Nano-octahedral electrocatalyst and preparation and application thereof

Abstract

The application discloses a kind of nano octahedral electrocatalyst and its preparation and application, belong to catalytic preparation technical field.The preparation method of the nano octahedral electrocatalyst of the application includes the following steps: Cu2O nano octahedron is used as template, (CoCu)2V2O7 active layer is deposited on its surface by deposition conversion strategy, then doped Ru, obtain nano octahedral electrocatalyst.The preparation process of the nano octahedral electrocatalyst of the application is simple, mild, short in time, low in cost, suitable for mass production, solves the problems of existing traditional catalyst, such as insufficient activity, poor stability, low selectivity, high energy consumption and slow kinetics, and the prepared electrocatalyst is suitable for PET plastic upgrading and utilization coupled with efficient hydrogen production, has the dual functions of environmental pollution control and clean energy production.

Description

Technical Field

[0001] This invention relates to the field of catalyst preparation technology, and in particular to a nano-octahedral electrocatalyst and its preparation and application. Background Technology

[0002] Hydrogen energy boasts advantages such as high calorific value, zero pollution, and zero emissions, playing a crucial role in future sustainable development. Currently, over 90% of hydrogen is produced using traditional fossil fuel steam reforming technology, a process that consumes fossil resources and generates greenhouse gases, harming the environment. In contrast, water electrolysis for hydrogen production utilizes surplus electricity generated from intermittent renewable energy sources (such as solar, wind, and tidal power) to drive water splitting and produce high-purity hydrogen. This technology is mature, the equipment is simple, and the reaction conditions are mild, showing great application potential. However, water electrolysis for hydrogen production suffers from high anode energy consumption, low efficiency, and slow reaction kinetics, requiring highly efficient catalysts to improve energy conversion efficiency. Therefore, replacing the anode oxygen evolution reaction with thermodynamically more favorable electro-oxidation of smaller molecules (such as ethylene glycol and urea) is a recently emerging hydrogen production strategy.

[0003] Plastics, as the most important polymer, possess multiple advantages such as light weight, low cost, and ease of processing, and have been widely used in various fields including daily packaging, building materials, electronics, medical equipment, and energy storage, becoming necessities for human social development and daily life. However, the huge market demand has led to a rapid increase in global plastic production, resulting in massive accumulations of waste plastics and causing irreparable damage to water sources, soil, air, and oceans. With the development of renewable energy, the plastic upgrading and utilization coupled with hydrogen production based on electrochemical catalysis technology holds promise as an important pathway for environmental pollution control and the efficient production of green hydrogen.

[0004] Currently, the electrocatalytic oxidation (EGOR) of ethylene glycol (EG), a hydrolysate of PET plastics, coupled with cathode hydrogen production (HER) mainly relies on noble metal catalysts, such as Ru, Pt, and Pd. For the EGOR process, noble metal catalysts tend to produce high-value-added C2 products (such as glycolic acid, GA), while non-noble metal catalysts tend to produce low-value-added C1 products (such as formic acid). However, noble metal catalysts are severely limited by the high sensitivity to carbonyl intermediates, and their activity generally decreases rapidly within 10 hours. Furthermore, their high cost and limited reserves objectively restrict the large-scale industrialization of this technology. Therefore, developing a highly efficient, stable, and inexpensive electrocatalyst to reduce energy consumption and improve selectivity is of significant practical importance. Summary of the Invention

[0005] The purpose of this invention is to provide a nano-octahedral electrocatalyst and its preparation and application, so as to solve the problems existing in the prior art.

[0006] To achieve the above objectives, the present invention provides the following solution:

[0007] One of the technical solutions of the present invention: a method for preparing a nano-octahedral electrocatalyst, comprising the following steps:

[0008] (1) Preparation of Cu2O nano octahedrons: Add a mixed solution of alkali and reducing agent B to a mixed solution A of soluble inorganic copper salt and surfactant, heat to react, centrifuge, wash and dry to obtain the Cu2O nano octahedrons (templates);

[0009] (2) The Cu2O nano octahedrons were dispersed in a mixed solution of Na2S2O3, vanadate and cobalt salt, stirred and reacted, centrifuged, washed and dried to obtain (CoCu)2V2O7@Cu2O core-shell structure intermediate (i.e., (CoCu)2V2O7 active layer was deposited on the surface of Cu2O nano octahedrons).

[0010] (3) The (CoCu)2V2O7@Cu2O core-shell structure intermediate was dispersed in a mixed solution of vanadate, ruthenium salt, reducing agent and water, stirred and reacted under ice bath conditions, washed and dried to obtain the nano octahedral electrocatalyst (i.e., the multi-level structure Ru-(CoCu)2V2O7@Cu2O nano octahedral electrocatalyst).

[0011] The multi-level structure refers to the fact that the electrocatalyst has a core-shell structure, and the shell is covered with an array of nanosheets.

[0012] In step (1), the reducing agent includes L-ascorbic acid (C6H8O6);

[0013] And / or, the soluble inorganic copper salt is selected from any one of copper nitrate, copper chloride, and copper sulfate;

[0014] And / or, the surfactant includes polyvinylpyrrolidone (PVP);

[0015] And / or, the heating reaction is carried out at a temperature of 80–90°C for a duration of 3–6 hours;

[0016] And / or, the molar ratio of the soluble inorganic copper salt to the reducing agent is 1:(5-7);

[0017] And / or, the surfactant content in the mixed solution A is 40-60 g / L;

[0018] And / or, the drying temperature is 60–80°C, and the time is 12–18 hours;

[0019] And / or, the centrifugal washing includes washing the product with water and anhydrous ethanol at least three times each, with a centrifugation speed of 6000-9500 rpm and a time of 6-10 min.

[0020] In step (2), the vanadate is selected from sodium orthovanadate or sodium metavanadate; preferably sodium orthovanadate;

[0021] And / or, the cobalt salt is selected from at least one of cobalt nitrate, cobalt chloride, and cobalt sulfate;

[0022] And / or, the ratio of Cu2O nano-octahedrons, Na2S2O3, cobalt salt and vanadate is 50-100g:1200-1300g:0.2-0.5mol:0.2-0.5mol;

[0023] And / or, the concentration of the Cu2O nano octahedrons in the mixed solution is 10–20 g / L;

[0024] And / or, the stirring reaction time is 10 to 30 minutes;

[0025] And / or, the drying temperature is 60–80°C, and the time is 12–18 hours;

[0026] And / or, the centrifugal washing includes washing the product with water and anhydrous ethanol at least three times each, with a centrifugation speed of 6000-9500 rpm and a time of 6-10 min.

