A hollow carbon sphere loaded with metal phosphide, a preparation method and application in the field of electrocatalytic hydrogen production

Abstract

The application belongs to the technical field of electrocatalytic materials, and particularly relates to a hollow carbon sphere loaded with metal phosphide, a preparation method and application in the field of electrocatalytic hydrogen production. The preparation method of the hollow carbon sphere loaded with metal phosphide is as follows: (1) metal salt, trimesic acid and a surfactant are added into an organic solvent for dissolution, and a solvothermal reaction is performed to obtain a precursor; (2) the precursor and a phosphorus source are simultaneously placed in a protective atmosphere for heating and phosphorization treatment, and a hollow carbon sphere loaded with metal phosphide is obtained. The preparation method has the advantages of simple preparation process, strong repeatability and low cost. The obtained hollow carbon sphere loaded with metal phosphide has high application value in the field of electrocatalytic hydrogen production.

Description

Technical Field

[0001] This invention belongs to the field of electrocatalytic materials technology, specifically relating to a hollow carbon sphere loaded with metal phosphide, its preparation method, and its application in the field of electrocatalytic hydrogen production. Background Technology

[0002] The information disclosed in the background section is intended only to enhance understanding of the overall background of the invention and is not necessarily to be construed as an admission or in any way implying that such information has become prior art known to those skilled in the art.

[0003] Metal phosphides are highly effective catalysts for water electrolysis in the field of electrocatalysis. However, during water electrolysis, metal phosphides often become deactivated due to structural transformations or loss of active sites. Therefore, exploring novel supports for supporting metal phosphides is crucial. Novel supports require high conductivity, long-term stability, and the ability to expose a large number of active sites during the catalytic reaction. Hollow carbon spheres with their unique hollow structure meet these requirements while also promoting electrolyte transport and increasing the reaction rate. However, the preparation of hollow carbon spheres is complex, often requiring templates, which complicates the derivatization and preparation of new materials. Therefore, using novel metal-organic frameworks (MOFs) to derive hollow carbon spheres offers unique advantages. MOFs possess unique advantages such as designable overall structure, tunable pore structure, controllable specific surface area, and simple synthesis methods. Thus, using MOFs as a substrate to control the design of hollow carbon spheres loaded with metal phosphides is feasible, economical, and readily available. The invention patents CN201010128464.2 ("A Method for Preparing Monodisperse Hollow Carbon Spheres") and CN201610797467.2 ("A Nitrogen-Rich Hollow Carbon Sphere / Sulfur Composite Cathode Material for Lithium-Sulfur Batteries and Its Preparation Method") disclose methods for preparing hollow carbon spheres using a template method combined with subsequent acid treatment. These methods often require subsequent acid treatment to remove the template, frequently resulting in environmental pollution and structural damage. The invention patent CN201910670472.0 ("A Method for Preparing Hollow Carbon Spheres") discloses a method for preparing hollow carbon spheres, but this method requires a suitable pyrolytic carbon source. Meanwhile, conventional carbon materials require activation treatment before being used as electrode materials to increase the active sites and active specific surface area. In-situ activated carbon materials can eliminate the need for adding activators and subsequent activator treatment steps, saving energy, reducing emissions, and enhancing the economic value of carbon materials. Therefore, the in-situ activated hollow metal-organic framework-derived hollow carbon sphere preparation method is more beneficial for obtaining materials with excellent structure and good performance, and has high economic value. Thus, hollow carbon spheres loaded with metal phosphides can fully utilize the internal hollow structure to store and transport electrolytes. The highly conductive carbon support can accelerate electron transport in the catalytic reaction, and the in-situ activated metal phosphide active sites have a higher binding force with the carbon support, which helps to improve the activity and stability of the catalyst.

