrane electrocatalyst is as follows: Weigh 4.5 mg of the template agent PEO 10500 -b-PMMA 18000The nickel foam was ultrasonically dissolved in 0.6 mL THF, and then 0.5 mL anhydrous ethanol, 2.35 mL deionized water, and 0.053 mL 3 M HCl were added to form a micelle solution. Then, 0.1 mL RuCl3, 0.1 mL K3RhCl6, 0.1 mL CuSO4, 0.1 mL CoCl2, and 0.1 mL LaCl3 solutions (all at 40 mM) were added dropwise to the prepared micelle solution to obtain a metal precursor solution. A nickel foam (1 cm × 1.5 cm) was first soaked in 3 M HCl for 20 min, then rinsed three times alternately with water and ethanol, and then fixed on a platinum electrode holder (the exposed deposition area of ​​the nickel foam was 1 cm × 1 cm) as the working electrode. Platinum wire and Ag / AgCl (3 M KCl) were used as the counter and reference electrodes, respectively, with the metal precursor solution as the electrolyte. Electrodeposition was performed at room temperature in a three-electrode system with a deposition potential of -2.5 V and a deposition time of 4000 seconds. After deposition, the working electrode was immersed in THF and stored at room temperature for 24 h to remove micelles. Then, it was rinsed three times alternately with deionized water and ethanol to obtain a hexa-membered high-entropy alloy mesoporous membrane electrocatalyst. Example 3

[0022] The preparation method of a hexa-membered high-entropy alloy mesoporous membrane electrocatalyst is as follows: Weigh 4.5 mg of the template agent PEO 10500 -b-PMMA 18000 The nickel foam was ultrasonically dissolved in 0.6 mL THF, and then 0.5 mL anhydrous ethanol, 2.35 mL deionized water, and 0.053 mL 3 M HCl were added to form a micelle solution. Then, 0.3 mL RuCl3, 0.05 mL K3RhCl6, 0.05 mL CuSO4, 0.05 mL CoCl2, and 0.05 mL LaCl3 solutions (all at 40 mM) were added dropwise to the prepared micelle solution to obtain a metal precursor solution. A nickel foam (1 cm × 1.5 cm) was first soaked in 3 M HCl for 20 min, then rinsed three times alternately with water and ethanol, and then fixed on a platinum electrode holder (the exposed deposition area of ​​the nickel foam was 1 cm × 1 cm) as the working electrode. Platinum wire and Ag / AgCl (3 M KCl) were used as the counter and reference electrodes, respectively, with the metal precursor solution as the electrolyte. Electrodeposition was performed at room temperature in a three-electrode system at a deposition potential of -3.0 V and a deposition time of 1200 seconds. After deposition, the working electrode was immersed in THF and stored at room temperature for 24 h to remove micelles. Then, it was rinsed three times alternately with deionized water and ethanol to obtain a hexa-membered high-entropy alloy mesoporous membrane electrocatalyst. Example 4

[0023] The preparation method of a hexa-membered high-entropy alloy mesoporous membrane electrocatalyst is as follows: Weigh 4.5 mg of the template agent PEO 10500 -b-PMMA 18000 The nickel foam was ultrasonically dissolved in 0.6 mL THF, and then 0.5 mL anhydrous ethanol, 2.35 mL deionized water, and 0.053 mL 3 M HCl were added to form a micelle solution. Then, 0.3 mL RuCl3, 0.05 mL K3RhCl6, 0.05 mL CuSO4, 0.05 mL CoCl2, and 0.05 mL LaCl3 solutions (all at 40 mM) were added dropwise to the prepared micelle solution to obtain a metal precursor solution. The nickel foam (1 cm × 1.5 cm) was first soaked in 3 M HCl for 20 min, then rinsed three times alternately with water and ethanol, and then fixed on a platinum electrode holder (the exposed deposition area of ​​the nickel foam was 1 cm × 1 cm) as the working electrode. Platinum wire and Ag / AgCl (3 M KCl) were used as the counter and reference electrodes, respectively, with the metal precursor solution as the electrolyte. Electrodeposition was performed at room temperature in a three-electrode system with a deposition potential of -0.5 V and a deposition time of 4000 seconds. After deposition, the working electrode was immersed in THF and stored at room temperature for 24 h to remove micelles. Then, it was rinsed three times alternately with deionized water and ethanol to obtain a hexa-membered high-entropy alloy mesoporous membrane electrocatalyst. Example 5

[0024] The hexa-membered high-entropy alloy mesoporous membrane electrocatalyst prepared by the methods in Examples 1-5 was applied to the electro-oxidation catalysis of 5-hydroxymethylfurfural.

