Preparation method of molybdenum phosphide carbon nanosphere loaded platinum as hydrogen evolution reaction catalyst

Abstract

The invention discloses a molybdenum phosphide carbon nanosphere loaded noble metal Pt as an efficient hydrogen evolution reaction catalyst and a preparation method thereof. The preparation method of the electrochemical catalyst comprises the following steps: firstly preparing a molybdenum phosphorus carbon nanosphere precursor by a hydrothermal method, then carrying out heat treatment in a hydrogen-argon mixed gas atmosphere, and finally loading noble metal platinum by a hydrothermal method to obtain the MoP / C-Pt catalyst. According to the MoP / C-Pt catalyst prepared through the method, molybdenum phosphide carbon nanospheres serve as a carrier, Pt nano-particle aggregation is obviously inhibited through the interaction between metal and the carrier, the problems that in the electrochemical hydrogen evolution reaction, the precious metal utilization rate of the catalyst is low, and stability is poor are effectively solved, in addition, MoP has special Mo delta + and P delta-active sites, and the stability of the catalyst is improved. According to the present invention, the carbon carrier is introduced, such that the water decomposition can be catalyzed under the low potential, the conductivity of the catalyst is enhanced due to the introduction of the carbon carrier, and the catalyst can provide the excellent electro-catalysis performance especially in the acidic and alkaline electrolyte. The preparation method is simple and can be widely applied to industrial production.

Description

Technical Field

[0001] The invention relates to the field of hydrogen production by electrolysis of water, and more specifically to a molybdenum phosphide carbon nanosphere loaded with platinum as a hydrogen evolution reaction catalyst, a preparation method thereof, and an application of the molybdenum phosphide carbon nanosphere in catalyzing hydrogen evolution reaction in an acidic or alkaline electrolyte. Background Art

[0002] Energy conversion is one of the important challenges facing today's society, among which the electrolysis of water is an effective way to produce hydrogen as a potential source of clean fuel. In the process of water electrolysis, the hydrogen evolution reaction is crucial, and an efficient and stable catalyst is required to promote this reaction. At present, the most common method in industry is to use precious metals such as platinum as catalysts to promote the electrolysis of water to produce hydrogen. However, the high cost and scarcity of precious metals such as platinum limit the large-scale commercial application of hydrogen energy. Therefore, it is particularly important to find a way to effectively load platinum into the catalyst carrier to improve its utilization efficiency and reduce costs.

[0003] The introduction of common carbon nanomaterial carriers, such as C2N, carbon nanotubes and graphene, can provide a large surface area and rapid electron transfer, effectively avoid the agglomeration of nanoparticles, and improve the utilization rate of precious metals. However, all of the above carriers are produced through cumbersome and complex processes under high-temperature calcination or in a highly corrosive environment, which seriously hinders their large-scale application in hydroelectric hydrogen analysis.

[0004] In recent years, researchers have begun to explore the use of transition metal compounds as carriers to load platinum nanoparticles on their surfaces as efficient catalysts for hydrogen evolution reaction. Because transition metal compounds have good stability around the Fermi level, high conductivity, and platinum-like electronic structures, they are promising carrier materials for hydrogen evolution reaction (HER). Among them, molybdenum phosphide is particularly suitable for hydrogen evolution reaction (HER) because of its intrinsic charged properties (Mo δ+ and P δ- ), good chemical stability and abundant active sites. In the molybdenum phosphide lattice, negatively charged phosphorus atoms can capture protons during the catalytic process, providing a good "hydrogen transfer" system. Previous studies have shown that using molybdenum phosphide as a carrier, loaded platinum nanoparticles have excellent hydrogen evolution activity and stability, and have lower cost than pure platinum catalysts. However, there are some challenges in the preparation process, such as the control of the synthesis method, the uniform dispersion of loaded platinum nanoparticles, and the long-term stability of the catalyst, which need to be solved urgently. Therefore, this patent aims to provide a new preparation method for molybdenum phosphide carbon nanospheres loaded with platinum as a hydrogen evolution reaction catalyst, so as to overcome the limitations of existing methods and provide a more efficient, stable and economically feasible water decomposition hydrogen production technology. Summary of the invention

[0005] The purpose of the present invention is to provide a method for preparing molybdenum phosphide carbon nanospheres loaded with platinum as a hydrogen evolution reaction catalyst, so as to solve the technical problems of high catalyst cost, complicated carrier preparation process and low electrocatalytic activity described in the background technology.

[0006] In order to achieve the above object, the technical solution provided by the present invention is as follows: A method for preparing a molybdenum phosphide carbon nanosphere-supported platinum electrocatalytic hydrogen evolution catalyst comprises the following steps: S1. Dissolve a certain amount of ammonium molybdate tetrahydrate and glucose in a mixture of ethylene glycol and water, and stir evenly with magnetic stirring.

