Hollow Dahlia-shaped nickel cobalt selenide composite electrocatalytic material and synthesis method and application thereof

Abstract

The application discloses a hollow dahlia-shaped nickel-cobalt selenide composite electrocatalytic material and a synthesis method and application thereof. The hollow dahlia-shaped nickel-cobalt selenide composite electrocatalytic material is prepared by adopting a hydrothermal-solvothermal combined method with SiO2 balls as a template. Specifically, a nickel silicon hydroxide precursor is prepared by a hydrothermal reaction method. The method is simple in operation, environment-friendly and energy-saving, and the morphology structure is easy to control. Then, a NiSe / Co9Se8 hollow nanoflower composite material is prepared by a solvothermal method. The method can effectively inhibit oxidation and has the advantages of wide application range, easy control of a reaction process, low crystallization temperature and the like. Therefore, the combination of the two methods can precisely control crystal growth and a microstructure, so that an electrocatalyst with high activity, high stability and high specific surface area is prepared, and the electrocatalyst exhibits excellent electrocatalytic HER and OER performance under alkaline conditions.

Description

Technical Field

[0001] This invention belongs to the field of electrocatalytic materials, specifically relating to a hollow dahlia-shaped nickel-cobalt-selenide composite electrocatalytic material, its synthesis method, and its application. Background Technology

[0002] In today's world, energy issues and environmental challenges are becoming increasingly severe. Against this backdrop, the hydrogen economy, as a clean and efficient energy solution, has attracted much attention. Electrocatalytic water splitting technology can generate "green hydrogen" using renewable energy sources such as wind, hydro, and solar power. It has advantages such as readily available raw materials, high energy utilization, simple operation, and environmental friendliness, making it one of the most promising sustainable hydrogen production methods currently available.

[0003] Electrocatalytic water splitting mainly involves two half-reactions: the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) (Lakhan, M.; Hanan, A.; Hussain, A.; Soomro, I.; Wang, Y.; Ahmed, M.; Aftab, U.; Sun, H.; Arandiyan, H. Transition metal-based electrocatalysts for alkaline overall water splitting: advances, challenges, and perspectives, Chemical Communications, 2024, 60(39): 5104-5135.). HER, occurring at the cathode, reduces protons to hydrogen, and its efficiency and selectivity are crucial to the economics and practicality of hydrogen production from water splitting. OER, occurring at the anode, is a complex process involving multiple electron transfer steps and is relatively slower kinetics, often becoming the rate-limiting step in the water splitting reaction. Therefore, developing efficient and stable bifunctional electrocatalysts is of great significance.

[0004] Transition metal chalcogenides possess advantages such as tunable phase structures, high carrier mobility, and flexible electronic structures, which can effectively improve the efficiency of electrocatalytic reactions and have great application potential in the field of energy conversion. Compared with oxygen and sulfur in the same group, selenium has a large radius, strong metallicity, and low electronegativity, which makes selenides often have more easily modulated electronic structures and bonding states, thereby improving the efficiency of electrocatalytic reactions (Chen, D.; Zhao, Z.; Chen, G.; Li, T.; Chen, J.; Ye, Z.; Lu, J. Metal selenides for energy storage and conversion: A comprehensive review. Coordination Chemistry Reviews, 2023, 479: 214984.). Among them, nickel-based electrocatalytic materials are inexpensive, highly conductive, and have good stability under alkaline conditions, making them suitable for large-scale applications. Therefore, nickel selenide has attracted widespread attention due to its simple synthesis method, high conductivity, and abundant crystal phases. However, nickel-based materials often exhibit a low-spin state, meaning their low-energy orbitals (t... 2g The presence of a fully filled molecule would impede electron transport in pure nickel-based materials (Xu, J.; Ruan, J.; Jian, Y.; Lao, J.; Li, Z.; Xie, F.; Jin, Y.; Yu, X.; Lee, M.; Wang, Z.; Wang, N.; Meng, H. Cobalt-doping induced formation of five-coordinated nickel selenide for enhanced ethanol assisted overall watersplitting, Small, 2024, 20(11): 2305905.). Summary of the Invention

[0005] The purpose of this invention is to provide a hollow dahlia-shaped nickel-cobalt-selenide composite electrocatalytic material, its synthesis method, and its application. It can precisely control crystal growth and microstructure, thereby preparing an electrocatalyst with high activity, high stability, and high specific surface area. Moreover, the product exhibits excellent electrocatalytic HER and OER performance under alkaline conditions.

