An oxygen-enriched vacancy nitrogen-doped nickel phosphide / ceria composite catalyst, a preparation method and application thereof

Abstract

The application belongs to the technical field of new energy materials and electrochemical catalysis, and provides an oxygen vacancy-rich nitrogen-doped nickel phosphide / cerium oxide composite catalyst, a preparation method and application thereof. A foam nickel is used as a working electrode, a platinum sheet is used as a counter electrode, and a Hg / HgO electrode is used as a reference electrode. In an electrolyte solution containing a nickel salt and a cerium salt, electrodeposition is performed to obtain a precursor. The precursor includes the foam nickel and cerium and nickel deposited on the foam nickel. The precursor is soaked in a tannic acid solution to obtain an impregnated precursor. Ammonium hypophosphite is placed upstream, and the impregnated precursor placed downstream is subjected to phosphorus nitride doping treatment to obtain the oxygen vacancy-rich nitrogen-doped nickel phosphide / cerium oxide composite catalyst. The obtained oxygen vacancy-rich nitrogen-doped nickel phosphide / cerium oxide composite catalyst exhibits excellent electrocatalytic performance for methanol oxidation reaction (MOR) and can be used as a high-efficiency anode catalyst for a direct methanol fuel cell (DMFC).

Description

Technical Field

[0001] This invention relates to the fields of new energy materials and electrochemical catalysis technology, and in particular to an oxygen-rich vacancy nitrogen-doped nickel phosphide / cerium oxide composite catalyst, its preparation method, and its application. Background Technology

[0002] With the global energy crisis and environmental problems becoming increasingly severe, efficient, low-cost, and sustainable electrochemical energy conversion and high-value-added chemical electrosynthesis technologies have become important development directions. Methanol oxidation (MOR), as the core reaction of technologies such as direct methanol fuel cells and methanol-water coupled electrolysis for hydrogen production, has attracted widespread attention due to its advantages such as high energy density and convenient raw material storage and transportation. However, problems such as slow reaction kinetics, high cost of precious metal catalysts, susceptibility to intermediate poisoning, and poor structural stability under high current severely restrict its practical application. Therefore, developing highly active, highly stable, and CO-poison-resistant non-precious metal electrocatalysts is of great significance.

[0003] Among numerous non-noble metal catalysts, nickel phosphide (Ni2P) stands out as an ideal material for methanol oxidation catalysis due to its suitable electronic structure, good conductivity, and moderate adsorption capacity for reaction intermediates. However, pure nickel phosphide has limited active sites, weak electronic regulation capabilities, and is prone to structural collapse under harsh conditions, making it difficult to meet the requirements for high-efficiency and long-life catalysis. Current research indicates that strategies such as constructing heterostructures, defect engineering, and heteroatom doping can effectively improve catalytic performance. Among these, coupling nickel phosphide with cerium oxide (CeO2) to form a heterostructure can utilize the CeO2... 3+ / Ce 4+ The reversible redox cycle enables efficient electron transport, generates abundant oxygen vacancies, and promotes the oxidative removal of toxic CO intermediates, significantly enhancing the catalyst's resistance to poisoning and intrinsic activity.

[0004] However, existing CeO2 heterostructure systems generally suffer from insufficient oxygen vacancy concentration and low density of highly active sites, making it difficult to further improve catalytic performance. Summary of the Invention

[0005] In view of this, the purpose of this invention is to provide an oxygen-vacancy nitrogen-doped nickel phosphide / cerium oxide composite catalyst, its preparation method, and its application. The preparation method provided by this invention can endow the catalyst with oxygen-rich vacancies and a high active site density, enabling it to exhibit excellent electrocatalytic performance for the methanol oxidation reaction (MOR).

[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a method for preparing an oxygen-rich, vacancy-doped nickel phosphide / cerium oxide composite catalyst, comprising the following steps: Using nickel foam as the working electrode, a platinum sheet as the counter electrode, and an Hg / HgO electrode as the reference electrode, electrodeposition was performed in an electrolyte solution containing nickel and cerium salts to obtain a precursor; the precursor includes nickel foam, as well as cerium and nickel deposited on the nickel foam. The precursor is immersed in a tannic acid solution to obtain an impregnated precursor; Ammonium hypophosphite is placed upstream, and the impregnation precursor placed downstream is subjected to phosphide doping treatment to obtain the oxygen-rich vacancy nitrogen-doped nickel phosphide / cerium oxide composite catalyst.

[0007] Preferably, the molar ratio of nickel salt to cerium salt in the electrolyte solution is 1:0.1~1.

[0008] Preferably, the nickel salt is at least one of nickel acetate, nickel sulfate, and nickel nitrate, and the cerium salt is at least one of cerium nitrate, cerium sulfate, and cerium chloride.

[0009] Preferably, the electrodeposition potential is -1 to -1.4V vs. Hg / HgO, and the time is 10 to 60 minutes.

[0010] Preferably, the concentration of the tannic acid solution is 10~40g / L.

[0011] Preferably, the soaking time is 0.5 to 2 hours.

[0012] Preferably, the amount of ammonium hypophosphite used is 0.2 to 0.8 g of ammonium hypophosphite per cubic centimeter of nickel foam.

[0013] Preferably, the temperature of the phosphorus doping treatment is 300~400℃ and the time is 1~3h.

[0014] The present invention also provides an oxygen-rich vacancy nitrogen-doped nickel phosphide / cerium oxide composite catalyst prepared by the preparation method described above.

[0015] The present invention also provides the application of the oxygen-rich vacancy nitrogen-doped nickel phosphide / cerium oxide composite catalyst described in the above technical solution in methanol fuel cells.

[0016] This invention provides an oxygen-rich vacancy nitrogen-doped nickel phosphide / cerium oxide composite catalyst (N-Ni2P / CeO2-V) O Preparation method of ).

[0017] The preparation method of the present invention has the following beneficial effects: (1) This invention achieves the construction of phosphating and nitrogen doping, heterojunction and oxygen vacancy simultaneously through tannic acid-mediated vacancy engineering and low-temperature phosphating nitrogen doping. The three synergistically regulate N-Ni2P / CeO2-V OElectronic structure and surface properties: Ni-N bonds formed by nitrogen doping optimize the electron density of Ni2P, reducing the energy barrier for methanol adsorption and dehydrogenation; the heterojunction constructed by CeO2 and Ni2P accelerates interfacial charge transfer, Ce 4+ / Ce 3+ Reversible transformation promotes intermediate conversion; the synergistic effect of weakly acidic etching, phenolic hydroxyl coordination chelation, and surface charge rearrangement of tannic acid selectively disrupts lattice oxygen bonds, regulates metal valence state balance, and directionally constructs stable oxygen vacancies. This abundant oxygen vacancy site efficiently removes poisoning intermediates such as CO, significantly enhancing the catalytic anti-poisoning ability. Furthermore, it can regulate the electronic structure and optimize surface adsorption characteristics, thereby improving the utilization rate of active sites. Notably, tannic acid contains abundant carbon, which, after sintering, forms a carbon coating layer on the catalyst surface, improving the material's electrical and mechanical properties. Specifically, the peak current density at 1.726V (vs. RHE) reaches as high as 423.8 mA·cm⁻¹. -2 And it reaches 10 mA·cm -2 50mA·cm -2 and 100mA·cm -2 The required potentials for the current densities are only 1.348V, 1.383V, and 1.391V (vs. RHE), respectively, with Tafel slopes as low as 59.5mV·dec. -1 After 60 hours of continuous operation at a potential of 1.526V (vs. RHE), the current density retention rate reached 81.5%, demonstrating excellent electrocatalytic activity for methanol oxidation (MOR), rapid reaction kinetics, and good long-term stability.