[0027] In step (3), the vanadate is selected from sodium orthovanadate or sodium metavanadate;

[0028] And / or, the ruthenium salt is selected from ruthenium nitrate or ruthenium trichloride;

[0029] And / or, the reducing agent includes NaBH4;

[0030] And / or, the molar ratio of the vanadate, ruthenium salt and reducing agent is (5-10):(1-5):(40-50);

[0031] And / or, the temperature of the ice bath is 0–5°C;

[0032] And / or, the stirring reaction time is 10 to 30 minutes;

[0033] And / or, the drying temperature is 60–80°C, and the time is 12–18 hours;

[0034] And / or, the washing includes washing twice by centrifugation with water and ethanol, respectively, at a speed of 6000-9500 rpm for 6-10 min.

[0035] The second technical solution of the present invention: a nano-octahedral electrocatalyst (a multi-level structure Ru-(CoCu)2V2O7@Cu2O nano-octahedral electrocatalyst) prepared by the above preparation method.

[0036] The multi-level Ru-(CoCu)₂V₂O₇@Cu₂O electrocatalyst of this invention combines the dual properties of noble metals and oxygen-loving non-noble metals, reducing energy consumption while preventing excessive oxidation and improving the selectivity of C₂ products. The electrocatalyst of this invention has a unique multi-level core-shell structure, which enhances the structural toughness and stability of the electrocatalyst. It has advantages such as high efficiency, stability, low cost, and good selectivity. Using this electrocatalyst can realize the upgraded utilization of PET and energy-saving green hydrogen production.

[0037] The edge length of the multi-level structure Ru-(CoCu)2V2O7@Cu2O nano-octahedral electrocatalyst is 800-1000 nm.

[0038] The average particle size of Ru-(CoCu)2V2O7 nanoparticles in the multi-level structured Ru-(CoCu)2V2O7@Cu2O nano-octahedral electrocatalyst is 50-80 nm; the thickness of the (CoCu)2V2O7 active layer is 60-100 nm.

[0039] The third technical solution of the present invention: the application of the above-mentioned nano-octahedral electrocatalyst in hydrogen energy production.

[0040] The fourth technical solution of the present invention: the application of the above-mentioned nano-octahedral electrocatalyst in hydrogen production by coupled cathode of ethylene glycol electrocatalytic oxidation (EGOR).

[0041] The present invention discloses the following technical effects:

[0042] (1) The multi-level structure Ru-(CoCu)2V2O7@Cu2O nano-octahedral electrocatalyst of the present invention has a simple preparation process, mild conditions, short time consumption and low cost, and is suitable for large-scale production. It solves the problems of insufficient activity, poor stability, low selectivity, high energy consumption and slow kinetics of existing traditional catalysts. The prepared electrocatalyst is suitable for the coupling of PET plastic upgrading and efficient hydrogen production, and has the dual functions of environmental pollution control and clean energy production. It provides a new solution for the development of electrocatalysts in EGOR reaction and has broad application prospects and important scientific value in the field of plastic upgrading and hydrogen production coupling.

[0043] (2) The synergistic effect of multi-level structure and element doping endows the catalyst with significant ethylene glycol electrocatalytic oxidation performance, and high value-added C2 products are selectively prepared, realizing the upgrading and utilization of polyethylene terephthalate (PET) plastic.

[0044] (3) Compared with traditional preparation methods, the present invention achieves comprehensive optimization of multi-strategy synergistic regulation and surface electronic properties, and has the advantages of unique morphology, adjustable composition and stable structure. It can overcome the problems of high energy consumption, poor stability and low selectivity faced by EGOR catalysts under alkaline conditions. Compared with the prior art, the electrocatalyst prepared by the present invention has the following advantages:

[0045] By leveraging the synergistic effect of noble metals and oxyphilic non-noble elements, the adsorption behavior of the key intermediate (*OCCH2OH) at Ru sites can be enhanced, thereby increasing selectivity and yielding high-value-added C2 products.

[0046] By doping elements, the electronic structure and local coordination environment of Co sites can be adjusted, increasing the number of effective active sites, accelerating electron transport, improving catalytic efficiency, and reducing energy consumption.

[0047] The uniquely designed multi-level structure enriches the active specific surface area, shortens the mass transfer path, accelerates the diffusion rate, and enhances structural flexibility and stability.

[0048] The preparation method of the present invention has universal applicability. By simply changing the type and dosage of soluble metal inorganic salts, a series of hierarchical nano-octahedral electrocatalysts with similar morphology and structure can be obtained. Attached Figure Description

[0049] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in 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.

[0050] Figure 1 A schematic diagram of the synthesis process of the hierarchical Ru-(CoCu)2V2O7@Cu2O nano-octahedral electrocatalyst;

[0051] Figure 2 XRD pattern of Cu2O nano-octahedrons prepared in Example 1;

[0052] Figure 3 SEM images of Cu2O nano octahedrons prepared in Example 1, where (a) and (b) are SEM images at different magnifications;

[0053] Figure 4 The XRD pattern of the Ru-(CoCu)2V2O7@Cu2O nano-octahedral electrocatalyst prepared in Example 1;

[0054] Figure 5SEM image of the Ru-(CoCu)2V2O7@Cu2O nano-octahedral electrocatalyst prepared in Example 1;

[0055] Figure 6 TEM image of the Ru-(CoCu)2V2O7@Cu2O nano-octahedral electrocatalyst prepared in Example 1;

[0056] Figure 7 EDX-Mapping diagram of Ru-(CoCu)2V2O7@Cu2O nano-octahedral electrocatalyst prepared in Example 1, where (a) represents element Ru, (b) represents element Co, (c) represents element Cu, (d) represents element V, (e) represents element O, and (f) represents all elements;

[0057] Figure 8 SEM images and EDS linear scan elemental distribution maps of the Ru-(CoCu)2V2O7@Cu2O nano-octahedral electrocatalyst prepared in Example 1 are shown. (a) is the SEM image, (b) to (f) are the distribution maps of each element, and (g) is the comprehensive distribution map of all elements.