[0004] The invention patents CN201910660022.3 ("A Porous Hollow Carbon Material Loaded with Metal Phosphides, Its Preparation and Application") and CN202110480941.X ("A Preparation Method of a Platinum-Cobalt Oxide Composite Electrocatalytic Material Loaded on Nitrogen-Doped Mesoporous Hollow Carbon Spheres, Its Products and Applications") disclose methods for preparing hollow carbon spheres using a template method, and then reloading metal phosphides and metal oxides onto the hollow carbon spheres. Compared with this method, the method of directly preparing metal phosphides using metal-organic frameworks is simpler and easier to operate. The article "Ultrafast Synthesis of Transition MetalPhosphides in Air via Pulsed Laser Shock" reports a method for directly preparing phosphides using metal-organic frameworks, but this method requires pulsed laser shock assisted preparation, which is difficult to achieve in conventional laboratories and has limited universality. Meanwhile, the advantage of directly deriving metal phosphides from metal-organic frameworks lies in its ability to directly restrict the growth of metal phosphide particles during the carbonization process of organic ligands, effectively reducing particle size, increasing the number of active sites, and improving catalyst stability. Therefore, the method of preparing hollow carbon spheres supported on metal phosphides directly derived from metal-organic frameworks is more likely to yield catalyst materials with excellent structure, high catalytic activity and long-term stability, and has high economic value. Summary of the Invention

[0005] To address the shortcomings of the prior art, the present invention provides the following technical solution:

[0006] In one aspect, a hollow carbon sphere loaded with metal phosphides is provided. This material uses hollow carbon spheres with a diameter of 0.68–1.02 μm as a carrier, and the sphere shells are loaded with metal phosphide particles with a size of 3.5–38.9 nm, resulting in a specific surface area of ​​196–671 cm². 2 g -1 .

[0007] The elements and their proportions contained in the hollow carbon spheres loaded with metal phosphides described in the first aspect are as follows: Ni 0~18.6 at.%, Co 0~17.5 at.%, Zn 5.7~30.2 at.%, P 7.2~13.8 at.%, C 43.5~80.9 at.%, N 0.2~5.6 at.% and O 2.4~9.3 at.%.

[0008] In one embodiment where the effect is better, the diameter of the hollow carbon sphere is 0.75~0.85μm, and the surface of the sphere shell is loaded with metal phosphide particles of 28~32 nm.

[0009] The elements and their proportions contained in the above hollow carbon spheres are as follows: Ni content is 18.0~19.0 at.%, Zn content is 26.0~27.0 at.%, P content is 10.0~11.0 at.%, C content is 43.0~44.0 at.%, N content is 3.0~4.0 at.%, and O content is 8.0~9.0 at.%.

[0010] Secondly, a method for preparing the hollow carbon spheres loaded with metal phosphides as described in the first aspect is provided, comprising the following steps:

[0011] S1: The precursor is obtained by dissolving the metal salt, trimesic acid, and surfactant in an organic solvent and then carrying out a solvothermal reaction.

[0012] S2: The precursor and phosphorus source are placed together in a protective atmosphere and heated for phosphating treatment to obtain hollow carbon spheres loaded with metal phosphides.

[0013] The above-mentioned S1 has the following preferred technical solution:

[0014] Tristyric acid is a tridentate carboxylic acid ligand that coordinates with metal ions through its carboxyl group (-COOH) to form a porous organic framework structure; metal salts provide metal ions as coordination centers to form coordination polymers with the ligands.

[0015] The metal salt is a mixture of two or three of nickel, cobalt, and zinc salts, preferably an inorganic salt, and further, an inorganic acid salt, namely, a hydrochloride, nitrate, or sulfate of nickel, cobalt, or zinc. In some embodiments of the present invention with better effects, the metal salt contains at least a zinc salt, and also contains one of nickel and cobalt salts, or a combination thereof, and the dosage ratio of zinc salt to the above salts or the combination thereof is 41:4 to 43:2.

[0016] Suitable surfactants are selected from one or a mixture of several of the following: polyvinylpyrrolidone (PVP), fatty alcohol polyoxyethylene ether (AEO), sodium dodecyl sulfate (SDS), hexadecyltrimethylammonium bromide (CTAB), carboxymethyl cellulose (CMC), and polyvinyl alcohol (PVA). Suitable organic solvents are selected from N,N-dimethylformamide, ethylene glycol, isopropanol, N,N-dimethylacetamide (DMAC), etc.