[0006] To achieve the above objectives, the synthesis method employed in this invention includes the following steps:

[0007] S1: Disperse 285.24–356.55 mg of nickel source powder in 25–30 mL of deionized water and mix well. Then add 133.75–149.8 mg of ammonium chloride and 280.36–308.4 mg of hexamethylenetetramine powder and stir well. Finally, add alkaline solution and stir well to adjust the pH value to 8.5–9.0 to obtain solution A.

[0008] S2: Disperse 210.35–228.38 mg of SiO2 powder ultrasonically in 25–30 mL of deionized water, and stir until homogeneous to obtain solution B;

[0009] S3: Add solution A dropwise to solution B, stir evenly, pour into a polytetrafluoroethylene hydrothermal reactor, heat to 125-135℃ and maintain for 25-30 hours, then cool naturally to room temperature. The reaction product obtained in the polytetrafluoroethylene hydrothermal reactor is then centrifuged and vacuum dried with ultrapure water and ethanol to obtain nickel silicon hydroxide precursor powder.

[0010] S4: Dissolve 78.96–102.65 mg of Se powder in 2.2–2.5 mL of hydrazine hydrate and stir until homogeneous to obtain solution C;

[0011] S5: Add solution C to a mixed solution of 9-11 mL ethylene glycol and 12-14 mL ethylenediamine and stir until homogeneous to obtain solution D;

[0012] S6: Add 237.9–285.5 mg of cobalt source, 88.91–114.14 mg of polyvinylpyrrolidone and 150–155 mg of nickel silicon hydroxide precursor powder to solution D, and stir until homogeneous to obtain solution E;

[0013] S7: Add solution E to the hydrothermal reactor of para-polystyrene, heat to 175-180℃ and maintain for 15-18h, then cool naturally to room temperature. The reaction product obtained in the hydrothermal reactor of para-polystyrene is then centrifuged and vacuum dried with ultrapure water and ethanol to obtain the target product NiSe / Co9Se8.

[0014] Preferably, the nickel source in step S1 is one or more of nickel chloride hexahydrate, nickel nitrate hexahydrate, or nickel acetylacetonate, and the alkaline solution is one or more of 1 mol / L ammonia, sodium hydroxide, or potassium hydroxide.

[0015] Preferably, the stirring process in steps S1, S5 and S6 is magnetic stirring.

[0016] Preferably, the filling ratio of the mixed solution of A and B in step S3 to the hydrothermal reactor is 54% to 65%.

[0017] Preferably, the reaction products in steps S3 and S7 are subjected to alternating centrifugation with ultrapure water and anhydrous ethanol 3 to 4 times, and vacuum drying at a temperature of 70 to 80°C.

[0018] Preferably, the stirring method in step S4 is magnetic stirring at a temperature of 62-65°C.

[0019] Preferably, the cobalt source in step S6 is one or more of cobalt chloride hexahydrate, cobalt nitrate hexahydrate, or cobalt acetylacetonate.

[0020] Preferably, the filling ratio of solution E to the hydrothermal reactor of para-polystyrene in step S7 is 46-55%.

[0021] A hollow dahlia-shaped nickel-cobalt-selenide composite electrocatalytic material prepared by the method described in any of the preceding claims.

[0022] Application of a hollow dahlia-shaped nickel-cobalt-selenide composite electrocatalytic material as described above in the electrocatalytic hydrogen evolution and oxygen evolution reactions under alkaline conditions.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] (1) In terms of preparation strategy, this scheme adopts a hydrothermal-solvothermal combined method to prepare hollow dahlia-shaped nickel cobalt selenide composite electrocatalytic materials, which has significant advantages. Specifically, nickel silicon hydroxide precursor is first prepared by hydrothermal reaction. This method is simple to operate, environmentally friendly and energy-saving, and its morphology and structure are easy to control. Then, NiSe / Co9Se8 hollow nanoflower composite material is prepared by solvothermal method. This method can effectively inhibit oxidation and has the advantages of wide applicability, easy control of reaction process, and low crystallization temperature. Therefore, the combination of the two methods can accurately control crystal growth and microstructure, thereby preparing an electrocatalyst with high activity, high stability and high specific surface area.