[0018] (2) The present invention adopts a continuous preparation process of "electrochemical deposition - tannic acid etching - one-step nitrogen phosphide doping". Compared with the comparative sample without tannic acid treatment and without nitrogen doping, the catalytic performance is significantly superior: the N-Ni2P / CeO2 catalyst without tannic acid treatment lacks oxygen vacancies, and the peak current density under the same test conditions (1.726V (vs. RHE potential)) is only 363.6 mA·cm. -2 Reaching 10 mA·cm -2 50mA·cm -2 and 100mA·cm -2 The required current densities are 1.370V, 1.387V, and 1.398V (vs. RHE), respectively, with a Tafel slope of 96.2mV·dec. -1 The nitrogen-free Ni₂P / CeO₂ catalyst, due to its unoptimized electronic structure, exhibits a peak current density of 325.6 mA·cm⁻¹. -2 Reaching 10 mA·cm -2 50mA·cm -2 and 100mA·cm -2The required current densities are 1.369V, 1.389V, and 1.404V (vs. RHE), respectively, with a Tafel slope of 108.3mV·dec. -1 The peak current density of unmodified Ni₂P is 237.6 mA·cm⁻¹. -2 Reaching 10 mA·cm -2 50mA·cm -2 and 100mA·cm -2 The required current densities are 1.373V, 1.404V, and 1.433V (vs. RHE), with a Tafel slope of 116.1mV·dec. -1 The catalytic performance of these catalysts is weaker than that of the catalyst of this invention. Furthermore, this process avoids the problems of loose heterojunction bonding and easy loss of defect sites caused by stepwise preparation, enabling the catalyst to form a stable heterostructure and abundant mesopores, thereby improving the specific surface area and electrolyte contact rate.

[0019] (3) The N-Ni2P / CeO2-V prepared in this invention O The catalyst uses non-precious metals as the core active component, with low-cost and readily available raw materials. The preparation process does not require harsh conditions such as high temperature and high pressure, and avoids the resource scarcity and high cost of precious metals. It is easy to achieve large-scale production and industrial application, providing a feasible solution for the low cost and high performance of anode catalysts for direct methanol fuel cells (DMFC). Attached Figure Description

[0020] Figure 1 The X-ray diffraction (XRD) patterns of the catalysts obtained in Example 1 and Comparative Examples 1-3 are shown below. Figure 2 The catalysts obtained in Examples 1-4 were reacted in a 1M KOH + 0.5M CH3OH solution at a rate of 50 mV·s. -1 Cyclic voltammetry (CV) curves from sweep rate testing; Figure 3 The catalysts obtained in Examples 1, 5, and 6 were reacted in a 1M KOH + 0.5M CH3OH solution at a rate of 50 mV·s. -1 CV curve of sweep speed test; Figure 4 The catalysts obtained in Examples 1, 7, and 8 were reacted in a 1M KOH + 0.5M CH3OH solution at a rate of 50 mV·s. -1 CV curve of sweep speed test; Figure 5 The catalysts obtained in Examples 1, 9, and 10 were reacted in 1M KOH + 0.5M CH3OH solution at a rate of 50 mV·s. -1 CV curve of sweep speed test; Figure 6 The catalysts obtained in Examples 1 and Comparative Examples 1-3 were reacted in 1M KOH + 0.5M CH3OH solution at a rate of 50 mV·s. -1 CV curve of sweep speed test; Figure 7 The Tafel curves of the catalysts obtained in Example 1 and Comparative Examples 1-3 in 1M KOH + 0.5M CH3OH solution are shown. Figure 8 The catalysts obtained in Example 1 and Comparative Example 4 were reacted in a 1M KOH + 0.5M CH3OH solution at a rate of 50 mV·s. -1 CV curve of sweep speed test; Figure 9 The catalysts obtained in Example 1 and Comparative Example 5 were reacted in a 1M KOH + 0.5M CH3OH solution at a rate of 50 mV·s. -1 CV curve of sweep speed test; Figure 10 The time-current (it) curves of the catalysts obtained in Example 1 and Comparative Examples 1-3 in 1M KOH + 0.5M CH3OH solution at a potential of 1.526V (vs. RHE) are shown. Figure 11 The image shows a scanning electron microscope (SEM) image of the catalyst obtained in Example 1. Figure 12 The image shows the SEM image of the catalyst obtained in Comparative Example 1. Figure 13 This is a transmission electron microscope (TEM) image of the catalyst obtained in Example 1. Detailed Implementation

[0021] This invention provides a method for preparing an oxygen-rich, vacancy-doped nickel phosphide / cerium oxide composite catalyst, comprising the following steps: Using nickel foam as the working electrode, a platinum sheet as the counter electrode, and an Hg / HgO electrode as the reference electrode, electrodeposition was performed in an electrolyte solution containing nickel and cerium salts to obtain a precursor; the precursor includes nickel foam, as well as cerium and nickel deposited on the nickel foam. The precursor is immersed in a tannic acid (TA) solution to obtain an impregnated precursor; Ammonium hypophosphite is placed upstream, and the impregnation precursor placed downstream is subjected to phosphide doping treatment to obtain the oxygen-rich vacancy nitrogen-doped nickel phosphide / cerium oxide composite catalyst.

[0022] Unless otherwise specified, the raw materials used in this invention are preferably commercially available products.

[0023] This invention uses nickel foam as the working electrode, a platinum sheet as the counter electrode, and an Hg / HgO electrode as the reference electrode. Electrodeposition is performed in an electrolyte solution containing nickel salt and cerium salt to obtain a precursor. The precursor includes nickel foam and cerium and nickel deposited on the nickel foam.

[0024] In this invention, the nickel foam is preferably pretreated before use. The pretreatment preferably includes sequential ultrasonic acid washing, ultrasonic alcohol washing, and ultrasonic water washing. The reagent used for ultrasonic acid washing is preferably hydrochloric acid, and the concentration of the hydrochloric acid is preferably 0.5~1M. The reagent used for ultrasonic alcohol washing is preferably ethanol. The reagent used for ultrasonic water washing is preferably deionized water. The time for ultrasonic acid washing, ultrasonic alcohol washing, and ultrasonic water washing is preferably 10~20 min, and more preferably 15 min.

[0025] In this invention, the nickel salt is preferably at least one of nickel acetate, nickel sulfate, and nickel nitrate, more preferably nickel acetate, and even more preferably nickel acetate tetrahydrate (Ni(CH3COO)2·4H2O). In this invention, the cerium salt is preferably at least one of cerium nitrate, cerium sulfate, and cerium chloride, more preferably cerium nitrate, and even more preferably cerium nitrate hexahydrate (Ce(NO3)3·6H2O). In this invention, the molar ratio of nickel salt to cerium salt in the electrolyte solution is preferably 1:0.1 to 1, specifically preferably 1:0.1, 1:0.2, 1:0.3, 1:0.4, 1:0.5, 1:0.6, 1:0.7, 1:0.8, 1:0.9, or 1:1; the concentration of nickel salt is preferably 1 mol / L, and the concentration of cerium salt is specifically preferably 0.1 mol / L, 0.2 mol / L, 0.3 mol / L, 0.4 mol / L, 0.5 mol / L, 0.6 mol / L, 0.7 mol / L, 0.8 mol / L, 0.9 mol / L, or 1 mol / L. In this invention, the solvent of the electrolyte solution is preferably water, more preferably deionized water.