[0017] In one embodiment verified by the present invention, the surfactant is polyvinylpyrrolidone, and the organic solvent is N,N-dimethylformamide. In this embodiment, the dosage ratio of the metal salt, trimesic acid, polyvinylpyrrolidone and N,N-dimethylformamide is 450 mg: (100~200) mg: 1 g: 40 mL.

[0018] The temperature of the solvothermal reaction is 120~220℃, and the reaction time is 1~24 hours.

[0019] In the phosphating reaction described in S2 above, the precursor and phosphorus source are heated in the same environment. After the phosphorus source is heated and vaporized, it undergoes a gas-solid reaction with the precursor material to form phosphide particles, which are uniformly deposited on the shell of the hollow carbon spheres. Further, the phosphorus source is sodium hypophosphite or disodium hydrogen phosphate, the protective atmosphere is nitrogen, argon or a hydrogen-argon mixture, the phosphating temperature is 600~1200℃, and the phosphating time is 1~10 hours.

[0020] In one feasible implementation, the above-mentioned gas-solid reaction is carried out in a tube furnace with a heating rate of 0.2~10℃ / min. After the phosphating reaction is completed, the hollow carbon spheres loaded with metal phosphides are obtained by natural cooling.

[0021] In one embodiment of the present invention where the effect is optimal, the specific steps of the preparation method are as follows:

[0022] N,N-dimethylformamide, polyvinylpyrrolidone, trimesic acid, zinc nitrate, and nickel nitrate were stirred with a magnetic stirrer until the salt solution was completely dissolved, resulting in a homogeneous solution. The solution was then transferred to a polytetrafluoroethylene reactor and kept at 180°C for 12 hours. After natural cooling, the solution was washed and dried to obtain a metal-organic framework precursor.

[0023] The above precursor was transferred to a tube furnace, sodium hypophosphite was placed at the front end of the gas inlet, and after a hydrogen-argon mixture was introduced for 20 minutes, the temperature was raised to 750°C at a rate of 7°C / min, held for 6 hours, and then naturally cooled to room temperature to obtain hollow carbon spheres loaded with metal phosphides.

[0024] In the above preparation method, the dosage ratio of N,N-dimethylformamide, polyvinylpyrrolidone, trimesic acid, zinc nitrate, nickel nitrate, and sodium hypophosphite is 40 mL: 1 g: 180 mg: 410 mg: 40 mg: 200 mg.

[0025] Thirdly, the application of the hollow carbon spheres loaded with metal phosphides described in the first aspect in the field of electrocatalytic hydrogen production is provided.

[0026] Furthermore, the application method is for preparing an anode. In a specific example, the preparation method is as follows: the hollow carbon spheres loaded with metal phosphide described in the first aspect are dispersed into an ion-exchange resin to form ink, which is then dropped onto a foamed nickel electrode with the oil film removed, and dried to obtain the anode.

[0027] Compared with the prior art, the beneficial effects of the present invention are:

[0028] Firstly, this invention provides a metal-organic framework-derived hollow carbon sphere loaded with metal phosphides, possessing a high specific surface area, with the metal phosphides uniformly loaded onto the hollow carbon sphere shell. The metal phosphide sites supported by this material play a major role in the catalytic reaction, while the hollow carbon spheres provide abundant attachment sites and rapid solution transport channels for the catalytic reaction, and can limit the collapse and deactivation of active sites, significantly improving the catalytic cycle stability.

[0029] Secondly, the present invention also provides a method for preparing the above-mentioned hollow carbon spheres loaded with metal phosphides. This method is simple, does not require the prior preparation of hollow carbon spheres, is easy to operate, and has low cost and low pollution in the phosphating process. The method has good scalability and can be applied on a large scale.

