Electrocatalyst as well as preparation method and application thereof

Abstract

The invention discloses an electrocatalyst as well as a preparation method and application thereof, and relates to the technical field of catalysts. The preparation method of the electrocatalyst comprises the following steps: dissolving metal salt in water to form a transparent solution, and then sequentially adding an alkaline substance aqueous solution, an organic acid aqueous solution and a phosphorus-containing substance aqueous solution for reaction to obtain a reaction mixture; carrying out centrifugal separation on the reaction mixture, and washing and drying the obtained precipitate to obtain solid powder; etching the solid powder by using strong acid; and then washing and drying to obtain the electrocatalyst. According to the invention, PO4 < 3-> modification is realized on the surfaces of oxides such as nickel / cobalt and the like through a hydrothermal-etching method, the electrocatalyst which can be used for EGOR and HMOR is successfully prepared, the catalyst shows high activity and product selectivity on both EGOR and HMOR, and an efficient catalytic solution is provided for recycling of plastics and synthesis of bio-based materials.

Description

Technical Field

[0001] The present invention relates to the technical field of catalysts, and in particular to an electrocatalyst, a preparation method thereof, and an application thereof. Background Art

[0002] Converting PET into high-value-added chemicals or developing green alternatives such as biomass-based poly(ethylene furanoate) (PEF) can effectively reduce the generation of PET waste. Against this background, an electroconversion strategy driven by renewable electricity provides a practical path for the circular plastic economy. This strategy can convert the hydrolysis product of PET, ethylene glycol (EG), into high-value-added chemicals. At the same time, it can also convert 5-hydroxymethylfurfural (HMF) derived from biomass into 2,5-furandicarboxylic acid (FDCA), which is a monomer of bio-based PEF. The successful implementation of this electrochemical conversion strategy depends to a large extent on the high efficiency and selectivity of the electrocatalyst.

[0003] Nickel-based catalysts have shown efficient and competitive performance in the electrooxidation of organic substances. During the anodic reaction process, the nickel center undergoes a transformation and finally forms a high-valent metal (oxy) hydroxide (NiOOH), which becomes the actual high-activity site for the ethylene glycol oxidation reaction (EGOR) or the 5-hydroxymethylfurfural oxidation reaction (HMFOR). However, there are still many challenges in this field: 1) The reaction energy barrier for generating the actual active site is relatively high, resulting in a relatively high initial potential, which in turn affects the activity performance of the catalyst; 2) The mass transfer process of organic substrates is limited, affecting the reaction efficiency; 3) The effects of various organic substrates on the catalyst are complex and variable, increasing the difficulty of catalyst design and optimization.

[0004] Therefore, developing electrocatalysts with high activity and high selectivity to achieve the efficient operation of the PET circular economy is still a challenging task. Summary of the Invention

[0007] To solve the above problems, the present invention provides an electrocatalyst, a preparation method thereof, and an application thereof.

[0008] In a first aspect, the present invention provides a preparation method of an electrocatalyst, and the preparation method includes the following steps:

[0009] Dissolve a metal salt in water to form a transparent solution, and then sequentially add an aqueous solution of an alkaline substance, an aqueous solution of an organic acid, and an aqueous solution of a phosphorus-containing substance for reaction to obtain a reaction mixture;

[0010] Centrifuge the reaction mixture, and then wash and dry the obtained precipitate to obtain a solid powder. Etch the solid powder with a strong acid, and then wash and dry it to obtain the electrocatalyst;

[0011] Among them, the metal salt includes nickel salt.

[0012] Furthermore, the metal salt further includes other metal salts besides nickel salt, and the other metal salts are selected from: cobalt salt, manganese salt or copper salt. The mass ratio of the nickel salt to the other metal salts is 1:(0-1), the mass ratio of the phosphorus-containing substance to the nickel salt is (1-2):1, and the mass ratio of the nickel salt to the alkaline substance is 1:(0.4-1).