[0026] In this invention, each cubic centimeter (cm) 3 The nickel foam requires the addition of 0.10~0.25 mol of nickel salt to the electrolyte solution, specifically preferably 0.10 mol, 0.11 mol, 0.12 mol, 0.13 mol, 0.14 mol, 0.15 mol, 0.16 mol, 0.167 mol, 0.17 mol, 0.18 mol, 0.19 mol, 0.20 mol, 0.21 mol, 0.22 mol, 0.23 mol, 0.24 mol, or 0.25 mol.

[0027] In this invention, the electrodeposition is a constant potential deposition, and the electrodeposition potential is preferably -1 to -1.4V (vs. Hg / HgO), specifically -1 vs. Hg / HgO, -1.1 vs. Hg / HgO, -1.2V vs. Hg / HgO, -1.3V vs. Hg / HgO, or -1.4V vs. Hg / HgO. In this invention, the electrodeposition time is preferably 10 to 60 minutes, specifically 10 minutes, 20 minutes, 30 minutes, 40 minutes, 50 minutes, or 60 minutes; the ambient temperature is preferably room temperature.

[0028] After electrodeposition, the present invention preferably further includes: removing the electrodeposited nickel foam and sequentially washing the electrodeposited nickel foam with water (referred to as the first water wash), washing with alcohol (referred to as the first alcohol wash), and drying (referred to as the first drying) to obtain the precursor. In the present invention, the reagent for the first water wash is preferably deionized water, and the reagent for the first alcohol wash is preferably ethanol, more preferably anhydrous ethanol. In the present invention, the temperature of the first drying is preferably 60~80℃, specifically preferably 60℃, 70℃, or 80℃, and the time is preferably 6~8h, specifically preferably 6h, 7h, or 8h. The first drying is preferably carried out in an oven.

[0029] In this invention, the precursor comprises nickel foam, and cerium and nickel deposited on the nickel foam.

[0030] After obtaining the precursor, the present invention soaks the precursor in a tannic acid solution to obtain an impregnated precursor. In the present invention, the concentration of the tannic acid solution is preferably 10-40 g / L, specifically preferably 10 g / L, 15 g / L, 20 g / L, 25 g / L, 30 g / L, 35 g / L, or 40 g / L. In the present invention, the soaking time is preferably 0.5-2 hours, specifically preferably 0.5 hours, 1 hour, 1.5 hours, or 2 hours. In the present invention, the soaking temperature is preferably room temperature, i.e., neither additional heating nor additional cooling is required.

[0031] After the soaking is completed, the present invention preferably further includes: taking out the soaked precursor and sequentially washing it with water (referred to as the second water wash), washing it with alcohol (referred to as the second alcohol wash), and drying it (referred to as the second drying); the reagent used for the second water wash is preferably water, and the water is preferably deionized water; the reagent used for the second alcohol wash is preferably ethanol, and the ethanol is preferably anhydrous ethanol; the temperature of the second drying is preferably 60~80℃, the time is preferably 6~8h, and the second drying is preferably carried out in a vacuum oven.

[0032] In this invention, the precursor is immersed in a tannic acid solution, allowing the phenolic hydroxyl groups of the tannic acid to preferentially and fully react with Ce on the precursor. 4+(Partially inert) strong chelation occurs, leading to an increase in MO (metal-oxygen) bond length and a decrease in bond energy, thus promoting the removal of lattice oxygen (forming oxygen vacancies). Secondly, tannic acid has weak reducing properties, which can reduce the Ce precursor... 4+ Restored to Ce 3+ This process disrupts the lattice charge balance, causing the lattice to spontaneously release oxygen atoms and form oxygen vacancies. This invention utilizes tannic acid to etch the precursor, generating a large number of uniform oxygen vacancies while simultaneously optimizing the metal valence state and constructing highly defective active sites, significantly improving electrocatalytic performance.

[0033] After obtaining the impregnation precursor, this invention places ammonium hypophosphite upstream and performs phosphide doping treatment on the downstream impregnation precursor to obtain the oxygen-rich vacancy nitrogen-doped nickel phosphide / cerium oxide composite catalyst. In this invention, the amount of ammonium hypophosphite added is per cubic centimeter (cm³). 3 The foamed nickel requires 0.2~0.8g of ammonium hypophosphate, preferably 0.2g, 0.3g, 0.4g, 0.5g, 0.6g, 0.7g or 0.8g.

[0034] In this invention, the temperature of the phosphorus doping treatment is preferably 300~400℃, specifically preferably 300℃, 310℃, 320℃, 330℃, 340℃, 350℃, 360℃, 370℃, 380℃, 390℃ or 400℃, and the time is preferably 1~3h, more preferably 2h; the rate of heating to the temperature of the phosphorus doping treatment is preferably 2~5℃ / min.

[0035] In this invention, the phosphorus doping treatment is preferably carried out under a protective atmosphere, preferably argon. The upstream and downstream positions, relative to the direction of the protective atmosphere flow, are defined as follows: the position where the protective atmosphere first passes through is called the upstream, and the position where it passes through later is called the downstream. In this invention, the phosphorus doping treatment is preferably carried out in a tube furnace.

[0036] After the phosphorus doping treatment, the present invention preferably further includes: natural cooling to room temperature.

[0037] The innovative aspects of the preparation method of this invention can be summarized in the following four points: (1) For the first time, a two-step preparation of nitrogen doping + heterojunction + oxygen vacancy is achieved without multiple complex processing steps, and all structural control is completed in two steps. (2) Oxygen vacancies are constructed in a mild and controllable manner, without destroying the host phase or etching to remove specific elements, which is completely different from the traditional strong acid / strong base / strong etching method. (3) With the help of the properties of cerium, a nickel phosphide / cerium oxide heterostructure is constructed, which realizes the high dispersion of Ni2P and the strong electron interaction of CeO2, improves the burst rate of active sites, improves conductivity, significantly enhances stability, and has outstanding performance. (4) The preparation process is green, safe, free of toxic reagents, and low in cost.

[0038] The present invention also provides an oxygen-rich vacancy nitrogen-doped nickel phosphide / cerium oxide composite catalyst prepared by the preparation method described above.

[0039] In this invention, the oxygen-rich vacancy nitrogen-doped nickel phosphide / cerium oxide composite catalyst includes nickel foam, and nitrogen-doped Ni2P (N-Ni2P) and CeO2 attached to the nickel foam.

[0040] The oxygen-vacancy nitrogen-doped nickel phosphide / cerium oxide composite catalyst provided by this invention achieves synergistic enhancement through multiple mechanisms: nitrogen doping regulates the microstructure of Ni2P; the heterojunction accelerates charge transfer; and Ce... 4+ / Ce 3+ Reversible transformation promotes intermediate conversion; oxygen vacancies optimize electron configuration. Electrochemical tests show that in a 1M KOH + 0.5M methanol electrolyte, an overpotential of only 1.348V (vs. RHE) is required to reach 10 mA·cm⁻¹. -2 Current density, Tafel slope as low as 59.5 mV·dec -1 The 60-hour chronocurrent retention rate reached 81.5%. The nitrogen-doped nickel phosphide / cerium oxide composite catalyst of the present invention can be used as a high-efficiency anode catalyst for DMFC, providing key support for the commercialization of clean energy devices, and has both economic and environmental value.