[0030] Furthermore, the present invention also provides the application of the above-mentioned hollow carbon spheres loaded with metal phosphides in the field of electrocatalytic hydrogen production. The above-mentioned material, as an electrocatalytic anode catalyst, has a significantly improved lifespan and significantly improves the performance of water electrolysis. Attached Figure Description

[0031] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0032] Figure 1 This is an SEM image of the hollow carbon spheres loaded with metal phosphides in Example 1;

[0033] Figure 2 This is an SEM image of the hollow carbon spheres loaded with metal phosphides in Example 2;

[0034] Figure 3 This is an SEM image of the hollow carbon spheres loaded with metal phosphides in Example 3;

[0035] Figure 4 This is a TEM image of the hollow carbon spheres loaded with metal phosphides in Example 3;

[0036] Figure 5 This is a SEM image of the hollow carbon spheres loaded with metal phosphides in Example 4;

[0037] Figure 6 SEM images of the sample in Comparative Example 1;

[0038] Figure 7 SEM images of the samples in Comparative Example 2;

[0039] Figure 8 The image shows the SEM image of the sample in Comparative Example 3. Detailed Implementation

[0040] It should be noted that the following detailed description is illustrative and intended to provide further explanation of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0041] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0042] To enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below with reference to specific embodiments and comparative examples.

[0043] Example 1

[0044] In this embodiment, a hollow carbon sphere loaded with a metal phosphide and its preparation method are provided. The preparation method includes the following steps:

[0045] 40 mL of N,N-dimethylformamide, 1 g of polyvinylpyrrolidone, 100 mg of trimesic acid, 430 mg of zinc nitrate, 10 mg of nickel nitrate, and 10 mg of cobalt nitrate were stirred with a magnetic stirrer until the salt solution was completely dissolved, resulting in a homogeneous solution. The solution was then transferred to a polytetrafluoroethylene reactor and kept at 160°C for 24 hours. After natural cooling, the solution was washed and dried to obtain the metal-organic framework precursor.

[0046] The above precursor was transferred to a tube furnace, and 100 mg of sodium hypophosphite was placed at the front end of the gas inlet. After the hydrogen-argon mixture was introduced for 20 minutes, the temperature was raised to 600℃ at a rate of 0.2℃ / min and held for 10 hours. The mixture was then allowed to cool naturally to room temperature to obtain hollow carbon spheres loaded with metal phosphides.

[0047] The microstructure of the hollow carbon spheres loaded with metal phosphides described above was observed using a scanning electron microscope as follows: Figure 1 As shown, the outer diameter is 1.02 μm, the metal phosphide size is 10.5 nm, and the specific surface area is 589 cm². 2 g -1 The content of Ni is 4.8 at.%, the content of Co is 5.2 at.%, the content of Zn is 30.2 at.%, the content of P is 7.2 at.%, the content of C is 53.2 at.%, the content of N is 0.2 at.%, and the content of O is 6.4 at.%.

[0048] The hollow carbon spheres loaded with metal phosphide prepared in Example 1 were used as the anode catalyst to prepare the oxygen evolution anode. The steps are as follows: 4 mg of the hollow carbon spheres loaded with metal phosphide prepared in Example 1 were dispersed in 900 μL of anhydrous ethanol and ultrasonically dispersed evenly. Then, 100 μL of Nafion was added and ultrasonically treated for 30 minutes to form ink.

[0049] Oil film removal was performed on the nickel foam support as follows: the nickel foam was ultrasonically treated for 15 minutes each in acetone, hydrochloric acid, water, and ethanol, and then dried to obtain the oil-free nickel foam support. The resulting ink was then dropped onto the oil-free nickel foam support and allowed to dry completely at room temperature to obtain the anode. The cathode electrode material was 20 wt% Pt / C catalyst, and the two electrodes were assembled into a water electrolyzer. The water electrolysis performance of this electrolyzer in 1 M KOH aqueous solution was then tested, as shown in Table 1.

