Preparation method and application of Eu-doped Ni (PO3) 2 porous nanosheet electrocatalyst

Abstract

The invention discloses a preparation method and application of an Eu-doped Ni (PO3) 2 porous nanosheet electrocatalyst. According to the method, carbon cloth is taken as a substrate, europium inorganic salt is taken as a europium source, nickel inorganic salt is taken as a nickel source, amino acid is taken as a rare earth anchoring agent, ammonium fluoride is taken as a precipitator, urea is taken as a reducing agent, a carbon cloth-loaded Eu-doped Ni (OH) 2 precursor is synthesized through a hydrothermal reaction, and finally the catalyst is prepared through a low-temperature phosphorization process in an Ar / H2 atmosphere. Europium is doped in nickel metaphosphate, and the catalytic activity and stability of the catalyst are improved through the synergistic effect of europium and nickel; and the catalyst is good in morphology maintenance degree and high in selectivity for oxygen evolution reaction (OER), and has a good market prospect.

Description

Technical Field

[0001] The present invention belongs to the technical field of electrocatalyst preparation, and specifically relates to a preparation method and application of Eu-doped Ni(PO3)2 porous nanosheet electrocatalyst. Background Art

[0002] With the development of society, energy shortage and environmental problems are becoming increasingly serious, and the society's demand for clean energy such as wind energy, hydropower and solar energy is increasing. Among them, hydrogen energy has attracted widespread attention as an energy source with high energy density, abundant reserves and wide applications. At present, the main methods for industrial production of hydrogen are high-temperature cracking of natural gas, water gas method, water electrolysis method, etc. Among them, the water electrolysis method uses water as raw material, has the advantages of environmental protection and non-toxic and pollution-free products, and is considered to have broad application prospects.

[0003] The electrolytic water reaction consists of HER and OER. At present, the most ideal catalysts for HER and OER are precious metal Pt-based and RuO2, IrO2 materials, respectively. However, the large-scale application of precious metal catalysts is greatly limited by their scarce reserves, high prices, slow kinetics and easy poisoning. Oxygen evolution reaction (OER) is an important component of electrolytic water, and Ni-based phosphate catalysts are a class of potential electrolytic water catalysts. Although they have advantages such as environmental friendliness, abundant reserves, and easily controllable electronic structure. However, their poor intrinsic activity and slow kinetics make it difficult to meet the practical application in electrolytic water. Therefore, it is very important to study and develop cheap and efficient non-precious metal Ni-based phosphate catalysts. Summary of the invention

[0004] In view of the shortcomings of the prior art, the present invention aims to provide a method for preparing and applying Eu-doped Ni(PO3)2 porous nanosheet electrocatalyst. The Eu-doped Ni(PO3)2 porous nanosheet electrocatalyst prepared by hydrothermal and low-temperature phosphating method has better OER electrocatalytic activity and stability than commercial RuO2.

[0005] In order to solve the problems of the prior art, the technical solution adopted by the present invention is:

[0006] A method for preparing Eu-doped Ni(PO3)2 porous nanosheet electrocatalyst, which takes hydrophilic carbon cloth as substrate, europium inorganic salt as europium source, nickel inorganic salt as nickel source, amino acid as rare earth anchoring agent, ammonium fluoride as precipitant, urea as reducing agent, synthesizes carbon cloth-supported Eu-doped Ni(OH)2 precursor through hydrothermal reaction, and finally prepares the catalyst through low-temperature phosphating process in Ar / H2 atmosphere.