[0058] Figure 9 The XPS spectra of the Ru-(CoCu)2V2O7@Cu2O nano-octahedral electrocatalyst prepared in Example 1 are shown in the following figures: (a) Cu 2p spectrum, (b) Cu LMM Auger spectrum, (c) Co 2p spectrum, (d) Ru 3p spectrum, (e) V2p spectrum, and (f) O1s spectrum.

[0059] Figure 10 The XRD pattern of the Ru-(CoCu)2V2O7@Cu2O nano-octahedral electrocatalyst prepared in Example 2;

[0060] Figure 11 SEM image of the Ru-(CoCu)2V2O7@Cu2O nano-octahedral electrocatalyst prepared in Example 2;

[0061] Figure 12 The XRD pattern of the Ru-(CoCu)2V2O7@Cu2O nano-octahedral electrocatalyst prepared in Example 3;

[0062] Figure 13 SEM image of the Ru-(CoCu)2V2O7@Cu2O nano-octahedral electrocatalyst prepared in Example 3;

[0063] Figure 14 The XRD pattern of the Ru-Cu2V2O7@Cu2O nano-octahedral electrocatalyst prepared in Comparative Example 1;

[0064] Figure 15SEM image of the Ru-Cu2V2O7@Cu2O nano-octahedral electrocatalyst prepared in Comparative Example 1;

[0065] Figure 16 XRD pattern of the (CoCu)2V2O7@Cu2O core-shell structured nano-octahedral electrocatalyst prepared in Comparative Example 2;

[0066] Figure 17 SEM images of the (CoCu)2V2O7@Cu2O core-shell structured nano-octahedral electrocatalyst prepared in Comparative Example 2, where (a) and (b) are SEM images at different magnifications;

[0067] Figure 18 LSV diagrams of OER and EGOR generated by the Ru-(CoCu)2V2O7@Cu2O nano-octahedral electrocatalyst prepared in Example 1;

[0068] Figure 19 The current-potential diagrams for OER and EGOR of the Ru-(CoCu)2V2O7@Cu2O nano-octahedral electrocatalyst prepared in Example 1 are shown.

[0069] Figure 20 Tafel slope diagrams for OER and EGOR generation of the Ru-(CoCu)2V2O7@Cu2O nano-octahedral electrocatalyst prepared in Example 1;

[0070] Figure 21 The image shows the it curves of the Ru-(CoCu)2V2O7@Cu2O nano-octahedral electrocatalyst prepared in Example 1 under different voltages.

[0071] Figure 22 The Ru-(CoCu)₂V₂O₇@Cu₂O nano-octahedral electrocatalyst prepared in Example 1 was tested for EGOR under different voltages. 1 HNMR spectrum;

[0072] Figure 23 The LSV curves of the electrocatalysts prepared in Examples 1-3 and Comparative Examples 1-2 in 1M KOH + 1M EG electrolyte;

[0073] Figure 24 The electrocatalysts prepared in Examples 1-3 and Comparative Examples 1-2 are shown in the current-potential diagrams in 1M KOH + 1M EG electrolyte.

[0074] Figure 25 The stability curves of the electrocatalysts prepared in Example 1 and Comparative Examples 1-2 in 1M KOH + 1M EG electrolyte are shown.

[0075] Figure 26The LSV curves of the Ru-(CoCu)2V2O7@Cu2O nano-octahedral electrocatalyst prepared in Example 1 in 1M KOH+1MEG and PET hydrolysate are shown.

[0076] Figure 27 The product of the electrooxidation of the Ru-(CoCu)₂V₂O₇@Cu₂O nano-octahedral electrocatalyst prepared in Example 1 in PET hydrolysate. 1 HNMR spectrum;

[0077] Figure 28 The product of the electrooxidation of the Ru-(CoCu)₂V₂O₇@Cu₂O nano-octahedral electrocatalyst prepared in Example 1 in PET hydrolysate. 13 C NMR spectrum. Detailed Implementation

[0078] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0079] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0080] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0081] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be obvious to those skilled in the art. This specification and embodiments are merely exemplary.

[0082] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0083] Unless otherwise specified, the materials in the following examples were prepared according to existing methods or purchased directly from the market.

[0084] In the following examples, cobalt nitrate is used as the cobalt source. However, cobalt nitrate can also be replaced by cobalt sulfate or cobalt chloride. Sodium vanadate can be replaced by sodium metavanadate, and ruthenium chloride can be replaced by ruthenium nitrate. Thus, a hierarchical Ru-(CoCu)2V2O7@Cu2O nano-octahedral electrocatalyst is prepared.

[0085] Example 1

[0086] A method for preparing a hierarchical Ru-(CoCu)2V2O7@Cu2O nano-octahedral electrocatalyst:

[0087] (1) Preparation of Cu2O nano octahedrons:

[0088] 0.171 g of CuCl2·2H2O (1 mmol) solid was dissolved in 100 mL of deionized water to form a solution. 5.556 g of PVP was added as a surfactant under uniform stirring in an oil bath at 80 °C to prepare mixed solution A.

[0089] Mix 15 mL of 2 mol / L NaOH solution and 10 mL of 0.6 mol / L L-ascorbic acid solution (6 mmol) to obtain mixed solution B.

[0090] Mixed solution A was added to mixed solution B, and the mixture was stirred thoroughly in an oil bath at 80°C for 5 min by liquid-phase diffusion. After stirring, the mixture was allowed to stand and age in an oil bath at 80°C for 4 h. The product was washed three times each with deionized water and anhydrous ethanol (centrifuged at 9600 rpm / min for 10 min for water washing and at 6000 rpm / min for 6 min for anhydrous ethanol washing). The resulting product was then placed in a drying oven and dried at 60°C for 12 h to obtain Cu2O nano-octahedrons (template).

[0091] (2) Preparation of (CoCu)2V2O7@Cu2O core-shell structure intermediate: 0.2 mmol Co(NO3)2·6H2O, 0.2 mmol Na3VO4·12H2O and 1.24 g Na2S2O3 were added to 5 mL of deionized water and mixed evenly to obtain a mixed solution;

[0092] 50 mg of Cu2O nano-octahedral powder was added to the mixed solution and stirred at room temperature for 10 min. The mixture was then washed three times each with deionized water and anhydrous ethanol (centrifuged at 9600 rpm for 10 min during washing). The resulting product was then placed in a drying oven and dried at 60 °C for 12 h to obtain the (CoCu)2V2O7@Cu2O core-shell structure intermediate (an active layer of (CoCu)2V2O7 was generated on the surface of Cu2O nano-octahedral through a precipitation conversion strategy, which is (CoCu)2V2O7@Cu2O nano-octahedral).