[0041] The present invention also provides the application of the oxygen-rich vacancy nitrogen-doped nickel phosphide / cerium oxide composite catalyst described in the above technical solution in methanol fuel cells.

[0042] The present invention does not impose specific limitations on the application of the oxygen-rich vacancy nitrogen-doped nickel phosphide / cerium oxide composite catalyst; any operation known to those skilled in the art can be used.

[0043] The following detailed description, in conjunction with embodiments, illustrates the oxygen-rich vacancy nitrogen-doped nickel phosphide / cerium oxide composite catalyst, its preparation method, and its applications. However, these descriptions should not be construed as limiting the scope of protection of this invention.

[0044] Example 1 The preparation method of the oxygen-rich vacancy nitrogen-doped nickel phosphide / cerium oxide composite catalyst in this embodiment includes the following steps: (1) Add 0.1 mol Ni(CH3COO)2·4H2O and 0.06 mol Ce(NO3)3·6H2O to 100 mL of deionized water and stir to form solution A. Using solution A as electrolyte solution, the precursor was deposited in a three-electrode system using an electrochemical workstation: using foamed nickel (1.5 mm (thickness) × 2 cm × 2 cm) that was ultrasonically cleaned for 15 min in sequence with 0.5 M hydrochloric acid, ethanol and deionized water as working electrode, platinum sheet as counter electrode, Hg / HgO electrode as reference electrode, and deposited at constant potential (-1.2 V vs. Hg / HgO) for 30 min. Then, it was cleaned with deionized water and anhydrous ethanol respectively, and then placed in a vacuum oven at 60 °C for 8 h to obtain nickel-cerium precursor.

[0045] (2) Prepare a 10 g / L tannic acid solution, immerse the nickel-cerium precursor obtained in step (1) in the tannic acid solution for 1 h, so that the phenolic hydroxyl groups in the tannic acid can fully coordinate and chelate with the surface of the precursor, and then take it out, rinse and dry it.

[0046] (3) Place the nickel-cerium precursor obtained in step (2) downstream of the ceramic boat and place 0.3g of ammonium hypophosphate upstream of the ceramic boat; then place the ceramic boat into a high-temperature tube furnace and heat it at 5℃·min under the protection of inert argon gas. -1 The heating rate was increased to 350℃, and after 2 hours of reaction, the temperature was lowered to room temperature to obtain an oxygen-rich, nitrogen-doped nickel phosphide / cerium oxide composite catalyst, denoted as N-Ni2P / CeO2-V. O Composite catalyst.

[0047] Example 2 The preparation method of the oxygen-rich vacancy nitrogen-doped nickel phosphide / cerium oxide composite catalyst in this embodiment includes the following steps: (1) Add 0.1 mol Ni(CH3COO)2·4H2O and 0.02 mol Ce(NO3)3·6H2O to 100 mL of deionized water and stir to form solution A. Using solution A as electrolyte solution, the precursor was deposited in a three-electrode system using an electrochemical workstation: using foamed nickel (1.5 mm (thickness) × 2 cm × 2 cm) that was ultrasonically cleaned for 15 min in sequence with 0.5 M hydrochloric acid, ethanol and deionized water as working electrode, platinum sheet as counter electrode, Hg / HgO electrode as reference electrode, and deposited at constant potential (-1.2 V vs. Hg / HgO) for 30 min. Then, it was cleaned with deionized water and anhydrous ethanol respectively, and then placed in a vacuum oven at 60 °C for 8 h to obtain nickel-cerium precursor.

[0048] (2) Prepare a 10 g / L tannic acid solution, immerse the nickel-cerium precursor obtained in step (1) in the tannic acid solution for 1 h, so that the phenolic hydroxyl groups in the tannic acid can fully coordinate and chelate with the surface of the precursor, and then take it out, rinse and dry it.

[0049] (3) Place the nickel-cerium precursor obtained in step (2) downstream of the ceramic boat and place 0.3g of ammonium hypophosphate upstream of the ceramic boat; then place the ceramic boat into a high-temperature tube furnace and heat it at 5℃·min under the protection of inert argon gas. -1 The heating rate was increased to 350℃, and after 2 hours of reaction, the temperature was lowered to room temperature to obtain an oxygen-rich, nitrogen-doped nickel phosphide / cerium oxide composite catalyst, denoted as N-Ni2P / CeO2-V. O Composite catalyst.

[0050] Example 3 The preparation method of the oxygen-rich vacancy nitrogen-doped nickel phosphide / cerium oxide composite catalyst in this embodiment includes the following steps: (1) Add 0.1 mol Ni(CH3COO)2·4H2O and 0.04 mol Ce(NO3)3·6H2O to 100 mL of deionized water and stir to form solution A. Using solution A as electrolyte solution, the precursor was deposited in a three-electrode system using an electrochemical workstation: using foamed nickel (1.5 mm (thickness) × 2 cm × 2 cm) that was ultrasonically cleaned for 15 min in sequence with 0.5 M hydrochloric acid, ethanol and deionized water as working electrode, platinum sheet as counter electrode, Hg / HgO electrode as reference electrode, and deposited at constant potential (-1.2 V vs. Hg / HgO) for 30 min. Then, it was cleaned with deionized water and anhydrous ethanol respectively, and then placed in a vacuum oven at 60 °C for 8 h to obtain nickel-cerium precursor.

[0051] (2) Prepare a 10 g / L tannic acid solution, immerse the nickel-cerium precursor obtained in step (1) in the tannic acid solution for 1 h, so that the phenolic hydroxyl groups in the tannic acid can fully coordinate and chelate with the surface of the precursor, and then take it out, rinse and dry it.

[0052] (3) Place the nickel-cerium precursor obtained in step (2) downstream of the ceramic boat and place 0.3g of ammonium hypophosphate upstream of the ceramic boat; then place the ceramic boat into a high-temperature tube furnace and heat it at 5℃·min under the protection of inert argon gas. -1 The heating rate was increased to 350℃, and after 2 hours of reaction, the temperature was lowered to room temperature to obtain an oxygen-rich, nitrogen-doped nickel phosphide / cerium oxide composite catalyst, denoted as N-Ni2P / CeO2-V. O Composite catalyst.

[0053] Example 4 The preparation method of the oxygen-rich vacancy nitrogen-doped nickel phosphide / cerium oxide composite catalyst in this embodiment includes the following steps: (1) Add 0.1 mol Ni(CH3COO)2·4H2O and 0.08 mol Ce(NO3)3·6H2O to 100 mL of deionized water and stir to form solution A. Using solution A as electrolyte solution, the precursor was deposited in a three-electrode system using an electrochemical workstation: using foamed nickel (1.5 mm (thickness) × 2 cm × 2 cm) that was ultrasonically cleaned for 15 min in sequence with 0.5 M hydrochloric acid, ethanol and deionized water as working electrode, platinum sheet as counter electrode, Hg / HgO electrode as reference electrode, and deposited at constant potential (-1.2 V vs. Hg / HgO) for 30 min. Then, it was cleaned with deionized water and anhydrous ethanol respectively, and then placed in a vacuum oven at 60 °C for 8 h to obtain nickel-cerium precursor.

[0054] (2) Prepare a 10 g / L tannic acid solution, immerse the nickel-cerium precursor obtained in step (1) in the tannic acid solution for 1 h, so that the phenolic hydroxyl groups in the tannic acid can fully coordinate and chelate with the surface of the precursor, and then take it out, rinse and dry it.