[0025] (2) In this scheme, SiO2 spheres are used as templates. They have rich porous structures and high specific surface area. Therefore, the electrocatalysts synthesized with them as precursors are more regular in structure, which is conducive to the uniform distribution of active sites. Moreover, their high chemical stability allows them to maintain the integrity of their own structure during the synthesis of electrocatalysts. Furthermore, they are easy to modify the surface through various chemical methods to precisely control the composition and structure of the electrocatalysts, thereby improving the electrocatalytic performance.

[0026] (3) The NiSe / Co9Se8 hollow nanoflower structure prepared by this scheme not only has a larger specific surface area and more accessible active sites, which can effectively increase the full contact between the electrolyte and the catalyst and enhance the point catalytic activity, but its unique hollow and porous structure can also serve as a fast mass transfer channel to accelerate the transport of ions and electrons and further improve the electrocatalytic performance.

[0027] (4) In this scheme, the morphology regulator hexamethylenetetramine is also introduced. By strictly controlling the mass ratio of hexamethylenetetramine to nickel source and ammonium chloride, reaction temperature, reaction time and reaction filling ratio, the inductive effect of hexamethylenetetramine is fully utilized, and the structure of the nickel silicon hydroxide precursor prepared with SiO2 spheres as templates is controlled during the reaction process.

[0028] (5) In this scheme, polyvinylpyrrolidone, a morphology modifier, is added to the reaction solvent. By strictly and synergistically controlling the volume of ethylene glycol and ethylenediamine, the concentration and ratio of cobalt source and selenium source, reaction time, reaction temperature and reaction filling ratio, etc., the state of NiSe / Co9Se8 hollow nanoflower composite material in the reaction is controlled.

[0029] (6) In this scheme, the solvents used for the heat of dissolution reaction are ethylene glycol and ethylenediamine. The electrocatalyst synthesized by the mixed solvent utilizes the reducing properties and good dispersibility of ethylene glycol and the coordination ability of ethylenediamine to effectively control the particle size and morphology of the catalyst and improve the activity and stability of the catalyst.

[0030] (7) This scheme uses SiO2 spheres as templates to construct NiSe / Co9Se8 hollow nanoflower composite materials. It utilizes the advantages of multi-component synergistic effect and structural complementarity to improve the electrocatalytic performance of the materials. In particular, by introducing cobalt selenide materials with special valence electron structure and adjustable binding energy with oxygen-containing groups, the electron distribution of active sites can be changed to optimize the adsorption / desorption energy of reaction intermediates, thereby improving the electrocatalytic performance of composite materials. Attached Figure Description

[0031] Figure 1 The X-ray diffraction (XRD) pattern of the NiSe / Co9Se8 composite electrocatalyst prepared in Example 1 of this invention;

[0032] Figure 2 This is a low-magnification scanning electron microscope (SEM) image of the NiSe / Co9Se8 composite electrocatalyst prepared in Example 1 of the present invention;

[0033] Figure 3 This is a high-magnification scanning electron microscope (SEM) image of the NiSe / Co9Se8 composite electrocatalyst prepared in Example 1 of the present invention;

[0034] Figure 4The hydrogen production performance (HER) curve of the NiSe / Co9Se8 composite electrocatalyst prepared in Example 1 of this invention is obtained by linear sweep voltammetry (LSV) under alkaline conditions.

[0035] Figure 5 This is an oxygen evolution performance (OER) curve of the NiSe / Co9Se8 composite electrocatalyst prepared in Example 1 of the present invention under alkaline conditions, obtained by linear sweep voltammetry (LSV). Detailed Implementation

[0036] The present invention will be further described in detail below with reference to specific embodiments. These descriptions are for explanation purposes only and are not intended to limit the scope of the invention.

[0037] Example 1:

[0038] S1: Disperse 285.24 mg of nickel chloride hexahydrate in 25 mL of deionized water and mix well. Then add 133.75 mg of ammonium chloride and 280.36 mg of hexamethylenetetramine powder and stir evenly with magnetic force. Then add 1 mol / L ammonia water and stir evenly to adjust the pH value to 9.0 to obtain solution A.

[0039] S2: Disperse 210.35 mg of SiO2 powder in 25 mL of deionized water and sonicate for 1.2 h. After stirring evenly, obtain solution B.

