A ZnIn2S4 / NiWO4 / NiS2 heterogeneous photocatalyst and its preparation method
By constructing a ZnIn2S4/NiWO4/NiS2 heterostructure, NiS2 hollow microspheres were synthesized using a hydrothermal method, and ZnIn2S4 nanosheets were grown to form NiWO4 nanoparticle bridges. This solved the problems of low light absorption capacity and fast recombination of photogenerated carriers in the ZnIn2S4 photocatalyst, achieving efficient photocatalytic hydrogen production and improved stability.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- HUBEI UNIV
- Filing Date
- 2022-10-28
- Publication Date
- 2026-07-03
AI Technical Summary
Existing ZnIn2S4 photocatalysts have low light absorption capacity and fast recombination of photogenerated carriers, resulting in insufficient photocatalytic efficiency and stability. It is necessary to improve their photocatalytic activity and interfacial hydrogen desorption process.
By constructing a hierarchical heterostructure of ZnIn2S4/NiWO4/NiS2, NiS2 hollow microspheres were synthesized by hydrothermal method, and ZnIn2S4 nanosheets were grown in situ on them to form NiWO4 nanoparticles as electron bridges, which promoted charge transfer and interfacial hydrogen desorption.
It significantly improves the efficiency of photocatalytic hydrogen production, with a photocatalytic hydrogen evolution performance of 11.919 mmol/g·h, and maintains good stability after multiple cycles, making it suitable for large-scale industrial production.
Smart Images
Figure CN118002156B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a photocatalytic material, specifically to a method for preparing a ZnIn2S4 / NiWO4 / NiS2 heterogeneous photocatalyst, belonging to the field of materials synthesis technology. Background Technology
[0002] With rapid social and economic development, a series of problems related to fossil fuels, such as overuse, limited reserves, and negative environmental impacts, have become increasingly prominent. Therefore, seeking sustainable and clean energy is of great significance to addressing the growing energy demands and accompanying environmental issues in modern society. Hydrogen can be produced from water without generating any pollutants during its use. In the context of carbon neutrality, hydrogen is considered the ultimate form of energy for the future. In recent years, my country has explicitly stated its support for the development of the hydrogen energy industry in several industrial policies. At the same time, the issue of large-scale, high-purity hydrogen supply at low cost urgently needs in-depth research to ensure the rapid development of the hydrogen energy industry. The U.S. Department of Energy has predicted that, compared to fossil fuels, the production cost of hydrogen as fuel must be below $4 per kg to be competitive. Photocatalysts can utilize solar energy to decompose water and produce hydrogen, offering advantages such as low cost, environmental friendliness, and sustainable development. This can serve as a new method for low-cost production of high-purity hydrogen. Photocatalytic water splitting technology utilizes water and solar energy, two of the most abundant, clean, and renewable natural energy sources. By converting low-density solar energy into high-density hydrogen energy, its potential economic and environmental benefits can meet and solve today's increasingly prominent energy and environmental problems.
[0003] The ternary sulfide ZnIn2S4, as the only AB2X4 group semiconductor with a layered structure, is highly attractive for photocatalytic hydrogen production due to its high activity, good chemical stability, and suitable bandgap structure that allows it to generate photocatalytic activity upon absorbing visible light. However, the photocatalytic efficiency of pure ZnIn2S4 remains unsatisfactory due to its low light absorption and rapid recombination of photogenerated carriers. Both photocatalytic efficiency and long-term stability need improvement. Therefore, a series of strategies have been employed to enhance its photocatalytic activity, such as constructing advanced photocatalytic structures, doping, and modifying heterojunctions with co-catalysts. Co-catalysts can enhance light capture, reduce the overpotential of photocatalytic surface reactions, promote interfacial charge transfer, and provide additional active sites, thereby promoting photocatalytic reactions. Therefore, modification with co-catalysts is an effective method to improve photocatalytic reaction activity. NiS2, as a nickel-based material, is well-suited as a low-cost alternative to Pt as a hydrogen evolution co-catalyst due to its cost-effectiveness and platinum-like co-catalytic behavior. However, according to relevant research reports, the hydrogen production efficiency of NiS cocatalysts is limited by the insufficient number of exposed active sulfur sites and the strong bond (S-H1) between the sites and the absorbed hydrogen atoms. Therefore, strategies such as constructing low-dimensional structures, controlling nanostructures, and building S-rich surfaces have been proposed to effectively expose the edge active S sites on NiS cocatalysts. However, the interfacial hydrogen desorption process is still limited by the strength of the exposed active S sites and the strong bond between the adsorbed hydrogen atoms. Therefore, achieving a balance between hydrogen adsorption and desorption on the cocatalyst surface is the key and challenge for obtaining high hydrogen production performance.
