Oxygen-rich vacancy spinel catalyst, preparation method and method for electrocatalytic glycerol

Abstract

This invention provides an oxygen-vacancy-enriched spinel catalyst, wherein the structural formula of the oxygen-vacancy-enriched spinel catalyst is O. v -MCo2O4 / MO / CPF, where M is selected from Fe 2+ Co 2+ Ni 2+ Cu 2+ or Zn 2+ Any one or more of the oxygen-enriched vacancy spinel catalysts have a specific surface area of ​​300-500 m². 2 / g. In this invention, more oxygen vacancies are formed in the MCo2O4 / MO / CPF composite nanomaterial by low-temperature hydrogen reduction. The method does not change the nanoarray structure of the MCo2O4 / MO / CPF composite nanomaterial. The synergy between oxygen vacancies and Co sites can improve the site-directed activation ability of the secondary hydroxyl group of glycerol, and the selectivity of dihydroxyacetone is as high as 72.3%.

Description

Technical Field

[0001] This invention belongs to the field of inorganic nanocatalytic materials and electrocatalysis, specifically relating to an oxygen-rich spinel catalyst, its preparation method, and a method for electrocatalyzing glycerol. Background Technology

[0002] Biodiesel has attracted widespread attention due to its advantages such as renewability, safety, efficiency, and biodegradability. During biodiesel production, 10 kg of glycerol is generated as a byproduct for every 100 kg produced. Glycerol, as an important biomass platform molecule, currently faces significant overcapacity. Using glycerol as a raw material for catalytic oxidation to produce dihydroxyacetone can increase the added value of glycerol, alleviate the overcapacity problem, and represents a green, environmentally friendly, and mild synthetic route with significant application value in promoting the efficient conversion of biomass.

[0003] Dihydroxyacetone is an important high-value fine chemical with wide applications in the cosmetics, pharmaceutical intermediates, and food additive industries. Methods for preparing dihydroxyacetone by glycerol oxidation include enzymatic oxidation and direct catalytic oxidation. In 1994, Glaret et al. first used *Glucosinolates* to ferment glycerol into dihydroxyacetone (Appl. Microbiol. Biotechnol., 1994, 41, 359-365). This method has high product selectivity, but the bioconversion rate is low and the production cost is high. Furthermore, dihydroxyacetone is difficult to extract from fermentation broths rich in polyols, amino acids, various trace elements, and vitamins. Li et al. reported a heterogeneous catalytic method (J. Catal., 2019, 377, 271-282) using Au / ZnO with oxygen-vacancy-rich sites as a catalyst to catalytically oxidize glycerol to DHA under an O2 atmosphere and at 80 °C. The highest DHA yield reached 56.3%, but the use of precious metals and the thermal catalytic reaction conditions limited the widespread application of this method. Garcia et al. employed a green and mild electrocatalytic method (J. Catal., 2017, 346, 117–124) to selectively oxidize glycerol to DHA using a Pt-Bi catalyst, achieving a DHA selectivity of 50%. However, this method has high energy consumption and low selectivity.

[0004] CN109806886B discloses a catalyst for the oxidation of glycerol to dihydroxyacetone, its preparation method, and its application. The catalyst is an Au-based catalyst, supported by a copper-zirconium composite oxide, with a copper to zirconium molar ratio of 1:100-100:1. A preparation method for the catalyst and its application in the oxidation of glycerol to dihydroxyacetone are also provided. The prepared supported Au catalyst can efficiently catalyze the oxidation of glycerol to dihydroxyacetone (DHA) in a heterogeneous alkaline medium, achieving a glycerol conversion rate of up to 80% and a DHA selectivity of over 95%. However, a drawback of this technology is the use of a precious metal in the catalyst, which increases the cost of the catalytic reaction and hinders industrial application.

[0005] CN105439831A discloses a method for the catalytic oxidation of glycerol to 1,3-dihydroxyacetone using a supported gold catalyst. This method uses an aqueous glycerol solution and oxygen as raw materials, and ZnO, copper-aluminum layered double hydroxide (TLH), or spinel-supported gold as a catalyst. Under alkali-free conditions, it achieves a highly selective conversion of glycerol to 1,3-dihydroxyacetone via oxidation. Specifically, glycerol and oxygen are reacted in a high-pressure reactor under the action of a supported gold catalyst to obtain 1,3-dihydroxyacetone. The support for the supported gold catalyst is any one of ZnO, copper-aluminum layered double hydroxide (TLH), or spinel with a copper-aluminum ratio of 5:1 or 1:3. However, the drawback of this patent application is the use of precious metals and the high-pressure environment for catalytic reaction, which leads to high energy consumption and increased application costs.