[0050] Example 2

[0051] In this embodiment, another type of hollow carbon sphere loaded with metal phosphide and its preparation method are provided. The preparation method includes the following steps:

[0052] 40 mL of N,N-dimethylformamide, 1 g of polyvinylpyrrolidone, 120 mg of trimesic acid, 410 mg of zinc nitrate, 20 mg of nickel nitrate, and 20 mg of cobalt nitrate were stirred with a magnetic stirrer until the salt solution was completely dissolved, resulting in a homogeneous solution. The solution was then transferred to a polytetrafluoroethylene reactor and kept at 120 °C for 6 hours. After natural cooling, the solution was cleaned and dried to obtain a metal-organic framework precursor. The precursor was then transferred to a tube furnace, and 150 mg of disodium hydrogen phosphate was placed at the gas inlet. After introducing a hydrogen-argon mixture for 20 minutes, the temperature was raised to 800 °C at a rate of 3 °C / min and held for 5 hours. The solution was then naturally cooled to room temperature to obtain hollow carbon spheres loaded with metal phosphides.

[0053] The microstructure of the hollow carbon spheres loaded with metal phosphides described above was observed using a scanning electron microscope as follows: Figure 2 As shown, the outer diameter is 0.96 μm, the metal phosphide size is 3.5 nm, and the specific surface area is 196 cm². 2 g -1 The content of Ni is 9.5 at.%, the content of Co is 10.2 at.%, the content of Zn is 15.6 at.%, the content of P is 13.5 at.%, the content of C is 49.5 at.%, the content of N is 5.6 at.%, and the content of O is 9.3 at.%.

[0054] The hollow carbon spheres loaded with metal phosphide prepared in Example 2 were used as anode catalysts for water electrolysis performance testing. The preparation and testing methods were the same as in Example 1.

[0055] Example 3

[0056] In this embodiment, another type of hollow carbon sphere loaded with metal phosphide and its preparation method are provided. The preparation method includes the following steps:

[0057] 40 mL of N,N-dimethylformamide, 1 g of polyvinylpyrrolidone, 180 mg of trimesic acid, 410 mg of zinc nitrate, and 40 mg of nickel nitrate were stirred with a magnetic stirrer until the salt solution was completely dissolved, resulting in a homogeneous solution. The solution was then transferred to a polytetrafluoroethylene reactor and kept at 180°C for 12 hours. After natural cooling, the solution was cleaned and dried to obtain a metal-organic framework precursor. The precursor was then transferred to a tube furnace, and 200 mg of sodium hypophosphite was placed at the gas inlet. After introducing a hydrogen-argon mixture for 20 minutes, the temperature was raised to 750°C at a rate of 7°C / min and held for 6 hours. The solution was then naturally cooled to room temperature to obtain hollow carbon spheres loaded with metal phosphides.

[0058] The microstructure of the hollow carbon spheres loaded with metal phosphides described above was observed using a scanning electron microscope as follows: Figure 3 As shown, the outer diameter is 0.80 μm, the metal phosphide size is 31.5 nm, and the specific surface area is 350 cm². 2 g -1 The Ni content is 18.6 at.%, the Zn content is 26.3 at.%, the P content is 10.2 at.%, the C content is 43.5 at.%, the N content is 3.2 at.%, and the O content is 8.4 at.%. Figure 4 This is a TEM image of the hollow carbon spheres loaded with metal phosphides prepared in Example 3. The TEM image shows a weaker central shadow on the carbon spheres, indicating a hollow structure, with the shells of the hollow carbon spheres uniformly loaded with metal phosphides.

[0059] The hollow carbon spheres loaded with metal phosphide prepared in Example 3 were used as anode catalysts for water electrolysis performance testing. The preparation and testing methods were the same as in Example 1.

[0060] Example 4

[0061] In this embodiment, another type of hollow carbon sphere loaded with metal phosphide and its preparation method are provided. The preparation method includes the following steps:

[0062] 40 mL of N,N-dimethylformamide, 1 g of polyvinylpyrrolidone, 200 mg of trimesic acid, 410 mg of zinc nitrate, and 40 mg of cobalt nitrate were stirred with a magnetic stirrer until the salt solution was completely dissolved, resulting in a homogeneous solution. The solution was then transferred to a polytetrafluoroethylene reactor and kept at 220°C for 1 hour. After natural cooling, the solution was cleaned and dried to obtain a metal-organic framework precursor. The precursor was then transferred to a tube furnace, and 300 mg of sodium hypophosphite was placed at the gas inlet. After introducing a hydrogen-argon mixture for 20 minutes, the temperature was raised to 1200°C at a rate of 10°C / min and held for 1 hour. The solution was then allowed to cool naturally to room temperature to obtain hollow carbon spheres loaded with metal phosphides.

