A copper-cobalt bimetallic nitride nanowire array electrocatalyst and a preparation method thereof

Abstract

The present application relates to a kind of copper cobalt bimetallic nitride nano array electrocatalyst and its preparation method. Cu (OH) 2 Nanowire is grown on foam copper by impregnation method;Co (OH) 2 is hydrothermally grown on Cu (OH) 2 Nanowire, and copper cobalt hydroxide / foam copper precursor is obtained;The copper cobalt hydroxide / foam copper precursor is treated by hot ammonia, and copper cobalt bimetallic nitride nano array electrocatalyst is obtained. The copper cobalt bimetallic nitride nano array electrocatalyst prepared by this method is grown on foam copper conductive substrate, including CuN nanorod and CoN nanoparticle grown on the surface of CuN nanorod;It presents obvious rod particle hierarchical structure, and the whole is nano array. The catalyst material preparation process of the present application is simple, environmental protection and low in production cost, device equipment is simple, and repeatability is strong, has wide market application prospect in electrocatalytic organic synthesis and new energy field.

Description

Technical Field

[0001] This invention relates to the field of electrocatalysis, specifically to a copper-cobalt bimetallic nitride nanoarray electrocatalyst and its preparation method. Background Technology

[0002] With the increasing consumption of traditional fossil fuels, these fuels will inevitably be depleted, and the increase in carbon dioxide emissions will trigger a series of extreme global climate changes. These are key motivations for exploring renewable energy and pursuing sustainable technologies. The development and utilization of hydrogen energy and biomass are considered the most promising and important ways to solve these problems.

[0003] Biomass is the only renewable organic carbon source on Earth, and developing high-value-added products from biomass has enormous economic potential and social benefits. 5-Hydroxymethylfurfural (HMF), one of the most important renewable platform chemicals, is formed by the dehydration of hexosyl biomass such as fructose and glucose. It is a multifunctional intermediate, providing raw materials for pharmaceutical synthesis and important bio-based chemicals for the synthesis of various commercially useful acids, aldehydes, alcohols, and amines. High-quality bio-based platform chemicals can be prepared by catalytically oxidizing aldehydes and hydroxyl groups at different positions and to varying degrees in HMF. Most attractively, 2,5-furandicarboxylic acid (FDCA) has a chemical structure similar to the petroleum-based monomer terephthalic acid (TPA) and is a precursor for the synthesis of bio-based polyester polyethylene furanate (PEF). Compared to petroleum-based polyethylene terephthalate (PET), bio-based PEF has a lower carbon footprint, sustainability, and excellent barrier properties, making it highly likely to replace PET in the packaging market in the future.

[0004] The traditional method for producing FDCA from HMF using thermochemical catalysis is commonly employed. However, to improve conversion efficiency, chemical potential is typically used as the driving force, employing noble metal catalysts at high temperatures (>100℃) and high oxygen pressures (0.3-2.0 MPa). This not only increases production costs but also poses safety hazards.

[0005] Electrocatalysis is a clean, safe, and promising technology with mild operating conditions, controllable selectivity, and scalable reaction substrates. Hydrogen production via water electrolysis is limited by the slow four-electron oxygen evolution reaction (OER) at the anode, resulting in high energy consumption and low added value of the oxygen produced. Electrocatalytic HMF oxidation (HMFOR) for FDCA production is thermodynamically and kinetically superior to OER. Therefore, using HMFOR instead of OER in coupling with the hydrogen evolution reaction (HER) is beneficial for rationally reducing hydrogen production energy consumption. Furthermore, it can generate value-added compounds at the anode, significantly improving energy efficiency.