[0013] Furthermore, the nickel salt includes at least one of NiSO4·6H2O, NiCl2·6H2O and Ni(NO3)2·6H2O; the cobalt salt includes at least one of CoSO4·6H2O, CoCl2·6H2O and Ni(NO3)2·6H2O; the manganese salt includes MnCl2; the copper salt includes CuCl2.

[0014] Furthermore, the alkaline substance includes at least one of NaOH, KOH and NH3·H2O; the phosphorus-containing substance includes at least one of NaH2PO2·H2O, NaH2PO4·H2O and Na5P3O 10 ·6H2O.

[0015] Furthermore, the temperature for dissolving the metal salt in water to form a transparent solution is 90-120 °C; the reaction time after adding the aqueous solution of the phosphorus-containing substance is 1-5 h.

[0016] In a second aspect, based on the same inventive concept, the present invention provides an electrocatalyst, which is prepared by using the preparation method of the electrocatalyst according to any one of the first aspect.

[0017] In a third aspect, based on the same inventive concept, the present invention provides an application of the electrocatalyst according to any one of the second aspect in electrocatalytic ethylene glycol oxidation reaction and electrocatalytic hydroxymethylfurfural oxidation reaction.

[0018] In a fourth aspect, based on the same inventive concept, the present invention provides a method for preparing formate by electrocatalytic ethylene glycol oxidation reaction, using the electrocatalyst according to any one of the second aspect.

[0019] In a fifth aspect, based on the same inventive concept, the present invention provides a method for preparing 2,5-furandicarboxylic acid by electrocatalytic 5-hydroxymethylfurfural oxidation reaction, using the electrocatalyst according to any one of the second aspect.

[0020] The above technical solutions provided by the embodiments of the present invention have at least the following advantages compared with the prior art:

[0021] Embodiments of the present invention provide an electrocatalyst, a preparation method thereof, and an application thereof. The present invention realizes PO4 modification on the surface of oxides such as nickel / cobalt through a hydrothermal-etching method, and successfully prepares an electrocatalyst that can be used for EGOR and HMFOR. This catalyst shows high activity and product selectivity for both EGOR and HMFOR, providing an efficient catalytic solution for plastic recycling and the synthesis of bio-based materials. Specifically: 3- The present invention successfully prepares an electrocatalyst, such as a Ni / Co-based oxide catalyst modified with PO4 (hereinafter simply denoted as PO4 / Ni4CoO

[0022] ), aiming to efficiently upgrade and recycle ethylene glycol (EG, derived from polyethylene terephthalate (PET) waste) to formate (FA, an important chemical raw material) through an electrocatalytic oxidation process (this process is hereinafter referred to as EGOR). At the same time, 5-hydroxymethylfurfural (HMF, a biomass-derived organic compound) is also upgraded and recycled to 2,5-furandicarboxylic acid (FDCA, used as a monomer for producing biodegradable polymers) (this process is hereinafter referred to as HMFOR). 3 ), aiming to efficiently upgrade and recycle ethylene glycol (EG, derived from polyethylene terephthalate (PET) waste) to formate (FA, an important chemical raw material) through an electrocatalytic oxidation process (this process is hereinafter referred to as EGOR). At the same time, 5-hydroxymethylfurfural (HMF, a biomass-derived organic compound) is also upgraded and recycled to 2,5-furandicarboxylic acid (FDCA, used as a monomer for producing biodegradable polymers) (this process is hereinafter referred to as HMFOR). x )

[0023] In the present invention, the inventors adopted a nickel oxide-cobalt oxide electrocatalyst decorated with phosphate (i.e., PO4 / Ni4CoO x ). Under the voltage condition of 1.45 V versus the reversible hydrogen electrode (RHE), this catalyst exhibited excellent electrocatalytic performance, achieving high faradaic efficiencies of FA and FDCA with current densities as high as 478.9 mA cm -2 and 324.6 mA cm -2 respectively, with specific values of 85.50% and 87.44%.