[0004] NiWO4 nanoparticles are widely used in photocatalysis and photoelectrocatalysis due to their excellent photoadsorption properties in the ultraviolet and visible light regions and their superior conductivity in their amorphous state. Using amorphous NiWO4 nanoparticles to modify NiS2 cocatalysts allows for strong electronic interactions that induce charge redistribution, forming electron-rich active Ni and S sites. This effectively promotes water adsorption and weakens the SH bonds at the S sites, optimizing the free energy of interfacial hydrogen desorption. Simultaneously, the highly conductive amorphous NiWO4 nanoparticles act as an electron bridge between the NiS2 cocatalyst and the host photocatalyst ZnIn2S4, accelerating carrier transfer and significantly improving photocatalytic hydrogen production efficiency.
[0005] To date, there have been no reports on ZnIn2S4 / NiWO4 / NiS2 composite photocatalysts. Summary of the Invention
[0006] To address the technical problems of poor stability and low efficiency of composite photocatalysts for visible light water splitting to produce hydrogen, the following preparation method for composite photocatalysts is provided.
[0007] This invention employs a hydrothermal method to synthesize NiS2 hollow microspheres, followed by chemical co-precipitation to anchor amorphous NiWO4 nanoparticles onto NiS2. Finally, ZnIn2S4 nanosheets are grown in situ on the surface of the NiS2 / NiWO4 cocatalyst using an oil bath method to obtain a ZnIn2S4 / NiWO4 / NiS2 layered heterostructure photocatalyst. The prepared ZnIn2S4 / NiWO4 / NiS2 photocatalyst exhibits a photocatalytic hydrogen evolution performance as high as 11.919 mmol / g at AM1.5. -1 h -1 .
[0008] This invention provides a method for preparing a ZnIn2S4 / NiWO4 / NiS2 composite photocatalyst, the method comprising the following steps:
[0009] (1) Preparation of NiS2 hollow microspheres: Nickel source and urea were dissolved in deionized water to form a homogeneous solution. The solution formed by dissolving sulfur source in deionized water was then mixed with the above solution and subjected to ultrasonic treatment. The final solution was transferred to a stainless steel high-pressure reactor lined with polytetrafluoroethylene and then sealed in a hydrothermal box for a certain period of time for hydrothermal reaction. The synthesized sample was washed three times with deionized water and anhydrous ethanol, dried in a vacuum drying oven for 12 hours, and then ground to obtain NiS2 hollow microspheres;
[0010] (2) Preparation of NiS2 / NiWO4: NiS2 hollow microspheres were ultrasonically dispersed in deionized water, and nickel source and sodium tungstate with a molar ratio of 1:1 were added under strong stirring. The mixture was stirred for a certain period of time to obtain NiS2 / NiWO4 cocatalyst and then dried.
[0011] (3) Preparation of ZnIn2S4 / NiWO4 / NiS2: NiS2 / NiWO4 was ultrasonically dispersed in hydrochloric acid buffer solution, an appropriate amount of glycerol was added, and after stirring thoroughly, zinc source, indium source and sulfur source with a molar ratio of 1:2:4 were added in sequence. After stirring, a uniformly dispersed suspension was obtained. The solution was placed in a round-bottom flask and subjected to an oil bath for a certain period of time to obtain ZnIn2S4 / NiWO4 / NiS2 composite photocatalyst and dried.
[0012] In the above preparation method, in step (1), the nickel source can be selected from nickel nitrate, nickel chloride, nickel sulfate, nickel bromide or nickel hydroxyl.
[0013] In the above preparation method, in step (1), the sulfur source can be selected from thioacetamide, thiourea, or L-cysteine.
[0014] In the above preparation method, in step (1), the molar ratio of nickel source and sulfur source is 1:1-1:2.
[0015] In the above preparation method, in step (1), the concentration of urea is 0.05-0.1 mmol / L.
[0016] In the above preparation method, in step (1), the ultrasonic time is 0.5-2h.
[0017] In the above preparation method, in step (1), the hydrothermal reaction temperature is 80-180 °C.
[0018] In the above preparation method, the hydrothermal reaction time in step (1) is 12-24 h.
[0019] In the above preparation method, in step (2), the nickel source can be selected as nickel nitrate, nickel chloride, nickel sulfate, nickel bromide or nickel hydroxyl.
[0020] In the above preparation method, in step (2), the molar ratio of NiS2, the newly added nickel source and the tungsten source is 10:1:1-15:1:1.
[0021] In the above preparation method, the stirring time in step (2) is 1-4 hours.
[0022] In the above preparation method, in step (3), the zinc source is zinc nitrate, zinc chloride, zinc sulfate, etc.
[0023] In the above preparation method, in step (3), the indium source is indium nitrate, indium chloride, indium sulfate, etc.