[0025] To further verify the reliability of the present invention and select the optimal solution, the inventors conducted a series of experiments, as follows: 1. Materials and Reagents All chemical reagents and solvents were used directly after purchase without further purification. Block copolymer PEO 10500 -b-PMMA 18000Purchased from Polymer Source; potassium rhodium chloride (K3RhCl6, 98%) and platinum carbon (Pt / C, 20%) were purchased from Adamas Beta; ruthenium chloride hydrate (RuCl3·xH2O, 99.95%), anhydrous copper sulfate (CuSO4, 99%), lanthanum chloride heptahydrate (LaCl3·7H2O, 99.99%), cobalt chloride hexahydrate (CoCl2·6H2O, 99.99%), potassium hydroxide (KOH, 85%), isopropanol (99.5%), and potassium chloride solution (3... M), hydrochloric acid (37%), sulfuric acid (95%-98%), Nafion solution (5.0%-5.4% soluble in a mixed solvent of water and isopropanol, containing 42%-48% water), 5-hydroxymethylfurfural (HMF, 99%), 5-hydroxymethyl-2-furanic acid (HMFCA, 98%), 2,5-dicarboxyfuran (DFF, 98%), 5-formyl-2-furanic acid (FFCA, 98%), and 2,5-furandicarboxylic acid (FDCA, 98%) were all purchased from Shanghai Aladdin Company; anhydrous ethanol (AR) and tetrahydrofuran (THF, AR) were produced by Tianjin Fuyu Reagent; deionized water was purchased Wahaha purified water.

[0026] 2. Preparation and structural characterization of m-HEA / NF 2.1 Preparation of m-HEA / NF A typical preparation process is as follows: Weigh 4.5 mg of PEO 10500 -b-PMMA 18000 The electrolyte was ultrasonically dissolved in 0.6 mL THF, and then 0.5 mL anhydrous ethanol, 2.35 mL deionized water, and 0.053 mL 3 M HCl were added to form a micelle solution. Next, 0.3 mL RuCl3 (40 mM), 0.05 mL K3RhCl6 (40 mM), 0.05 mL CuSO4 (40 mM), 0.05 mL CoCl2 (40 mM), and 0.05 mL LaCl3 (40 mM) were added dropwise to the prepared micelle solution to obtain the metal precursor solution for electrodeposition. The pH of the solution was approximately 1, and electrodeposition was performed at room temperature (24 °C). The deposition process was carried out in a conventional three-electrode system. The working electrode consisted of nickel foam (NF, 1 cm × 1.5 cm), which had been pre-soaked in 3 M HCl for 20 min and then alternately washed three times with water and ethanol, fixed on a platinum electrode holder (deposition area 1 × 1 cm). 2Platinum wire and silver chloride (3 M KCl) were used as the counter electrode and reference electrode, respectively, and a metal precursor solution was used as the electrolyte. A typical mesoporous membrane was obtained by deposition at -2.5 V (vs. Ag / AgCl) for 4000 s. After deposition, the working electrode (NF) was immersed in THF and stored at room temperature for 24 h to remove micelles. Then, it was rinsed three times alternately with deionized water and ethanol to obtain the product, which was then sealed in deionized water for later use.

[0027] 2.2 Structural characterization of m-HEA / NF m-HEA / NF and control samples (HEA / NF, m-RhNi / NF) were prepared using the above method, and their structures were characterized. All control samples were prepared using similar steps. It is worth noting that the total volume of metal solutions of equal concentration should be controlled to be 0.5 mL.

[0028] The XRD patterns of m-HEA / NF, HEA / NF, and m-RhNi / NF are shown below. Figure 1 As shown. Electron micrographs of m-HEA / NF and elemental mappings of their corresponding positions are shown below. Figure 2 As shown. Electron micrographs of HEA / NF and their corresponding elemental mappings are shown below. Figure 3 As shown. Electron micrographs of m-RhNi / NF and elemental mappings of their corresponding positions are shown below. Figure 4 As shown. High-resolution XPS images of the m-HEA / NF, HEA / NF, and m-RhNi / NF elemental orbitals are shown below. Figure 5 As shown.

