Mott-Schottky junction composite material rich in sulfur vacancies and preparation method and application thereof
By constructing a Mott-Schottky junction composite material rich in sulfur vacancies, the problems of expensive noble metal catalysts and insufficient electrochemical performance of transition metal sulfides were solved, achieving a highly efficient electrochemical water splitting hydrogen production effect.
Patent Information
- Application Number
- CN202511114897.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-11
- Publication Date
- 2025-10-31
AI Technical Summary
Existing precious metal catalysts are expensive, and transition metal sulfides have limited electrochemical kinetics and poor conductivity, which restricts their application in electrochemical water splitting for hydrogen production.
A sulfur-vacancy-rich Mott-Schottky junction composite material was constructed. NiCo-MOF was synthesized via a solvothermal method, followed by sulfidation and reduction treatment to form a NiCo@C/NiCoSv structure. The sulfur vacancies and the Mott-Schottky junction were used to synergistically regulate interfacial charge transfer and optimize electrocatalytic activity.
It significantly improved electrocatalytic performance, reduced the overpotential of oxygen evolution reaction and hydrogen evolution reaction, enhanced the conductivity and catalytic activity of electrode materials, and achieved highly efficient electrochemical water splitting.
Smart Images
Figure CN120866871A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of electrode material technology, and specifically relates to a method for preparing a Mott-Schottky junction composite material rich in sulfur vacancies. Background Technology
[0002] Electrochemical water splitting for hydrogen production is a research hotspot for alleviating energy and environmental problems and achieving sustainable development. Noble metal materials such as IrO2 and Pt / C are excellent catalysts, but their high cost limits their widespread application. Therefore, finding inexpensive and readily available electrocatalysts to replace noble metal catalysts is imperative.
[0003] Transition metal sulfides possess abundant active sites and redox activity, making them promising candidates for applications in the energy sector. However, limited electrochemical kinetics and poor conductivity hinder their application. This invention constructs a Mott-Schottky heterostructure, which can accelerate charge transfer, modulate the adsorption energy of reaction intermediates, and provide additional active sites, considered an effective means to improve catalytic activity. Furthermore, introducing sulfur vacancies can enhance the conductivity of the electrode material and promote electron / ion transfer kinetics. Therefore, combining sulfur vacancies and the Mott-Schottky junction can synergistically regulate interfacial charge transfer and optimize electrocatalytic activity. Summary of the Invention
[0004] The purpose of this invention is to provide a method for preparing a sulfur-vacancy-rich Mott-Schottky junction composite material, which has the advantage of significantly improved electrochemical performance.
[0005] The technical solution of this invention is: a method for preparing a Mott-Schottky junction composite material rich in sulfur vacancies, characterized by comprising the following steps:
[0006] (1) Take a certain amount of cobalt chloride hexahydrate, nickel chloride hexahydrate and terephthalic acid and dissolve them in a mixed solvent containing 42 mL N,N-dimethylformamide, 3 mL anhydrous ethanol and 3 mL deionized water. After stirring for 30 minutes, transfer the mixed solution to a reaction vessel; add a piece of cleaned nickel foam, and carry out a solvothermal reaction at a certain temperature for a certain time. Then take it out, wash and dry it to obtain NiCo-MOF.
[0007] (2) Take a certain amount of sulfur source and dissolve it in anhydrous ethanol. After stirring for 30 minutes, transfer the solution to the reaction vessel. Put the NiCo-MOF obtained in step (1) into the reaction vessel and carry out the sulfidation reaction for a certain time at a certain temperature. Then take it out, wash and dry it to obtain NiCo-MOF / NiCoS.
[0008] (3) The NiCo-MOF / NiCoS obtained in step (2) is placed in a quartz boat and then placed in a tube furnace. It is heated to the target reduction temperature at a heating rate of 5℃ / min under a 5% H2 / Ar atmosphere, and then rapidly cooled to room temperature to obtain a sulfur-vacancy-rich Mott-Schottky junction composite material, abbreviated as NiCo@C / NiCoS. v .