[0093] (3) Preparation of multi-level structure Ru-(CoCu)2V2O7@Cu2O nano octahedral electrocatalyst: 0.5 mmol Na3VO4·12H2O, 0.5 mmol RuCl3 and 4 mmol NaBH4 were added to 10 mL of deionized water and mixed evenly to obtain a mixed solution;

[0094] The (CoCu)2V2O7@Cu2O core-shell structure intermediate prepared in step (2) was added to the mixed solution. The reaction was stopped after stirring for 10 min under the reaction conditions of ice-water bath at 0-5℃. The product was washed twice by centrifugation with deionized water and anhydrous ethanol (centrifugation at 9600 rpm / min for 10 min for water washing and centrifugation at 6000 rpm / min for 6 min for anhydrous ethanol washing). The obtained product was then placed in a drying oven and dried at 60℃ for 12 h to obtain the multi-level structure Ru-(CoCu)2V2O7@Cu2O nano octahedral electrocatalyst (i.e., Ru-(CoCu)2V2O7@Cu2O nano octahedral electrocatalyst).

[0095] A schematic diagram of the synthesis process of the Ru-(CoCu)2V2O7@Cu2O nano-octahedral electrocatalyst is shown below. Figure 1 .

[0096] The XRD pattern of the Cu₂O nanooctahedrons prepared in this embodiment is shown in the figure. Figure 2 .

[0097] from Figure 2 As can be seen from the above, all XRD diffraction peaks of the Cu2O nano-octahedron prepared in this embodiment match the standard card (JCPDS No. 05-0667) of cubic Cu2O, indicating that the above preparation method successfully synthesized the Cu2O precursor.

[0098] SEM images of the Cu₂O nanooctahedrons prepared in this embodiment are shown below. Figure 3 , Figure 3 (a) and (b) are SEM images at different magnifications.

[0099] from Figure 3As can be seen from this embodiment, the method can be used to prepare monodisperse Cu2O nano octahedrons on a large scale, with a side length of 700-900 nm, a smooth surface, and a regular and uniform structure.

[0100] The XRD pattern of the Ru-(CoCu)2V2O7@Cu2O nanooctahedral electrocatalyst prepared in this embodiment is shown in the figure. Figure 4 .

[0101] from Figure 4 As can be seen from the data, the Ru-(CoCu)₂V₂O₇@Cu₂O nano-octahedral electrocatalyst prepared in this embodiment contains undissolved Cu₂O cores, as well as Cu₂V₂O₇ and Co₂V₂O₇. Simultaneously, due to the successful doping of Ru atoms, a slight negative shift in its diffraction peak position is observed. The absence of other impurity phases indicates the successful synthesis of the Ru-(CoCu)₂V₂O₇@Cu₂O nano-octahedral electrocatalyst.

[0102] The SEM image of the Ru-(CoCu)2V2O7@Cu2O nanooctahedral electrocatalyst prepared in this embodiment is shown below. Figure 5 .

[0103] from Figure 5 As can be seen, a Ru-doped (CoCu)₂V₂O₇ active layer was successfully deposited on the surface of Cu₂O nano-octahedra, forming Ru-(CoCu)₂V₂O₇@Cu₂O nano-octahedra with a multi-level structure. This material inherits the nano-octahedral morphology of the Cu₂O precursor, but its particle size is significantly increased, with an edge length of 800–1000 nm. The results indicate that the Ru-(CoCu)₂V₂O₇@Cu₂O nano-octahedral electrocatalyst synthesized by the method in this embodiment possesses high structural stability.

[0104] TEM images of the Ru-(CoCu)2V2O7@Cu2O nanooctahedral electrocatalyst prepared in this embodiment are shown below. Figure 6 .

[0105] from Figure 6 As can be seen from the data, the Ru-(CoCu)2V2O7@Cu2O nano-octahedral electrocatalyst has a multi-level core-shell structure.

[0106] Figure 7 The image shows the EDX-Mapping diagram of the Ru-(CoCu)2V2O7@Cu2O nano-octahedral electrocatalyst prepared in this embodiment, where (a) represents element Ru, (b) represents element Co, (c) represents element Cu, (d) represents element V, (e) represents element O, and (f) represents all elements.

[0107] from Figure 7As can be seen, the catalyst contains five elements: Ru, Co, Cu, V, and O. All elements are distributed relatively evenly, and no phase segregation is observed, indicating that the noble metal Ru has been successfully doped into the (CoCu)2V2O7@Cu2O electrocatalyst.

[0108] Figure 8 The images show the SEM image and EDS linear scan elemental distribution map of the Ru-(CoCu)2V2O7@Cu2O nano-octahedral electrocatalyst prepared in this embodiment. (a) is the SEM image, (b) to (f) are the distribution maps of each element, and (g) is the comprehensive distribution map of all elements.

[0109] from Figure 8 As can be seen in Figure (a), the catalyst has a multi-level structure, and the marked areas in the figure are the measurement paths for elemental distribution.

[0110] from Figure 8 As shown in Figures (b) to (g), each element exhibits different distribution intensities along the scanning path. The results indicate that Ru, Co, Cu, V, and O elements are relatively uniformly distributed within the catalyst structure, without significant separation, suggesting that these elements are evenly distributed within the material. Figure 7 The results are consistent. This uniform distribution ensures the synergistic effect of multiple active sites, thus contributing to the high activity and stability of the catalyst in electrocatalytic reactions.

[0111] Figure 9 The images show the XPS spectra of the Ru-(CoCu)2V2O7@Cu2O nano-octahedral electrocatalyst prepared in this embodiment, where (a) is the Cu 2p spectrum, (b) is the Cu LMM Auger spectrum, (c) is the Co 2p spectrum, (d) is the Ru 3p spectrum, (e) is the V2p spectrum, and (f) is the O1s spectrum.

[0112] from Figure 9 As can be seen from the above, the Ru-(CoCu)2V2O7@Cu2O nano-octahedral electrocatalyst prepared in this embodiment contains Cu. 2+ Cu + Co 2+ Co 3+ Ru 3+ Ru 4+ V 4+ V 5+ .