[0024] In the above preparation method, in step (3), the sulfur source is thioacetamide, thiourea, L-cysteine, etc.
[0025] In the above preparation method, in step (3), the volume fraction of glycerol is 10%-30%.
[0026] In the above preparation method, in step (3), the oil bath temperature is 60-100 °C.
[0027] In the above preparation method, in step (3), the oil bath time is 1-4 hours.
[0028] The ZnIn2S4 / NiWO4 / NiS2 composite photocatalyst prepared using this technology has a simple preparation process, low cost, and is conducive to large-scale industrial production. It also has high photocatalytic activity, with a photocatalytic hydrogen evolution performance of up to 11.919 mmol / gh under AM1.5. Moreover, it can maintain good stability after multiple cycles, which has high practical value and application prospects. Attached Figure Description
[0029] Figure 1The XRD pattern is shown in Example 1 of this invention for the ZnIn2S4 / NiWO4 / NiS2 composite photocatalyst.
[0030] Figure 2 This is a graph showing the photocatalytic hydrogen evolution performance of the ZnIn2S4 / NiWO4 / NiS2 composite photocatalyst prepared in Example 1 of this invention. Detailed Implementation
[0031] The technical solution of the present invention will be further described below with reference to the embodiments.
[0032] This invention proposes a method for preparing a high-performance ZnIn2S4 / NiWO4 / NiS2 composite photocatalyst. The method involves synthesizing NiS2 hollow microspheres via a hydrothermal method, then loading amorphous NiWO4 nanoparticles onto the NiS2 hollow microspheres using an ion precipitation method to obtain NiS2 / NiWO4. Finally, ZnIn2S4 nanosheets are grown in situ on NiS2 / NiWO4 using an oil bath method to prepare the ZnIn2S4 / NiWO4 / NiS2 composite photocatalyst. The method includes the following steps and contents:
[0033] (1) Dissolve the nickel source and urea in deionized water, then dissolve the sulfur source in deionized water and mix with the above solution. Sonicate the mixture to obtain a uniformly dispersed suspension. Transfer the mixture to a stainless steel high-pressure reactor lined with polytetrafluoroethylene for hydrothermal reaction to obtain NiS2 hollow microspheres. The nickel source can be selected from nickel nitrate, nickel chloride, nickel sulfate, nickel bromide or nickel hydroxyl, and the sulfur source can be selected from thioacetamide, thiourea, L-cysteine.
[0034] (2) Disperse NiS2 hollow microspheres in deionized water by ultrasonication, add an appropriate amount of nickel source and sodium tungstate under strong stirring, and stir for a certain time to obtain NiS2 / NiWO4 cocatalyst. The nickel source can be nickel nitrate, nickel chloride, nickel sulfate, nickel bromide or nickel hydroxyl, etc.
[0035] (3) NiS2 / NiWO4 was ultrasonically dispersed in hydrochloric acid buffer solution, an appropriate amount of glycerol was added, and after thorough stirring, zinc source, indium source and sulfur source were added in sequence. After stirring, a uniformly dispersed suspension was obtained. The solution was placed in a round-bottom flask and subjected to an oil bath for a fixed time. The solution was collected and dried at 80 °C to obtain ZnIn2S4 / NiWO4 / NiS2 composite photocatalyst, wherein the zinc source is one of zinc nitrate, zinc chloride and zinc sulfate, and the indium source is one of indium nitrate, indium chloride and indium sulfate.
[0036] In summary, this technology can be used to obtain high-performance ZnIn2S4 / NiWO4 / NiS2 composite photocatalysts.
[0037] Example 1: Step 1: Dissolve 1 mmol of Ni(NO3)2·6H2O and 1 mmol of urea in 20 mL of deionized water, stir magnetically for 5 min, then add 4 mmol of L-cysteine and 50 mL of deionized water, sonicate for 1 h, stir for 10 min until a uniformly dispersed solution is formed. Transfer the final solution to a 100 mL PTFE-lined stainless steel autoclave, seal it, and heat in an oven at 120 °C for 24 h. At the end of the reaction, cool the autoclave to room temperature. Then, centrifuge the black precipitate and wash it three times with deionized water and ethanol, respectively. Finally, dry it in a vacuum oven at 60 °C for 12 h to obtain the product NiS2. Step 2: Add 200 mg of NiS2 to 50 mL of deionized water, stir magnetically for 10 min to obtain a uniformly dispersed solution, then add 38 mg of Ni(NO3)2·6H2O and 43 mg of Na2WO4·2H2O to the above solution under strong stirring. Finally, the black precipitate was separated by centrifugation, washed three times with deionized water and ethanol, and dried at 60°C for 12 h to obtain NiS2 / NiWO4. Step 3: 10 mg of the prepared NiS2 / NiWO4 sample was dissolved in 8 mL of water (pH=2.5) and 2 mL of glycerol. After sonication for 30 min, 27.2 mg ZnCl2, 58.6 mg InCl3·4H2O, and 30 mg TAA were added to the solution. The resulting mixture was then stirred for 10 min and continuously heated in an oil bath at 80°C for 2 h. The product after the oil bath was collected, washed with ethanol, and dried overnight at 60°C to obtain the final product ZnIn2S4 / NiWO4 / NiS2.