[0006] Therefore, developing a low-cost, simple-to-prepare, and efficient catalyst, as well as a green, environmentally friendly, mild-condition, and highly selective 1,3-dihydroxyacetone catalytic application for glycerol, are urgent problems to be solved. Summary of the Invention

[0007] To address the problems of low selectivity, high cost of precious metal catalysts, and high energy consumption in the existing glycerol oxidation process for dihydroxyacetone, this invention provides an oxygen-enriched spinel catalyst, its preparation method, and a method for electrocatalyzing glycerol. The oxygen-enriched spinel catalyst uses carbon paper (CFP) as a substrate. An MCo-LDHs / CFP material is formed on the carbon paper surface through a simple electrochemical deposition method. Then, high-temperature calcination under nitrogen protection yields an MCo2O4 / CFP electrode material. Low-temperature treatment under H2 / N2 atmosphere results in a specific surface area of ​​300-500 m² / g. 2 / g of oxygen-vacancy-rich MCo2O4 / CFP catalyst.

[0008] The technical solution of the present invention is as follows:

[0009] This invention provides an oxygen-vacancy-enriched spinel catalyst, wherein the structural formula of the oxygen-vacancy-enriched spinel catalyst is O. v -MCo2O4 / MO / CFP, where M is selected from Fe 2+ Co 2+ Ni 2+ Cu 2+ or Zn 2+ Any one or more of the oxygen-enriched vacancy spinel catalysts have a specific surface area of ​​300-500 m². 2 / g.

[0010] Furthermore, the oxygen-rich vacancy spinel catalyst is a nanoarray structure formed by growing MCo2O4 / MO nanosheets on the surface of CFP substrate carbon paper.

[0011] Furthermore, the oxygen vacancy content on the surface of the oxygen-rich spinel catalyst is 40-90%.

[0012] Furthermore, the surface oxygen vacancy content of the oxygen-rich spinel catalyst is 67.5%, 73.5%, 49.6%, 80.6%, 68.1%, or 46.2%.

[0013] The present invention also provides a method for preparing the aforementioned oxygen-enriched spinel catalyst, the method comprising the following steps: Step 1: Pretreatment of carbon paper The carbon paper was placed in a hydrothermal reactor containing a nitric acid aqueous solution and subjected to a hydrothermal reaction at a temperature of 60-90°C for 2-4 hours. After the reaction was completed, the carbon paper was washed and dried. Step 2: Preparation of MCo-LDHs / CFP precursors The electrodeposition process is carried out in a three-electrode system, with the working electrode set as the pretreated carbon paper, the counter electrode as a platinum sheet, the reference electrode as a saturated Ag / AgCl electrode, and the electrolyte as a mixed solution of 0.015~0.025 M Co(NO3)2, 0.015~0.025 M M M(NO3)2 and 0.15~0.25 M NH4Cl. During electrochemical deposition, the deposition current is kept constant at 10~15 mA / cm. -2 The deposition time was set to 400~600 s, and the temperature was kept constant at 60~80℃. After the deposition reaction was completed, the MCo-LDHs / CFP precursor was obtained. Step 3: Preparation of MCo2O4 / MO / CFP electrocatalyst The MCo-LDHs / CFP precursor obtained in step 2 was heated to 400-600 ℃ at a heating rate of 5-10 ℃ / min under nitrogen atmosphere protection, held at that temperature for 3-5 hours, and then naturally cooled to room temperature to obtain MCo2O4 / MO / CFP nanocomposite material with spinel structure. Step 4: O v -MCo2O4 / MO / CFP electrocatalyst The MCo2O4 / MO / CFP nanocomposite material obtained in step 3 was treated in an H2 / N2 atmosphere and heated to 100-300°C. o C, incubate for 1-3 hours, then cool to room temperature, finally obtaining oxygen-rich vacancy O. v -MCo2O4 / MO / CFP electrocatalyst.

[0014] Furthermore, in step 1, the concentration of the nitric acid aqueous solution is 3% to 6%.

[0015] Further, in step 1, after the hydrothermal reaction is completed, the carbon paper is taken out and soaked and washed with 40-60 mL of deionized water for 10-12 h to remove the residual nitric acid on the surface of the carbon paper. Finally, the carbon paper is dried in a forced-air drying oven at 40-60 ℃ for 10-12 h.

[0016] In step 1, the carbon paper is treated with nitric acid to pre-oxidize it, increase the number of oxygen-containing functional groups on the surface of the carbon paper, improve its hydrophilicity, and enable the electrochemically deposited hydrotalcite precursors MCo-LDHs / CFP to adhere more firmly to the carbon paper substrate surface.

[0017] Furthermore, in step 2, the area of ​​the carbon paper immersed in the electrolyte is 1. 1.5 cm 2 .

[0018] In step 2, the main function of NH4Cl is to ensure that the prepared MCo-LDHs nanosheets have an interconnected structure. That is, the interconnection between different nanosheets is beneficial to charge transport in the electrocatalytic reaction. The better the connection between the nanosheets, the faster the charge transport of the catalyst itself and the higher its activity.

[0019] Further, in step 4, the MCo2O4 / MO / CFP nanocomposite material is treated in an H2 / N2 atmosphere and heated to 100 ℃, 200 ℃ and 300 ℃ respectively at a heating rate of 5~10 ℃ / min.