[0113] from Figure 9 As shown in Figure (b), Cu undergoes L-shell electron excitation and Auger transition. The LMM peak further confirms the oxidation state of Cu, mainly as Cu. 2+ exist.

[0114] from Figure 9 The binding energy of the 1s orbital of O can be seen in figure (f), where O v O ads The MO bond represents an oxygen vacancy, adsorbed oxygen, and a metal-oxygen bond, respectively.

[0115] The above results indicate that the metal elements in the Ru-(CoCu)₂V₂O₇@Cu₂O nano-octahedral electrocatalyst exhibit multiple oxidation states, and oxygen also exists in different chemical environments. These characteristics suggest that the catalyst possesses a complex electronic structure and redox properties, which can enhance its activity in electrocatalytic processes.

[0116] Example 2

[0117] Same as Example 1, except that the amount of RuCl3 used in step (3) is 0.3 mmol.

[0118] The XRD pattern of the Ru-(CoCu)2V2O7@Cu2O nanooctahedral electrocatalyst prepared in this embodiment is shown in the figure. Figure 10 .

[0119] from Figure 10 As can be seen, the characteristic diffraction peaks of Cu₂V₂O₇, Co₂V₂O₇, and Cu₂O all exist at this ruthenium concentration, and their positions are basically consistent. This indicates that low-dose ruthenium doping does not significantly change the crystal structure of the host phase.

[0120] The SEM image of the Ru-(CoCu)2V2O7@Cu2O nanooctahedral electrocatalyst prepared in this embodiment is shown below. Figure 11 .

[0121] from Figure 11 As can be seen from the above, the Ru-(CoCu)2V2O7@Cu2O nano-octahedral electrocatalyst prepared in this embodiment has a similar structure to that of Example 1 (multi-level structure and nano-octahedral morphology).

[0122] Example 3

[0123] Same as Example 1, except that the amount of RuCl3 used in step (3) is 0.1 mmol.

[0124] The XRD pattern of the Ru-(CoCu)2V2O7@Cu2O nanooctahedral electrocatalyst prepared in this embodiment is shown in the figure. Figure 12 .

[0125] from Figure 12 As can be seen, the characteristic diffraction peaks of Cu₂V₂O₇, Co₂V₂O₇, and Cu₂O are all present at this ruthenium concentration, and the peak positions are basically consistent. This indicates that the crystal structure of these main phases does not undergo significant changes at this ruthenium concentration.

[0126] The SEM image of the Ru-(CoCu)2V2O7@Cu2O nanooctahedral electrocatalyst prepared in this embodiment is shown below. Figure 13 .

[0127] from Figure 13 As can be seen, compared with RuCl3 concentration of 0.5 mmol, the catalyst particles synthesized at a ruthenium concentration of 0.1 mmol are significantly smaller, more irregular in shape, and have a smoother surface, lacking obvious nanoscale rough structures. This indicates that the concentration of ruthenium has an impact on crystal growth and surface structure formation, and higher concentrations of ruthenium make it more conducive to the formation of rough, nanoscale surface structures.

[0128] Comparative Example 1

[0129] Preparation method of Ru-Cu2V2O7@Cu2O nano-octahedral electrocatalyst:

[0130] (1) Preparation of Cu2O nano octahedrons:

[0131] 0.171 g of CuCl2·2H2O (1 mmol) solid was dissolved in 100 mL of deionized water to form a solution. 5.556 g of PVP was added as a surfactant under uniform stirring in an oil bath at 80 °C to prepare mixed solution A.

[0132] Mix 15 mL of 2 mol / L NaOH solution and 10 mL of 0.6 mol / L L-ascorbic acid solution (6 mmol) to obtain mixed solution B.

[0133] Mixed solution A was added to mixed solution B, and the mixture was stirred thoroughly in an oil bath at 80°C for 5 min by liquid-phase diffusion. After stirring, the mixture was allowed to stand and age in an oil bath at 80°C for 4 h. The product was washed three times each with deionized water and anhydrous ethanol (centrifuged at 9600 rpm / min for 10 min for water washing and at 6000 rpm / min for 6 min for anhydrous ethanol washing). The resulting product was then placed in a drying oven and dried at 60°C for 12 h to obtain Cu2O nano-octahedrons (template).

[0134] (2) Preparation of Ru-Cu2V2O7@Cu2O nano octahedral electrocatalyst: 0.5 mmol Na3VO4·12H2O, 0.5 mmol RuCl3 and 4 mmol NaBH4 were added to 10 mL of deionized water and mixed evenly to obtain a mixed solution;

[0135] The Cu2O nano-octahedrons prepared in step (2) were added to the mixed solution and stirred for 10 min in an ice-water bath at 0-5℃. The reaction was then stopped. The product was washed twice by centrifugation with deionized water and anhydrous ethanol (for water washing, centrifugation was performed at 9600 rpm / min for 10 min; for anhydrous ethanol washing, centrifugation was performed at 6000 rpm / min for 6 min). The resulting product was then placed in a drying oven and dried at 60℃ for 12 h to obtain the Ru-Cu2V2O7@Cu2O nano-octahedron electrocatalyst.

[0136] The XRD pattern of the Ru-Cu2V2O7@Cu2O nano-octahedral electrocatalyst prepared in this comparative example is shown below. Figure 14 .

[0137] from Figure 14 As can be seen from the results, all diffraction peaks of the Ru-Cu2V2O7@Cu2O nano-octahedral electrocatalyst prepared in this comparative example can identify the Cu2O and Cu2V2O7 phases, and the diffraction peak positions show a slight shift, indicating that Ru element is uniformly doped into the surface active phase. Therefore, the Ru-Cu2V2O7@Cu2O nano-octahedral electrocatalyst was successfully synthesized.

[0138] SEM images of the Ru-Cu2V2O7@Cu2O nano-octahedral electrocatalyst prepared in this comparative example are shown below. Figure 15 .

[0139] from Figure 15 As can be seen, compared with Ru-(CoCu)₂V₂O₇@Cu₂O, Ru-Cu₂V₂O₇@Cu₂O exhibits an irregular aggregated morphology and lacks a clear geometric shape. This disordered aggregated morphology leads to a lower specific surface area and uneven distribution of active sites, affecting the catalyst's activity and stability. This indicates that Co doping plays a crucial role in maintaining structural integrity and promoting the formation of a regular morphology; Co doping can make the catalyst's morphology more uniform and stable.