[0024] This achievement not only confirmed the successful modification of PO4 3- on the Ni / Co-based oxide, but also pioneered a new strategy: designing electrocatalysts through a surface anion modification strategy. The Co sites and the self-adaptive electrode-electrolyte interface provided by PO4 3- provide thermodynamic advantages for the formation of NiOOH and the adsorption of organic substrates, resulting in high activity to significantly improve its electrocatalytic oxidation performance. The present invention emphasizes the importance of the electrode-electrolyte interface and provides broad prospects for electrochemical conversion by constructing a self-optimizing chemical / electrical environment. This strategy provides new ideas and methods for the electrocatalysis field, and is expected to promote breakthroughs in the upgrading and recycling technologies of organic compounds such as ethylene glycol and 5-hydroxymethylfurfural. Brief Description of the Drawings

[0025] The accompanying drawings here are incorporated into the specification and form a part of this specification, showing embodiments in accordance with the present invention, and are used together with the specification to explain the principles of the present invention.

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings required for use in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0027] Figure 1 Morphology characterization and structural analysis diagram of the catalyst PO4 / Ni4CoO obtained in Example 1 of the present invention x ; wherein, Figure 1 in: a is the SEM image, b is the TEM image, c is the HRTEM image, and d is the partial enlarged view of the HRTEM.

[0028] Figure 2 Microstructural comparative analysis diagram of different catalysts obtained in Example 1, Comparative Example 1, and Comparative Example 2 of the present invention; wherein, Figure 2 in: a is the Raman spectrum, b is the XPS P2p spectrum, c is the XPS Ni2p spectrum, and d is the XPS Co2p spectrum.

[0029] Figure 3 Electrocatalytic performance test results of different catalysts obtained in Example 1, Comparative Example 1, and Comparative Example 2 of the present invention Figure 1 ; wherein, Figure 3 in: a is the EGOR performance test result of different catalysts, b is the test result of the OER and EGOR activity difference of PO4 / Ni4CoO x ; c is the product analysis test result of NMR 1 H detection electrolyte, and d is the test result of the electrolyte composition change.

[0030] Figure 4 Electrocatalytic performance test results of different catalysts obtained in Example 1, Comparative Example 1, and Comparative Example 2 of the present invention Figure 2 ; wherein, Figure 4 in: a is the HMFOR performance test result of different catalysts in 20 mM HMF, b is the test result of the OER and HMFOR activity difference of PO4 / Ni4CoO x ; c is the product analysis test result of HPLC detection electrolyte, and d is the test result of the electrolyte composition change.

[0031] Figure 5 Catalytic activity test result diagram of the catalysts obtained in Examples 2 to 5 of the present invention; wherein, Figure 5In the figure: a represents the EGOR activity results of the catalysts obtained from different embodiments, and b represents the HMF activity diagram of Ni / Co oxides modified with different proportions of phosphoric acid.

[0032] Figure 6 It is a diagram showing the catalytic activity test results of the catalysts obtained in Examples 6 - 7 of the present invention; among them, Figure 6 In the figure: a represents the EGOR activity results of the catalysts obtained from different embodiments, and b represents the HMFOR activity diagram. Detailed implementation manners

[0033] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0034] Unless otherwise specifically stated, all kinds of raw materials, reagents, instruments, and equipment used in the present invention can be obtained through market purchases or can be prepared by existing methods.

[0035] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and not to limit the scope of the present invention. The experimental methods without specific conditions noted in the following embodiments are usually determined according to national standards. If there is no corresponding national standard, they are carried out according to general international standards, conventional conditions, or conditions recommended by the manufacturer.

[0036] Example 1

[0037] This example provides an electrocatalyst, and its preparation method includes the following steps:

[0038] Mix 2.625 grams of NiSO4·6H2O and 0.700 grams of CoSO4·6H2O with 25 milliliters of water to form a transparent solution at 100°C; then add 25 mL of an aqueous NaOH (1.275 g) solution and react for 15 minutes; then add 0.5 mL of water containing 0.1 g of citric acid to the above solution and react for 5 minutes; then add 25 mL of an aqueous sodium hypophosphite (2.65 g) solution to the above solution and react at 100°C for 2 hours; centrifuge the product at a speed of 9000 revolutions per minute for 3 minutes, wash it with water 2 times and with ethanol 1 time, dry the obtained precipitate under vacuum at 60°C overnight; finally, etch the powder with 0.5 wt% nitric acid for 10 minutes, wash it alternately with water and ethanol 3 - 5 times, and then dry the product under vacuum at 60°C overnight; the product obtained in this example is denoted as PO4 / Ni4CoO x .