[0009] In step (1), the preferred molar ratio of cobalt chloride hexahydrate, nickel chloride hexahydrate, and terephthalic acid is (0.5-2.5):1:(1-2).
[0010] In step (1), the solvothermal reaction is preferably carried out at a temperature of 100-155°C and for a time of 4-18 hours.
[0011] In step (2), the sulfur source includes, but is not limited to, sodium sulfide, thiourea, thioacetamide or one or more, preferably thioacetamide.
[0012] In step (2), the concentration of the sulfur source is preferably 0.2-1 mol / L.
[0013] In step (2), the vulcanization reaction is preferably carried out at a temperature of 60-110℃ and for a time of 2-12 hours.
[0014] In step (3), the target reduction temperature is preferably 250-400℃.
[0015] In summary, the sulfur-vacancy-rich Mott-Schottky junction composite material of the present invention has the following beneficial effects:
[0016] (1) NiCo@C / NiCoS v When composite materials are grown directly on a self-supporting carrier (nickel foam) for catalytic reactions, it is more conducive to gas production and degassing, and can effectively prevent the catalyst from falling off during the reaction.
[0017] (2) NiCo@C / NiCoS v Composite materials include NiCo alloys and semiconductor NiCoS. v The Schottky effect at the conductor-semiconductor interface can induce the formation of a built-in electric field, thereby significantly enhancing electron transport. The band gap, work function, and electrode potential of semiconductors are significantly lower than those of metallic conductors. Based on the difference in their work functions, electrons spontaneously transfer from the semiconductor to the metallic conductor, and electron-hole vacancies accumulate on the semiconductor side through the heterogeneous interface. Benefiting from the abundant heterogeneous interface and the built-in electric field, electrocatalytic activity can be enhanced by optimizing the adsorption energy of intermediates and triggering the redistribution of interfacial charges.
[0018] (3) Reduction treatment in a 5% H2 / Ar atmosphere increased the number of sulfur vacancies, increased active sites, generated more internal electron transport channels, and lowered the Gibbs free energy of the surface reaction, thereby reducing the energy barrier required for the redox reaction of the electrode material. NiCo@C / NiCoS v The composite material was tested in 1M KOH electrolyte solution at 10, 50, and 100 mA / cm². 2 At current densities of 10, 50, and 100 mA / cm², the overpotentials for the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) were as low as 117, 232, and 276 mV and 60, 128, and 195 mV, respectively. Furthermore, a full water splitting electrolyzer assembled using this catalyst as both cathode and anode achieved overpotentials of 117, 232, and 276 mV and 60, 128, and 195 mV, respectively. 2 The decomposition voltages at the time of decomposition were 1.44, 1.57, and 1.63 V, respectively.
[0019] (4) The preparation method of this invention is simple and efficient. Combining sulfur vacancies and Mott-Schottky junctions can regulate interfacial charge transfer and optimize electrocatalytic activity. This demonstrates the positive influence of vacancies and Mott-Schottky heterojunctions on the construction of metal sulfide electrode materials. Attached Figure Description
[0020] Figure 1 This is a scanning electron microscope image of the NiCo-MOF obtained in step (1) of Embodiment 1 of the present invention;
[0021] Figure 2 This is a scanning electron microscope image of NiCo-MOF / NiCoS obtained in step (2) of Example 1 of the present invention;
[0022] Figure 3 The NiCo@C / NiCoS obtained in step (3) of Embodiment 1 of this invention. v Scanning electron microscope image;
[0023] Figure 4 The NiCo@C / NiCoS obtained in step (3) of Embodiment 1 of this invention. v X-ray diffraction pattern;
[0024] Figure 5 The NiCo@C / NiCoS obtained in step (3) of Embodiment 1 of this invention. v OER polarization curve of the electrode material as an electrocatalytic electrode in 1M KOH electrolyte solution;
[0025] Figure 6 The NiCo@C / NiCoS obtained in step (3) of Embodiment 1 of this invention. v HER polarization curves of the electrode material as an electrocatalytic electrode in 1MKOH electrolyte solution;
[0026] Figure 7 The NiCo@C / NiCoS obtained in step (3) of Embodiment 1 of this invention. v Linear sweep voltammetry curves of an electrolytic cell assembled as positive and negative electrodes in 1M KOH electrolyte solution;
[0027] Figure 8 The NiCo@C / NiCoS obtained in step (3) of Embodiment 1 of this invention. v The electrolytic cell, assembled as the positive and negative electrodes, is in a 1M KOH electrolyte solution with a current of 100 mA / cm². 2 Timing potential curves at current density. Detailed Implementation
[0028] The preferred embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples.