[0140] Comparative Example 2

[0141] Preparation method of (CoCu)2V2O7@Cu2O core-shell structured nano-octahedral electrocatalyst:

[0142] (1) Preparation of Cu2O nano octahedrons: 0.171g CuCl2·2H2O (1mmol) solid was dissolved in 100mL deionized water to form a solution. 5.556g PVP was added as a surfactant under uniform stirring in an oil bath at 80℃ to prepare mixed solution A.

[0143] Mix 15 mL of 2 mol / L NaOH solution and 10 mL of 0.6 mol / L L-ascorbic acid solution (6 mmol) to obtain mixed solution B.

[0144] Mixed solution A was added to mixed solution B, and the mixture was stirred thoroughly in an oil bath at 80°C for 5 min by liquid-phase diffusion. After stirring, the mixture was allowed to stand and age in an oil bath at 80°C for 4 h. The product was washed three times each with deionized water and anhydrous ethanol (centrifuged at 9600 rpm / min for 10 min for water washing and at 6000 rpm / min for 6 min for anhydrous ethanol washing). The resulting product was then placed in a drying oven and dried at 60°C for 12 h to obtain Cu2O nano-octahedrons (template).

[0145] (2) Preparation of (CoCu)2V2O7@Cu2O core-shell structured nano-octahedral electrocatalyst: 0.2 mmol Co(NO3)2·6H2O, 0.2 mmol Na3VO4·12H2O, and 1.24 g Na2S2O3 were added to 5 mL of deionized water to obtain a mixed solution;

[0146] 50 mg of Cu2O nano-octahedral precursor powder was added to the mixed solution, stirred at room temperature for 10 min, and then washed three times with deionized water (centrifuged at 9600 rpm / min for 10 min during washing). The resulting product was then placed in a drying oven and dried at 60 °C for 12 h to obtain (CoCu)2V2O7@Cu2O core-shell structured nano-octahedral electrocatalyst.

[0147] The XRD pattern of the (CoCu)₂V₂O₇@Cu₂O core-shell structured nano-octahedral electrocatalyst prepared in this comparative example is shown below. Figure 16 .

[0148] from Figure 16 As can be seen from the results, all diffraction peaks of the (CoCu)2V2O7@Cu2O core-shell octahedral nanocatalyst prepared in this comparative example can identify the Cu2O, Cu2V2O7 and Co2V2O7 phases, indicating that the (CoCu)2V2O7@Cu2O core-shell octahedral nanocatalyst was successfully synthesized.

[0149] SEM images of the (CoCu)₂V₂O₇@Cu₂O core-shell structured nano-octahedral electrocatalyst prepared in this comparative example are shown below. Figure 17 , Figure 17 (a) and (b) are SEM images at different magnifications.

[0150] from Figure 17As can be seen, the (CoCu)2V2O7@Cu2O core-shell structured nano-octahedral electrocatalyst has a regular octahedral core-shell structure, and its surface (CoCu)2V2O7 active layer forms a uniform nanosheet morphology, which is regularly loaded on the surface of the nano-octahedral shell.

[0151] Example 1

[0152] The composition of the electrocatalysts prepared in the examples and comparative examples was further analyzed by inductively coupled atomic emission spectrometry (ICP-AES), and the results are shown in Table 1.

[0153] Table 1. Inductively Coupled Atomic Emission Spectroscopy (ICP-ESI) data of the electrocatalysts prepared in the examples and comparative examples.

[0154]

[0155] Example 2

[0156] (I) Fabrication of the working electrode:

[0157] 10 mg of the Ru-(CoCu)₂V₂O₇@Cu₂O nano-octahedral electrocatalyst prepared in Example 1 was weighed and dispersed in 500 μL of a mixed solution containing 150 μL of 5 wt.% Nafion solution and 350 μL of anhydrous ethanol. The solution was then sonicated in an ultrasonic cell disruptor for 30 min to ensure uniform dispersion. The catalyst solution was then continuously agitated on a shaker for 12 h to form a uniformly dispersed catalyst slurry. 20 μL of the catalyst slurry was pipetted onto a polished glassy carbon electrode sheet (GCE, 5 mm diameter), allowing it to diffuse naturally to cover the electrode surface. The electrode was then allowed to air dry to obtain the glassy carbon electrode as the working electrode.

[0158] (II) Performance Testing

[0159] (1) OER and EGOR activity tests of Ru-(CoCu)2V2O7@Cu2O nano-octahedral electrocatalysts:

[0160] The OER used a 1 mol / L potassium hydroxide solution (KOH, pH = 14.00) as the electrolyte, and the EGOR used a mixed solution of 1 mol / L KOH and 1 mol / L LEG as the electrolyte. Both used a Hg / HgO electrode as the reference electrode, a carbon rod electrode as the counter electrode, and a glassy carbon electrode as the working electrode. The electrochemical performance of the Ru-(CoCu)₂V₂O₇@Cu₂O nano-octahedral electrocatalyst was tested using a Shanghai Chenhua electrochemical workstation (model CHI660E or CHI760E). The performance of OER and EGOR was tested using linear sweep voltammetry, with a test range of 0–2.0 V and a scan rate of 5 mV / s. Ohmic drop caused by solution resistance was compensated for using 95% iR correction. All potentials were normalized to the potential of the reversible hydrogen electrode (RHE) using the formula: E RHE =E Hg / HgO +0.059pH+0.098. The logarithms of the overpotential (η) and current density (j) are processed to plot the Tafel curve. The linear part is fitted to the Tafel equation: η=blog(j)+a, and the Tafel slope is calculated.

[0161] (2) Stability tests of OER and EGOR of Ru-(CoCu)2V2O7@Cu2O nano-octahedral electrocatalysts:

[0162] Using a test system similar to that in step (1), OER used 1 mol / L potassium hydroxide solution (KOH, pH = 14.00) as the electrolyte, and EGOR used a mixed solution of 1 mol / L KOH solution and 1 mol / L LEG as the electrolyte. Both used Hg / HgO electrode as reference electrode, carbon rod electrode as counter electrode, and glassy carbon electrode as working electrode. On the Shanghai Chenhua electrochemical workstation (model CHI660E or CHI760E), the constant voltage stability test of Ru-(CoCu)2V2O7@Cu2O nano octahedral electrocatalyst was carried out by chronoamperometry in a potential range of 0.6V to 1.1V.