[0039] Example 2

[0040] This example provides an electrocatalyst and its preparation method. The difference from Example 1 is only that the mass ratio of NiSO4·6H2O to CoSO4·6H2O is 1:0; the remaining steps and parameters are the same.

[0041] Example 3

[0042] This example provides an electrocatalyst and its preparation method. The difference from Example 1 is only that the mass ratio of NiSO4·6H2O to CoSO4·6H2O is 1:0.3; the remaining steps and parameters are the same.

[0043] Example 4

[0044] This example provides an electrocatalyst and its preparation method. The difference from Example 1 is only that the mass ratio of NiSO4·6H2O to CoSO4·6H2O is 1:0.5; the remaining steps and parameters are the same.

[0045] Example 5

[0046] This example provides an electrocatalyst and its preparation method. The difference from Example 1 is only that the mass ratio of NiSO4·6H2O to CoSO4·6H2O is 1:1; the remaining steps and parameters are the same.

[0047] Example 6

[0048] This example provides an electrocatalyst and its preparation method. The difference from Example 1 is only that CoSO4·6H2O is replaced by CuCl2; the remaining steps and parameters are the same.

[0049] Example 7

[0050] This example provides an electrocatalyst and its preparation method. The difference from Example 1 is only that CoSO4·6H2O is replaced by MnCl2; the remaining steps and parameters are the same.

[0051] Comparative Example 1

[0052] This example provides a catalyst, and its preparation method includes the following steps:

[0053] Under magnetic stirring, 2.625 g of NiSO4·6H2O and 0.700 g of CoSO4·6H2O were mixed with 25 mL of water to form a transparent solution at 100 °C; then 25 mL of an aqueous NaOH (1.275 g) solution was added and reacted for 15 minutes; then 0.5 mL of water containing 0.1 g of citric acid was added to the above solution and reacted at 100 °C for 2 hours. The product was collected, centrifuged at 9000 rpm for 3 minutes, washed twice with water and once with ethanol; the obtained precipitate was dried overnight under vacuum at 60 °C; finally, the powder was annealed in air at 200 °C for 2 hours, and the obtained catalyst was denoted as Ni4CoO x 。

[0054] Comparative Example 2

[0055] This example provides a catalyst, and its preparation method includes the following steps:

[0056] 0.295 g of NiSO4·6H2O and 0.0735 g of CoSO4·6H2O were dissolved in ethanol (20 mL) by ultrasonic wave to form a homogeneous solution; ammonium phosphate was dissolved in 20 mL of water, and then the aqueous solution was added dropwise to the cobalt alcohol solution under ultrasonic conditions; centrifuged at 9000 rpm for 3 minutes, the product was collected, washed twice with water and once with ethanol; the obtained precipitate was dried overnight under vacuum at 60 °C, and the obtained catalyst was denoted as Ni4Co(PO4) x 。

[0057] Test Example 1

[0058] This example characterized the morphology and analyzed the structure of the PO4 / Ni4CoO obtained in Example 1 above x as follows, and the test results are as Figure 1 shown; among them, Figure 1 in: a is the SEM image, b is the TEM image, c is the HRTEM image, and d is the enlarged view of a part of the HRTEM image.

[0059] It can be seen from Figure 1 that: the catalyst obtained in the present invention shows a uniform wrinkled microsphere structure with a diameter of about 170 nm( Figure 1 a, b). The high-resolution transmission electron microscope (HRTEM) image shows that PO4 / Ni4CoO x is an amorphous structure( Figure 1 c), and small crystalline regions are observed at the edge of the microsphere( Figure 1 d).