[0020] The catalyst of this invention employs a sheet-like nanoarray structure of MCo2O4 grown on the surface of a substrate carbon paper using a hydrotalcite precursor. The MCo2O4 nanoarray can significantly increase the specific surface area of ​​the catalyst, achieving a specific surface area of ​​300-500 m². 2 / g, thus exposing more active sites, and this nanoarray structure also facilitates the diffusion of electrolyte solution on the catalyst surface, which is more conducive to the electrocatalytic oxidation of glycerol.

[0021] The present invention also provides a method for electrocatalyzing glycerol, wherein dihydroxyacetone is prepared by electrocatalyzing glycerol using the oxygen-vacancy-rich spinel catalyst.

[0022] Further, the method includes: removing the O from the oxygen-rich vacancies. v The catalyst MCo2O4 / MO / CFP was used as the working electrode, the calomel electrode as the reference electrode, and the Pt electrode as the counter electrode. The electrolyte was used to assemble an electrolytic cell. A mixed solution of potassium tetraborate and glycerol was added to the electrolyte. The pH of the electrolyte was 9-14. The reaction temperature was controlled at 10-60 °C, and the applied potential was 1-2.5 V.

[0023] Furthermore, the electrolyte is a mixed aqueous solution of 0.1 mol / L potassium tetraborate and 0.1 mol / L glycerol.

[0024] Furthermore, the reaction temperature is room temperature.

[0025] Furthermore, the applied potential is 1.5~2.0 V.

[0026] Furthermore, the selectivity of the dihydroxyacetone is 20-80%.

[0027] Furthermore, the selectivity of the dihydroxyacetone is as high as 72.3%.

[0028] The beneficial effects of this invention are as follows: (1) This invention directly grows MCo-LDHs / CFP catalyst precursors on the surface of carbon paper using a simple one-step electrodeposition method. The MCo-LDHs / CFP catalyst precursors are then calcined to transform them into MCo2O4 / MO / CFP nanoarrays. Further reduction with hydrogen yields oxygen-rich vacancy MCo2O4 / MO / CFP catalysts, maintaining a good nanoarray structure. The preparation steps are simple and cost-effective. Because the spinel-structured MCo2O4 / MO / CFP composite nanomaterials possess good oxidizing and conductive properties, the obtained oxygen-rich vacancy MCo2O4 / MO / CFP electrocatalyst exhibits not only high electrocatalytic activity and strong stability, but also achieves high performance at 3 mA·cm⁻¹. -2After continuous electrolysis at a current density for 24 hours, its potential shows almost no decay, resulting in a long service life.

[0029] (2) In this invention, more oxygen vacancies are formed in the MCo2O4 / MO / CFP composite nanomaterial by low-temperature hydrogen reduction. The method does not change the nanoarray structure of the MCo2O4 / MO / CFP composite nanomaterial. The synergy between oxygen vacancies and Co sites can improve the site-directed activation ability of the secondary hydroxyl group of glycerol, thereby further improving the selectivity of dihydroxyacetone.

[0030] (3) In this invention, a nano-array structure formed by many MCo2O4 / MO nanosheets is grown on the carbon paper substrate of the MCo2O4 / MO / CFP electrocatalyst. The MCo2O4 / MO nano-array structure can increase the specific surface area of ​​the catalyst and expose more active sites. Moreover, when an external potential is applied, this nano-array structure will form a special electric field at the edge of the nanosheet to change the local electrolyte concentration, which is more conducive to the electrocatalytic oxidation of glycerol to prepare dihydroxyacetone.

[0031] (4) In this invention, the catalyst has good catalytic performance and can be used to electrocatalyze the oxidation of glycerol to achieve highly selective conversion of glycerol to dihydroxyacetone. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the three-electrode device used in the fabrication of the MCo2O4 / MO / CFP electrode in this invention. WE is the working electrode, RE is the reference electrode, and CE is the counter electrode.

[0033] Figure 2 The images are scanning electron microscope (SEM) images of the MCo2O4 / MO / CFP catalyst in this invention. (a) to (f) are MnCo2O4 / MnOx / CFP, FeCo2O4 / FeOx / CFP, CoCo2O4 / CoOx / CFP, NiCo2O4 / NiOx / CFP, CuCo2O4 / CuO / CFP, and ZnCo2O4 / ZnO / CFP, respectively.

[0034] Figure 3 The X-ray photoelectron spectroscopy (XPS) spectra of the MO / MCo2O4 / CFP catalysts in this invention are shown. Data analysis revealed that the oxygen vacancy contents on the surface of the MnCo2O4 / MnOx / CFP, FeCo2O4 / FeOx / CFP, CoCo2O4 / CoOx / CFP, NiCo2O4 / NiOx / CFP, CuCo2O4 / CuO / CFP, and ZnCo2O4 / ZnO / CFP catalysts are 67.5%, 73.5%, 49.6%, 80.6%, 68.1%, and 46.2%, respectively. Detailed Implementation

[0035] The present invention will be further described below with reference to the embodiments, but the present invention is not limited to the following embodiments.