[0029] Depend on Figure 1 It can be seen that the crystal structure of m-HEA / NF is a single-phase solid solution dominated by the face-centered cubic (FCC) structure of Rh, but the peak position shows a significant rightward shift, indicating that lattice compression has occurred. Figure 2 It is known that it has a mesoporous morphology and is rich in defects and lattice distortion, which is due to the difference in atomic radii of the alloying elements. The elements are evenly distributed, proving the successful preparation of m-HEA / NF. Figure 3 This indicates that the HEA / NF prepared without the aid of a soft template lacks mesoporous morphology but is rich in lattice distortion and defects. Cu exhibits significant segregation, while other elements are uniformly distributed. Figure 1 It can be seen that it also possesses the FCC structure of Rh. The morphology and structure of m-RhNi / NF can be obtained from... Figure 1 and Figure 4 Analysis revealed that, similar to m-HEA / NF, it possesses an Rh-based FCC structure and exhibits better compatibility with the Rh-PDF#05-0685 standard card. It also displays a uniform and ordered mesoporous morphology with significant lattice distortion around the mesopores, which is attributed to the confinement effect of the soft template. The elemental distribution is uniform, with no segregation. Figure 5 The results show that Rh, Ru, Cu, Co, and Ni exist in the catalyst in both the 0-valence metallic state and the high-valence oxidation state, while La exists entirely in the oxidation state. The presence of oxidation states of each element may be due to oxidation occurring in the air.

[0030] 2.3 Comparative Experiment (1) Effect of different deposition potentials on the morphology of mesoporous membranes Experimental design: Under the condition that other deposition conditions of the typical m-HEA / NF sample remain unchanged, deposition was carried out by changing the deposition potential to -0.5 V, -1.0 V, -1.5 V, -2.0 V, -2.5 V, and -3.0 V, respectively. The morphology of the resulting mesoporous films is as follows. Figure 6 As shown.

[0031] Depend on Figure 6 It can be seen that when the deposition potential is below -2.5 V, although pore morphology can be successfully prepared, the pore shape is irregular and the distribution is uneven. When the potential is above -2.5 V, the reduction rate is too fast, resulting in more metal clusters accumulating on the surface of the mesoporous membrane. Only when the potential is below -2.5 V can the mesoporous morphology be prepared as a regular and ordered non-clustered mesoporous membrane.

[0032] (2) Effect of different metal precursor ratios on mesoporous membrane morphology Experimental design: The deposition potential was -2.5 V (vs. Ag / AgCl). With other deposition conditions remaining constant for the typical m-HEA / NF sample, deposition was performed by changing the amount of metal precursor used to Ru:Rh:Cu:Co:La = 3:4:1:1:1, 4:3:1:1:1, 5:2:1:1:1, 3:1:4:1:1, 2:1:5:1:1, and 1:1:6:1:1. The morphology of the resulting mesoporous films is shown in the figure. Figure 7 .

[0033] Depend on Figure 7 It can be observed that as the amount of Rh precursor decreases and the amount of Ru precursor increases, the metal film gradually transforms from a clustered metal film to a smooth film. Conversely, as the amount of Cu metal precursor increases, the mesoporous film gradually changes from an irregular mesoporous morphology to a relatively regular mesoporous morphology, but still exhibits a significant amount of particle accumulation. This experiment demonstrates that the optimal ratio for preparing a mesoporous film with uniform, ordered particle accumulation is Ru:Rh:Cu:Co:La = 6:1:1:1:1.

[0034] (3) Effect of different carriers on the morphology of mesoporous membranes Experimental design: Deposition potential was -2.5 V (vs. Ag / AgCl), Ru:Rh:Cu:Co:La = 6:1:1:1:1. With other deposition conditions unchanged for the typical m-HEA / NF sample, deposition was performed separately using titanium foam and carbon cloth as the support. The morphology of the resulting mesoporous films is shown in [Figure number missing]. Figure 8 .

[0035] Depend on Figure 8 It can be seen that mesoporous morphology can be prepared on both titanium foam and carbon cloth, but the mesoporous film on titanium foam has more cracks, while the mesoporous film on carbon cloth has lower mesoporous density and irregular mesopores.