[0029] Example 1:
[0030] (1) Dissolve 0.38g cobalt chloride hexahydrate, 0.19g nickel chloride hexahydrate and 0.20g terephthalic acid in a mixed solvent containing 42mL N,N-dimethylformamide, 3mL anhydrous ethanol and 3mL deionized water. After stirring for 30 minutes, transfer the mixed solution to a reaction vessel. Add a piece of cleaned nickel foam and carry out a solvothermal reaction at 125℃ for 12 hours. Then take it out, wash and dry it to obtain NiCo-MOF.
[0031] Scanning electron microscope image of the prepared NiCo-MOF is shown below. Figure 1 As shown, it presents a plate-like morphology;
[0032] (2) Dissolve 0.18g of thioacetamide in 60mL of anhydrous ethanol, stir for 30 minutes, and then transfer the solution to a reaction vessel; put the NiCo-MOF obtained in step (1) into the reaction vessel, carry out the sulfidation reaction at 90℃ for 6 hours, and then take it out for washing and drying to obtain NiCo-MOF / NiCoS;
[0033] Scanning electron microscope images of the prepared NiCo-MOF / NiCoS are shown below. Figure 2 As shown, the surface of the plate-shaped sample becomes rough;
[0034] (3) The NiCo-MOF / NiCoS obtained in step (2) is placed in a quartz boat and then placed in a tube furnace. It is heated to 350°C at a heating rate of 5°C / min under a 5% H2 / Ar atmosphere, and then rapidly cooled to room temperature to obtain a sulfur-vacancy-rich Mott-Schottky junction composite material, abbreviated as NiCo@C / NiCoS. v .
[0035] NiCo@C / NiCoS v Scanning electron microscope image as follows Figure 3 As shown, the sample exhibits a porous, plate-like nanosheet array structure.
[0036] The NiCo@C / NiCoS prepared according to the above steps v X-ray diffraction pattern, such as Figure 4 As shown, the phases of the sample are NiCo and (Co,Ni)3S4;
[0037] The NiCo@C / NiCoS prepared by the above steps v As an electrocatalytic electrode material, its catalytic performance was tested in 1 MkOH electrolyte solution, and the OER polarization curve is shown below. Figure 5 As shown; HER polarization curve, as Figure 6 As shown;
[0038] The NiCo@C / NiCoS prepared by the above steps v The electrolytic cell, used as both positive and negative electrodes, was tested for its total water splitting performance in a 1M KOH electrolyte solution. Figure 7 As shown, at 10, 50, and 100 mA / cm 2 At current densities of [value missing], the required cell voltages are only 1.48, 1.67, and 1.83 V, while the cell voltages for the commercial catalyst RuO2||Pt / C are 1.64, 1.85, and 2 V, respectively; at 100 mA / cm [value missing], the required cell voltages are only 1.48, 1.67, and 1.83 V, respectively; 2 Chronopotential measurements were performed under constant current density, such as... Figure 8 As shown, its catalytic performance did not decline significantly during the 100-hour continuous testing period, maintaining 98.9% of its original performance, indicating that it has good overall water splitting activity and stability.
[0039] Example 2:
[0040] (1) Dissolve 0.38g of cobalt chloride hexahydrate, 0.38g of nickel chloride hexahydrate and 0.27g of terephthalic acid in a mixed solvent containing 42mL of N,N-dimethylformamide, 3mL of anhydrous ethanol and 3mL of deionized water. After stirring for 30 minutes, transfer the mixed solution to a reaction vessel. Add a piece of cleaned nickel foam and carry out a solvothermal reaction at 125℃ for 12 hours. Then take it out, wash and dry it to obtain NiCo-MOF.