[0007] The preparation method of the above-mentioned Eu-doped Ni(PO3)2 porous nanosheet electrocatalyst comprises the following steps:

[0008] Step 1, Preparation of Eu-doped Ni(OH)2 precursor

[0009] Mix europium salt, nickel salt, urea, ammonium fluoride and amino acid, wherein the molar ratio of europium salt, nickel salt, urea and ammonium fluoride is 0.05-0.1:1.2-3:1-5:2-3, and the content of amino acid should exceed 2% of the molar content of the system, dissolve in water, add pretreated hydrophilic carbon cloth, and carry out hydrothermal reaction, the reaction temperature is 100-150°C, the reaction time is 8-12 hours, the reaction is completed, washed and dried, and Eu-doped Ni(OH)2 precursor is obtained, wherein the molar amount of nickel salt corresponding to each square centimeter of hydrophilic carbon cloth is 0.15-0.23 mmol;

[0010] Step 2, Preparation of Eu-Ni(PO3)2

[0011] The Eu-doped Ni(OH)2 precursor of step 1 is placed in a quartz boat downstream of the Ar / H2 gas flow, and the phosphorus source is placed in a quartz boat upstream of the Ar / H2 gas flow. The air in the tube furnace is ventilated until all the air is exhausted, and then the temperature is raised to 250-450°C and calcined for 30-150 minutes. During the calcination process, ventilation is continued to obtain a carbon cloth-loaded Eu-Ni(PO3)2 oxygen evolution electrocatalyst.

[0012] Preferably, the amino acid in step 1 is lysine or arginine. The amino group and other groups in the amino acid bind to the europium ions and attract each other to form coordination, and the formed clusters can be effectively embedded in the vacancies of Ni(OH)2 supported by the carbon cloth, thereby ensuring that no rare earth phosphide is generated but metaphosphate is generated in the subsequent phosphating process.

[0013] Preferably, the pretreatment steps of the hydrophilic carbon cloth in step 1 are as follows: the cut hydrophilic carbon cloth is ultrasonically cleaned in ethanol, then rinsed with deionized water, then acidified with dilute acid for 12 hours, and finally rinsed with deionized water until neutral, and set aside to remove oil and oxide layer on the surface of the hydrophilic carbon cloth.

[0014] More preferably, the dilute acid is a 1-3 mol / L nitric acid solution.

[0015] Preferably, the europium salt in step 1 is europium nitrate hexahydrate or europium chloride hexahydrate; and the nickel salt is nickel nitrate hexahydrate, nickel chloride hexahydrate or nickel sulfate hexahydrate.

[0016] Preferably, the phosphorus source in step 2 is sodium hypophosphite or potassium hypophosphite, and the mass of the phosphorus source required for calcining the unit carbon cloth loaded sample to the carbon cloth area ratio should be not less than 0.06 g cm -2 .

[0017] Preferably, the heating rate of calcination in step 2 is 1-5°C / min. Low-temperature phosphating technology has the advantages of low energy required, controllable heating rate and low toxicity of byproducts. The controllable heating rate is conducive to maintaining the morphology of the catalyst during sintering, generating a larger specific surface area, and achieving improved catalytic performance.

[0018] The Eu-doped Ni(PO3)2 porous nanosheet electrocatalyst prepared by the above preparation method is used as an anode catalyst in an anion exchange membrane water electrolysis device.

[0019] Invention mechanism:

[0020] The rare earth element Eu has attracted more and more attention in adjusting the electronic structure and improving the catalytic performance of transition metal-based materials due to its variable coordination number and unique chemical and electronic properties of the 4f-sublayer orbital. The present invention dopes the rare earth element Eu into Eu-Ni(PO3)2, optimizes the electronic structure of the Eu-Ni(PO3)2 catalyst and the adsorption energy of the reaction intermediate species, reduces the energy barrier of the complete water splitting reaction, and effectively improves the catalytic activity of the catalyst.