[0055] (3) Place the nickel-cerium precursor obtained in step (2) downstream of the ceramic boat and place 0.3g of ammonium hypophosphate upstream of the ceramic boat; then place the ceramic boat into a high-temperature tube furnace and heat it at 5℃·min under the protection of inert argon gas. -1 The heating rate was increased to 350℃, and after 2 hours of reaction, the temperature was lowered to room temperature to obtain an oxygen-rich, nitrogen-doped nickel phosphide / cerium oxide composite catalyst, denoted as N-Ni2P / CeO2-V. O Composite catalyst.

[0056] Example 5 The preparation method of the oxygen-rich vacancy nitrogen-doped nickel phosphide / cerium oxide composite catalyst in this embodiment includes the following steps: (1) Add 0.1 mol Ni(CH3COO)2·4H2O and 0.06 mol Ce(NO3)3·6H2O to 100 mL of deionized water and stir to form solution A. Using solution A as electrolyte solution, the precursor was deposited in a three-electrode system using an electrochemical workstation: using foamed nickel (1.5 mm (thickness) × 2 cm × 2 cm) that was ultrasonically cleaned for 15 min in sequence with 0.5 M hydrochloric acid, ethanol and deionized water as working electrode, platinum sheet as counter electrode, Hg / HgO electrode as reference electrode, and deposited at constant potential (-1.2 V vs. Hg / HgO) for 15 min. Then, it was cleaned with deionized water and anhydrous ethanol respectively, and then placed in a vacuum oven at 60 °C for 8 h to obtain nickel-cerium precursor.

[0057] (2) Prepare a 10 g / L tannic acid solution, immerse the nickel-cerium precursor obtained in step (1) in the tannic acid solution for 1 h, so that the phenolic hydroxyl groups in the tannic acid can fully coordinate and chelate with the surface of the precursor, and then take it out, rinse and dry it.

[0058] (3) Place the nickel-cerium precursor obtained in step (2) downstream of the ceramic boat and place 0.3g of ammonium hypophosphate upstream of the ceramic boat; then place the ceramic boat into a high-temperature tube furnace and heat it at 5℃·min under the protection of inert argon gas. -1 The heating rate was increased to 350℃, and after 2 hours of reaction, the temperature was lowered to room temperature to obtain an oxygen-rich, nitrogen-doped nickel phosphide / cerium oxide composite catalyst, denoted as N-Ni2P / CeO2-V. O Composite catalyst.

[0059] Example 6 The preparation method of the oxygen-rich vacancy nitrogen-doped nickel phosphide / cerium oxide composite catalyst in this embodiment includes the following steps: (1) Add 0.1 mol Ni(CH3COO)2·4H2O and 0.06 mol Ce(NO3)3·6H2O to 100 mL of deionized water and stir to form solution A. Using solution A as electrolyte solution, the precursor was deposited in a three-electrode system using an electrochemical workstation: using foamed nickel (1.5 mm (thickness) × 2 cm × 2 cm) that was ultrasonically cleaned for 15 min in sequence with 0.5 M hydrochloric acid, ethanol and deionized water as working electrode, platinum sheet as counter electrode, Hg / HgO electrode as reference electrode, and deposited at constant potential (-1.2 V vs. Hg / HgO) for 60 min. After cleaning with deionized water and anhydrous ethanol respectively, it was placed in a vacuum oven at 60 °C for 8 h to obtain nickel-cerium precursor.

[0060] (2) Prepare a 10 g / L tannic acid solution, immerse the nickel-cerium precursor obtained in step (1) in the tannic acid solution for 1 h, so that the phenolic hydroxyl groups in the tannic acid can fully coordinate and chelate with the surface of the precursor, and then take it out, rinse and dry it.

[0061] (3) Place the nickel-cerium precursor obtained in step (2) downstream of the ceramic boat and place 0.3g of ammonium hypophosphate upstream of the ceramic boat; then place the ceramic boat into a high-temperature tube furnace and heat it at 5℃·min under the protection of inert argon gas. -1 The heating rate was increased to 350℃, and after 2 hours of reaction, the temperature was lowered to room temperature to obtain an oxygen-rich, nitrogen-doped nickel phosphide / cerium oxide composite catalyst, denoted as N-Ni2P / CeO2-V. O Composite catalyst.

[0062] Example 7 The preparation method of the oxygen-rich vacancy nitrogen-doped nickel phosphide / cerium oxide composite catalyst in this embodiment includes the following steps: (1) Add 0.1 mol Ni(CH3COO)2·4H2O and 0.06 mol Ce(NO3)3·6H2O to 100 mL of deionized water and stir to form solution A. Using solution A as electrolyte solution, the precursor was deposited in a three-electrode system using an electrochemical workstation: using foamed nickel (1.5 mm (thickness) × 2 cm × 2 cm) that was ultrasonically cleaned for 15 min in sequence with 0.5 M hydrochloric acid, ethanol and deionized water as working electrode, platinum sheet as counter electrode, Hg / HgO electrode as reference electrode, and deposited at constant potential (-1.2 V vs. Hg / HgO) for 30 min. Then, it was cleaned with deionized water and anhydrous ethanol respectively, and then placed in a vacuum oven at 60 °C for 8 h to obtain nickel-cerium precursor.

[0063] (2) Prepare a 5 g / L tannic acid solution, immerse the nickel-cerium precursor obtained in step (1) in the tannic acid solution for 1 h, so that the phenolic hydroxyl groups in the tannic acid can fully coordinate and chelate with the surface of the precursor, and then take it out, rinse and dry it.

[0064] (3) Place the nickel-cerium precursor obtained in step (2) downstream of the ceramic boat and place 0.3g of ammonium hypophosphate upstream of the ceramic boat; then place the ceramic boat into a high-temperature tube furnace and heat it at 5℃·min under the protection of inert argon gas. -1 The heating rate was increased to 350℃, and after 2 hours of reaction, the temperature was lowered to room temperature to obtain an oxygen-rich, nitrogen-doped nickel phosphide / cerium oxide composite catalyst, denoted as N-Ni2P / CeO2-V. O Composite catalyst.

[0065] Example 8 The preparation method of the oxygen-rich vacancy nitrogen-doped nickel phosphide / cerium oxide composite catalyst in this embodiment includes the following steps: (1) Add 0.1 mol Ni(CH3COO)2·4H2O and 0.06 mol Ce(NO3)3·6H2O to 100 mL of deionized water and stir to form solution A. Using solution A as electrolyte solution, the precursor was deposited in a three-electrode system using an electrochemical workstation: using foamed nickel (1.5 mm (thickness) × 2 cm × 2 cm) that was ultrasonically cleaned for 15 min in sequence with 0.5 M hydrochloric acid, ethanol and deionized water as working electrode, platinum sheet as counter electrode, Hg / HgO electrode as reference electrode, and deposited at constant potential (-1.2 V vs. Hg / HgO) for 30 min. Then, it was cleaned with deionized water and anhydrous ethanol respectively, and then placed in a vacuum oven at 60 °C for 8 h to obtain nickel-cerium precursor.

[0066] (2) Prepare a 20 g / L tannic acid solution, immerse the nickel-cerium precursor obtained in step (1) in the tannic acid solution for 1 h, so that the phenolic hydroxyl groups in the tannic acid can fully coordinate and chelate with the surface of the precursor, and then take it out, rinse and dry it.