[0041] (2) Dissolve 0.18g of thioacetamide in 60mL of anhydrous ethanol, stir for 30 minutes, and then transfer the solution to a reaction vessel; put the NiCo-MOF obtained in step (1) into the reaction vessel, carry out the sulfidation reaction at 90℃ for 6 hours, and then take it out for washing and drying to obtain NiCo-MOF / NiCoS;
[0042] (3) The NiCo-MOF / NiCoS obtained in step (2) is placed in a quartz boat and then placed in a tube furnace. It is heated to 350°C at a heating rate of 5°C / min under a 5% H2 / Ar atmosphere, and then rapidly cooled to room temperature to obtain a sulfur-vacancy-rich Mott-Schottky junction composite material, abbreviated as NiCo@C / NiCoS. v .
[0043] The NiCo@C / NiCoS prepared by the above steps v The electrolyzer, used as the positive and negative electrodes, was tested for its total water splitting performance in a 1M KOH electrolyte solution at 10, 50, and 100 mA / cm². 2 At current densities of 1.52, 1.71, and 1.90 V, the required tank voltages are only 1.52, 1.71, and 1.90 V.
[0044] Example 3:
[0045] (1) Dissolve 0.38g cobalt chloride hexahydrate, 0.19g nickel chloride hexahydrate and 0.20g terephthalic acid in a mixed solvent containing 42mL N,N-dimethylformamide, 3mL anhydrous ethanol and 3mL deionized water. After stirring for 30 minutes, transfer the mixed solution to a reaction vessel. Add a piece of cleaned nickel foam and carry out a solvothermal reaction at 125℃ for 12 hours. Then take it out, wash and dry it to obtain NiCo-MOF.
[0046] (2) Dissolve 0.22g of thioacetamide in 60mL of anhydrous ethanol, stir for 30 minutes, and then transfer the solution to a reaction vessel; put the NiCo-MOF obtained in step (1) into the reaction vessel, carry out the sulfidation reaction at 100℃ for 4 hours, and then take it out for washing and drying to obtain NiCo-MOF / NiCoS.
[0047] (3) The NiCo-MOF / NiCoS obtained in step (2) is placed in a quartz boat and then placed in a tube furnace. It is heated to 350°C at a heating rate of 5°C / min under a 5% H2 / Ar atmosphere, and then rapidly cooled to room temperature to obtain a sulfur-vacancy-rich Mott-Schottky junction composite material, abbreviated as NiCo@C / NiCoS. v .
[0048] The NiCo@C / NiCoS prepared by the above steps v The electrolyzer, used as the positive and negative electrodes, was tested for its total water splitting performance in a 1M KOH electrolyte solution at 10, 50, and 100 mA / cm². 2 At the given current densities, the required tank voltages are 1.54, 1.76, and 1.93 V.
[0049] Example 4:
[0050] (1) Dissolve 0.38g of cobalt chloride hexahydrate, 0.38g of nickel chloride hexahydrate and 0.27g of terephthalic acid in a mixed solvent containing 42mL of N,N-dimethylformamide, 3mL of anhydrous ethanol and 3mL of deionized water. After stirring for 30 minutes, transfer the mixed solution to a reaction vessel. Add a piece of cleaned nickel foam and carry out a solvothermal reaction at 125℃ for 12 hours. Then take it out, wash and dry it to obtain NiCo-MOF.
[0051] (2) Dissolve 0.18g of thioacetamide in 60mL of anhydrous ethanol, stir for 30 minutes, and then transfer the solution to a reaction vessel; put the NiCo-MOF obtained in step (1) into the reaction vessel, carry out the sulfidation reaction at 90℃ for 6 hours, and then take it out for washing and drying to obtain NiCo-MOF / NiCoS;
[0052] (3) The NiCo-MOF / NiCoS obtained in step (2) is placed in a quartz boat and then placed in a tube furnace. It is heated to 300°C at a heating rate of 5°C / min under a 5% H2 / Ar atmosphere, and then rapidly cooled to room temperature to obtain a sulfur-vacancy-rich Mott-Schottky junction composite material, abbreviated as NiCo@C / NiCoS. v .