[0063] The microstructure of the hollow carbon spheres loaded with metal phosphides described above was observed using a scanning electron microscope as follows: Figure 5 As shown, the outer diameter is 0.68 μm, the metal phosphide size is 26.5 nm, and the specific surface area is 480 cm². 2 g -1 The Co content is 17.5 at.%, the Zn content is 5.7 at.%, the P content is 9.3 at.%, the C content is 70.1 at.%, the N content is 4.3 at.%, and the O content is 2.4 at.%. The main difference between Example 4 and the above examples is that the heating rate is too fast, which leads to certain defects in the morphology of the hollow carbon spheres.

[0064] The hollow carbon spheres loaded with metal phosphide prepared in Example 4 were used as anode catalysts for water electrolysis performance testing. The preparation and testing methods were the same as in Example 1.

[0065] Comparative Example 1

[0066] The only difference between this comparative example and Example 3 is that it contains only one metal salt, namely 450 mg of zinc nitrate.

[0067] The above samples were observed using a scanning electron microscope, and their microstructure is as follows: Figure 6 As shown, the outer diameter is 0.78 μm, the metal phosphide size is 38.9 nm, and the specific surface area is 671 cm². 2 g -1 The Zn content was 5.6 at.%, the P content was 13.8 at.%, the C content was 80.9 at.%, the N content was 5.0 at.%, and the O content was 8.5 at.%. (Comparison) Figure 3 and Figure 6 It can be seen that the material prepared in this embodiment can maintain a spherical hollow structure.

[0068] Hollow carbon spheres loaded with metal phosphides prepared in Comparative Example 1 were used as electrode materials for water electrolysis performance testing. The preparation and testing methods were consistent with those in Example 1.

[0069] Comparative Example 2

[0070] The only difference between this comparative example and Example 3 is that it contains only one metal salt, namely 450 mg of nickel nitrate.

[0071] The above samples were observed using a scanning electron microscope, and their microstructure is as follows: Figure 7 As shown, the metal phosphide has a size of 156 nm and a specific surface area of ​​80 cm². 2 g -1 The Ni content is 28.6 at.%, the P content is 14.9 at.%, the C content is 62.4 at.%, the N content is 4.5 at.%, and the O content is 4.5 at.%. (Comparison) Figure 3 and Figure 7 The derived carbon obtained in this comparative example does not have a hollow structure but is coated on the surface of the phosphide particles, which appear as large, non-uniform spherical particles. The results of Comparative Example 2 show that using only nickel salt as the metal source, with a high nickel content and a low carbon content, results in carbon coating on the surface of the phosphide particles and significant particle growth, exceeding the nanoscale.

[0072] The carbon-coated metal phosphide particles prepared in Comparative Example 2 were used as electrode materials for water electrolysis performance testing. The preparation and testing methods were the same as in Example 1.

[0073] Comparative Example 3

[0074] The only difference between this comparative example and Example 3 is that the heating rate is changed to 15°C / min.

[0075] The above samples were observed using a scanning electron microscope, and their microstructure is as follows: Figure 8 As shown, the metal phosphide has a size of 125 nm and a specific surface area of ​​285 cm². 2 g -1 The Ni content is 19.3 at.%, the Zn content is 6.5 at.%, the P content is 9.8 at.%, the C content is 67.2 at.%, the N content is 3.8 at.%, and the O content is 3.2 at.%. According to... Figure 8 As shown, this comparative synthesis of three-dimensional porous carbon loaded with metal phosphides demonstrates that excessively rapid heating rates can cause the hollow structure to collapse into a three-dimensional continuous support.