[0036] Example 1 This embodiment provides an O v -MnCo2O4 / MnO / CFP electrocatalyst with a surface oxygen vacancy content of 67.5%, its preparation method includes the following steps: Step 1: Pretreatment of carbon paper The carbon paper was placed in a 5% nitric acid aqueous solution and hydrothermally treated at 80℃ for 3 h. After the reaction was completed, the carbon paper was taken out and soaked and washed with 50 mL of deionized water for 12 h to remove the residual nitric acid on the surface of the carbon paper. Finally, the carbon paper was dried in a 60℃ forced-air drying oven for 10~12 h for later use. Step 2: Preparation of MnCo-LDHs / CFP precursors The electrodeposition process was completed in a three-electrode system, with the working electrode being pretreated carbon paper, the counter electrode being a platinum sheet, and the reference electrode being a saturated Ag / AgCl electrode. The carbon paper treated as described above was placed in a mixed solution containing 0.02 M Co(NO3)2, 0.02 M Mn(NO3)2, and 0.2 M NH4Cl, with the deposition current kept constant at 12.5 mA cm⁻¹. -2 The deposition time was 500 s, the temperature was kept constant at 70℃, and the MnCo-LDHs / CFP precursor was obtained after the deposition reaction was completed. Step 3: Preparation of MCo2O4 / MO / CFP electrocatalyst The carbon paper with the catalyst precursor obtained in step 2 was calcined under a nitrogen atmosphere with a gas flow rate of 50 ml / min. The calcination temperature was increased from room temperature to 500 ℃ at a heating rate of 5 ℃ / min, and then calcined and held at the temperature for 4 h. The reaction pressure was maintained at 0.1 MPa. After the reaction was completed, the MnO / MnCo2O4 / CFP electrocatalyst was obtained. Step 4: O v Preparation of MnO / MnCo2O4 / CFP electrocatalysts The MnO / MnCo2O4 / CFP electrocatalyst obtained in step 3 was treated under a H2 / N2 atmosphere, heated to 100 ℃, 200 ℃, and 300 ℃ respectively at a heating rate of 5 ℃ / min, held at these temperatures for 2 h, and finally cooled to room temperature; after the reaction was completed, the O of this embodiment was obtained. v -MnO / MnCo2O4 / CFP electrocatalyst.

[0037] The catalyst obtained in this embodiment was used for the electrocatalytic oxidation of glycerol to produce dihydroxyacetone. The conditions for the electrocatalytic oxidation reaction were: oxygen-rich vacancy O v Using a MnO / MnCo2O4 / CFP electrocatalyst as the working electrode, a calomel electrode as the reference electrode, and a Pt electrode as the counter electrode, an electrolytic cell was assembled with the electrolyte. A mixed aqueous solution of 0.1 mol / L glycerol and 0.1 mol / L potassium tetraborate was added to the electrolyte. A constant potential of 1.77 V (vs. RHE) was applied at room temperature, and glycerol was oxidized to dihydroxyacetone with a selectivity of 21.0%.

[0038] Example 2 This embodiment provides an O v -FeCo2O4 / FeO / CFP electrocatalyst with a surface oxygen vacancy content of 73.5%, its preparation method includes the following steps: Step 1: Pretreatment of carbon paper The carbon paper was placed in a 5% nitric acid aqueous solution and hydrothermally treated at 80℃ for 3 h. After the reaction was completed, the carbon paper was taken out and soaked and washed with 50 mL of deionized water for 12 h to remove the residual nitric acid on the surface of the carbon paper. Finally, the carbon paper was dried in a 60℃ forced-air drying oven for 10~12 h for later use. Step 2: Preparation of FeCo-LDHs / CFP precursor The electrodeposition process was completed in a three-electrode system, with the working electrode being pretreated carbon paper, the counter electrode being a platinum sheet, and the reference electrode being a saturated Ag / AgCl electrode. The carbon paper treated as described above was placed in a mixed solution containing 0.02 M Co(NO3)2, 0.02 M Fe(NO3)2, and 0.2 M NH4Cl, with the deposition current kept constant at 12.5 mA cm⁻¹. -2 The deposition time was 500 s, the temperature was kept constant at 70℃, and FeCo-LDHs / CFP precursors were obtained after the deposition reaction was completed. Step 3: Preparation of FeCo2O4 / FeO / CFP electrocatalyst The carbon paper with the catalyst precursor obtained in step 2 was calcined under a nitrogen atmosphere with a gas flow rate of 50 ml / min. The calcination temperature was increased from room temperature to 500 ℃ at a heating rate of 5 ℃ / min, and then calcined and held at the temperature for 4 h. The reaction pressure was maintained at 0.1 MPa. After the reaction was completed, the FeO / FeCo2O4 / CFP electrocatalyst was obtained. Step 4: O v Preparation of FeO / FeCo2O4 / CFP electrocatalyst The FeO / FeCo2O4 / CFP electrocatalyst obtained in step 3 was treated under a H2 / N2 atmosphere, heated to 100 °C, 200 °C, and 300 °C respectively at a heating rate of 5 °C / min, held at these temperatures for 2 h, and finally cooled to room temperature; after the reaction was completed, the O of this embodiment was obtained. v -FeO / FeCo2O4 / CFP electrocatalyst.