[0036] (4) Universality test of the preparation scheme Experimental design: Under the condition that other deposition conditions of typical sample m-HEA / NF remain unchanged, the type and proportion of metal precursor, deposition potential, and deposition time were changed, and deposition was carried out on NF respectively. The resulting morphologies are shown in the figure. Figure 9 .

[0037] Depend on Figure 9 It is evident that this method is less effective in producing uniform and ordered mesoporous morphologies when preparing metal compositions containing only Ru as a noble metal.

[0038] (5) Effect of different template agents on the morphology of mesoporous membranes Experimental design: Under the condition that other deposition conditions of the typical m-HEA / NF sample remain unchanged, the template agent used is changed to PS-b-PEO. The mesoporous morphologies prepared under different metal combinations are shown in the figure. Figure 10 .

[0039] Depend on Figure 10 It is known that when Ru, Rh and Cu are present in a ratio of 6:1:1, there is a high probability of preparing mesoporous morphology. With the improvement of the preparation method, it is expected that the mesoporous morphology can be made more uniform and ordered.

[0040] In conclusion, Figure 6 , Figure 7 , Figure 8 The results indicate that the optimal deposition potential for m-HEA / NF is -2.5V vs. Ag / AgCl, the optimal metal precursor ratio is Ru:Rh:Cu:Co:La=6:1:1:1:1, and the optimal support is NF. Figure 9 This indicates that further exploration is needed to find more suitable conditions for preparing mesoporous morphologies for other combinations of metal elements. Figure 10 This indicates that PS-b-PEO also has the ability to prepare mesoporous morphologies.

[0041] 3. m-HEA / NF performance testing 3.1 Experimental Methods All electrochemical tests were performed using a Shanghai Chenhua CHI 760E electrochemical workstation. The three-electrode system used a graphite rod and mercuric oxide (Hg / HgO, 1 M KOH) as the counter and reference electrodes, respectively, with NF (nitrogenous flux) supported on a platinum electrode holder serving as the working electrode. Tests were conducted in a single cell. For HER and OER-related tests, a 1 M KOH electrolyte solution was used; for HMFOR-related tests, a 1 M KOH solution containing 10 mM HMF was used. The potential of the three-electrode system in this study was calibrated to the reversible hydrogen electrode (RHE) according to the following formula: ; Cyclic voltammetry (CV) and linear sweep voltammetry (LSV) were performed at 5 mV·s. -1 The scan was performed at a high scan rate and with 95% iR compensation to reduce the interference of capacitive current and solution internal resistance on the test results. Electrochemical impedance spectroscopy (EIS) tests were performed in 1 M KOH with and without 10 mM HMF at a test frequency of 10 Hz. -2 -10 5 The test voltage range for OER and HMFOR was 1.224 - 1.624 V vs. RHE, and the test voltage for HER was -0.076 V vs. RHE. The electrochemical area (ECSA) of the catalyst was obtained by CV cycling tests, and the electrochemical double-layer capacitance (C) was calculated. dl The value of ) is used for evaluation. The CV test conditions are as follows: in a 1 M KOH solution containing 10 Mm HMF, the test voltage range is a non-Radida voltage window, and the scan rates are 20, 40, 60, 80, 100, and 120 mV·s, respectively. -1 The data.

[0042] 3.2 Results and Analysis The performance test results of m-HEA / NF are as follows: Figure 11 As shown, Figure 11 The experimental data for ag are shown in Table 1. Figure 11 As can be seen from this, compared to the LSV data of OER in 1 M KOH alone, the addition of HMF resulted in m-HEA / NF reaching 50 mA·cm⁻¹. -2 The required overpotential decreased by 144 mV. In a 1 M KOH solution containing 10 mM HMF, the m-HEA / NF achieved a higher peak current density and a correspondingly lower overpotential, with a Tafel slope of only 21.6 mV·dec. -1 C dl The value reached 51.88 mF·cm -2 The smallest electrochemical impedance radius and the largest open-circuit potential drop ( Figure 11 These data indicate that m-HEA / NF possesses higher HMFOR activity, superior HMFOR kinetics, a larger electrochemical active area, lower charge transfer impedance, and stronger HMFOR adsorption performance. The cycling stability of m-HEA / NF was tested, as shown in the following figures. Figure 11 As shown in g, after 30 cycles, the conversion rate, yield, selectivity, and Faraday efficiency did not decrease significantly, indicating that m-HEA / NF has excellent HMFOR stability.