[0067] (3) Place the nickel-cerium precursor obtained in step (2) downstream of the ceramic boat and place 0.3g of ammonium hypophosphate upstream of the ceramic boat; then place the ceramic boat into a high-temperature tube furnace and heat it at 5℃·min under the protection of inert argon gas. -1 The heating rate was increased to 350℃, and after 2 hours of reaction, the temperature was lowered to room temperature to obtain an oxygen-rich, nitrogen-doped nickel phosphide / cerium oxide composite catalyst, denoted as N-Ni2P / CeO2-V. O Composite catalyst.

[0068] Example 9 The preparation method of the oxygen-rich vacancy nitrogen-doped nickel phosphide / cerium oxide composite catalyst in this embodiment includes the following steps: (1) Add 0.1 mol Ni(CH3COO)2·4H2O and 0.06 mol Ce(NO3)3·6H2O to 100 mL of deionized water and stir to form solution A. Using solution A as electrolyte solution, the precursor was deposited in a three-electrode system using an electrochemical workstation: using foamed nickel (1.5 mm (thickness) × 2 cm × 2 cm) that was ultrasonically cleaned for 15 min in sequence with 0.5 M hydrochloric acid, ethanol and deionized water as working electrode, platinum sheet as counter electrode, Hg / HgO electrode as reference electrode, and deposited at constant potential (-1.2 V vs. Hg / HgO) for 30 min. Then, it was cleaned with deionized water and anhydrous ethanol respectively, and then placed in a vacuum oven at 60 °C for 8 h to obtain nickel-cerium precursor.

[0069] (2) Prepare a 10 g / L tannic acid solution, immerse the nickel-cerium precursor obtained in step (1) in the tannic acid solution for 0.5 h, so that the phenolic hydroxyl groups in the tannic acid can fully coordinate and chelate with the surface of the precursor, and then take it out, rinse and dry it.

[0070] (3) Place the nickel-cerium precursor obtained in step (2) downstream of the ceramic boat and place 0.3g of ammonium hypophosphate upstream of the ceramic boat; then place the ceramic boat into a high-temperature tube furnace and heat it at 5℃·min under the protection of inert argon gas. -1 The heating rate was increased to 350℃, and after 2 hours of reaction, the temperature was lowered to room temperature to obtain an oxygen-rich, nitrogen-doped nickel phosphide / cerium oxide composite catalyst, denoted as N-Ni2P / CeO2-V. O Composite catalyst.

[0071] Example 10 The preparation method of the oxygen-rich vacancy nitrogen-doped nickel phosphide / cerium oxide composite catalyst in this embodiment includes the following steps: (1) Add 0.1 mol Ni(CH3COO)2·4H2O and 0.06 mol Ce(NO3)3·6H2O to 100 mL of deionized water and stir to form solution A. Using solution A as electrolyte solution, the precursor was deposited in a three-electrode system using an electrochemical workstation: using foamed nickel (1.5 mm (thickness) × 2 cm × 2 cm) that was ultrasonically cleaned for 15 min in sequence with 0.5 M hydrochloric acid, ethanol and deionized water as working electrode, platinum sheet as counter electrode, Hg / HgO electrode as reference electrode, and deposited at constant potential (-1.2 V vs. Hg / HgO) for 30 min. Then, it was cleaned with deionized water and anhydrous ethanol respectively, and then placed in a vacuum oven at 60 °C for 8 h to obtain nickel-cerium precursor.

[0072] (2) Prepare a 10 g / L tannic acid solution, immerse the nickel-cerium precursor obtained in step (1) in the tannic acid solution for 2 h, so that the phenolic hydroxyl groups in the tannic acid can fully coordinate and chelate with the surface of the precursor, and then take it out, rinse and dry it.

[0073] (3) Place the nickel-cerium precursor obtained in step (2) downstream of the ceramic boat and place 0.3g of ammonium hypophosphate upstream of the ceramic boat; then place the ceramic boat into a high-temperature tube furnace and heat it at 5℃·min under the protection of inert argon gas. -1 The heating rate was increased to 350℃, and after 2 hours of reaction, the temperature was lowered to room temperature to obtain an oxygen-rich, nitrogen-doped nickel phosphide / cerium oxide composite catalyst, denoted as N-Ni2P / CeO2-V. O Composite catalyst.

[0074] Comparative Example 1 The preparation method of the N-Ni2P / CeO2 catalyst in this comparative example is as follows: (1) Add 0.1 mol Ni(CH3COO)2·4H2O and 0.06 mol Ce(NO3)3·6H2O to 100 mL of deionized water and stir to form solution A. Using solution A as electrolyte solution, the precursor was deposited in a three-electrode system using an electrochemical workstation: using foamed nickel (1.5 mm (thickness) × 2 cm × 2 cm) that was ultrasonically cleaned for 15 min in sequence with 0.5 M hydrochloric acid, ethanol and deionized water as working electrode, platinum sheet as counter electrode, Hg / HgO electrode as reference electrode, and deposited at constant potential (-1.2 V vs. Hg / HgO) for 30 min. Then, it was cleaned with deionized water and anhydrous ethanol respectively, and then placed in a vacuum oven at 60 °C for 8 h to obtain nickel-cerium precursor.

[0075] (2) Place the nickel-cerium precursor obtained in step (1) downstream of the ceramic boat and place 0.3g of ammonium hypophosphate upstream of the ceramic boat; then place the ceramic boat in a high-temperature tube furnace and heat it at 5℃·min under the protection of inert argon gas. -1The heating rate was increased to 350℃, and after 2 hours of reaction, the temperature was reduced to room temperature to obtain a nitrogen-doped nickel phosphide / cerium oxide composite catalyst, denoted as N-Ni2P / CeO2 composite catalyst.

[0076] Comparative Example 2 The preparation method of the Ni2P / CeO2 composite catalyst in this comparative example is as follows: (1) Add 0.1 mol Ni(CH3COO)2·4H2O and 0.06 mol Ce(NO3)3·6H2O to 100 mL of deionized water and stir to form solution A. Using solution A as electrolyte solution, the precursor was deposited in a three-electrode system using an electrochemical workstation: using foamed nickel (1.5 mm (thickness) × 2 cm × 2 cm) that was ultrasonically cleaned for 15 min in sequence with 0.5 M hydrochloric acid, ethanol and deionized water as working electrode, platinum sheet as counter electrode, Hg / HgO electrode as reference electrode, and deposited at constant potential (-1.2 V vs. Hg / HgO) for 30 min. Then, it was cleaned with deionized water and anhydrous ethanol respectively, and then placed in a vacuum oven at 60 °C for 8 h to obtain nickel-cerium precursor.

[0077] (2) Place the nickel-cerium precursor obtained in step (1) downstream of the ceramic boat and place 0.3g of sodium hypophosphite upstream of the ceramic boat; then place the ceramic boat into a high-temperature tube furnace and heat it at 5℃·min under the protection of inert argon gas. -1 The heating rate was increased to 350℃, and after 2 hours of reaction, the temperature was reduced to room temperature to obtain a nickel phosphide / cerium oxide composite catalyst, denoted as Ni2P / CeO2 composite catalyst.