[0060] This example also comparatively analyzed the microstructures of different catalysts obtained in Example 1, Comparative Example 1 and Comparative Example 2 above, and the test results are as Figure 2 shown; among them, Figure 2In the figure: a is the Raman spectrum, b is the XPS P2p spectrum, c is the XPS Ni2p spectrum, and d is the XPS Co2p spectrum.

[0061] It can be seen from Figure 2 that: as Figure 2 shown in a, the Raman spectrum of PO4 / Ni4CoO x has two bands at 954 and 1063 cm -1 , belonging to the asymmetric stretching vibration of PO4 3- , indicating the successful modification of PO4 3- on the catalyst surface. To further analyze the composition and electronic structure of PO4 / Ni4CoO x , the inventors used X-ray photoelectron spectroscopy (XPS). In the P2p XPS spectrum, the PO4 / Ni4CoO x catalyst shows a single peak at 133.08 eV, which is negatively shifted compared with that of PO4 / Ni4CoO x (134.26 eV), indicating a slight decrease in the oxidizing property of P ( Figure 2 b). Comparing Ni4CoO x and Ni4Co(PO4) x , the Ni2p peak of PO4 / Ni4CoO x shifts to higher energy, indicating an increase in the valence of Ni ( Figure 2 c). Only Co x can be observed in the Co2p of PO4 / Ni4CoO 2+ , without Co 3 + and Co 0 ( Figure 2 d), which indicates that the autocatalytic process provides suitable reaction conditions for the formation of oxides. The above characterization results show that the amorphous Ni4CoO 3- modified by PO4 x is successfully synthesized.

[0062] Test Example 2

[0063] In this example, the electrocatalytic performance of different catalysts obtained in the above Example 1, Comparative Example 1, and Comparative Example 2 was tested.

[0064] Due to the unique structure of PO4 / Ni4CoO x , that is, Ni4CoO 3- surface-modified by PO4 x , its electrocatalytic performance of EGOR and HMFOR in 1.0 M KOH solution was evaluated.

[0065] Preparation of Ink: 10 mg of catalyst powder was mixed with 100 μL of Nafion solution (5 wt%) and 900 μL of ethanol to prepare catalyst ink in an ultrasonic bath; then 100 μL of the catalyst ink was transferred onto the surface of carbon cloth to achieve a catalyst loading of 1 mg cm -2 .

[0066] Electrocatalytic Tests: Electrochemical performance was measured using a Gamry Reference 600 workstation (Gamry, USA) with a standard three-electrode system. An electrolyte was prepared by dissolving 33 g of KOH (reagent grade, 85%, Aladdin Co.) in 500 mL of ultrapure water. A reversible hydrogen electrode (RHE) was used as the reference electrode and placed in 1.0 M saturated KOH solution, and a graphite rod was used as the counter electrode. The electrooxidation reaction activity of various catalysts was evaluated using a carbon cloth with an area of 1 cm 2 as the substrate of the working electrode.

[0067] The EGOR activity was tested in 1.0 M KOH containing 0.3 M EG. As Figure 3 shown in x a, the onset potential of PO4 / Ni4CoO x was the lowest, at 1.28 V. For comparison, the EGOR performance of Ni4Co(PO4) x and Ni4CoO x was also evaluated under the same conditions. Compared with Ni4Co(PO4) x and Ni4CoO -2 , Example 1 exhibited significantly higher EGOR activity. In the absence of EG, to achieve a current density of 100 mA cm x for OER, a high anodic potential of 1.61 V was required for PO4 / Ni4CoO Figure 3 b). However, under the condition of 0.3 M EG, the EGOR potentials required for the PO4 / Ni4CoO x catalyst to reach 100, 200, 300, and 400 mA cm -2 were 1.34, 1.36, 1.39, and 1.41 V, respectively, which were significantly lower than the OER potential. Subsequently, the effect of the applied potential was studied by chronopotentiometry and 1H NMR to determine the optimal applied potential of 1.45 V vs. RHE, with an EG conversion rate close to 100% and a Faraday efficiency of 85%. As the electrocatalytic oxidation proceeded at 1.45 V, the concentration of EG gradually decreased and the concentration of FA continued to increase, indicating that EG was almost completely converted to FA Figure 3 c, d).