[0163] The LSV diagrams of OER and EGOR of the Ru-(CoCu)2V2O7@Cu2O nano-octahedral electrocatalyst prepared in Example 1 are shown below. Figure 18 .

[0164] from Figure 18 As can be seen from the results, the Ru-(CoCu)2V2O7@Cu2O nano-octahedral electrocatalyst EGOR prepared in Example 1 has a lower onset potential than that of the OER reaction, and at the same time has a higher current density response at a lower operating voltage, indicating that the catalyst has excellent EGOR catalytic activity.

[0165] The current-potential diagrams for OER and EGOR of the Ru-(CoCu)2V2O7@Cu2O nano-octahedral electrocatalyst prepared in Example 1 are shown below. Figure 19 .

[0166] from Figure 19 As can be seen, at the same current density, the potential during EGOR is lower than that during OER. When it reaches 350 mA / cm²... 2 At the current density, the OER reaction requires a voltage drive of 2.03V, while the EGOR reaction only requires 0.88V, reducing the voltage loss by 1.15V.

[0167] The Tafel slope diagrams of OER and EGOR generation of the Ru-(CoCu)2V2O7@Cu2O nano-octahedral electrocatalyst prepared in Example 1 are shown below. Figure 20 .

[0168] from Figure 20 As can be seen from the data, the Tafel slope of the Ru-(CoCu)2V2O7@Cu2O nano-octahedral electrocatalyst prepared in Example 1 for the EGOR reaction is low, only 76 mV / dec, while the Tafel slope for the OER reaction is as high as 163 mV / dec, indicating that the catalyst has a kinetic advantage in the EGOR reaction.

[0169] The it graphs of the Ru-(CoCu)2V2O7@Cu2O nano-octahedral electrocatalyst prepared in Example 1 at different voltages are shown below. Figure 21 .

[0170] from Figure 21 As can be seen, the Ru-(CoCu)2V2O7@Cu2O nano-octahedral electrocatalyst prepared in Example 1 showed relatively small current density decay and maintained good stability when operating for 30 minutes in a potential range of 0.6V to 1.0V.

[0171] Example 1: Ru-(CoCu)₂V₂O₇@Cu₂O nano-octahedral electrocatalyst prepared under different voltages after EGOR testing 1 HNMR image see Figure 22 . Figure 22 In this formula, FA stands for formic acid, D2O for heavy water, GA for glycolic acid, EG for ethylene glycol, and DMSO for dimethyl sulfoxide.

[0172] from Figure 22 As can be seen, the EGOR process at 1.1V exhibits the highest selectivity for producing high-value-added C2 products (glycolic acid, GA), indicating that this catalysis has the potential to upgrade and utilize PET plastics.

[0173] Example 3

[0174] (1) The LSV curves of EGOR generated by the electrocatalysts prepared in Examples 1-3 and Comparative Examples 1-2 were measured in 1 mol / L KOH solution and 1 mol / L EG electrolyte. The measurement method was the same as in Effect Example 2. The results are shown in […]. Figure 23 .

[0175] from Figure 23 As can be seen from the results, the Ru-(CoCu)2V2O7@Cu2O nano-octahedral electrocatalyst prepared in Example 1 has better EGOR activity than that of Comparative Examples 1-2, and its activity is not much different from that of Examples 2-3. Even at a low operating voltage, it can still have a high current response, indicating that the synergistic effect of the noble metal Ru and the oxygen-loving non-noble element Co plays an important role in improving the EGOR activity of the catalyst.

[0176] The Ru-Cu2V2O7@Cu2O nano-octahedral electrocatalyst prepared in Comparative Example 1 showed better EGOR activity than that in Comparative Example 2, but it was much lower than that in Examples 1-3, indicating that cobalt also plays an important role in improving the EGOR activity of the catalyst.

[0177] The (CoCu)2V2O7@Cu2O core-shell nano-octahedral electrocatalyst prepared in Comparative Example 2 had the lowest EGOR activity, which was much lower than that of Examples 1-3 and slightly lower than that of Comparative Example 1, indicating that ruthenium plays an important role in improving the EGOR activity of the catalyst.

[0178] (2) The current-potential of the electrocatalysts prepared in Examples 1-3 and Comparative Examples 1-2 was measured in 1 mol / L KOH solution and 1 mol / L EG electrolyte. The measurement method was the same as in Effect Example 2, and the results are shown in [Figure 2]. Figure 24 .

[0179] from Figure 24 As can be seen, the Ru-(CoCu)₂V₂O₇@Cu₂O nano-octahedral electrocatalyst prepared in Example 1 exhibits better electrochemical performance than the electrocatalysts prepared in Examples 2-3 and Comparative Examples 1-2, generating a higher current density at the same voltage. When the anodic decomposition voltage is 1.0V, the Ru-(CoCu)₂V₂O₇@Cu₂O nano-octahedral electrocatalyst prepared in Example 1 exhibits an EGOR current density as high as 429 mA / cm². 2 It is far higher than that of Comparative Example 1 (142 mA / cm). 2 ) and Comparative Example 2 (43 mA / cm 2 ).

[0180] from Figure 24As can be seen, the Ru-(CoCu)2V2O7@Cu2O nano-octahedral electrocatalyst prepared in Example 2 exhibits higher EGOR catalytic performance than the electrocatalysts prepared in Comparative Examples 1 and 2, with a current density of 380 mA / cm² at a voltage of 1.0 V. 2 That is, it can generate a larger current density under the same voltage.

[0181] from Figure 24 As can be seen from the results, the Ru-(CoCu)2V2O7@Cu2O nano-octahedral electrocatalyst prepared in Example 3 has better electrochemical performance than the electrocatalysts prepared in Comparative Examples 1 and 2, and can generate a larger current density at the same voltage.

[0182] from Figure 24 As can be seen, the Ru-Cu2V2O7@Cu2O nano-octahedral electrocatalyst prepared in Comparative Example 1 has better electrochemical performance than the electrocatalyst prepared in Comparative Example 2, and can generate a larger current density at the same voltage, but it is much lower than that in Examples 1-3.

[0183] from Figure 24 As can be seen from the data, the (CoCu)2V2O7@Cu2O core-shell nano-octahedral electrocatalyst prepared in Comparative Example 2 has the lowest EGOR catalytic activity. Under the same voltage, it can only produce the minimum current density, which is much lower than that of Examples 1-3 and slightly lower than that of Comparative Example 1.