[0021] Beneficial effects:

[0022] Compared with the prior art, the preparation method and application of Eu-doped Ni(PO3)2 porous nanosheet electrocatalyst of the present invention have the following significant advantages:

[0023] (1) The catalyst of the present invention is doped with europium in nickel metaphosphate, and the catalytic activity and stability of the catalyst are improved under the synergistic effect of nickel and europium;

[0024] (2) The Eu-Ni(PO3)2 loaded on the surface of the hydrophilic carbon cloth is in the form of porous sheets. This structure provides a huge specific surface area and abundant active sites, further improving the catalytic activity of the catalyst;

[0025] (3) The method of the present invention is simple and quick to operate and can be scaled up for production. The low-temperature phosphating treatment can better anchor rare earth atoms, and the resulting catalyst has stable structure and high performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a high resolution scanning electron microscope (HRSEM) photograph of the precursor obtained in step (2) of Example 2, wherein (a) is a scale of 4 μm and (b) is a scale of 2 μm;

[0027] Figure 2 HRSEM photos of the Eu-Ni(PO3)2 catalyst prepared in Example 2, wherein (a) is a scale of 20 μm and (b) is a scale of 10 μm;

[0028] Figure 3 A transmission electron microscope (TEM) photograph of the Eu-Ni(PO3)2 catalyst prepared in Example 2;

[0029] Figure 4 X-ray diffraction pattern (XRD) of the Eu-Ni(PO3)2 catalyst prepared in Example 2;

[0030] Figure 5 X-ray photoelectron spectrum (XPS) of the Eu-Ni(PO3)2 catalyst prepared in Example 2;

[0031] Figure 6 OER curves of Eu-Ni(PO3)2 catalyst prepared in Example 2 compared with commercially available RuO2 catalyst in 1M KOH solution;

[0032] Figure 7 Stability test curve of the Eu-Ni(PO3)2 catalyst prepared in Example 2 in 1M KOH solution. DETAILED DESCRIPTION

[0033] The technical solution of the present invention is further described below in conjunction with embodiments.

[0034] Example 1

[0035] A method for preparing a carbon cloth-supported Eu-Ni(PO3)2 oxygen evolution electrocatalyst comprises the following steps:

[0036] (1) A 2 cm*4 cm hydrophilic carbon cloth was ultrasonically cleaned in ethanol and deionized water in turn, and then treated in a 2 mol / L dilute nitric acid solution for 12 h to remove the oxide film on the surface, and then rinsed with deionized water until neutral, and dried at 60°C for later use;

[0037] (2) Weigh 0.08 mmol europium nitrate, 1.2 mmol nickel nitrate, 2 mmol urea, 0.5 g lysine and 2 mmol ammonium fluoride and dissolve them in 30 mL deionized water, stir them well, add the hydrophilic carbon cloth treated in step (1), and react in a reactor at 150 ° C for 8 h. After the reaction is completed, wash and dry to obtain Eu-doped Ni(OH)2 precursor;

[0038] (3) In a tubular furnace, the carbon treated in step 1 is placed in a quartz boat upstream of the gas flow and downstream of the Ar / H2 gas flow. 2 g of potassium hypophosphite as a phosphorus source is placed in another quartz boat upstream of the gas flow. Ar / H2 gas is introduced to expel the air in the tubular furnace. Ar / H2 is continued to be introduced, and the temperature is increased to 300°C at a heating rate of 2°C / min in an Ar / H2 atmosphere. The mixture is calcined for 90 min to obtain a carbon cloth-supported Eu-Ni(PO3)2 oxygen evolution electrocatalyst.

[0039] Example 2

[0040] A carbon cloth-supported Eu-Ni(PO3)2 oxygen evolution electrocatalyst, the preparation method of which comprises the following steps:

[0041] (1) A 2 cm*4 cm hydrophilic carbon cloth was ultrasonically cleaned in ethanol and deionized water in turn, and then treated in a 3 mol / L dilute nitric acid solution for 12 h to remove the oxide film on the surface, and then rinsed with deionized water until neutral, and dried at 60°C for later use;

[0042] (2) Weigh 0.1 mmol europium nitrate, 1.2 mmol nickel nitrate, 8 mmol urea, 0.2 g lysine and 2 mmol ammonium fluoride, dissolve in 30 mL deionized water and stir well, add the hydrophilic carbon cloth treated in step (1), and react in a reactor at 120° C. for 12 h. After the reaction is completed, wash and dry to obtain a Eu-doped Ni(OH)2 precursor;