[0078] Comparative Example 3 The preparation method of the Ni2P catalyst in this comparative example is as follows: (1) Add 0.1 mol Ni(CH3COO)2·4H2O to 100 mL of deionized water and stir to form solution A. Using solution A as electrolyte solution, the precursor was deposited in a three-electrode system using an electrochemical workstation: using a foamed nickel (2 cm × 2 cm) that was ultrasonically cleaned for 15 min in sequence with 0.5 M hydrochloric acid, ethanol and deionized water as the working electrode, a platinum sheet as the counter electrode and an Hg / HgO electrode as the reference electrode. After deposition at a constant potential (-1.2 V vs. Hg / HgO) for 30 min, it was cleaned with deionized water and anhydrous ethanol respectively, and then placed in a vacuum oven at 60 °C for 8 h to obtain the nickel-cerium precursor.

[0079] (2) Place the nickel-cerium precursor obtained in step (1) downstream of the ceramic boat and place 0.3g of sodium hypophosphite upstream of the ceramic boat; then place the ceramic boat into a high-temperature tube furnace and heat it at 5℃·min under the protection of inert argon gas. -1The heating rate was increased to 350℃, and after 2 hours of reaction, the temperature was reduced to room temperature to obtain a nickel phosphide catalyst, denoted as Ni2P catalyst.

[0080] Comparative Example 4 The preparation method of the nitrogen-doped nickel phosphide / cerium oxide composite catalyst with oxygen-rich vacancies in this comparative example includes the following steps: (1) Add 0.1 mol Ni(CH3COO)2·4H2O and 0.06 mol Ce(NO3)3·6H2O to 100 mL of deionized water and stir to form solution A. Using solution A as electrolyte solution, the precursor was deposited in a three-electrode system using an electrochemical workstation: using foamed nickel (1.5 mm (thickness) × 2 cm × 2 cm) that was ultrasonically cleaned for 15 min in sequence with 0.5 M hydrochloric acid, ethanol and deionized water as working electrode, platinum sheet as counter electrode, Hg / HgO electrode as reference electrode, and deposited at constant potential (-1.2 V vs. Hg / HgO) for 30 min. Then, it was cleaned with deionized water and anhydrous ethanol respectively, and then placed in a vacuum oven at 60 °C for 8 h to obtain nickel-cerium precursor.

[0081] (2) Place the nickel-cerium precursor obtained in step (1) downstream of the ceramic boat and place 0.3g of ammonium hypophosphate upstream of the ceramic boat; then place the ceramic boat in a high-temperature tube furnace and heat it at 5℃·min under the protection of inert argon gas. -1 The heating rate was increased to 350℃, and the reaction was cooled to room temperature after 2 hours.

[0082] (3) Prepare a 10 g / L tannic acid solution, immerse the sample after calcination in step (2) in the tannic acid solution for 1 hour, so that the phenolic hydroxyl groups in the tannic acid can fully coordinate and chelate with the surface of the precursor, and then take it out, rinse and dry.

[0083] (4) Place the etched sample obtained in step (3) downstream of the ceramic boat and place 0.3g of ammonium hypophosphate upstream of the ceramic boat; then place the ceramic boat in a high-temperature tube furnace and, under the protection of inert argon gas, heat it at 5℃·min. -1 The heating rate was increased to 350℃, and after 2 hours of reaction, the temperature was lowered to room temperature to obtain an oxygen-rich, nitrogen-doped nickel phosphide / cerium oxide composite catalyst, denoted as N-Ni2P / CeO2-V. O -c composite catalyst.

[0084] Comparative Example 5 The difference from Example 1 is that tannic acid is replaced with gallic acid (GA), and the other operations are the same as in Example 1.

[0085] The crystal structure and catalytic performance of the catalysts prepared in the examples and comparative examples were tested.

[0086] (1) Crystal structure The XRD patterns of the catalysts obtained in Examples 1 and 1-3 are as follows: Figure 1 As shown. When compared with standard card PDF# 03-0953, the weak diffraction peaks at diffraction angles of 2θ = 40.9°, 47.5° and 54.4° correspond to the (111), (210) and (300) crystal planes of Ni2P, respectively; when compared with standard card PDF# 43-1002, the weak diffraction peak at diffraction angle of 2θ = 46.3° corresponds to the (110) crystal plane of CeO2, proving that the active material in the catalysts obtained in Examples 1, Comparative Examples 1 and 2 is Ni2P / CeO2, and the active material in the catalyst obtained in Comparative Example 3 is Ni2P.

[0087] (2) Catalytic performance The Ni2P-based catalysts obtained in Examples 1-10 and Comparative Examples 1-4 were used as electrode materials to test the electrocatalytic oxidation performance of methanol. The specific testing method was as follows: a three-electrode test system was assembled using the obtained Ni2P-based catalyst as the working electrode, a platinum sheet as the counter electrode, and an Hg / HgO electrode as the reference electrode (all potentials mentioned herein are converted to potentials relative to the reversible hydrogen electrode (RHE)). CV and it tests were performed, with 1M KOH and 1M KOH + 0.5M CH3OH solutions as the electrolytes.

[0088] The N-Ni2P / CeO2-V obtained in Examples 1-4 O The composite catalyst in 1M KOH + 0.5M CH3OH solution at 50 mV·s -1 The CV curves tested at the scan rate are as follows: Figure 2 As shown in the figure. It can be seen that N-Ni2P / CeO2-V O The peak current densities of the composite catalyst at a potential of 1.726 V (vs. RHE) were 423.8, 213.1, 298.8, and 302.6 mA·cm⁻¹, respectively. -2 This indicates that all three have good catalytic performance for MOR, and that the N-Ni2P / CeO2-V prepared with a molar ratio of nickel acetate to cerium nitrate of 1:0.6 is the best. O The composite catalyst exhibits optimal catalytic performance for methanol oxidation (MOR).

[0089] The N-Ni2P / CeO2-V obtained in Examples 1, 5, and 6 O The composite catalyst in 1M KOH + 0.5M CH3OH solution at 50 mV·s -1 The CV curves tested at the scan rate are as follows: Figure 3 As shown. According to Figure 3 N-Ni2P / CeO2-V OThe peak current densities of the composite catalyst at 1.726 V (vs. RHE) were 423.8, 260.3, and 274.7 mA·cm⁻¹, respectively. -2 This indicates that all three have good catalytic performance for MOR, and the N-Ni2P / CeO2-V prepared with a deposition time of 30 min is particularly effective. O The composite catalyst exhibits optimal catalytic MOR performance.

[0090] The N-Ni2P / CeO2-V obtained in Examples 1, 7, and 8 O The composite catalyst in 1M KOH + 0.5M CH3OH solution at 50 mV·s -1 The CV curves tested at the scan rate are as follows: Figure 4 As shown. According to Figure 4 N-Ni2P / CeO2-V O The peak current densities of the composite catalyst at a potential of 1.726 V (vs. RHE) were 423.8, 343.8, and 328.1 mA·cm⁻¹, respectively. -2 This indicates that all three have good catalytic performance for MOR, and the N-Ni2P / CeO2-V prepared with a tannic acid (TA) solution concentration of 10 g / L... O The composite catalyst exhibits optimal catalytic MOR performance.

[0091] The N-Ni2P / CeO2-V obtained in Examples 1, 9, and 10 O The composite catalyst in 1M KOH + 0.5M CH3OH solution at 50 mV·s -1 The CV curves tested at the scan rate are as follows: Figure 5 As shown. According to Figure 5 N-Ni2P / CeO2-V O The peak current densities of the composite catalyst at a potential of 1.726 V (vs. RHE) were 423.8, 351.1, and 324.2 mA·cm⁻¹, respectively. -2 This indicates that all three have good catalytic performance for MOR, and the N-Ni2P / CeO2-V prepared with a tannic acid (TA) solution concentration of 10 g / L and an etching time of 60 min is the best. O The composite catalyst exhibits optimal catalytic MOR performance.