[0184] (3) The stability curves (1.0V (vs. RHE) of the electrocatalysts prepared in Example 1 and Comparative Examples 1-2 were measured in 1 mol / L KOH solution and 1 mol / L EG electrolyte. The measurement method was the same as in Effect Example 2. The results are shown in […]. Figure 25 .

[0185] from Figure 25 As can be seen from the results, the Ru-(CoCu)2V2O7@Cu2O nano-octahedral electrocatalyst prepared in Example 1 has better stability than Comparative Examples 1 and 2. Even after 40 hours of continuous operation, the current density did not show a significant decrease.

[0186] from Figure 25 As can be seen, the Ru-Cu2V2O7@Cu2O nano-octahedral electrocatalyst prepared in Comparative Example 1 has a relatively low current density and a faster decay, indicating that its stability and activity are not as good as those in Example 1, but slightly higher than those in Comparative Example 2, which shows that cobalt plays an important role in improving the stability and activity of the catalyst.

[0187] from Figure 25As can be seen from the data, the (CoCu)2V2O7@Cu2O core-shell structured nano-octahedral electrocatalyst prepared in Comparative Example 2 has the lowest current density and the most significant decay, indicating that its stability and activity are far inferior to those of Example 1 and Comparative Example 1. This demonstrates that ruthenium plays the most important role in improving the stability and activity of the catalyst.

[0188] Example of effect 4

[0189] (1) The LSV curves of the Ru-(CoCu)2V2O7@Cu2O nano-octahedral electrocatalyst prepared in Example 1 were measured in 1M KOH+1MEG or PET hydrolysate (PET hydrolysate was prepared by dissolving PET in 1mol / L KOH). The results are shown in […]. Figure 26 .

[0190] from Figure 26 As can be seen from the data, the LSV curves of the Ru-(CoCu)2V2O7@Cu2O nano-octahedral electrocatalyst prepared in Example 1 almost overlap in 1M KOH+1M EG and PET hydrolysate, proving that the catalyst has significant EGOR electrocatalytic performance for PET hydrolysate and showing its application potential for upgrading and utilizing PET plastics.

[0191] (2) The electro-oxidation products of the Ru-(CoCu)2V2O7@Cu2O nano-octahedral electrocatalyst prepared in Example 1 were determined in PET hydrolysate. 1 H NMR spectrum, results are shown in Figure 27 . Figure 27 In this formula, FA stands for formic acid, TPA for terephthalic acid, D2O for heavy water, GA for glycolic acid, EG for ethylene glycol, and DMSO for dimethyl sulfoxide.

[0192] from Figure 27 As can be seen, the main product of the electro-oxidation of PET hydrolysate is high-value-added C2 product glycolic acid (GA), with only a very small amount of EG being peroxidized to low-value-added chemical formic acid (FA), demonstrating excellent selectivity. Meanwhile, the TPA present in the PET hydrolysate has almost no effect on the EGOR process, further proving that this catalyst has great application potential in the electrocatalytic upgrading of PET plastics to high-value-added GA products.

[0193] (3) The electro-oxidation products of the Ru-(CoCu)2V2O7@Cu2O nano-octahedral electrocatalyst prepared in Example 1 were determined in PET hydrolysate. 13 C NMR spectrum, results are shown in Figure 28 .

[0194] from Figure 28 As can be seen, the main product of the electro-oxidation of PET hydrolysate is GA, and the byproduct is FA. Figure 27 The conclusions are consistent, proving that this catalyst has great application potential in the electrocatalytic upgrading of PET plastics into high-value-added GA products.

[0195] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for preparing a nano-octahedral electrocatalyst, characterized in that, Includes the following steps: Using Cu2O nano-octahedrons as templates, an active layer of (CoCu)2V2O7 was deposited on their surface through a precipitation conversion strategy, and then Ru was doped to obtain the nano-octahedron electrocatalyst. The deposition of an active (CoCu)₂V₂O₇ layer on its surface via a precipitation conversion strategy includes: Cu2O nano-octahedrons were dispersed in a mixed solution of Na2S2O3, vanadate and cobalt salt, and the reaction was stirred to obtain (CoCu)2V2O7@Cu2O core-shell structure intermediate; The doped Ru includes: The (CoCu)2V2O7@Cu2O core-shell structure intermediate was dispersed in a mixed solution of vanadate, ruthenium salt, reducing agent and water, and the reaction was carried out under ice bath conditions with stirring to obtain the nano-octahedral electrocatalyst.

2. The preparation method according to claim 1, characterized in that, The method for preparing the Cu2O nano octahedron includes the following steps: A mixed solution of alkali and reducing agent, B, is added to a mixed solution A of soluble inorganic copper salt and surfactant, and the mixture is heated to react and obtain the Cu2O nano octahedrons.

3. The preparation method according to claim 2, characterized in that, The reducing agent includes L-ascorbic acid; And / or, the surfactant includes polyvinylpyrrolidone; And / or, the heating reaction is carried out at a temperature of 80-90 °C for a duration of 3-6 h; And / or, the molar ratio of the soluble inorganic copper salt to the reducing agent is 1:(5~7); And / or, the surfactant content in the mixed solution A is 40~60 g / L.

4. The preparation method according to claim 1, characterized in that, The vanadate is selected from sodium orthovanadate or sodium metavanadate. And / or, the cobalt salt is selected from at least one of cobalt nitrate, cobalt chloride, and cobalt sulfate; And / or, the ratio of Cu2O nano-octahedrons, Na2S2O3, cobalt salt and vanadate is 50~100g:1200~1300g:0.2~0.5mol:0.2~0.5mol; And / or, the stirring reaction time is 10~30 min.

5. The preparation method according to claim 1, characterized in that, The vanadate is selected from sodium orthovanadate or sodium metavanadate. And / or, the ruthenium salt is selected from ruthenium nitrate or ruthenium trichloride; And / or, the reducing agent includes NaBH4; And / or, the molar ratio of the vanadate, ruthenium salt and reducing agent is (5~10):(1~5):(40~50); And / or, the stirring reaction time is 10~30 min.

6. A nano-octahedral electrocatalyst prepared by the preparation method according to any one of claims 1 to 5.

7. The application of the nano-octahedral electrocatalyst according to claim 6 in the electrolytic hydrogen production.

8. The application of the nano-octahedral electrocatalyst according to claim 6 in the electrocatalytic oxidation of ethylene glycol coupled to a cathode for hydrogen production.

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