[0039] The catalyst obtained in this embodiment was used for the electrocatalytic oxidation of glycerol to produce dihydroxyacetone. The conditions for the electrocatalytic oxidation reaction were: oxygen-rich vacancy O v The FeO / FeCo2O4 / CFP electrocatalyst was used as the working electrode, the calomel electrode as the reference electrode, and the Pt electrode as the counter electrode. These were assembled with the electrolyte to form an electrolytic cell. A mixed aqueous solution of 0.1 mol / L glycerol and 0.1 mol / L potassium tetraborate was added to the electrolyte. A constant potential of 1.77 V (vs. RHE) was applied at room temperature. Glycerol was oxidized to dihydroxyacetone with a selectivity of 36.9%.

[0040] Example 3 This embodiment provides an O v -CoCo2O4 / CoO / CFP electrocatalyst with a surface oxygen vacancy content of 49.6%, its preparation method includes the following steps: Step 1: Pretreatment of carbon paper The carbon paper was placed in a 5% nitric acid aqueous solution and hydrothermally treated at 80℃ for 3 h. After the reaction was completed, the carbon paper was taken out and soaked and washed with 50 mL of deionized water for 12 h to remove the residual nitric acid on the surface of the carbon paper. Finally, the carbon paper was dried in a 60℃ forced-air drying oven for 10~12 h for later use. Step 2: Preparation of CoCo-LDHs / CFP precursors The electrodeposition process was completed in a three-electrode system, with the working electrode being pretreated carbon paper, the counter electrode being a platinum sheet, and the reference electrode being a saturated Ag / AgCl electrode. The carbon paper treated as described above was placed in a mixed solution containing 0.04 M Co(NO3)2 and 0.2 M NH4Cl, and the deposition current was kept constant at 12.5 mA cm⁻¹. -2 The deposition time was 500 s, the temperature was kept constant at 70℃, and the CoCo-LDHs / CFP precursor was obtained after the deposition reaction was completed. Step 3: Preparation of CoCo2O4 / CoO / CFP electrocatalyst The carbon paper with catalyst precursor obtained in step 2 was calcined under a nitrogen atmosphere with a gas flow rate of 50 ml / min. The calcination temperature was increased from room temperature to 500 ℃ at a heating rate of 5 ℃ / min, and then calcined and held at the temperature for 4 h. The reaction pressure was maintained at 0.1 MPa. After the reaction was completed, the CoO / CoCo2O4 / CFP electrocatalyst was obtained. Step 4: O v Preparation of CoO / CoCo2O4 / CFP electrocatalysts The CoO / CoCo2O4 / CFP electrocatalyst obtained in step 3 was treated under an H2 / N2 atmosphere, heated to 100 °C, 200 °C, and 300 °C respectively at a heating rate of 5 °C / min, held at these temperatures for 2 h, and finally cooled to room temperature; after the reaction was completed, the O of this embodiment was obtained. v -CoO / CoCo2O4 / CFP electrocatalyst.

[0041] The catalyst obtained in this embodiment was used for the electrocatalytic oxidation of glycerol to produce dihydroxyacetone. The conditions for the electrocatalytic oxidation reaction were: oxygen-rich vacancy O v A CoO / CoCo2O4 / CFP electrocatalyst was used as the working electrode, a calomel electrode as the reference electrode, and a Pt electrode as the counter electrode. These were assembled with the electrolyte to form an electrolytic cell. A mixed aqueous solution of 0.1 mol / L glycerol and 0.1 mol / L potassium tetraborate was added to the electrolyte. A constant potential of 1.77 V (vs. RHE) was applied at room temperature. Glycerol was oxidized to dihydroxyacetone with a selectivity of 51.1%.

[0042] Example 4 This embodiment provides an O v -NiCo2O4 / NiO / CFP electrocatalyst with a surface oxygen vacancy content of 80.6%, its preparation method includes the following steps: Step 1: Pretreatment of carbon paper The carbon paper was placed in a 5% nitric acid aqueous solution and hydrothermally treated at 80℃ for 3 h. After the reaction was completed, the carbon paper was taken out and soaked and washed with 50 mL of deionized water for 12 h to remove the residual nitric acid on the surface of the carbon paper. Finally, the carbon paper was dried in a 60℃ forced-air drying oven for 10~12 h for later use. Step 2: Preparation of NiCo-LDHs / CFP precursors The electrodeposition process was completed in a three-electrode system, with the working electrode being pretreated carbon paper, the counter electrode being a platinum sheet, and the reference electrode being a saturated Ag / AgCl electrode. The carbon paper treated as described above was placed in a mixed solution containing 0.02 M Co(NO3)2, 0.02 M Ni(NO3)2, and 0.2 M NH4Cl, with the deposition current kept constant at 12.5 mA cm⁻¹. -2 The deposition time was 500 s, the temperature was kept constant at 70℃, and NiCo-LDHs / CFP precursor was obtained after the deposition reaction was completed; Step 3: Preparation of NiCo2O4 / NiO / CFP electrocatalyst The carbon paper with the catalyst precursor obtained in step 2 was calcined under a nitrogen atmosphere with a gas flow rate of 50 ml / min. The calcination temperature was increased from room temperature to 500 ℃ at a heating rate of 5 ℃ / min, and then calcined and held at the temperature for 4 h. The reaction pressure was maintained at 0.1 MPa. After the reaction was completed, the NiO / NiCo2O4 / CFP electrocatalyst was obtained. Step 4: O v Preparation of NiO / NiCo2O4 / CFP electrocatalysts The NiO / NiCo2O4 / CFP electrocatalyst obtained in step 3 was treated under a H2 / N2 atmosphere, heated to 100 °C, 200 °C, and 300 °C respectively at a heating rate of 5 °C / min, held at these temperatures for 2 h, and finally cooled to room temperature; after the reaction was completed, the O of this embodiment was obtained. v -NiO / NiCo2O4 / CFP electrocatalyst.