[0043] (3) In a tubular furnace, the carbon treated in step 1 is placed in a quartz boat upstream of the gas flow and downstream of the Ar / H2 gas flow. 0.5 g of sodium hypophosphite is placed in another quartz boat upstream of the gas flow as a phosphorus source. Ar / H2 gas is introduced to expel the air in the tubular furnace. Ar / H2 is continued to be introduced, and the temperature is raised to 450°C in an Ar / H2 atmosphere at a heating rate of 2°C / min. The mixture is calcined for 150 min to obtain a carbon cloth-supported Eu-Ni(PO3)2 oxygen evolution electrocatalyst.

[0044] Performance Characterization

[0045] (1) The catalyst prepared in Example 2 was physically characterized by HRSEM, TEM, XRD and other methods.

[0046] By HRSEM( Figure 1 , Figure 2 ) photos show that the prepared Ni(PO3)2 nanosheets are evenly distributed on the surface of the carbon cloth, arranged neatly, and have similar morphologies, proving that the main morphology of the material is not affected during the Eu element incorporation and subsequent calcination process, further confirming the good stability of the material.

[0047] By TEM( Figure 3 ) The photo also clearly shows the two-dimensional lamellar morphology of Eu-Ni(PO3)2 nanocrystals. The average particle size of Eu-Ni(PO3)2 nanosheets is about 500nm.

[0048] From the XRD pattern ( Figure 4) It can be obtained that the diffraction peaks of the catalyst are completely consistent with the standard card of Ni(PO3)2 (JCPDS standard card #28-0708) and there is no obvious Eu diffraction signal, which further illustrates that the Eu element enters Ni(PO3)2 in the form of doping, and the incorporation of Eu does not change the phase and crystallographic information of Ni(PO3)2.

[0049] From the XPS spectrum ( Figure 5 ) It can be seen that the coexistence of Eu, Ni, P and O signals in Eu-Ni(PO3)2 nanoneedles further confirms the existence form of Eu.

[0050] Example 3

[0051] The carbon cloth-supported Eu-Ni(PO3)2 oxygen evolution electrocatalyst of the present invention comprises the following steps:

[0052] (1) A 2 cm*4 cm hydrophilic carbon cloth was ultrasonically cleaned in ethanol and deionized water in turn, and then treated in a 2 mol / L dilute nitric acid solution for 12 h to remove the oxide film on the surface, and then rinsed with deionized water until neutral, and dried at 60°C for later use;

[0053] (2) Weigh 0.05 mmol europium nitrate, 2.4 mmol nickel nitrate, 1 mmol urea, 0.4 g lysine and 3 mmol ammonium fluoride, dissolve in 30 mL deionized water and stir well, add the hydrophilic carbon cloth treated in step (1), and react in a reactor at 120° C. for 12 h. After the reaction is completed, wash and dry to obtain a Eu-doped Ni(OH)2 precursor;

[0054] (3) In a tubular furnace, the carbon treated in step 1 is placed in a quartz boat upstream of the gas flow and downstream of the Ar / H2 gas flow. 0.8 g of sodium hypophosphite is placed in another quartz boat as a phosphorus source and upstream of the gas flow. Ar / H2 gas is introduced to expel the air in the tubular furnace. Ar / H2 is continued to be introduced, and the temperature is increased to 350°C at a heating rate of 2°C / min under an Ar / H2 atmosphere. The mixture is calcined for 90 min to obtain a carbon cloth-supported Eu-Ni(PO3)2 oxygen evolution electrocatalyst.