[0006] Developing low-cost, highly active, and highly stable bifunctional electrocatalysts is of great significance. Transition metal nitrides (TMNs), possessing physical properties similar to noble metals and unique electronic structures, are considered highly efficient electrocatalysts in energy-related processes. However, bulk TMNs are typically limited by a limited number of active sites, slow mass transfer, and less-than-ideal electrochemical performance. Therefore, designing nanostructures with controllable morphology and good dispersibility—that is, optimizing the design to give TMNs a larger specific surface area, more active sites, and shorter mass-charge transport distances—is an effective strategy to address these issues. Summary of the Invention

[0007] The purpose of this invention is to overcome the deficiencies and defects mentioned in the background art above, and to provide a transition metal nitride nanoarray catalyst with controllable morphology and good dispersibility nanostructure.

[0008] To achieve the above objectives, this application provides a method for preparing a copper-cobalt bimetallic nitride nanoarray electrocatalyst (CuCoN), the technical solution of which is as follows:

[0009] Step (1) Add ammonium persulfate and sodium hydroxide to water and stir to dissolve them to obtain a mixed solution. The concentration of persulfate in the mixed solution is 0.05-0.15 mol / L and the concentration of sodium hydroxide is 1.5-3.5 mol / L. Immerse the ultrasonically treated copper foam into the mixed solution. Let it stand at room temperature for 5-20 minutes. After removing the copper foam, wash and dry it to obtain copper foam with Cu(OH)2 nanowires grown on it.

[0010] Step (2) Dissolve cobalt salt and urea in water to obtain a precursor solution. The concentration of cobalt salt in the precursor solution is 0.05-0.1 mol / L and the concentration of urea is 0.2-0.5 mol / L. Transfer the precursor solution into a hydrothermal reactor. Then immerse the copper foam with Cu(OH)2 nanowires grown on it into the precursor solution for hydrothermal reaction. Then cool it to room temperature. After removing the copper foam, wash and dry it to obtain copper foam with copper cobalt hydroxide precursor grown on it.

[0011] Step (3) involves thermal ammoniation of the above copper-cobalt hydroxide precursor to obtain a copper-cobalt bimetallic nitride nanoarray electrocatalyst (CuCoN).

[0012] The copper-cobalt bimetallic nitride nanoarray electrocatalyst prepared by the above method is grown on a foamed copper conductive substrate and includes CuN nanorods and CoN nanoparticles grown on the surface of CuN nanorods; it exhibits a clear rod-particle hierarchical structure and is an overall nanoarray.

[0013] Significant advantages of this invention:

[0014] (1) The preparation method of the present invention consists of simple impregnation, hydrothermal treatment and calcination. The process is simple, the raw materials are inexpensive, the production cost is low and the repeatability is strong.

[0015] (2) The catalyst obtained by the preparation method provided by the present invention can be directly used as an electrode material. Its catalytic active material is a copper-cobalt bimetallic nitride nanoarray, which has a high specific surface area and can expose abundant highly active sites, which is beneficial to the electrocatalytic oxidation of HMF and hydrogen evolution reaction.

[0016] (3) The support of copper foam is conducive to promoting the diffusion of electrolyte and reaction substrate and the release of bubbles, avoiding poisoning of active sites. At the same time, the substrate improves conductivity. These factors synergistically enhance the electrocatalytic ability of the material in electrolyte.

[0017] (4) The catalyst provided by this invention can be directly used as a working electrode. Under normal temperature and pressure conditions, it can effectively realize the electrocatalytic oxidation of HMF to FDCA, showing excellent HMFOR Faraday efficiency (greater than 95%) and FDCA yield (greater than 97%).

[0018] (5) The catalyst provided by the present invention has excellent cycle stability when used directly as a working electrode. After 8 cycles, it still maintains about 95% Faraday efficiency and 97% FDCA yield.

[0019] (6) This invention provides a copper-cobalt bimetallic nitride nanoarray catalyst with broad application prospects in the electrocatalytic oxidation of small biomass molecules, such as furfuryl alcohol, furfural oxidation, and methanol oxidation. In particular, it exhibits excellent conversion rate, high selectivity for 2,5-furandicarboxylic acid, high Faradaic efficiency, and good stability in the electrocatalytic oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA). The entire reaction process is simple, thus possessing broad market application prospects. Attached Figure Description

[0020] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein:

[0021] Figure 1 This is the X-ray diffraction pattern of the CuCoN electrode material prepared in Example 1 of this invention.