[0040] S3: Add solution A dropwise to solution B, stir for 30 min, and then pour it into a polytetrafluoroethylene hydrothermal reactor at a filling ratio of 54%. Heat the polytetrafluoroethylene hydrothermal reactor to 125℃ and maintain it for 30 h, then let it cool naturally to room temperature. Then, centrifuge the reaction product obtained in the polytetrafluoroethylene hydrothermal reactor three times alternately with ultrapure water and ethanol, and dry it under vacuum conditions at a temperature of 70℃ for 18 h to obtain nickel silicon hydroxide precursor powder.

[0041] S4: Dissolve 78.96 mg of Se powder in 2.2 mL of hydrazine hydrate and stir magnetically at 62 °C to obtain solution C for 50 min.

[0042] S5: Add solution C to a mixed solution of 9 mL ethylene glycol and 12 mL ethylenediamine and stir magnetically until homogeneous to obtain solution D. The stirring time is 25 min.

[0043] S6: Add 237.9 mg of cobalt chloride hexahydrate, 88.91 mg of polyvinylpyrrolidone and 150 mg of nickel silicon hydroxide precursor powder to solution D, and stir magnetically until homogeneous to obtain solution E. The stirring time is 25 min.

[0044] S7: Add solution E to the hydrothermal reactor of para-polystyrene at a filling ratio of 46%, heat the hydrothermal reactor of para-polystyrene to 175°C and maintain it for 18 hours, then let it cool naturally to room temperature. Then, centrifuge the reaction product obtained in the hydrothermal reactor of para-polystyrene three times alternately with ultrapure water and ethanol, and dry it under vacuum at a temperature of 70°C for 15 hours to obtain the target product NiSe / Co9Se8.

[0045] Figure 1 The image shows the X-ray diffraction (XRD) pattern of the NiSe / Co9Se8 composite electrocatalyst prepared in Example 1 of this invention. It can be seen from the figure that there are two phases: one is the diffraction peak of NiSe (PDF#75-0610), and the other is the diffraction peak of Co9Se8 (PDF#09-0233).

[0046] Figure 2 The image shown is a low-magnification scanning electron microscope (SEM) image of the NiSe / Co9Se8 composite electrocatalyst prepared in Example 1 of this invention, revealing the morphology of nanoflowers assembled from nanosheets.

[0047] Figure 3 The high-magnification scanning electron microscope (SEM) image of the NiSe / Co9Se8 composite electrocatalyst prepared in Example 1 of this invention shows that the morphology of NiSe / Co9Se8 is a hollow nanoflower structure.

[0048] Figure 4 The image shows the hydrogen production performance (HER) of the NiSe / Co9Se8 composite electrocatalyst prepared in Example 1 of this invention under alkaline conditions, obtained from a linear sweep voltammetry (LSV) curve. The NiSe / Co9Se8 composite material exhibits good electrocatalytic hydrogen production activity, with a current density reaching 10 mA / cm². 2 The required overpotentials are 152mV.

[0049] Figure 5 The image shows the oxygen evolution performance (OER) curve of the NiSe / Co9Se8 composite electrocatalyst prepared in Example 1 of this invention under alkaline conditions, obtained from a linear sweep voltammetry (LSV) curve. The NiSe / Co9Se8 composite material exhibits good electrocatalytic oxygen evolution activity, with a current density reaching 10 mA / cm². 2 The required overpotentials are 280mV.

[0050] Example 2:

[0051] S1: Disperse 300 mg of nickel nitrate hexahydrate powder in 26 mL of deionized water and mix well. Then add 140 mg of ammonium chloride and 290 mg of hexamethylenetetramine powder and stir evenly with magnetic force. Then add 1 mol / L sodium hydroxide solution and stir evenly to adjust the pH value to 8.5 to obtain solution A.

[0052] S2: Disperse 215 mg of SiO2 powder in 26 mL of deionized water and sonicate for 1.3 h. After stirring evenly, obtain solution B.

[0053] S3: Add solution A dropwise to solution B, stir for 32 min, and then pour it into a polytetrafluoroethylene hydrothermal reactor at a filling ratio of 56%. Heat the polytetrafluoroethylene hydrothermal reactor to 127°C and maintain it for 29 h, then let it cool naturally to room temperature. Then, centrifuge the reaction product obtained in the polytetrafluoroethylene hydrothermal reactor three times alternately with ultrapure water and ethanol, and dry it under vacuum conditions at a temperature of 72°C for 17.5 h to obtain nickel silicon hydroxide precursor powder.

[0054] S4: Dissolve 85 mg of Se powder in 2.3 mL of hydrazine hydrate and stir magnetically at 63 °C to obtain solution C. The stirring time is 52 min.