[0068] The HMFOR activity was tested in 1.0 M KOH containing 20 mM and 50 mM. As Figure 4As shown in a, when the HMF concentration is 20 mM, at a potential of 1.45 V, the current density of Example 1 (134.30 mA cm -2 ) is much higher than that of Ni4CoO x (26.48 mA cm -2 ) and Ni4Co(PO4) x (19.09 mA cm -2 ), confirming that Ni4CoO 3- modified by PO4 x has higher HMFOR activity. After further increasing the HMF concentration to 50 mM, the current of Example 1 catalyzing HMFOR increased significantly. Compared with OER, the potentials reaching the current densities of 50, 100, 200, and 300 mA cm -2 decreased by 264, 279, 272, and 240 mV respectively ( Figure 4 b). Under the condition of 1.45 V vs. RHE, the Faradaic efficiency of FDCA reached 87.44%, and the highest productivity was 0.22 mmol cm -2 h -1 ( Figure 4 c). Chronoamperometry measurements were carried out under the condition of 1.45 V vs. RHE to study the reaction pathway of HMFOR on the PO4 / Ni4CoO x catalyst. As the reaction time extended, the HMF peak at about 11.5 minutes decreased rapidly, while the FDCA signal at 3.4 minutes gradually increased ( Figure 4 d). Two peaks could be observed at ~4.3 and ~5.0 minutes, which were attributed to 5-hydroxymethyl-2-furoic acid (HMFCA) and 5-formyl-2-furoic acid (FFCA) respectively.

[0069] The EGOR and HMFOR curves of the NiCo oxide (Ni4CoO 3- ) without PO4 x modification obtained in Comparative Example 1 of the present invention are as shown in Figure 3 a and Figure 4 a, and their limiting currents are all inferior to those of Example 1, indicating that PO4 3- modification greatly improves the electrocatalytic oxidation activity of the catalyst.

[0070] The EGOR and HMFOR curves of Ni4Co(PO4) x obtained in Comparative Example 2 of the present invention are as shown in Figure 3 a and Figure 4 a, and their limiting currents are all inferior to those of Example 1, indicating that the Ni / Co sites with PO4 3- coordination are not the real electrooxidation catalytic active sites, and the surface PO4 3-The speculated mechanism of the modification is to promote the mass transfer of organic substrates and the migration of intermediates.

[0071] In addition, the present invention also studied the EGOR and HMFOR catalytic activities of the catalysts obtained in Examples 2-5. As Figure 5 can be seen, the catalysts obtained in Examples 2-4 all have relatively excellent EGOR and HMFOR catalytic activities. Among them, Examples 2-5 all have good HMFOR catalytic activities, and Examples 2 and 5 have good EGOR catalytic activities. It can be seen from this that good electrocatalytic oxidation activities can be obtained when the ratio of nickel salt to cobalt salt is within 1:0 to 1.

[0072] The present invention also studied the EGOR and HMFOR catalytic activities of the products obtained in Examples 6-7. As Figure 6 can be seen, the catalysts obtained in Examples 6-7 all have relatively excellent EGOR and HMFOR catalytic activities. It can be seen from this that good electrocatalytic oxidation activities may be obtained by replacing Co with Cu and Mn.