[0007] S2. The mixed solution in S1 was transferred to a hydrothermal reactor. After a period of hydrothermal reaction, it was rinsed with ultrapure water and ethanol and then vacuum dried at 60°C for 10 h to obtain a brown solid.

[0008] S3. Take the brown solid of S2 and mix it with sodium hypophosphite, grind it evenly, and place it in a beaker containing 50 mL of ethylene glycol solution. After it is evenly dispersed, transfer the solution to a hydrothermal reactor. After reacting for a period of time, rinse it with ultrapure water and ethanol and vacuum dry it at 60°C for 10 h to obtain a gray-black solid.

[0009] S4. Heat-treat the gray-black solid in S3 in a hydrogen-argon mixed gas atmosphere to obtain a black solid.

[0010] S5. Take 30-50 mg of the black solid in S4 and dissolve it in 50 mL of ethylene glycol. Adjust the pH to 7-9 with ammonia water. After mixing and stirring evenly, add 0.3-0.5 mL of chloroplatinic acid aqueous solution. After stirring evenly, transfer the solution to a hydrothermal reactor. After a period of hydrothermal reaction, rinse with ultrapure water and ethanol and vacuum dry at 60°C for 10 h to obtain molybdenum phosphide carbon nanospheres loaded with platinum catalyst.

[0011] Preferably, the mass ratio of ammonium molybdate tetrahydrate to glucose in S1 is in the range of 1:5 to 1:10.

[0012] Preferably, calculated by volume ratio, the ratio of ethylene glycol to water is in the range of 1:1 to 2:1, and the total volume of the mixed solution is in the range of 30 to 60 mL.

[0013] Preferably, in step S2, the hydrothermal condition is to react at 200° C. for 8 to 12 h.

[0014] Preferably, in step S3, the mass ratio of the brown solid to sodium hypophosphite is 1:5-1:7, and the hydrothermal condition is to react at 160° C. for 4-6 h.

[0015] Preferably, in step S4, the heat treatment conditions are: in a hydrogen-argon mixed gas atmosphere, wherein the volume percentage of hydrogen is 5-10%, the temperature range is 700-950°C, the holding time is 100-200 min, and the heating rate is 3-5°C min -1 .

[0016] Preferably, in step S5, the content (mg / mL) of the chloroplatinic acid aqueous solution is 30, and the hydrothermal condition is to react at 160°C for 4-6 h.

[0017] Compared with the prior art, the present invention has the following advantages: The present invention provides a method for preparing a platinum electrocatalytic hydrogen evolution catalyst supported by molybdenum phosphide carbon nanospheres, which significantly inhibits the aggregation of Pt nanoparticles through the interaction between the metal and the carrier, effectively improves the stability of the catalyst and reduces the cost. δ+ and P δ- Active sites can catalyze water decomposition at a lower potential, and the glucose-derived carbon nanosphere carrier effectively avoids the aggregation of active nanoparticles and improves their conductivity. The obtained MoP / C-Pt catalyst has excellent electrocatalytic hydrogen evolution performance in both alkaline and acidic electrolytes. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 The XRD spectrum of the MoP / C-Pt electrocatalytic hydrogen evolution catalyst prepared in Example.

[0019] Figure 2 This is a SEM image of the MoP / C-Pt electrocatalytic hydrogen evolution catalyst prepared in Example.

[0020] Figure 3 The XRD spectrum of the MoP-Pt electrocatalytic hydrogen evolution catalyst prepared in comparative example.

[0021] Figure 4 It is the SEM image of the MoP-Pt electrocatalytic hydrogen evolution catalyst prepared in comparative example.

[0022] Figure 5 HER performance curves of the MoP / C-Pt electrocatalytic hydrogen evolution catalyst prepared in the example, the MoP-Pt electrocatalytic hydrogen evolution catalyst prepared in the comparative example, and the commercial platinum-carbon catalyst measured in 1.0 mol / L KOH solution.

[0023] Figure 6 Polarization curves of the MoP / C-Pt electrocatalytic hydrogen evolution catalyst prepared in the example before and after 1000 CV cycles in 1.0 mol / L KOH solution.

[0024] Figure 7HER performance curves of the MoP / C-Pt electrocatalytic hydrogen evolution catalyst prepared in the example, the MoP-Pt catalyst prepared in the comparative example, and the commercial platinum-carbon catalyst measured in 0.5 mol / L H2SO4 solution.

[0025] Figure 8 Polarization curves of the MoP / C-Pt electrocatalytic hydrogen evolution catalyst prepared in the example before and after 1000 CV cycles in 0.5 mol / L H2SO4 solution. DETAILED DESCRIPTION

[0026] The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, and all embodiments based on the present invention belong to the scope of protection of the present invention.