[0055] S5: Add solution C to a mixed solution of 10 mL ethylene glycol and 13 mL ethylenediamine and stir magnetically until homogeneous to obtain solution D. The stirring time is 26 min.

[0056] S6: Add 250 mg of cobalt nitrate hexahydrate, 95 mg of polyvinylpyrrolidone and 152 mg of nickel silicon hydroxide precursor powder to solution D, and stir magnetically until homogeneous to obtain solution E. The stirring time is 26 min.

[0057] S7: Add solution E to the hydrothermal reactor of para-polystyrene at a filling ratio of 50%, heat the hydrothermal reactor of para-polystyrene to 176°C and maintain it for 17 hours, then let it cool naturally to room temperature. Then, centrifuge the reaction product obtained in the hydrothermal reactor of para-polystyrene three times alternately with ultrapure water and ethanol, and dry it under vacuum at a temperature of 72°C for 15 hours to obtain the target product NiSe / Co9Se8.

[0058] Example 3:

[0059] S1: Disperse 320 mg of nickel acetylacetonate in 27 mL of deionized water and mix well. Then add 145 mg of ammonium chloride and 300 mg of hexamethylenetetramine powder and stir evenly with magnetic force. Then add 1 mol / L potassium hydroxide solution and stir evenly to adjust the pH value to 8.8 to obtain solution A.

[0060] S2: Disperse 220 mg of SiO2 powder in 27 mL of deionized water and sonicate for 1.4 h. After stirring evenly, solution B is obtained.

[0061] S3: Add solution A dropwise to solution B, stir for 34 min, and then pour it into a polytetrafluoroethylene hydrothermal reactor at a filling ratio of 58.5%. Heat the polytetrafluoroethylene hydrothermal reactor to 129°C and maintain it for 28 h, then let it cool naturally to room temperature. Then, centrifuge the reaction product obtained in the polytetrafluoroethylene hydrothermal reactor three times alternately with ultrapure water and ethanol, and dry it under vacuum conditions at a temperature of 74°C for 17 h to obtain nickel silicon hydroxide precursor powder.

[0062] S4: Dissolve 92 mg of Se powder in 2.4 mL of hydrazine hydrate and stir magnetically at 64 °C to obtain solution C. The stirring time is 53 min.

[0063] S5: Add solution C to a mixed solution of 10.5 mL ethylene glycol and 13.5 mL ethylenediamine and stir magnetically until homogeneous to obtain solution D. The stirring time is 27 min.

[0064] S6: Add 265 mg of cobalt acetylacetonate, 102 mg of polyvinylpyrrolidone and 153 mg of nickel silicon hydroxide precursor powder to solution D, and stir magnetically until homogeneous to obtain solution E. The stirring time is 27 min.

[0065] S7: Add solution E to the hydrothermal reactor of para-polystyrene at a filling ratio of 52.8%, heat the hydrothermal reactor of para-polystyrene to 177°C and maintain it for 16.5 h, then let it cool naturally to room temperature. Then, centrifuge the reaction product obtained in the hydrothermal reactor of para-polystyrene with ultrapure water and ethanol alternately four times, and dry it under vacuum at a temperature of 74°C for 14 h to obtain the target product NiSe / Co9Se8.

[0066] Example 4:

[0067] S1: Disperse 330 mg of nickel chloride hexahydrate and nickel nitrate hexahydrate powder in 28 mL of deionized water at a mass ratio of 1:1 and mix evenly. Then add 148 mg of ammonium chloride and 305 mg of hexamethylenetetramine powder and stir evenly with magnetic force. Then add 1 mol / L ammonia water and sodium hydroxide solution and stir evenly to adjust the pH value to 9.0 to obtain solution A.

[0068] S2: Disperse 225 mg of SiO2 powder in 28 mL of deionized water and sonicate for 1.45 h. After stirring evenly, obtain solution B.

[0069] S3: Add solution A dropwise to solution B, stir for 36 min, and then pour it into a polytetrafluoroethylene hydrothermal reactor at a filling ratio of 60%. Heat the polytetrafluoroethylene hydrothermal reactor to 131℃ and maintain it for 27 h, then let it cool naturally to room temperature. Then, centrifuge the reaction product obtained in the polytetrafluoroethylene hydrothermal reactor alternately with ultrapure water and ethanol 4 times, and dry it under vacuum conditions at a temperature of 76℃ for 16.5 h to obtain nickel silicon hydroxide precursor powder.