[0055] Example 4

[0056] A method for preparing a carbon cloth-supported Eu-Ni(PO3)2 oxygen evolution electrocatalyst comprises the following steps:

[0057] (1) A 2 cm*4 cm hydrophilic carbon cloth was ultrasonically cleaned in ethanol and deionized water in turn, and then treated in a 2 mol / L dilute nitric acid solution for 12 h to remove the oxide film on the surface, and then rinsed with deionized water until neutral, and dried at 60°C for later use;

[0058] (2) Weigh 0.1 mmol europium nitrate, 2 mmol nickel nitrate, 2 mmol urea, 0.6 g arginine and 2.5 mmol ammonium fluoride and dissolve them in 30 mL deionized water, stir them well, add the hydrophilic carbon cloth treated in step (1), and react in a reactor at 100 ° C for 9 h. After the reaction is completed, wash and dry to obtain Eu-doped Ni(OH)2 precursor;

[0059] (3) In a tubular furnace, the carbon treated in step 1 was placed in a quartz boat upstream of the gas flow and downstream of the Ar / H2 gas flow. 1.6 g of sodium hypophosphite was placed in another quartz boat upstream of the gas flow as a phosphorus source. Ar / H2 gas was introduced to expel the air in the tubular furnace. Ar / H2 was continued to be introduced, and the temperature was raised to 350°C at a heating rate of 1.5°C / min under an Ar / H2 atmosphere. The mixture was calcined for 120 min to obtain a carbon cloth-supported Eu-Ni(PO3)2 oxygen evolution electrocatalyst.

[0060] Example 5

[0061] A method for preparing a carbon cloth-supported Eu-Ni(PO3)2 oxygen evolution electrocatalyst comprises the following steps:

[0062] (1) A 2 cm*4 cm hydrophilic carbon cloth was ultrasonically cleaned in ethanol and deionized water in turn, and then treated in a 1 mol / L dilute nitric acid solution for 12 h to remove the oxide film on the surface, and then rinsed with deionized water until neutral, and dried at 60°C for later use;

[0063] (2) Weigh 0.06 mmol europium nitrate, 2 mmol nickel nitrate, 3 mmol urea, 0.3 g lysine and 2 mmol ammonium fluoride, dissolve in 30 mL deionized water and stir well, add the hydrophilic carbon cloth treated in step (1), and react in a reactor at 120° C. for 12 h. After the reaction is completed, wash and dry to obtain a Eu-doped Ni(OH)2 precursor;

[0064] (3) In a tubular furnace, the carbon treated in step 1 is placed in a quartz boat upstream of the gas flow and downstream of the Ar / H2 gas flow. 1 g of sodium hypophosphite is placed in another quartz boat upstream of the gas flow as a phosphorus source. Ar / H2 gas is introduced to expel the air in the tubular furnace. Ar / H2 is continued to be introduced, and the temperature is increased to 400°C at a heating rate of 1°C / min in an Ar / H2 atmosphere. The mixture is calcined for 150 min to obtain a carbon cloth-supported Eu-Ni(PO3)2 oxygen evolution electrocatalyst.

[0065] Example 6

[0066] A carbon cloth-supported Eu-Ni(PO3)2 oxygen evolution electrocatalyst, the preparation method of which comprises the following steps:

[0067] (1) A 2 cm*4 cm hydrophilic carbon cloth was ultrasonically cleaned in ethanol and deionized water in turn, and then treated in a 1 mol / L dilute nitric acid solution for 12 h to remove the oxide film on the surface, and then rinsed with deionized water until neutral, and dried at 60°C for later use;

[0068] (2) Weigh 0.06 mmol europium nitrate, 2 mmol nickel nitrate, 3 mmol urea, 0.5 g arginine and 2 mmol ammonium fluoride, dissolve in 30 mL deionized water and stir well, add the hydrophilic carbon cloth treated in step (1), and react in a reactor at 120° C. for 8 h. After the reaction is completed, wash and dry to obtain Eu-doped Ni(OH)2 precursor;

[0069] (3) In a tubular furnace, the carbon treated in step 1 is placed in a quartz boat upstream of the gas flow and downstream of the Ar / H2 gas flow. 1.2 g of potassium hypophosphite as a phosphorus source is placed in another quartz boat upstream of the gas flow. Ar / H2 gas is introduced to expel the air in the tubular furnace. Ar / H2 is continued to be introduced, and the temperature is increased to 450°C at a heating rate of 4°C / min in an Ar / H2 atmosphere. The mixture is calcined for 150 min to obtain a carbon cloth-supported Eu-Ni(PO3)2 oxygen evolution electrocatalyst.