[0043] The catalyst obtained in this embodiment was used for the electrocatalytic oxidation of glycerol to produce dihydroxyacetone. The conditions for the electrocatalytic oxidation reaction were: oxygen-rich vacancy O v Using a NiO / NiCo2O4 / CFP electrocatalyst as the working electrode, a calomel electrode as the reference electrode, and a Pt electrode as the counter electrode, an electrolytic cell was assembled with the electrolyte. A mixed aqueous solution of 0.1 mol / L glycerol and 0.1 mol / L potassium tetraborate was added to the electrolyte. A constant potential of 1.77 V (vs. RHE) was applied at room temperature, and glycerol was oxidized to dihydroxyacetone with a selectivity of 51.3%.

[0044] Example 5 This embodiment provides an O v The preparation method of the CuCo2O4 / CuO / CFP electrocatalyst includes the following steps: Step 1: Pretreatment of carbon paper The carbon paper was placed in a 5% nitric acid aqueous solution and hydrothermally treated at 80℃ for 3 h. After the reaction was completed, the carbon paper was taken out and soaked and washed with 50 mL of deionized water for 12 h to remove the residual nitric acid on the surface of the carbon paper. Finally, the carbon paper was dried in a 60℃ forced-air drying oven for 10~12 h for later use. Step 2: Preparation of CuCo-LDHs / CFP precursors The electrodeposition process was completed in a three-electrode system, with the working electrode being pretreated carbon paper, the counter electrode being a platinum sheet, and the reference electrode being a saturated Ag / AgCl electrode. The carbon paper treated as described above was placed in a mixed solution containing 0.02 M Co(NO3)2, 0.02 M Cu(NO3)2, and 0.2 M NH4Cl, with the deposition current kept constant at 12.5 mA cm⁻¹. -2 The deposition time was 500 s, the temperature was kept constant at 70℃, and CuCo-LDHs / CFP precursors were obtained after the deposition reaction was completed. Step 3: Preparation of CuCo2O4 / CuO / CFP electrocatalyst The carbon paper with the catalyst precursor obtained in step 2 was calcined under a nitrogen atmosphere with a gas flow rate of 50 ml / min. The calcination temperature was increased from room temperature to 500 ℃ at a heating rate of 5 ℃ / min, and then calcined and held at the temperature for 4 h. The reaction pressure was maintained at 0.1 MPa. After the reaction was completed, CuO / CuCo2O4 / CFP electrocatalyst was obtained. Step 4: O v Preparation of CuO / CuCo2O4 / CFP electrocatalyst The CuO / CuCo2O4 / CFP electrocatalyst obtained in step 3 was treated under an H2 / N2 atmosphere, heated to 100 °C, 200 °C, and 300 °C respectively at a heating rate of 5 °C / min, held at these temperatures for 2 h, and finally cooled to room temperature; after the reaction was completed, the O of this embodiment was obtained. v -CuO / CuCo2O4 / CFP electrocatalyst.

[0045] The catalyst obtained in this embodiment was used for the electrocatalytic oxidation of glycerol to produce dihydroxyacetone. The conditions for the electrocatalytic oxidation reaction were: oxygen-rich vacancy O v A CuO / CuCo2O4 / CFP electrocatalyst was used as the working electrode, a calomel electrode as the reference electrode, and a Pt electrode as the counter electrode. These were assembled with the electrolyte to form an electrolytic cell. A mixed aqueous solution of 0.1 mol / L glycerol and 0.1 mol / L potassium tetraborate was added to the electrolyte. A constant potential of 1.77 V (vs. RHE) was applied at room temperature. Glycerol was oxidized to dihydroxyacetone with a selectivity of 55.7%.