[0070] S4: Dissolve 98 mg of Se powder in 2.45 mL of hydrazine hydrate and stir magnetically at 64.5 °C to obtain solution C. The stirring time is 54 min.

[0071] S5: Add solution C to a mixed solution of 10.8 mL of ethylene glycol and 13.8 mL of ethylenediamine and stir magnetically until homogeneous to obtain solution D. The stirring time is 28 min.

[0072] S6: Add 275 mg of cobalt chloride hexahydrate and cobalt nitrate hexahydrate in a mass ratio of 1:1, 108 mg of polyvinylpyrrolidone and 154 mg of nickel silicon hydroxide precursor powder to solution D, and stir magnetically until homogeneous to obtain solution E. The stirring time is 28 min.

[0073] S7: Add solution E to the hydrothermal reactor of para-polystyrene at a filling ratio of 54%, heat the hydrothermal reactor of para-polystyrene to 178°C and maintain it for 16 hours, then let it cool naturally to room temperature. Then, centrifuge the reaction product obtained in the hydrothermal reactor of para-polystyrene with ultrapure water and ethanol alternately 4 times, and dry it under vacuum at a temperature of 76°C for 14 hours to obtain the target product NiSe / Co9Se8.

[0074] Example 5:

[0075] S1: Disperse 345 mg of nickel chloride hexahydrate and nickel acetylacetonate powder in 29 mL of deionized water at a mass ratio of 1:1 and mix evenly. Then add 149 mg of ammonium chloride and 307 mg of hexamethylenetetramine powder and stir evenly with magnetic force. Then add 1 mol / L ammonia water and potassium hydroxide solution and stir evenly to adjust the pH value to 8.5 to obtain solution A.

[0076] S2: Disperse 227 mg of SiO2 powder in 29 mL of deionized water and sonicate for 1.48 h. After stirring evenly, obtain solution B.

[0077] S3: Add solution A dropwise to solution B, stir for 38 min, and then pour it into a polytetrafluoroethylene hydrothermal reactor at a filling ratio of 62.5%. Heat the polytetrafluoroethylene hydrothermal reactor to 133℃ and maintain it for 26 h, then let it cool naturally to room temperature. Then, centrifuge the reaction product obtained in the polytetrafluoroethylene hydrothermal reactor alternately with ultrapure water and ethanol 4 times, and dry it under vacuum conditions at a temperature of 78℃ for 16 h to obtain nickel silicon hydroxide precursor powder.

[0078] S4: Dissolve 98 mg of Se powder in 2.48 mL of hydrazine hydrate, and stir magnetically at 64.8 °C to obtain solution C. The stirring time is 54.5 min.

[0079] S5: Add solution C to a mixed solution of 10.9 mL of ethylene glycol and 13.9 mL of ethylenediamine and stir magnetically until homogeneous to obtain solution D. The stirring time is 29 min.

[0080] S6: Add 280 mg of cobalt chloride hexahydrate and cobalt acetylacetonate in a mass ratio of 1:1, 112 mg of polyvinylpyrrolidone and 154.5 mg of nickel silicon hydroxide precursor powder to solution D, and stir magnetically until homogeneous to obtain solution E. The stirring time is 29 min.

[0081] S7: Add solution E to the hydrothermal reactor of para-polystyrene at a filling ratio of 54.5%, heat the hydrothermal reactor of para-polystyrene to 179°C and maintain it for 15.5 h, then let it cool naturally to room temperature. Then, centrifuge the reaction product obtained in the hydrothermal reactor of para-polystyrene with ultrapure water and ethanol alternately 4 times, and dry it under vacuum at a temperature of 78°C for 13 h to obtain the target product NiSe / Co9Se8.

[0082] Example 6:

[0083] S1: Disperse 356.55 mg of nickel nitrate hexahydrate and nickel acetylacetonate powder in 30 mL of deionized water at a mass ratio of 1:1 and mix well. Then add 149.8 mg of ammonium chloride and 308.4 mg of hexamethylenetetramine powder and stir magnetically until well mixed. Add 1 mol / L potassium hydroxide and sodium hydroxide solution and stir until well mixed. Adjust the pH value to 8.5 to obtain solution A.

[0084] S2: Disperse 228.38 mg of SiO2 powder in 30 mL of deionized water and sonicate for 1.5 h. After stirring evenly, obtain solution B.