[0070] Example 7

[0071] A method for preparing a carbon cloth-supported Eu-Ni(PO3)2 oxygen evolution electrocatalyst comprises the following steps:

[0072] (1) A 2 cm*4 cm hydrophilic carbon cloth was ultrasonically cleaned in ethanol and deionized water in turn, and then treated in a 1 mol / L dilute nitric acid solution for 12 h to remove the oxide film on the surface, and then rinsed with deionized water until neutral, and dried at 60°C for later use;

[0073] (2) Weigh 0.06 mmol europium chloride, 1.2 mmol nickel sulfate, 3 mmol urea, 0.1 g lysine and 2.5 mmol ammonium fluoride, dissolve in 30 mL deionized water and stir well, add the hydrophilic carbon cloth treated in step (1), and react in a reactor at 100 ° C for 8 h. After the reaction is completed, wash and dry to obtain Eu-doped Ni(OH)2 precursor;

[0074] (3) In a tubular furnace, the carbon treated in step 1 is placed in a quartz boat upstream of the gas flow and downstream of the Ar / H2 gas flow. 1.2 g of potassium hypophosphite as a phosphorus source is placed in another quartz boat upstream of the gas flow. Ar / H2 gas is introduced to expel the air in the tubular furnace. Ar / H2 is continued to be introduced, and the temperature is increased to 400°C at a heating rate of 5°C / min under an Ar / H2 atmosphere. The mixture is calcined for 100 min to obtain a carbon cloth-supported Eu-Ni(PO3)2 oxygen evolution electrocatalyst.

[0075] Example 8

[0076] A method for preparing a carbon cloth-supported Eu-Ni(PO3)2 oxygen evolution electrocatalyst comprises the following steps:

[0077] (1) A 2 cm*4 cm hydrophilic carbon cloth was ultrasonically cleaned in ethanol and deionized water in turn, and then treated in a 3 mol / L dilute nitric acid solution for 12 h to remove the oxide film on the surface, and then rinsed with deionized water until neutral, and dried at 60°C for later use;

[0078] (2) Weigh 0.08 mmol europium nitrate, 3 mmol nickel nitrate, 1 mmol urea, 0.4 g lysine and 2.5 mmol ammonium fluoride, dissolve in 30 mL deionized water and stir thoroughly, add the hydrophilic carbon cloth treated in step (1), and react in a reactor at 150° C. for 8 h. After the reaction is completed, wash, dry and set aside;

[0079] (3) In a tubular furnace, the carbon treated in step 1 is placed in a quartz boat upstream of the gas flow and downstream of the Ar / H2 gas flow. 1 g of sodium hypophosphite is placed in another quartz boat upstream of the gas flow as a phosphorus source. Ar / H2 gas is introduced to expel the air in the tubular furnace. Ar / H2 is continued to be introduced, and the temperature is increased to 300°C at a heating rate of 4°C / min in an Ar / H2 atmosphere. The mixture is calcined for 60 min to obtain a carbon cloth-supported Eu-Ni(PO3)2 oxygen evolution electrocatalyst.