[0073] In summary, the obtained catalysts can efficiently and highly selectively upgrade and recycle ethylene glycol (EG, from polyethylene terephthalate waste) to formate (FA, a chemical raw material) (EGOR), and upgrade and recycle 5-hydroxymethylfurfural (HMF, a biomass-derived organic compound) to 2,5-furandicarboxylic acid (FDCA, a monomer for producing biodegradable polymers) (HMFOR). Under the voltage condition of 1.45 V vs. RHE, the synthesized catalysts achieved high current densities (478.9 mA cm -2 and 324.6 mA cm -2 ), respectively) and relatively high Faradaic efficiencies of FA and FDCA (85.50% and 87.44%, respectively). The self-adaptive electrode-electrolyte interface provided by Co sites and PO43- provides a thermodynamic advantage for the formation of NiOOH and the adsorption of organic substrates, resulting in high activity. The present invention emphasizes the importance of the electrode-electrolyte interface and provides broad prospects for electrochemical conversion by constructing a self-optimized chemical / electrical environment.

[0074] The various embodiments of the present invention may exist in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity and should not be construed as a rigid limitation on the scope of the present invention; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single values within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single numbers within the range, such as 1, 2, 3, 4, 5, and 6, and this applies regardless of the range. Additionally, whenever a numerical range is indicated herein, it means including any cited number (fraction or integer) within the indicated range.

[0075] The above are only specific embodiments of the present invention, enabling those skilled in the art to understand or implement the present invention. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to these embodiments shown herein, but rather to the broadest scope consistent with the principles and novel features claimed herein.

Claims

1. A method for preparing an electrocatalyst, characterized in that, The preparation method includes the following steps: Dissolve the metal salt in water to form a transparent solution, and then sequentially add aqueous solutions of an alkaline substance, an organic acid, and a phosphorus-containing substance for reaction to obtain a reaction mixture; Centrifuge the reaction mixture, and then wash and dry the obtained precipitate to obtain a solid powder; then etch the solid powder with a strong acid, and then wash and dry it to obtain the electrocatalyst; Among them, the metal salt includes a nickel salt.

2. The preparation method of the electrocatalyst according to claim 1, wherein, The metal salt further includes other metal salts other than the nickel salt, the mass ratio of the nickel salt to the other metal salts is 1:(0-1), the mass ratio of the phosphorus-containing substance to the nickel salt is (1-2):1, and the mass ratio of the nickel salt to the alkaline substance is 1:(0.4-1); among them, the other metal salts are selected from: cobalt salts, manganese salts, or copper salts.

3. The preparation method of the electrocatalyst according to claim 1 or 2, characterized in that, The nickel salt includes at least one of NiSO4·6H2O, NiCl2·6H2O, and Ni(NO3)2·6H2O; the cobalt salt includes at least one of CoSO4·6H2O, CoCl2·6H2O, and Ni(NO3)2·6H2O; the manganese salt includes MnCl2; the copper salt includes CuCl2.

4. The preparation method of the electrocatalyst according to any one of claims 1 to 3, characterized in that, The alkaline substance includes at least one of NaOH, KOH, and NH3·H2O; or: The phosphorus-containing substance includes at least one of NaH2PO2·H2O, NaH2PO4·H2O, and Na5P3O 10 ·6H2O; Or: The aqueous solution of the organic acid includes an aqueous solution of citric acid; Or: The strong acid includes at least one of nitric acid, hydrochloric acid, and sulfuric acid.

5. The preparation method of the electrocatalyst according to any one of claims 1 to 4, characterized in that, The temperature for dissolving the metal salt in water to form a transparent solution is 90-120°C.

6. The preparation method of the electrocatalyst according to any one of claims 1 to 5, characterized in that, The reaction time after adding the aqueous solution of the phosphorus-containing substance is 1-5 h.

7. An electrocatalyst, characterized in that, The electrocatalyst is prepared by the preparation method according to any one of claims 1-6.

8. Use of the electrocatalyst according to claim 7 in electrocatalytic ethylene glycol oxidation reaction and electrocatalytic hydroxymethylfurfural oxidation reaction.

9. A method for preparing formate by electrocatalytic oxidation of ethylene glycol, characterized in that, In the method, the electrocatalyst according to claim 7 is used for catalytic reaction.

10. A method for preparing 2,5-furandicarboxylic acid by electrocatalytic oxidation of 5-hydroxymethylfurfural, characterized in that, In the method, the electrocatalyst according to claim 7 is used for catalytic reaction.

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