[0085] S3: Add solution A dropwise to solution B, stir for 40 min, and then pour it into a polytetrafluoroethylene hydrothermal reactor at a filling ratio of 65%. Heat the polytetrafluoroethylene hydrothermal reactor to 135℃ and maintain it for 25 h, then let it cool naturally to room temperature. Then, centrifuge the reaction product obtained in the polytetrafluoroethylene hydrothermal reactor alternately with ultrapure water and ethanol 4 times, and dry it under vacuum conditions at a temperature of 80℃ for 15 h to obtain nickel silicon hydroxide precursor powder.

[0086] S4: Dissolve 102.65 mg of Se powder in 2.5 mL of hydrazine hydrate and stir magnetically at 65 °C to obtain solution C. The stirring time is 55 min.

[0087] S5: Add solution C to a mixed solution of 11 mL ethylene glycol and 14 mL ethylenediamine and stir magnetically until homogeneous to obtain solution D. The stirring time is 30 min.

[0088] S6: Add 285.5 mg of cobalt nitrate hexahydrate and cobalt acetylacetonate in a mass ratio of 1:1, 114.14 mg of polyvinylpyrrolidone and 155 mg of nickel silicon hydroxide precursor powder to solution D, and stir magnetically until homogeneous to obtain solution E. The stirring time is 30 min.

[0089] S7: Add solution E to the hydrothermal reactor of para-polystyrene at a filling ratio of 55%, heat the hydrothermal reactor of para-polystyrene to 180°C and maintain it for 15 hours, then let it cool naturally to room temperature. Then, centrifuge the reaction product obtained in the hydrothermal reactor of para-polystyrene with ultrapure water and ethanol alternately 4 times, and dry it under vacuum at a temperature of 80°C for 13 hours to obtain the target product NiSe / Co9Se8.

[0090] Example 7:

[0091] S1: Disperse 356.55 mg of nickel nitrate hexahydrate and nickel acetylacetonate powder in any mass ratio in 30 mL of deionized water and mix evenly. Then add 149.8 mg of ammonium chloride and 308.4 mg of hexamethylenetetramine powder and stir evenly with magnetic force. Then add 1 mol / L potassium hydroxide and sodium hydroxide solution and stir evenly to adjust the pH value to 9.0 to obtain solution A.

[0092] S2: Disperse 228.38 mg of SiO2 powder in 30 mL of deionized water and sonicate for 1.5 h. After stirring evenly, obtain solution B.

[0093] S3: Add solution A dropwise to solution B, stir evenly, and pour it into a polytetrafluoroethylene hydrothermal reactor at a filling ratio of 62%. Heat the polytetrafluoroethylene hydrothermal reactor to 135°C and maintain it for 25 hours, then let it cool naturally to room temperature. Then, centrifuge the reaction product obtained in the polytetrafluoroethylene hydrothermal reactor alternately with ultrapure water and ethanol 4 times, and dry it under vacuum conditions at a temperature of 80°C for 15 hours to obtain nickel silicon hydroxide precursor powder.

[0094] S4: Dissolve 102.65 mg of Se powder in 2.5 mL of hydrazine hydrate and stir magnetically at 65 °C to obtain solution C. The stirring time is 55 min.

[0095] S5: Add solution C to a mixed solution of 11 mL ethylene glycol and 14 mL ethylenediamine and stir magnetically until homogeneous to obtain solution D. The stirring time is 30 min.

[0096] S6: Add 285.5 mg of cobalt nitrate hexahydrate and cobalt chloride hexahydrate in any mass ratio, 114.14 mg of polyvinylpyrrolidone and 155 mg of nickel silicon hydroxide precursor powder to solution D, and stir magnetically until homogeneous to obtain solution E. The stirring time is 30 min.

[0097] S7: Add solution E to the hydrothermal reactor of para-polystyrene at a filling ratio of 53%, heat the hydrothermal reactor of para-polystyrene to 180°C and maintain it for 15 hours, then let it cool naturally to room temperature. Then, centrifuge the reaction product obtained in the hydrothermal reactor of para-polystyrene with ultrapure water and ethanol alternately 4 times, and dry it under vacuum at a temperature of 80°C for 13 hours to obtain the target product NiSe / Co9Se8.

[0098] The above description is a further detailed explanation of the present invention in conjunction with specific embodiments. It should not be construed as limiting the specific implementation of the present invention to these inventions. For those skilled in the art, several simple deductions or substitutions can be made without departing from the concept of the present invention, and all such deductions or substitutions should be considered to fall within the protection scope of the present invention.