[0080] Example 9

[0081] A method for preparing a carbon cloth-supported Eu-Ni(PO3)2 oxygen evolution electrocatalyst comprises the following steps:

[0082] (1) A 2 cm*4 cm hydrophilic carbon cloth was ultrasonically cleaned in ethanol and deionized water in turn, and then treated in a 1 mol / L dilute nitric acid solution for 12 h to remove the oxide film on the surface, and then rinsed with deionized water until neutral, and dried at 60°C for later use;

[0083] (2) Weigh 0.08 mmol europium nitrate, 2 mmol nickel nitrate, 1 mmol urea, 0.1 g lysine and 3 mmol ammonium fluoride, dissolve in 30 mL deionized water and stir well, add the hydrophilic carbon cloth treated in step (1), and react in a reactor at 120° C. for 10 h. After the reaction is completed, wash and dry to obtain a Eu-doped Ni(OH)2 precursor;

[0084] (3) In a tubular furnace, the carbon treated in step 1 is placed in a quartz boat upstream of the gas flow and downstream of the Ar / H2 gas flow. 0.5 g of sodium hypophosphite is placed in another quartz boat upstream of the gas flow as a phosphorus source. Ar / H2 gas is introduced to expel the air in the tubular furnace. Ar / H2 is continued to be introduced, and the temperature is increased to 250°C at a heating rate of 2.5°C / min under an Ar / H2 atmosphere. The mixture is calcined for 90 min to obtain a carbon cloth-supported Eu-Ni(PO3)2 oxygen evolution electrocatalyst.

[0085] Example 10

[0086] A method for preparing a carbon cloth-supported Eu-Ni(PO3)2 oxygen evolution electrocatalyst comprises the following steps:

[0087] (1) A 2 cm*4 cm hydrophilic carbon cloth was ultrasonically cleaned in ethanol and deionized water in turn, and then treated in a 1 mol / L dilute nitric acid solution for 12 h to remove the oxide film on the surface, and then rinsed with deionized water until neutral, and dried at 60°C for later use;

[0088] (2) Weigh 0.08 mmol europium nitrate, 3 mmol nickel nitrate, 8 mmol urea, 0.3 g lysine and 2.5 mmol ammonium fluoride, dissolve in 30 mL deionized water and stir well, add the hydrophilic carbon cloth treated in step (1), and react in a reactor at 120° C. for 9 h. After the reaction is completed, wash and dry to obtain Eu-doped Ni(OH)2 precursor;

[0089] (3) In a tubular furnace, the carbon treated in step 1 is placed in a quartz boat upstream of the gas flow and downstream of the Ar / H2 gas flow. 1.5 g of sodium hypophosphite as a phosphorus source is placed in another quartz boat upstream of the gas flow. Ar / H2 gas is introduced to expel the air in the tubular furnace. Ar / H2 is continued to be introduced, and the temperature is increased to 300°C at a heating rate of 1°C / min in an Ar / H2 atmosphere. The mixture is calcined for 60 min to obtain a carbon cloth-supported Eu-Ni(PO3)2 oxygen evolution electrocatalyst.

[0090] Comparative Example 1

[0091] In step (2), no europium salt is added, and the rest is the same as in Example 2 to obtain a carbon cloth-supported Ni(PO3)2 oxygen evolution electrocatalyst.

[0092] Catalytic performance test of Example 2, Comparative Example 1 and RuO2 catalyst

[0093] Figure 6 The oxygen evolution (OER) curves of the catalyst prepared in Example 2, the catalyst prepared in Comparative Example 1 and the commercially available RuO2 catalyst (from Shanghai Dibai Biotechnology Co., Ltd.) in 1M KOH solution are shown in the figure. As can be seen from the figure, the catalyst prepared in Example 2 has a high current density of 10 mA cm -2 The overpotential is only 272 mV, which is better than the commercially available RuO2 catalyst (340 mV) and the catalyst of Comparative Example 1 without Eu doping (325 mV).

[0094] Depend on Figure 7 It can be seen from the chronopotentiometry (CP) test curve of the catalyst prepared in Example 2 that after the long-range constant current density test, the catalyst still maintains a relatively stable potential curve in an alkaline environment and has good stability.

[0095] In summary, the present invention dopes europium into nickel metaphosphate, and the synergistic effect of europium and nickel improves the catalytic activity and stability of the catalyst; and the catalyst has good morphology maintenance, high selectivity for oxygen evolution reaction (OER), and has good market prospects.