[0046] Example 6 This embodiment provides an O v The preparation method of the ZnCo2O4 / ZnO / CFP electrocatalyst includes the following steps: Step 1: Pretreatment of carbon paper The carbon paper was placed in a 5% nitric acid aqueous solution and hydrothermally treated at 80℃ for 3 h. After the reaction was completed, the carbon paper was taken out and soaked and washed with 50 mL of deionized water for 12 h to remove the residual nitric acid on the surface of the carbon paper. Finally, the carbon paper was dried in a 60℃ forced-air drying oven for 10~12 h for later use. Step 2: Preparation of ZnCo-LDHs / CFP precursors The electrodeposition process was completed in a three-electrode system, with the working electrode being pretreated carbon paper, the counter electrode being a platinum sheet, and the reference electrode being a saturated Ag / AgCl electrode. The carbon paper treated as described above was placed in a mixed solution containing 0.02 M Co(NO3)2, 0.02 M Zn(NO3)2, and 0.2 M NH4Cl, with the deposition current kept constant at 12.5 mA cm⁻¹. -2 The deposition time was 500 s, the temperature was kept constant at 70℃, and CuCo-LDHs / CFP precursors were obtained after the deposition reaction was completed. Step 3: Preparation of ZnCo2O4 / ZnO / CFP electrocatalyst The carbon paper with the catalyst precursor obtained in step 2 was calcined under a nitrogen atmosphere with a gas flow rate of 50 ml / min. The calcination temperature was increased from room temperature to 500 ℃ at a heating rate of 5 ℃ / min, and then calcined and held at the temperature for 4 h. The reaction pressure was maintained at 0.1 MPa. After the reaction was completed, the ZnO / ZnCo2O4 / CFP electrocatalyst was obtained. Step 4: O v Preparation of ZnO / ZnCo2O4 / CFP electrocatalysts The ZnO / ZnCo2O4 / CFP electrocatalyst obtained in step 3 was treated under an H2 / N2 atmosphere, heated to 100 °C, 200 °C, and 300 °C respectively at a heating rate of 5 °C / min, held at these temperatures for 2 h, and finally cooled to room temperature; after the reaction was completed, the O of this embodiment was obtained. v -ZnO / ZnCo2O4 / CFP electrocatalyst.

[0047] The catalyst obtained in this embodiment was used for the electrocatalytic oxidation of glycerol to produce dihydroxyacetone. The conditions for the electrocatalytic oxidation reaction were: oxygen-rich vacancy O v A ZnO / ZnCo2O4 / CFP electrocatalyst was used as the working electrode, a calomel electrode as the reference electrode, and a Pt electrode as the counter electrode. These were assembled with the electrolyte to form an electrolytic cell. A mixed aqueous solution of 0.1 mol / L glycerol and 0.1 mol / L potassium tetraborate was added to the electrolyte. A constant potential of 1.77 V (vs. RHE) was applied at room temperature. Glycerol was oxidized to dihydroxyacetone with a selectivity of 72.3%.

[0048] Figure 2 The images shown are scanning electron microscope (SEM) images of the catalysts obtained in Examples 1-6. It can be observed that all catalysts have a sheet-like nanoarray structure on the surface of the carbon paper.

[0049] Figure 3 The X-ray photoelectron spectra of the catalysts obtained in Examples 1-6 are shown below. Data from Examples 1-6 indicate that O v The ZnCo2O4 / ZnO / CFP catalyst exhibits high selectivity for electrocatalytic glycerol production, primarily due to the increased oxygen vacancies on the catalyst surface after hydrogen treatment. This catalyst also maintains a significant number of hydroxyl groups, enhancing its surface hydrophilicity. v The low selectivity of the MnO / MnCo2O4 / CFP catalyst is mainly due to the easy oxidation of Mn, which leads to further oxidation of the DHA product generated during electrocatalysis, promoting the breaking of the C-C bonds and generating more glycolic acid (36.8%) and formic acid (28.5%), thus reducing the selectivity for the target product.

[0050] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any other way. Any modifications or equivalent changes made based on the technical essence of this invention shall still fall within the scope of protection claimed by this invention.

Claims

1. An oxygen-vacancy-enriched spinel catalyst, characterized in that, The oxygen-enriched spinel catalyst has the structural formula O. v -MCo2O4 / MO / CFP, where M is selected from Fe 2+ Ni 2+ Cu 2+ or Zn 2+ Any one of the oxygen-enriched vacancy spinel catalysts has a specific surface area of ​​300-500 m². 2 / g; The preparation method of the oxygen-enriched vacancy spinel catalyst includes the following steps: Step 1: Pretreatment of carbon paper The carbon paper was placed in a hydrothermal reactor containing a nitric acid aqueous solution and subjected to a hydrothermal reaction at a temperature of 60-90°C for 2-4 hours. After the reaction was completed, the carbon paper was washed and dried. Step 2: Preparation of MCo-LDHs / CFP precursors The electrodeposition process is carried out in a three-electrode system, with the working electrode set as the pretreated carbon paper, the counter electrode as a platinum sheet, the reference electrode as a saturated Ag / AgCl electrode, and the electrolyte as a mixed solution of 0.015~0.025 M Co(NO3)2, 0.015~0.025 M M M(NO3)2 and 0.15~0.25 M NH4Cl. During electrochemical deposition, the deposition current is kept constant at 10~15 mA / cm. -2 The deposition time was set to 400~600 s, and the temperature was kept constant at 60~80℃. After the deposition reaction was completed, the MCo-LDHs / CFP precursor was obtained. Step 3: Preparation of MCo2O4 / MO / CFP electrocatalyst The MCo-LDHs / CFP precursor obtained in step 2 was heated to 400-600 ℃ at a heating rate of 5-10 ℃ / min under nitrogen atmosphere protection, held at that temperature for 3-5 hours, and then naturally cooled to room temperature to obtain MCo2O4 / MO / CFP nanocomposite material with spinel structure. Step 4: O v -MCo2O4 / MO / CFP electrocatalyst The MCo2O4 / MO / CFP nanocomposite material obtained in step 3 was treated in an H2 / N2 atmosphere and heated to 100-300°C. o C, incubate for 1-3 hours, then cool to room temperature, finally obtaining oxygen-rich vacancy O. v -MCo2O4 / MO / CFP electrocatalyst.