[0022] Figure 2These are scanning electron microscope images of the copper-cobalt hydroxide precursor prepared in Example 6 of this invention at low resolution (a) and high resolution (b, c).

[0023] Figure 3 These are scanning electron microscope images of CuCoN prepared in Example 1 of this invention at low resolution (a) and high resolution (b, c).

[0024] Figure 4 This is an energy dispersive X-ray image of CuCoN prepared in Example 1 of this invention.

[0025] Figure 5 This is an elemental mapping diagram of CuCoN prepared in Example 1 of this invention.

[0026] Figure 6 These are the OER polarization curves of CuCoN prepared in Example 1 and CuN and CoN prepared in Examples 4-5 of this invention in 1 mol / L KOH.

[0027] Figure 7 These are the HER polarization curves of CuCoN prepared in Example 1 and CuN and CoN prepared in Examples 4-5 of this invention in 1 mol / L KOH.

[0028] Figure 8 (a) shows the LSV curves of CuCoN prepared in Example 1 in 1 mol / L KOH with and without 50 mM HMF, scanned at 5 mV s⁻¹; (b) shows the comparison of current densities of CuCoN, CuN and CoN in 1 M KOH containing 50 mM HMF.

[0029] Figure 9 (a), (b), and (c) are CV graphs of CuCoN prepared in Example 1 and CuN and CoN prepared in Examples 4-5 at different scan rates in the range of 0.21-0.31V vs Hg / HgO; (d) is a graph showing the change of capacitive current density versus scan rate of CuCoN prepared in Example 1 and CoN and CuN prepared in Examples 4-5 at a potential of 0.26V vs Hg / HgO.

[0030] Figure 10 These are the normalized LSV curves of the electrochemical active area of ​​CuCoN prepared in Example 1 of this invention and CuN and CoN prepared in Examples 4-5.

[0031] Figure 11In Example 1, (a) shows the concentration of HMF and its oxidation products of CuCoN prepared in Example 1 in 10 mL of 1.0 M KOH containing 50 mM HMF at a potential of 1.45 V vs. RHE, as a function of charge; (b) shows the yield and FE of FDCA obtained by CuCoN electrode in 8 consecutive cycles of electrolysis.

[0032] Figure 12 This is a comparison of the HMFOR coupled HER and LSV curves of CuCoN prepared in Example 1 of this invention. Detailed Implementation

[0033] To facilitate understanding of the present invention, the present invention will be further described in detail below with reference to specific embodiments, but the scope of protection of the present invention is not limited to the following specific embodiments.

[0034] It should be noted that, unless otherwise defined, the technical terms used in the following embodiments have the same meaning as commonly understood by those skilled in the art. Unless otherwise specified, the experimental reagents used in the following embodiments are conventional biochemical reagents; and the experimental methods described are conventional methods.

[0035] This application provides a copper-cobalt bimetallic nitride nanoarray electrocatalyst and its preparation method. The copper-cobalt bimetallic nitride nanoarray electrocatalyst can effectively reduce the overpotential of HMF oxidation, exhibiting excellent electrocatalytic performance of HMF oxidation. The catalyst has high stability and is conducive to industrial production.

[0036] Example 1:

[0037] Preparation method of copper-cobalt bimetallic nitride nanoarray electrocatalyst:

[0038] (1) To remove copper oxide from the surface of the 2×3cm² conductive substrate of copper foam, it was ultrasonicated in 1M HCl for 15 minutes, and then ultrasonicated repeatedly with ultrapure water and anhydrous ethanol until neutral. Finally, the copper foam was dried with cold air for later use. NaOH and ((NH4)2S2O8 were dissolved in water to obtain a mixed solution with a NaOH concentration of 2.5 mol / L and a (NH4)2S2O8 concentration of 0.1 mol / L. The treated copper foam was immersed in the above solution and allowed to stand for 5–20 minutes. The copper foam was then removed, washed with ultrapure water and ethanol, and dried in a vacuum drying oven at 60°C for 6 hours to obtain copper foam with Cu(OH)2 nanowires grown on it.