[0027] Embodiment: A method for preparing a molybdenum phosphide carbon nanosphere-supported platinum electrocatalytic hydrogen evolution catalyst comprises the following steps: S1. Dissolve 180 mg of ammonium molybdate tetrahydrate and 1000 mg of glucose in a mixture of 20 mL of ethylene glycol and 10 mL of deionized water, and stir evenly with a magnetic stirrer. S2, transfer the mixed solution in S1 to a hydrothermal reactor, react at 200°C for 10 h, rinse the product with ethanol and ultrapure water, and then vacuum dry at 60°C for 10 h to obtain a brown solid; S3, take the brown solid of S2 and 1000 mg of sodium hypophosphite, mix and grind evenly, then place in a beaker containing 50 mL of ethylene glycol solution, transfer the solution to a hydrothermal reactor after uniform dispersion, react at 160°C for 4 h, rinse the product with ultrapure water and ethanol, and vacuum dry at 60°C for 10 h to obtain a gray-black solid; S4: The gray-black solid in S3 was heat treated in a hydrogen-argon mixed gas atmosphere (the volume percentage of hydrogen was 5%) at a temperature of 800 °C, a holding time of 120 min, and a heating rate of 5 °C min -1 , a black solid was obtained; S5. Take 40 mg of the black solid in S4 and dissolve it in 50 mL of ethylene glycol. Adjust the pH to 8 with ammonia water. After mixing and stirring evenly, add 0.33 mL of chloroplatinic acid aqueous solution. After stirring evenly, transfer the solution to a hydrothermal reactor and react at 160°C for 4 hours. After rinsing the product with ultrapure water and ethanol, vacuum dry it at 60°C for 10 hours to obtain molybdenum phosphide carbon nanospheres loaded with platinum catalyst, recorded as MoP / C-Pt.

[0028] Figure 1The XRD pattern of the electrocatalytic hydrogen evolution catalyst MoP / C-Pt prepared in the embodiment. As can be seen from the figure, the characteristic peaks of MoP and Pt are obvious and clear, respectively conforming to the standard PDF (89-5110) card and the standard (04-0802) card, indicating that the prepared MoP / C-Pt catalyst has good crystallinity.

[0029] Figure 2 SEM diagram of the electrocatalytic hydrogen evolution catalyst MoP / C-Pt prepared for the Examples. It can be seen from the figure that the carbon-supported molybdenum phosphide is spherical in shape with a small particle size and has a large surface area, effectively avoiding the aggregation of nanoparticles.

[0030] Comparative Example: S1. Dissolve 180 mg of ammonium molybdate tetrahydrate and 1000 mg of sodium hypophosphite in a mixture of 20 mL of ethylene glycol and 10 mL of deionized water, and stir evenly with a magnetic stirrer.

[0031] S2. Transfer the mixed solution in S1 to a hydrothermal reactor and react at 200°C for 10 h. Rinse the product with ethanol and ultrapure water and then vacuum dry it at 60°C for 10 h to obtain a gray-black solid.

[0032] S3: The gray-black solid in S2 was heat treated in a hydrogen-argon mixed gas atmosphere (the volume percentage of hydrogen was 5%) at a temperature of 800 °C, a holding time of 120 min, and a heating rate of 5 °C min -1 , to obtain a black solid.

[0033] S4. Take 40 mg of black solid in S3 in 50 mL of ethylene glycol, adjust the pH to 8, mix and stir evenly, add 0.33 mL of chloroplatinic acid aqueous solution, and transfer the solution to a hydrothermal reactor, react at 160°C for 4 hours. The product is washed with ultrapure water and ethanol and dried in vacuum at 60°C for 10 hours to obtain a molybdenum phosphide-supported platinum catalyst, and the obtained catalyst is denoted as MoP-Pt.

[0034] Figure 3 XRD map of the MoP-Pt electrocatalytic hydrogen evolution catalyst prepared for comparative examples. It can be seen from the figure that the characteristic peaks of MoP and Pt are weaker than those of MoP / C-Pt catalysts, indicating that the crystallinity of the obtained MoP-Pt catalyst is worse than that of the MoP / C-Pt catalysts.

[0035] Figure 4 The SEM image of the MoP-Pt electrocatalytic hydrogen evolution catalyst prepared in the comparative example shows that the Pt particles are obviously aggregated, which reduces the surface area of ​​the carrier and leads to a decrease in the effective catalytic sites.

[0036] Figure 5For the MoP / C-Pt electrocatalytic hydrogen evolution catalyst prepared in Examples, the HER performance curves measured by the catalyst MoP-Pt and commercial platinum carbon catalyst prepared in 1.0 mol / L KOH solution. It can be seen from the figure that the prepared MoP / C-Pt electrocatalyst has better catalytic performance than the MoP-Pt catalyst and commercial platinum carbon.