[0053] The NiCo@C / NiCoS prepared by the above steps v The electrolyzer, used as the positive and negative electrodes, was tested for its total water splitting performance in a 1M KOH electrolyte solution at 10, 50, and 100 mA / cm². 2 At the given current densities, the required tank voltages are 1.51, 1.72, and 1.91 V.
[0054] Example 5:
[0055] (1) Dissolve 0.38g of cobalt chloride hexahydrate, 0.38g of nickel chloride hexahydrate and 0.27g of terephthalic acid in a mixed solvent containing 42mL of N,N-dimethylformamide, 3mL of anhydrous ethanol and 3mL of deionized water. After stirring for 30 minutes, transfer the mixed solution to a reaction vessel. Add a piece of cleaned nickel foam and carry out a solvothermal reaction at 125℃ for 12 hours. Then take it out, wash and dry it to obtain NiCo-MOF.
[0056] (2) Dissolve 0.18g of thioacetamide in 60mL of anhydrous ethanol, stir for 30 minutes, and then transfer the solution to a reaction vessel; put the NiCo-MOF obtained in step (1) into the reaction vessel, carry out the sulfidation reaction at 90℃ for 12 hours, and then take it out for washing and drying to obtain NiCo-MOF / NiCoS.
[0057] (3) The NiCo-MOF / NiCoS obtained in step (2) is placed in a quartz boat and then placed in a tube furnace. It is heated to 400°C at a heating rate of 5°C / min under a 5% H2 / Ar atmosphere, and then rapidly cooled to room temperature to obtain a sulfur-vacancy-rich Mott-Schottky junction composite material, abbreviated as NiCo@C / NiCoS. v .
[0058] The NiCo@C / NiCoS prepared by the above steps v The electrolyzer, used as the positive and negative electrodes, was tested for its total water splitting performance in a 1M KOH electrolyte solution at 10, 50, and 100 mA / cm². 2 At the given current densities, the required tank voltages are 1.59, 1.79, and 1.98 V.
[0059] The embodiments described above are detailed descriptions of the technical solutions of the present invention and should be understood as specific implementation measures of the present invention. They are not intended to summarize the present invention. Any modifications, additions, or similar substitutions made within the scope of the principles of the present invention shall fall within the scope of protection that the present invention should enjoy.
Claims
1. A method for preparing a sulfur-vacancy-rich Mott-Schottky junction composite material, characterized by comprising the following steps: (1) Dissolve 0.38g cobalt chloride hexahydrate, 0.19g nickel chloride hexahydrate and 0.20g terephthalic acid in a mixed solvent containing 42mL N,N-dimethylformamide, 3mL anhydrous ethanol and 3mL deionized water. After stirring for 30 minutes, transfer the mixed solution to a reaction vessel. Add a piece of cleaned nickel foam and carry out a solvothermal reaction at 125℃ for 12 hours. Then take it out, wash and dry it to obtain NiCo-MOF. (2) Dissolve 0.18g of thioacetamide in 60mL of anhydrous ethanol, stir for 30 minutes, and then transfer the solution to a reaction vessel; put the NiCo-MOF obtained in step (1) into the reaction vessel, carry out the sulfidation reaction at 90℃ for 6 hours, and then take it out for washing and drying to obtain NiCo-MOF / NiCoS; (3) The NiCo-MOF / NiCoS obtained in step (2) is placed in a quartz boat and then placed in a tube furnace. It is heated to 350°C at a heating rate of 5°C / min under a 5% H2 / Ar atmosphere and then rapidly cooled to room temperature to obtain a sulfur-vacancy-rich Mott-Schottky junction composite material.
2. The use of the sulfur-vacancy-rich Mott-Schottky junction obtained by the preparation method according to claim 1 as a catalyst material for water electrolysis.