[0039] (2) A certain amount of cobalt salt and urea were dissolved in water to obtain a precursor solution. The concentration of cobalt salt in the precursor solution was 0.075 mol / L and the concentration of urea was 0.35 mol / L. The precursor solution was then transferred into a hydrothermal reactor. Then, copper foam with Cu(OH)2 nanowires was immersed in the precursor solution. The hydrothermal reactor was tightened and placed in an oven for hydrothermal reaction. The reaction was sealed at 85°C for 4 hours. Then, the reaction was allowed to cool naturally to room temperature. The copper foam was removed, washed with ultrapure water and ethanol, and dried at 60°C for 6 hours to obtain the copper cobalt hydroxide precursor.

[0040] (3) Under normal pressure, the copper-cobalt hydroxide precursor obtained in step (2) is placed in the center of the temperature zone of a tube furnace for ammoniation treatment. Ammonia is used as the nitrogen source, and the temperature is raised to 400℃ and kept constant for 2 hours. After the constant temperature calcination is completed, it is naturally cooled to room temperature to obtain copper-cobalt bimetallic nitride nanoarray electrocatalyst CuCoN.

[0041] The copper-cobalt bimetallic nitride nanoarray electrocatalyst prepared by this method is grown on a copper foam conductive substrate, comprising CuN nanorods and CoN nanoparticles grown on the surface of the CuN nanorods; it exhibits a distinct rod-particle hierarchical structure, forming an overall nanoarray. This method yields a high-activity-area nanorod-nanoparticle hierarchical structure and modulates the electronic structure of the original metals through metal interactions. The copper foam substrate possesses an interconnected open network structure, giving the electrode excellent mechanical strength, high conductivity, and a large specific surface area. As an integrated catalyst, CuCoN does not require a binder and can be used directly as an electrode; the high conductivity of copper foam promotes charge transfer during the electrode reaction process. Simultaneously, the catalyst has a three-dimensional structure, allowing bubbles to be released through an efficient pathway.

[0042] Example 2:

[0043] Another method for preparing copper-cobalt bimetallic nitride nanoarray electrocatalysts, optionally, in step (3), when the copper-cobalt hydroxide precursor is placed in the center of the temperature zone of the tube furnace for ammoniation treatment, ammonia is used as the nitrogen source, the temperature is raised to 300°C, and held at a constant temperature for 2 hours.

[0044] Example 3:

[0045] Another method for preparing copper-cobalt bimetallic nitride nanoarray electrocatalysts, optionally, in step (3), when the copper-cobalt hydroxide precursor is placed in the center of the temperature zone of the tube furnace for ammoniation treatment, ammonia is used as the nitrogen source, the temperature is raised to 500℃, and held at a constant temperature for 2 hours.

[0046] Example 4:

[0047] The preparation method of CuN electrocatalyst includes the following steps:

[0048] (1) Remove surface oxides by sonicating 2×3cm copper foam in 1M HCl for 15 minutes, then sonicate in ultrapure water and anhydrous ethanol for 10 minutes, repeat three times, and finally dry the copper foam with cold air for later use. Dissolve NaOH and ((NH4)2S2O8 in water to obtain a mixed solution with a NaOH concentration of 2.5 mol / L and a (NH4)2S2O8 concentration of 0.1 mol / L. Immerse the treated copper foam in the above solution, let it stand for 15 minutes, take out the copper foam, wash it with ultrapure water, and dry it in a vacuum drying oven at 60℃ for 6 hours to obtain copper foam with grown Cu(OH)2 nanowires.

[0049] (2) The Cu(OH)2 obtained in step (1) is placed in the center of the temperature zone of a tube furnace for ammoniation treatment. Ammonia is used as the nitrogen source, and the temperature is raised to 400℃ and kept constant for 2 hours. After the constant temperature calcination is completed, it is naturally cooled to room temperature to obtain the single metal nitride electrocatalyst CuN.