[0076] The three-dimensional porous carbon loaded with metal phosphide prepared in Comparative Example 3 was used as an anode catalyst for water electrolysis performance testing. The preparation and testing methods were consistent with those in Example 1.

[0077] Table 1. Electrolysis performance of Examples 1-4 and Comparative Examples 1-3

[0078]

[0079] According to the results shown in Table 1, the materials obtained in Comparative Examples 1-3 exhibit higher cell voltages, which leads to higher overpotentials in the catalyst. This results in the catalyst being highly susceptible to oxidation, deactivation, and detachment, thus significantly shortening its lifespan. Therefore, using a single metal salt feedstock or an extremely high heating rate can significantly affect the electrochemical water splitting activity and lifespan of the catalytic material.

[0080] In Examples 1-4, composite metal salts were used, which effectively reduced the cell voltage of the electrolyzer compared to the comparative examples. Although the higher heating rate in Example 4 resulted in spherical defects in the catalyst structure, it still exhibited good electrochemical water splitting performance. Furthermore, the catalyst lifespan in Example 3 significantly exceeded that of the other examples. This is because the hollow carbon sphere structure and uniformly loaded phosphide particles of the catalyst significantly reduced the cell voltage, making the catalyst less prone to oxidation and deactivation, thus maintaining high activity and continuous stable operation.

[0081] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A hollow carbon sphere loaded with a metal phosphide, characterized in that, This material uses hollow carbon spheres with a diameter of 0.68–1.02 μm as a carrier, with metal phosphide particles of 3.5–38.9 nm size loaded on the shell, resulting in a specific surface area of ​​196–671 cm². 2 g -1 ; The elements and their proportions contained in the hollow carbon spheres loaded with metal phosphides are as follows: Ni 0~18.6 at.%, Co 0~17.5 at.%, Zn 5.7~30.2 at.%, P 7.2~13.8 at.%, C 43.5~80.9 at.%, N 0.2~5.6 at.% and O 2.4~9.3 at.%; The method for preparing the hollow carbon spheres includes the following steps: S1: A precursor is obtained by dissolving a metal salt, trimesic acid, and a surfactant in an organic solvent and carrying out a solvothermal reaction; the metal salt contains at least a zinc salt, and also contains one or a combination of a nickel salt and a cobalt salt, wherein the mass ratio of the zinc salt to the latter is 41:4 to 43:

2. S2: The precursor and phosphorus source are placed together in a protective atmosphere and heated for phosphating treatment to obtain hollow carbon spheres loaded with metal phosphides.

2. The hollow carbon spheres loaded with metal phosphides as described in claim 1, characterized in that, The surfactant is polyvinylpyrrolidone, the organic solvent is N,N-dimethylformamide, and the dosage ratio of the metal salt, trimesic acid, polyvinylpyrrolidone and N,N-dimethylformamide is 450 mg: (100~200) mg: 1 g: 40 mL.

3. The hollow carbon spheres loaded with metal phosphides as described in claim 1, characterized in that, The temperature of the solvothermal reaction is 120~220℃, and the reaction time is 1~24 hours.

4. The hollow carbon spheres loaded with metal phosphides as described in claim 1, characterized in that, In step S2, the phosphorus source is sodium hypophosphite or disodium hydrogen phosphate, the protective atmosphere is nitrogen, argon or a hydrogen-argon mixture, the phosphating temperature is 600~1200℃, and the phosphating time is 1~10 hours.

5. The hollow carbon spheres loaded with metal phosphides as described in claim 1, characterized in that, The heating rate for phosphating is 0.2~10℃ / min. After the phosphating reaction is completed, the hollow carbon spheres loaded with metal phosphides are obtained by natural cooling.

6. The application of the hollow carbon spheres loaded with metal phosphides as described in claim 1 in the field of electrocatalytic hydrogen production, characterized in that, The application method is to prepare an electrolytic water anode. The preparation method is as follows: the hollow carbon spheres loaded with metal phosphide are dispersed in an ion-exchange resin to form ink, which is then dropped onto a foamed nickel electrode with the oil film removed, and dried to obtain the anode.

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