[0037] Figure 6 Polarization curve before and after 1000CV cycle was obtained for the MoP / C-Pt electrocatalytic hydrogen evolution catalyst in 1.0 mol / L KOH solution. It can be seen from the figure that after 1000 CV cycles under alkaline conditions, the overpotential of the catalyst only increased slightly, indicating that the MoP / C-Pt electrocatalyst has good stability under alkaline conditions.

[0038] Figure 7 For the MoP / C-Pt electrocatalytic hydrogen evolution catalyst prepared in the Example, the HER performance curves measured by the catalyst MoP-Pt and commercial platinum carbon catalyst prepared in 0.5 mol / L H2SO4 solution. It can be seen from the figure that the prepared MoP / C-Pt electrocatalyst has better catalytic performance than the MoP-Pt catalyst.

[0039] Figure 8 The polarization curve before and after the 1000CV cycle of the MoP / C-Pt electrocatalytic hydrogen evolution catalyst prepared for the Examples in 0.5 mol / L H2SO4 solution. It can be seen from the figure that after 1000 CV cycles under acidic conditions, the overpotential of the catalyst only increased slightly, indicating that the MoP / C-Pt electrocatalyst has good stability under acidic conditions.

Claims

1. A method for preparing a molybdenum phosphide carbon nanosphere-supported platinum efficient hydrogen evolution catalyst, characterized in that: The following steps are involved: S1. Dissolve ammonium molybdate tetrahydrate and glucose in a mixture of ethylene glycol and water, and stir evenly with magnetic stirring; S2, transfer the stirred solution in S1 to a hydrothermal reactor, rinse with ultrapure water and ethanol, and then vacuum dry at 60°C for 10 h to obtain a brown solid; S3, take the brown solid of S2 and mix it with sodium hypophosphite, grind it evenly, and then put it in a beaker containing 50 mL of ethylene glycol solution. After it is evenly dispersed, transfer the solution to a hydrothermal reactor. After the reaction, rinse it with ultrapure water and ethanol, and then vacuum dry it at 60°C for 10 hours to obtain a gray-black solid; S4, heat-treating the gray-black solid in S3 in a hydrogen-argon mixed gas atmosphere to obtain a black solid; S5. Take 30-50 mg of the black solid in S4 and dissolve it in 50 mL of ethylene glycol. Adjust the pH to 7-9 with ammonia water. After mixing and stirring evenly, add 0.3-0.5 mL of chloroplatinic acid aqueous solution. After stirring evenly, transfer the solution to a hydrothermal reactor. After the hydrothermal reaction, rinse with ultrapure water and ethanol and vacuum dry at 60°C for 10 h to obtain molybdenum phosphide carbon nanospheres loaded with platinum catalyst.

2. The method for preparing a molybdenum phosphide carbon nanosphere-supported platinum efficient hydrogen evolution catalyst according to claim 1, characterized in that: The mass ratio of ammonium molybdate tetrahydrate to glucose in S1 is in the range of 1:5 to 1:

10.

3. The method for preparing a molybdenum phosphide carbon nanosphere-supported platinum efficient hydrogen evolution catalyst according to claim 1, characterized in that: Calculated by volume ratio, the ratio of ethylene glycol to water ranges from 1:1 to 2:1, and the total volume of the mixed solution ranges from 30 to 60 mL.

4. The method for preparing a molybdenum phosphide carbon nanosphere-supported platinum efficient hydrogen evolution catalyst according to claim 1, characterized in that: In step S2, the hydrothermal condition is to react at 200° C. for 8 to 12 h.

5. The method for preparing a molybdenum phosphide carbon nanosphere-supported platinum efficient hydrogen evolution catalyst according to claim 1, characterized in that: In step S3, the mass ratio of the brown solid to sodium hypophosphite is 1:5-1:7, and the hydrothermal condition is to react at 160° C. for 4-6 h.

6. The method for preparing a molybdenum phosphide carbon nanosphere-supported platinum efficient hydrogen evolution catalyst according to claim 1, characterized in that: In step S4, the heat treatment conditions are as follows: in a hydrogen-argon mixed gas atmosphere, the volume percentage of hydrogen is 5-10%, the temperature range is 700-950°C, the holding time is 100-200 min, and the heating rate is 3-5°C min -1 .

7. The method for preparing a molybdenum phosphide carbon nanosphere-supported platinum efficient hydrogen evolution catalyst according to claim 1, characterized in that: In step S5, the content (mg / mL) of the chloroplatinic acid aqueous solution is 30, and the hydrothermal condition is to react at 160° C. for 4 to 6 h.

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