[0050] Example 5:

[0051] The preparation method of CoN electrocatalyst includes the following steps:

[0052] (1) Remove surface oxides by sonicating 2×3cm copper foam in 1M HCl for 15 minutes, then sonicate in ultrapure water and anhydrous ethanol for 10 minutes, repeat three times, and finally dry the copper foam with cold air for later use. Dissolve a certain amount of cobalt salt and urea in water to obtain a precursor solution with a cobalt salt concentration of 0.075 mol / L. Transfer the precursor solution to a hydrothermal reactor, immerse the pre-treated copper foam in the solution, tighten the hydrothermal reactor and place it in a forced-air oven for hydrothermal reaction. Maintain the reaction at 85℃ for 4 hours, then allow it to cool naturally to room temperature. Remove the copper foam, wash it with ultrapure water and ethanol, and then dry it to obtain copper foam with Co(OH)2 nanowires grown on it.

[0053] (2) The Co(OH)2 nanowires obtained in step (1) were placed in the center of the temperature zone of a tube furnace for ammoniation treatment. Ammonia was used as the nitrogen source, and the temperature was raised to 400℃ and kept constant for 2 hours. After the constant temperature calcination was completed, the nanowires were naturally cooled to room temperature to obtain the single metal nitride electrocatalyst CoN.

[0054] Example 6:

[0055] A method for preparing a copper-cobalt hydroxide precursor includes the following steps:

[0056] (1) The cleaned and dried commercial copper foam (2×3cm2) was placed in a mixed solution containing NaOH and ((NH4)2S2O8, with the concentration of NaOH being 2.5mol / L and the concentration of (NH4)2S2O8 being 0.1mol / L. The treated copper foam was immersed in the above solution and left to stand for 15 minutes. The copper foam was then removed, washed with ultrapure water and ethanol, and dried in a vacuum drying oven at 60℃ for 6 hours to obtain copper foam with Cu(OH)2 nanowires grown on it.

[0057] (2) Dissolve 0.65g CoSO4·7H2O and 0.63g urea in 30mL of water to obtain a precursor solution with a cobalt salt concentration of 0.075mol / L; transfer the precursor solution into a hydrothermal reactor, then immerse the copper foam with Cu(OH)2 nanowires grown in step (1) into the hydrothermal reactor, tighten the reactor, place it in an oven for hydrothermal reaction, and seal the reaction at 85℃ for 4 hours; then cool to room temperature, take out the copper foam, wash it with ultrapure water and ethanol, and dry it at 60℃ for 6 hours to obtain a precursor with copper cobalt hydroxide grown.

[0058] Catalyst structure and performance characterization

[0059] (I) Characterization Test

[0060] The cobalt-copper bimetallic nitride nanoarray electrocatalyst prepared in Example 1 was used as the test sample and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray diffraction (EDX), and elemental mapping. The experimental results are as follows: Figure 1 , Figure 2 As shown.

[0061] Figure 1 The image shows the XRD pattern of the copper-cobalt bimetallic nitride nanoarray electrocatalyst obtained in Example 1. It can be seen that the XRD diffraction peaks of the copper-cobalt bimetallic nitride catalyst match the standard card of CuCoN (card number: PDF#53-0435), proving that the obtained material is indeed a CuCoN bimetallic nitride catalyst.