Claims

1. A method for synthesizing a hollow dahlia-shaped nickel-cobalt-selenide composite electrocatalytic material, characterized in that, Includes the following steps: S1: Disperse 285.24–356.55 mg of nickel source powder in 25–30 mL of deionized water and mix well. Then add 133.75–149.8 mg of ammonium chloride and 280.36–308.4 mg of hexamethylenetetramine powder and stir well. Finally, add alkaline solution and stir well to adjust the pH to 8.5–9.0 to obtain solution A. S2: Disperse 210.35–228.38 mg of SiO2 powder ultrasonically in 25–30 mL of deionized water, and stir until homogeneous to obtain solution B; S3: Add solution A dropwise to solution B, stir evenly, pour into a polytetrafluoroethylene hydrothermal reactor, heat to 125-135℃ and maintain for 25-30 hours, then cool naturally to room temperature. The reaction product obtained in the polytetrafluoroethylene hydrothermal reactor is then centrifuged and vacuum dried with ultrapure water and ethanol to obtain nickel silicon hydroxide precursor powder. S4: Dissolve 78.96–102.65 mg of Se powder in 2.2–2.5 mL of hydrazine hydrate and stir until homogeneous to obtain solution C; S5: Add solution C to a mixed solution of 9-11 mL ethylene glycol and 12-14 mL ethylenediamine and stir until homogeneous to obtain solution D; S6: Add 237.9–285.5 mg of cobalt source, 88.91–114.14 mg of polyvinylpyrrolidone and 150–155 mg of nickel silicon hydroxide precursor powder to solution D, and stir until homogeneous to obtain solution E; S7: Add solution E to the hydrothermal reactor of para-polystyrene, heat to 175-180℃ and maintain for 15-18h, then cool naturally to room temperature. The reaction product obtained in the hydrothermal reactor of para-polystyrene is then centrifuged and vacuum dried with ultrapure water and ethanol to obtain the target product NiSe / Co9Se8.

2. The method for synthesizing a hollow dahlia-shaped nickel-cobalt-selenide composite electrocatalytic material according to claim 1, characterized in that, The nickel source in step S1 is one or more of nickel chloride hexahydrate, nickel nitrate hexahydrate, or nickel acetylacetonate, and the alkaline solution is one or more of 1 mol / L ammonia, sodium hydroxide, or potassium hydroxide.

3. The method for synthesizing a hollow dahlia-shaped nickel-cobalt-selenide composite electrocatalytic material according to claim 1, characterized in that, The stirring in steps S1, S5 and S6 is magnetic stirring.

4. The method for synthesizing a hollow dahlia-shaped nickel-cobalt-selenide composite electrocatalytic material according to claim 1, characterized in that, The filling ratio of the mixed solution of A and B in step S3 to the hydrothermal reactor is 54% to 65%.

5. The method for synthesizing a hollow dahlia-shaped nickel-cobalt-selenide composite electrocatalytic material according to claim 1, characterized in that, The reaction products in steps S3 and S7 are specifically subjected to alternating centrifugation with ultrapure water and anhydrous ethanol 3 to 4 times, and vacuum drying at a temperature of 70 to 80°C.

6. The method for synthesizing a hollow dahlia-shaped nickel-cobalt-selenide composite electrocatalytic material according to claim 1, characterized in that, The stirring method in step S4 is specifically magnetic stirring at a temperature of 62-65°C.

7. The method for synthesizing a hollow dahlia-shaped nickel-cobalt-selenide composite electrocatalytic material according to claim 1, characterized in that, The cobalt source in step S6 is one or more of cobalt chloride hexahydrate, cobalt nitrate hexahydrate, or cobalt acetylacetonate.

8. The method for synthesizing a hollow dahlia-shaped nickel-cobalt-selenide composite electrocatalytic material according to claim 1, characterized in that, In step S7, the filling ratio of solution E to the hydrothermal reactor for para-polystyrene is 46-55%.

9. A hollow dahlia-shaped nickel-cobalt-selenide composite electrocatalytic material prepared by the method according to any one of claims 1-8.

10. The application of a hollow dahlia-shaped nickel-cobalt-selenide composite electrocatalytic material as described in claim 9 in the electrocatalytic hydrogen evolution and oxygen evolution reactions under alkaline conditions.

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