Claims

1. A method for preparing Eu-doped Ni(PO3)2 porous nanosheet electrocatalyst, characterized in that: Using hydrophilic carbon cloth as substrate, europium inorganic salt as europium source, nickel inorganic salt as nickel source, amino acid as rare earth anchoring agent, ammonium fluoride as precipitant and urea as reducing agent, carbon cloth-supported Eu-doped Ni(OH)2 precursor was synthesized by hydrothermal reaction, and finally the catalyst was prepared by low-temperature phosphating process in Ar / H2 atmosphere.

2. The method for preparing a Eu-doped Ni(PO3)2 porous nanosheet electrocatalyst according to claim 1, characterized in that: The following steps are involved: Step 1, Preparation of Eu-doped Ni(OH)2 precursor Mix europium salt, nickel salt, urea, ammonium fluoride and amino acid, wherein the molar ratio of europium salt, nickel salt, urea and ammonium fluoride is 0.05-0.1:1.2-3:1-5:2-3, and the content of amino acid should exceed 2% of the molar content of the system, dissolve in water, add pretreated hydrophilic carbon cloth, and carry out hydrothermal reaction, the reaction temperature is 100-150°C, the reaction time is 8-12 hours, the reaction is completed, washed and dried, and Eu-doped Ni(OH)2 precursor is obtained, wherein the molar amount of nickel salt corresponding to each square centimeter of hydrophilic carbon cloth is 0.15-0.23 mmol; Step 2, Preparation of Eu-Ni(PO3)2 The Eu-doped Ni(OH)2 precursor of step 1 is placed in a quartz boat downstream of the Ar / H2 gas flow, and the phosphorus source is placed in a quartz boat upstream of the Ar / H2 gas flow. The air in the tube furnace is ventilated until all the air is exhausted, and then the temperature is raised to 250-450°C and calcined for 30-150 minutes. During the calcination process, ventilation is continued to obtain a carbon cloth-loaded Eu-Ni(PO3)2 oxygen evolution electrocatalyst.

3. The method for preparing a Eu-doped Ni(PO3)2 porous nanosheet electrocatalyst according to claim 2, characterized in that: The amino acid in step 1 is lysine or arginine.

4. The method for preparing a Eu-doped Ni(PO3)2 porous nanosheet electrocatalyst according to claim 2, characterized in that: The pretreatment steps of the hydrophilic carbon cloth in step 1 are as follows: the cut hydrophilic carbon cloth is ultrasonically cleaned in ethanol, then rinsed with deionized water, then acidified with dilute acid for 12 hours, and finally rinsed with deionized water until neutral, and set aside to remove the oil and oxide layer on the surface of the hydrophilic carbon cloth.

5. The method for preparing a Eu-doped Ni(PO3)2 porous nanosheet electrocatalyst according to claim 4, characterized in that: The dilute acid is a 1-3 mol / L nitric acid solution.

6. The method for preparing a Eu-doped Ni(PO3)2 porous nanosheet electrocatalyst according to claim 2, characterized in that: In step 1, the europium salt is europium nitrate hexahydrate or europium chloride hexahydrate; the nickel salt is nickel nitrate hexahydrate, nickel chloride hexahydrate or nickel sulfate hexahydrate.

7. The method for preparing a Eu-doped Ni(PO3)2 porous nanosheet electrocatalyst according to claim 2, characterized in that: The phosphorus source in step 2 is sodium hypophosphite or potassium hypophosphite, and the mass of the phosphorus source required for calcining the unit carbon cloth loaded sample to the carbon cloth area ratio should not be less than 0.06 g cm -2 .

8. The method for preparing a Eu-doped Ni(PO3)2 porous nanosheet electrocatalyst according to claim 2, characterized in that: The heating rate of calcination in step 2 is 1 to 5°C / min.

9. Use of the Eu-doped Ni(PO3)2 porous nanosheet electrocatalyst prepared by the preparation method described in any one of claims 1 to 8 as an anode catalyst in an anion exchange membrane water electrolysis device.

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