[0062] Figure 2 This is a SEM image of the copper-cobalt hydroxide precursor. Figure 2As shown in (a), (b), and (c), Cu(OH)₂ nanorods are vertically oriented and uniformly distributed on a copper foam substrate, with a length of approximately 6 micrometers and a diameter of approximately 200 nanometers. This serves as the scaffold for the growth of Co(OH)₂ nanowires. After the hydrothermal reaction, the surface of Cu(OH)₂ is uniformly covered with needle-like Co(OH)₂ nanowires with a length of approximately ~240 nanometers. That is, the copper cobalt hydroxide precursor consists of Cu(OH)₂ nanorods and an outer layer of Co(OH)₂ nanowires, exhibiting a distinct rod-wire hierarchical structure. Figure 3 This is a SEM image of a bimetallic nitride electrocatalyst. Figure 3 As shown in (a), (b), and (c), the three-dimensional hierarchical CuCoN nanorods obtained after heating and ammoniation consist of a hierarchical structure composed of nanorods and outer nanoparticles, maintaining the nanoarray structure and uniformity of the precursor. The hierarchical structure composed of nanorods and outer nanoparticles exhibits a large surface area, exposing numerous active sites, accelerating electron transfer, and contributing to improved catalytic performance of the electrocatalyst. Figure 4 and Figure 5 The figures show the EDX and elemental mapping diagrams of the bimetallic nitride electrocatalysts. Figure 4 DEX and Figure 5 The mapping diagram further confirms the composition of CuCoN, and the Cu, Co, and N elements are uniformly distributed in the hierarchical structure.

[0063] (II) Electrochemical Applications and Performance Testing

[0064] (1) The electrocatalysts prepared in Examples 1 and 4-5 above were applied to OER testing:

[0065] CuCoN-loaded copper foam was cut into 0.5cm × 1cm pieces, with the exposed 0.5cm × 0.5cm portion serving as the working electrode. An Hg / HgO electrode was used as the reference electrode, and a carbon rod as the counter electrode. A 1mol / L KOH alkaline solution was used as the electrolyte to create a three-electrode system. The OER performance was tested using a CHI 760E electrochemical workstation at a voltage range of 0.1V–0.8V with linear sweep voltammetry (LSV) at 5mV / s. The electrochemical test results for oxygen evolution are as follows: Figure 6 As shown.

[0066] Figure 6 In this study, compared with the monometallic CuN prepared in Example 4 (η50 = 400 mV) and the CoN prepared in Example 5 (η50 = 350 mV), the bimetallic nitride CuCoN had the lowest overpotential (η50 = 290 mV), indicating that CuCoN had the best OER performance in this case.

[0067] (2) The electrocatalysts prepared in Examples 1 and 4-5 above were applied to HER testing:

[0068] HER performance was tested using linear sweep voltammetry (LSV) at 5 mV / s within the 0 to -0.7 V vs RHE voltage range. Figure 7 As shown, at the same current density, the voltage of the bimetallic CuCoN hierarchical nanoarray electrocatalyst prepared in Example 1 is also lower than that of the single-metal CuN prepared in Example 4 and the CoN prepared in Example 5, indicating that CuCoN has better HER performance.

[0069] (3) Electrochemical performance testing of the electrocatalysts prepared in Examples 1 and 4-5 above for the oxidation of 5-hydroxymethylfurfural (HMFOR):

[0070] Fresh 50 mmol / L HMF was added to a 1 mol / L KOH solution as the electrolyte. Using the same three-electrode method and the same linear sweep voltammetry as the OER test described above, the HMFOR reaction performance was tested. The HMFOR electrochemical test results are as follows: Figure 8 As shown.

[0071] Figure 8 In (a), CuCoN undergoes water oxidation at potentials above 1.5 V vs RHE. The current density increases dramatically upon the addition of HMF, reaching 200 mA·cm⁻² at 1.39 V vs RHE and as high as 1000 mA·cm⁻² at 1.63 V vs RHE. The lower initial oxidation potential and increased HMF oxidation current density indicate that HMFOR is thermodynamically more favorable than OER. Meanwhile, in contrast, Figure 8 (b) The HMFOR performance of CuCoN prepared in Example 1, CuN prepared in Example 4 and CoN prepared in Example 5 is shown. It is found that CuCoN has a higher current density and a lower onset potential than CuN and CoN, indicating that CuCoN is more conducive to HMF oxidation, further emphasizing the good performance of CuCoN in HMF oxidation.