[0092] Example 1, N-Ni2P / CeO2-V obtained from Comparative Examples 1-3 O The catalysts N-Ni2P / CeO2, Ni2P / CeO2, and Ni2P in 1M KOH + 0.5M CH3OH solution at 50 mV·s -1 The CV curves tested at the scan rate are as follows: Figure 6 As shown. According to Figure 6 N-Ni2P / CeO2-V O The peak current densities of N-Ni2P / CeO2, Ni2P / CeO2, and Ni2P catalysts at a potential of 1.726 V (vs. RHE) were 423.8, 363.6, 325.6, and 237.7 mA·cm⁻¹, respectively. -2 This indicates that N-Ni2P / CeO2-V O The composite catalyst exhibits optimal catalytic MOR performance.

[0093] Example 1, N-Ni2P / CeO2-V obtained from Comparative Examples 1-3 O N-Ni2P / CeO2, Ni2P / CeO2, and Ni2P catalysts were reacted in 1M KOH + 0.5M CH3OH solution at a rate of 5 mV·s. -1 The linear sweep voltammetry (LSV) test was completed at a high sweep rate, and the fitted Tafel curve is shown below. Figure 7 As shown. According to Figure 7 N-Ni2P / CeO2-V O The Tafel slopes of the N-Ni2P / CeO2, Ni2P / CeO2, and Ni2P catalysts were 59.5, 96.2, 108.3, and 116.1 mV·dec, respectively. -1 This indicates that N-Ni2P / CeO2-V O The composite catalyst exhibits optimal catalytic MOR performance.

[0094] N-Ni2P / CeO2-V prepared in Example 1 and Comparative Example 4 O and N-Ni2P / CeO2-V O -c composite catalyst in 1M KOH + 0.5M CH3OH solution, at 50 mV·s -1 The CV curves tested at the scan rate are as follows: Figure 8 As shown. According to Figure 8 N-Ni2P / CeO2-V O and N-Ni2P / CeO2-V O The peak current densities of the -c composite catalyst at 1.726 V (vs. RHE) were 423.8 and 299.5 mA·cm⁻¹, respectively. -2 This indicates that the catalyst obtained by directly etching the precursor has significantly better catalytic activity than the catalyst obtained by etching and then sintering after sintering.

[0095] N-Ni2P / CeO2-V prepared in Example 1 and Comparative Example 5 O -c and N-Ni2P / CeO 2-GAThe composite catalyst in 1M KOH + 0.5M CH3OH solution at 50 mV·s -1 The CV curves tested at the scan rate are as follows: Figure 9 As shown. According to Figure 9 N-Ni2P / CeO2-V O and N-Ni2P / CeO 2-GA The peak current densities of the catalyst and the composite catalyst measured at 1.726 V (vs. RHE) were 423.8 and 397.8 mA·cm⁻¹, respectively. -2 This indicates that the catalyst obtained by etching with tannic acid has significantly better catalytic activity than the catalyst obtained by etching with gallic acid.

[0096] Example 1, N-Ni2P / CeO2-V obtained from Comparative Examples 1-3 O The it curves of N-Ni2P / CeO2, Ni2P / CeO2, and Ni2P catalysts at a potential of 1.526V (vs. RHE) in 1M KOH + 0.5M CH3OH solution are shown below. Figure 10 As shown. According to Figure 10 N-Ni2P / CeO2-V O The current density retention rate of the catalyst after 60 hours of continuous operation was 81.5%, indicating that the N-Ni2P / CeO2-V catalyst... O The composite catalyst exhibits considerable catalytic activity and excellent long-term catalytic stability.

[0097] The N-Ni2P / CeO2-V obtained in Example 1 O SEM images of the composite catalyst are shown below. Figure 11 As shown. In Figure 11 In the middle, N-Ni2P / CeO2-V O The composite catalyst exhibits a porous nanoaggregate structure with numerous mesopores on its surface, resulting in a large specific surface area and easy contact with electrolyte solutions.

[0098] The SEM image of the N-Ni2P / CeO2 composite catalyst obtained in Comparative Example 1 is shown below. Figure 12 As shown. In Figure 12 In the N-Ni2P / CeO2 composite catalyst, there is no obvious porous structure on the surface, resulting in a small specific surface area and insufficient contact with the electrolyte solution.

[0099] The N-Ni2P / CeO2-V obtained in Example 1 O TEM image of the composite catalyst is shown below Figure 13 As shown. In Figure 13 In the middle, N-Ni2P / CeO2-V OThe composite catalyst exhibits distinct internal crystalline regions and amorphous carbon at the edges, confirming the abundance of carbon in tannic acid. After sintering, a carbon coating layer is formed on the catalyst surface, which imparts higher electrical and mechanical properties to the material.

[0100] The preparation method provided by this invention achieves oxygen vacancy enrichment, cerium valence state optimization, interface electronic regulation and carbon coating stabilization simultaneously through green and mild etching, low-temperature phosphating and in-situ nitrogen doping, effectively solving the problems of high toxicity, poor controllability and insufficient activity and stability in the prior art.

[0101] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing an oxygen-rich vacancy nitrogen-doped nickel phosphide / cerium oxide composite catalyst, characterized in that, Includes the following steps: Using nickel foam as the working electrode, a platinum sheet as the counter electrode, and an Hg / HgO electrode as the reference electrode, electrodeposition was performed in an electrolyte solution containing nickel and cerium salts to obtain a precursor; the precursor includes nickel foam, as well as cerium and nickel deposited on the nickel foam. The precursor is immersed in a tannic acid solution to obtain an impregnated precursor; Ammonium hypophosphite is placed upstream, and the impregnation precursor placed downstream is subjected to phosphide doping treatment to obtain the oxygen-rich vacancy nitrogen-doped nickel phosphide / cerium oxide composite catalyst.

2. The preparation method according to claim 1, characterized in that, The molar ratio of nickel salt to cerium salt in the electrolyte solution is 1:0.1~1.

3. The preparation method according to claim 1 or 2, characterized in that, The nickel salt is at least one of nickel acetate, nickel sulfate, and nickel nitrate, and the cerium salt is at least one of cerium nitrate, cerium sulfate, and cerium chloride.

4. The preparation method according to claim 1 or 2, characterized in that, The electrodeposition potential is -1 to -1.4 V vs. Hg / HgO, and the time is 10 to 60 min.

5. The preparation method according to claim 1, characterized in that, The concentration of the tannic acid solution is 10~40g / L.

6. The preparation method according to claim 1 or 5, characterized in that, The soaking time is 0.5 to 2 hours.

7. The preparation method according to claim 1, characterized in that, The amount of ammonium hypophosphite used is 0.2~0.8g of ammonium hypophosphite per cubic centimeter of nickel foam.

8. The preparation method according to claim 1 or 7, characterized in that, The phosphorus doping treatment is performed at a temperature of 300-400℃ for 1-3 hours.

9. The oxygen-rich vacancy nitrogen-doped nickel phosphide / cerium oxide composite catalyst prepared by the preparation method according to any one of claims 1 to 8.

10. The application of the oxygen-rich vacancy nitrogen-doped nickel phosphide / cerium oxide composite catalyst according to claim 9 in a methanol fuel cell.

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