[0043] .

[0044] Although the present invention has been described in detail above with general descriptions, specific embodiments, and experiments, modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, all such modifications or improvements made without departing from the spirit of the present invention fall within the scope of protection claimed by the present invention.

Claims

1. A method for preparing a hexa-element high-entropy alloy mesoporous membrane electrocatalyst, characterized in that, Includes the following steps: S1, Apply template agent PEO 10500 -b-PMMA 18000 The sample was ultrasonically dissolved in THF, and anhydrous ethanol, deionized water, and HCl solution were added to form a micelle solution. RuCl3, K3RhCl6, CuSO4, CoCl2, and LaCl3 solutions were added dropwise to the micelle solution to obtain a metal precursor solution. The molar ratio of RuCl3, K3RhCl6, CuSO4, CoCl2, and LaCl3 was 1~6:1~4:1~6:1:

1. S2. Soak and wash the nickel foam, and fix it on the platinum electrode clip as the working electrode; S3. Platinum wire and Ag / AgCl with 3 M KCl were used as the counter electrode and reference electrode, respectively. The metal precursor solution prepared in S1 was used as the electrolyte. Electrodeposition was carried out at room temperature in a three-electrode system with a deposition potential of -0.5 V to -3.0 V and a deposition time of 1200 to 4000 s. S4. After deposition, immerse the working electrode in THF and store it at room temperature for 6 to 24 hours to remove micelles. Then, thoroughly wash it with deionized water and ethanol to obtain the final product.

2. The method for preparing the hexa-element high-entropy alloy mesoporous membrane electrocatalyst according to claim 1, characterized in that, The molar ratio of RuCl3, K3RhCl6, CuSO4, CoCl2 and LaCl3 in step S1 is 6:1:1:1:

1.

3. The preparation method of the hexa-element high-entropy alloy mesoporous membrane electrocatalyst according to claim 2, characterized in that, Step S1 specifically involves weighing 4.5 mg of the template agent PEO. 10500 -b-PMMA 18000 The solution was ultrasonically dissolved in 0.6 mL THF, and then 0.5 mL anhydrous ethanol, 2.35 mL deionized water and 0.053 mL 3 M HCl were added to form a micelle solution. Then, 0.3 mL RuCl3, 0.05 mL K3RhCl6, 0.05 mL CuSO4, 0.05 mL CoCl2 and 0.05 mL LaCl3 solutions, each with a concentration of 40 mM, were added dropwise to the prepared micelle solution to obtain the metal precursor solution.

4. The method for preparing the hexa-element high-entropy alloy mesoporous membrane electrocatalyst according to claim 1, characterized in that, Step S2 is as follows: First, soak the nickel foam in 3 M HCl for 20 min, then wash it three times alternately with water and ethanol, and then fix it on the platinum electrode holder as a working electrode.

5. The method for preparing the hexa-element high-entropy alloy mesoporous membrane electrocatalyst according to any one of claims 1 or 4, characterized in that, In step S2: the area of ​​the nickel foam is 1cm × 1.5cm; the exposed deposition area of ​​the nickel foam after being fixed to the platinum electrode clip is 1cm × 1cm.

6. The method for preparing the hexa-element high-entropy alloy mesoporous membrane electrocatalyst according to claim 1, characterized in that, In step S3: the room temperature is 24°C; the deposition potential is -2.0V ~ -3.0V; and the deposition time is 4000s.

7. The method for preparing the hexa-element high-entropy alloy mesoporous membrane electrocatalyst according to claim 6, characterized in that, The deposition potential in step S3 is -2.5 V.

8. The method for preparing the hexa-element high-entropy alloy mesoporous membrane electrocatalyst according to claim 1, characterized in that, Step S4 is as follows: After deposition, the working electrode is immersed in THF and stored at room temperature for 24 h to remove micelles. Then, it is rinsed three times alternately with deionized water and ethanol to obtain a hexa-membered high-entropy alloy mesoporous membrane electrocatalyst.

9. A hexa-element high-entropy alloy mesoporous membrane electrocatalyst prepared by the preparation method described in claim 1.

10. The application of a hexa-component high-entropy alloy mesoporous membrane electrocatalyst prepared by the method described in claim 1 in the electrocatalytic oxidation of 5-hydroxymethylfurfural.

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