[0072] (4) Electrochemical active area test:

[0073] In a 1 mol / L KOH solution, using the same three electrodes, cyclic voltammetry (CV) was performed at a scan rate of 10-60 mV / s in the voltage range of 0.21-0.31 V vs Hg / HgO to test the electrochemical active area of ​​Examples 1, 4, and 5.

[0074] like Figure 9As shown, cyclic voltammetry (CV) measurements collected in the non-Radgety region of 0.21–0.31 V vs Hg / HgO reveal the electrochemically active surface area (ECSA) of the catalysts. The ECSA of CuCoN (90.5 mF·cm⁻²) is almost twice that of CuN (56.3 mF·cm⁻²) and CoN (46.5 mF·cm⁻²), indicating that the hierarchical structure formed by CuCoN is crucial for increasing the specific surface area of ​​the catalyst. The increase in electrochemically active surface area significantly contributes to the apparent activity improvement of the HMFOR catalyst. To eliminate the influence of specific surface area and determine whether the intrinsic activity of the catalyst has been improved, the active specific surface area of ​​CuCoN, CuN, and CoN was normalized. Figure 10 As shown, the normalized CuCoN still has the highest current density and the lowest overpotential, indicating that the intrinsic activity of the catalyst has also been improved, promoting the HMFOR reaction kinetics. This performance improvement is the result of the combined effect of multiple factors: (1) Due to the introduction of cobalt, the synergistic effect of the bimetal can regulate the electronic structure of the metal matrix, and the catalytic activity and alkali resistance of CuCoN as a bifunctional electrocatalyst are significantly improved compared with single metal nitrides; (2) The CuCoN active material with nanorod array structure is uniformly fixed on the surface of the foamed copper substrate. The close bonding between the catalyst and the substrate can increase the contact surface between the catalyst and the electrolyte, shorten the electron transport path, and improve the reaction rate; (3) The nanoarray with hierarchical structure can effectively expose active sites, provide more active sites, increase the reaction probability, catalyze HER and HMFOR, and improve the apparent activity of the catalyst; (4) An interface is formed between copper nitride and cobalt nitride. The interaction of electrons at the interface can redistribute the electronic state density, which can optimize the adsorption strength of the intermediate. The recombinant active centers established at the interface can generate higher activity than single components. They improve reaction kinetics by optimizing the chemisorption of precursor molecules or reaction intermediates, thereby improving the intrinsic activity of the catalyst.

[0075] (5) Quantitative analysis of HMF oxidation products:

[0076] Quantitative analysis of the product was performed using high-performance liquid chromatography (HPLC, Shimadzu LC-2030C system, Japan) combined with a UV-Vis detector to analyze the HMF oxidation products. The detection wavelength of the UV-Vis detector was set to 265 nm. Mobile phase A was methanol, and mobile phase B was 5 mM ammonium formate aqueous solution, with a volume ratio of A:B of 3:7 and a flow rate of 0.6 mL min⁻¹. For each analysis, 20 μL of electrolyte after potentiostatic electrolysis was taken and diluted to 2 mL with ultrapure water. The chromatographic column was a 4.6 mm × 150 mm Shim-pack GWS 5 μm C18, and the separation time was 10 minutes each time. Qualitative and quantitative analysis of the separated samples was performed based on the retention time of the standard samples and the standard curves plotted for different concentrations.

[0077] like Figure 11 As shown in (a), the concentration of HMF decreases with increasing charge, while the main product FDCA increases with increasing charge, and other byproducts account for a very small proportion. Figure 11 As shown in (b), CuCoN underwent electrochemical conversion of HMF for eight consecutive cycles at an applied potential of 1.45 V vs RHE. CuCoN maintained a high FDCA yield (~97%) and FDCA Faradaic efficiency (~95%), demonstrating excellent stability.

[0078] (6) Electrochemical performance testing of copper-cobalt bimetallic nitride nanoarray electrocatalysts applied to HMFOR coupled with HER:

[0079] The coupling-to-decoupling reaction performance was tested in the voltage range of 1.1-2.0V.