[0038] The synthesized ZnIn2S4 / NiWO4 / NiS2 composite photocatalyst has a simple preparation process and exhibits good photocatalytic activity.
[0039] Example 2: Step 1: Dissolve 1 mmol of Ni(NO3)2·6H2O and 1 mmol of urea in 20 mL of deionized water, stir magnetically for 5 min, then add 4 mmol of L-cysteine and 50 mL of deionized water, sonicate for 1 h, stir for 10 min until a uniformly dispersed solution is formed. Transfer the final solution to a 100 mL PTFE-lined stainless steel autoclave, seal it, and heat in an oven at 120 °C for 24 h. At the end of the reaction, cool the autoclave to room temperature. Then, centrifuge the black precipitate and wash it three times with deionized water and ethanol, respectively. Finally, dry it in a vacuum oven at 60 °C for 12 h to obtain the product NiS2. Step 2: Dissolve 10 mg of the prepared NiS2 sample in 8 mL of water (pH = 2.5) and 2 mL of glycerol. After sonication for 30 min, add 27.2 mg of ZnCl2, 58.6 mg of InCl3·4H2O, and 30 mg of TAA to the solution. The resulting mixture was then stirred for 10 minutes and then heated continuously in an oil bath at 80°C for 2 hours. The product after the oil bath was collected, washed with ethanol, and dried overnight at 60°C to obtain the final product ZnIn2S4 / NiS2.
[0040] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made within the scope of the patent application of the present invention are within the scope of the present invention.
Claims
1. A method for preparing a ZnIn2S4 / NiWO4 / NiS2 heterogeneous photocatalyst, characterized in that, The method includes the following steps: (1) Preparation of NiS2 hollow microspheres: Nickel source and urea were dissolved in deionized water to form a homogeneous solution. The solution formed by dissolving sulfur source in deionized water was then mixed with the above solution and subjected to ultrasonic treatment. The final solution was transferred to a stainless steel high-pressure reactor lined with polytetrafluoroethylene and then sealed in a hydrothermal box for a certain period of time for hydrothermal reaction. The synthesized sample was washed three times with deionized water and anhydrous ethanol, dried overnight in a vacuum drying oven, and then ground to obtain NiS2 hollow microspheres. (2) Preparation of NiS2 / NiWO4: NiS2 hollow microspheres were ultrasonically dispersed in deionized water, and an appropriate amount of nickel source and sodium tungstate were added under strong stirring. The mixture was stirred for a certain period of time to obtain NiS2 / NiWO4 cocatalyst and then dried. (3) Preparation of Znln2S4 / NiWO4 / NiS2: NiS2 / NiWO4 was ultrasonically dispersed in hydrochloric acid buffer solution, an appropriate amount of glycerol was added, and after stirring thoroughly, zinc source, indium source and sulfur source were added in sequence. After stirring, a uniformly dispersed suspension was obtained. The solution was placed in a round-bottom flask and subjected to an oil bath for a certain period of time to obtain Znln2S4 / NiWO4 / NiS2 composite photocatalyst and dried.
2. The preparation method according to claim 1, characterized in that, In step (1), the nickel source is one of nickel nitrate, nickel chloride, nickel sulfate, nickel bromide, or nickel hydroxyl; in step (1), the sulfur source is one of thioacetamide, thiourea, or L-cysteine; in step (1), the molar ratio of nickel source to sulfur source is 1:1-1:2; in step (1), the concentration of urea is 0.05-0.1 mmol / L; in step (1), the hydrothermal reaction temperature is 80-180 °C; in step (1), the hydrothermal reaction time is 12-24 h; in step (2), the nickel source is one of nickel nitrate, nickel chloride, nickel sulfate, nickel bromide, or nickel hydroxyl; in step (2), the molar ratio of NiS2, the newly added nickel source, and the tungsten source is 10:1:1-15:1:1; in step (2), the stirring time is 1-4 h. h; In step (3), the zinc source is one of zinc nitrate, zinc chloride, or zinc sulfate; In step (3), the indium source is one of indium nitrate, indium chloride, or indium sulfate; In step (3), the sulfur source is one of thioacetamide, thiourea, or L-cysteine; In step (3), the volume fraction of glycerol is 10%-30%; In step (3), the oil bath temperature is 60-100 °C; In step (3), the oil bath time is 1-4 h.