2. The oxygen-enriched spinel catalyst according to claim 1, characterized in that, The oxygen-rich vacancy spinel catalyst is a nanoarray structure formed by growing MCo2O4 / MO nanosheets on the surface of CFP substrate carbon paper.

3. The oxygen-enriched spinel catalyst according to claim 1 or 2, characterized in that, The oxygen vacancy content on the surface of the oxygen-rich spinel catalyst is 40-90%.

4. The oxygen-enriched spinel catalyst according to claim 3, characterized in that, The oxygen vacancy content on the surface of the oxygen-rich spinel catalyst is 73.5%, 80.6%, 68.1%, or 46.2%.

5. A method for preparing an oxygen-enriched vacancy spinel catalyst according to any one of claims 1-4, characterized in that, The preparation method includes the following steps: Step 1: Pretreatment of carbon paper The carbon paper was placed in a hydrothermal reactor containing a nitric acid aqueous solution and subjected to a hydrothermal reaction at a temperature of 60-90°C for 2-4 hours. After the reaction was completed, the carbon paper was washed and dried. Step 2: Preparation of MCo-LDHs / CFP precursors The electrodeposition process is carried out in a three-electrode system, with the working electrode set as the pretreated carbon paper, the counter electrode as a platinum sheet, the reference electrode as a saturated Ag / AgCl electrode, and the electrolyte as a mixed solution of 0.015~0.025 M Co(NO3)2, 0.015~0.025 M M M(NO3)2 and 0.15~0.25 M NH4Cl. During electrochemical deposition, the deposition current is kept constant at 10~15 mA / cm. -2 The deposition time was set to 400~600 s, and the temperature was kept constant at 60~80℃. After the deposition reaction was completed, the MCo-LDHs / CFP precursor was obtained. Step 3: Preparation of MCo2O4 / MO / CFP electrocatalyst The MCo-LDHs / CFP precursor obtained in step 2 was heated to 400-600 ℃ at a heating rate of 5-10 ℃ / min under nitrogen atmosphere protection, held at that temperature for 3-5 hours, and then naturally cooled to room temperature to obtain MCo2O4 / MO / CFP nanocomposite material with spinel structure. Step 4: O v -MCo2O4 / MO / CFP electrocatalyst The MCo2O4 / MO / CFP nanocomposite material obtained in step 3 was treated in an H2 / N2 atmosphere and heated to 100-300°C. o C, incubate for 1-3 hours, then cool to room temperature, finally obtaining oxygen-rich vacancy O. v -MCo2O4 / MO / CFP electrocatalyst.

6. The preparation method according to claim 5, characterized in that, In step 1, the concentration of the nitric acid aqueous solution is 3% to 6%.

7. The preparation method according to claim 6, characterized in that, In step 1, after the hydrothermal reaction is completed, the carbon paper is taken out and soaked and washed with 40-60 mL of deionized water for 10-12 h to remove the residual nitric acid on the surface of the carbon paper. Finally, the carbon paper is dried in a forced-air drying oven at 40-60 ℃ for 10-12 h.

8. According to the preparation method of claim 7, in step 4, the MCo2O4 / MO / CFP nanocomposite material is treated in an H2 / N2 atmosphere and heated to 100 ℃, 200 ℃ and 300 ℃ respectively at a heating rate of 5~10 ℃ / min.

9. A method for electrocatalyzing glycerol, characterized in that, Dihydroxyacetone was prepared by electrocatalytically catalyzing glycerol using the oxygen-vacancy-rich spinel catalyst according to any one of claims 1-4.

10. The method according to claim 9, characterized in that, The oxygen-rich vacancy O v The electrolytic cell is assembled with an MCo2O4 / MO / CFP catalyst as the working electrode, a calomel electrode as the reference electrode, and a Pt electrode as the counter electrode, along with an electrolyte. A mixed solution of potassium tetraborate and glycerol is added to the electrolyte. The electrolyte pH is 9-14, the reaction temperature is controlled at 10-60 °C, and the applied potential is 1-2.5 V.

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