[0080] like Figure 12 As shown, when CuCoN is used as the anode and cathode catalyst for the overall electrolysis of the coupled reaction, after replacing HMF with OER for oxidation, the cathode potential of the mixed battery electrolysis reaction is significantly lower than that of the water cracking reaction. This is beneficial for producing hydrogen at a lower voltage, thereby improving energy utilization efficiency and reducing energy consumption.

Claims

1. A method for preparing a copper-cobalt bimetallic nitride nanoarray electrocatalyst, wherein the copper-cobalt bimetallic nitride nanoarray electrocatalyst is CuCoN, characterized in that... The method is as follows: Step (1) Add ammonium persulfate and sodium hydroxide to water and stir to dissolve them to obtain a mixed solution. The concentration of persulfate in the mixed solution is 0.05~0.15 mol / L and the concentration of sodium hydroxide is 1.5~3.5 mol / L. Immerse the ultrasonically treated copper foam into the mixed solution. Let it stand at room temperature for 5~20 minutes. After taking out the copper foam, wash and dry it to obtain copper foam with Cu(OH)2 nanowires grown on it. Step (2) Dissolve cobalt salt and urea in water to obtain a precursor solution. The concentration of cobalt salt in the precursor solution is 0.05~0.1 mol / L and the concentration of urea is 0.2~0.5 mol / L. Transfer the precursor solution into a hydrothermal reactor. Then immerse the copper foam with Cu(OH)2 nanowires grown on it into the precursor solution for hydrothermal reaction. Then cool it to room temperature. After taking out the copper foam, wash and dry it to obtain copper foam with copper cobalt hydroxide precursor grown on it. Step (3) The above copper-cobalt hydroxide precursor is subjected to thermal ammoniation treatment to obtain copper-cobalt bimetallic nitride nanoarray electrocatalyst; The copper-cobalt bimetallic nitride nanoarray electrocatalyst is used for the electrocatalytic oxidation of 5-hydroxymethylfurfural and hydrogen evolution reaction.

2. The preparation method according to claim 1, characterized in that, The concentration of persulfate in the solution is 0.1 mol / L, and the concentration of sodium hydroxide is 2.5 mol / L.

3. The preparation method according to claim 1, characterized in that, The settling time is 15 minutes.

4. The preparation method according to claim 1, characterized in that, The precursor solution contains 0.075 mol / L of cobalt salt and 0.35 mol / L of urea.

5. The preparation method according to claim 1, characterized in that, The hydrothermal reaction refers to immersing copper foam with Cu(OH)2 nanowires grown on it into the precursor solution containing cobalt salt and urea, and then sealing it for 4 hours under hydrothermal conditions at 85 °C.

6. The preparation method according to any one of claims 1-5, characterized in that, The thermal ammonification process is as follows: the copper-cobalt hydroxide precursor is placed in the center of the temperature zone of a tube furnace under normal pressure, and ammonia is used as the nitrogen source. The temperature is raised to 300~500 ℃ and held at a constant temperature for 1~4 h. After the constant temperature calcination is completed, the mixture is naturally cooled to room temperature to obtain a copper-cobalt bimetallic nitride nanoarray electrocatalyst.

7. The preparation method according to claim 6, characterized in that, Heat to 400 ℃.

8. The preparation method according to claim 6, characterized in that, Keep at a constant temperature for 2 hours.

9. A copper-cobalt bimetallic nitride nanoarray electrocatalyst, characterized in that, It is prepared by the method of any one of claims 1 to 6. The copper-cobalt bimetallic nitride nanoarray electrocatalyst is grown on a foamed copper conductive substrate and includes CuN nanorods and CoN nanoparticles grown on the surface of CuN nanorods, exhibiting a clear rod-particle hierarchical structure and forming an overall nanoarray. The copper-cobalt bimetallic nitride nanoarray electrocatalyst is used for the electrocatalytic oxidation of 5-hydroxymethylfurfural and hydrogen evolution reaction.

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