A single-atom composite Cu of metallic Cu + Preparation method of ZnIn2S4 doped photocatalyst

Abstract

The application discloses a kind of metal Cu single atom composite Cu + The application discloses a preparation method of a doped ZnIn2S4 photocatalyst, and belongs to the technical field of photocatalysis. First, a solvent-thermal method is used to dope Cu + Into ZnIn2S4, and then the Cu + Doped on the surface of ZnIn2S4 is reduced and leached out by NaBH4 immersion to form metal Cu single atoms and Cu / In / S vacancy clusters. The Cu + Doped ions and Cu / In / S vacancy clusters induce the formation of electron-poor regions in ZnIn2S4, while S vacancies and metal Cu single atoms induce the formation of electron-rich regions in ZnIn2S4, thereby generating a large number of local electric fields with different charge states in ZnIn2S4, accelerating the transfer and separation of photo-generated carriers, and significantly improving the photocatalytic performance of ZnIn2S4. The prepared metal Cu single atom composite Cu + The visible light water splitting hydrogen production rate of the doped ZnIn2S4 photocatalyst can reach 62.54-70.58 mmol·g −1 ·h −1 ·h −1 .

Description

Technical Field

[0001] This invention belongs to the field of photocatalysis technology, specifically relating to a single-atom Cu composite material. + Preparation method of ZnIn2S4 doped photocatalyst. Background Technology

[0002] Photocatalytic water splitting for hydrogen production offers a promising pathway to achieving peak carbon emissions and carbon neutrality. However, the scarcity of efficient photocatalysts has kept this technology largely confined to the laboratory research stage. Exploring novel and effective modification methods to improve the efficiency of existing photocatalysts in water splitting for hydrogen production is a crucial way to overcome the bottlenecks hindering the industrial application of photocatalytic water splitting for hydrogen production.

[0003] The ternary metal chalcogenide semiconductor ZnIn2S4 possesses advantages such as good visible light absorption, high photophysical and chemical stability, and simple preparation methods, making it a promising photocatalytic material. However, due to inefficient photogenerated carrier migration and separation efficiencies and slow surface reaction kinetics, the photocatalytic hydrogen production efficiency of intrinsic ZnIn2S4 is not high. Therefore, a series of modification methods have been used to overcome the inherent defects of ZnIn2S4 to improve its photocatalytic hydrogen production performance, which is currently one of the research hotspots in the field of photocatalysis. Shi et al. modified the surface of ZnIn2S4 with single-atom Pt, increasing the photocatalytic hydrogen production rate of ZnIn2S4 from 0.98 mmol·g⁻¹. −1 ·h −1 Increased to 17.5 mmol·g −1 ·h −1 Mechanistic studies show that the growth of single-atom Pt on the ZnIn2S4 surface opens up new channels for the transfer of photogenerated carriers, greatly improving the migration and separation efficiency of photogenerated carriers, and ultimately enhancing the performance of photocatalytic water splitting for hydrogen production (Shi, XW; Dai, C.; Wang, X.; Hu, JY; Zhang, JY; Zheng, LX; Mao, L.; Zheng, HJ; Zhu, MS Nat. Commun. 2022, 1287). Zhang et al. used Cu... 2+ Incorporating ZnIn2S4 improves its photocatalytic water splitting hydrogen production performance by 14.8 times. Research results indicate that Cu... 2+ By replacing part of Zn 2+ Entering ZnIn2S4, and Cu 2+ Doping induced the formation of adaptive S vacancies in Cu. 2+S-vacancy sites, acting as trapping centers for photogenerated holes and electrons respectively, significantly improve the separation efficiency of photogenerated carriers (Zhang, SQ; Zhang, ZF; Si, YM; Li, B.; Deng, F.; Yang, LX; Liu, X.; Dai, WL; Luo, SL ACS Nano 2021, 15, 9, 15238–15248). Wang et al. created a large number of S-vacancy defects in ZnIn2S4 by pressurized hydrogenation. The results showed that S-vacancy sites, as trapping centers for photogenerated electrons, suppressed the recombination of photogenerated carriers and promoted the migration and separation of photogenerated carriers, ultimately improving the photocatalytic water splitting hydrogen production performance of ZnIn2S4 by 8.6 times (Wang, YZ; Chen, D.; Qin, LS; Liang, JH; Huang, YX Phys. Chem. Chem. Phys., 2019, 21, 25484-25494). The above studies show that single-atom modification, metal ion doping, or vacancy introduction can all promote the migration and separation of photogenerated charge carriers, thereby improving the photocatalytic hydrogen production performance of ZnIn2S4. However, it is worth noting that the improvement effect of a single modification strategy on the photocatalytic hydrogen production performance of ZnIn2S4 is very limited. Therefore, exploring the combination of several modification methods to simultaneously collect the promoting effects of single-atom modification, metal ion doping, and vacancy defect introduction on the photocatalytic hydrogen production process is expected to further improve the photocatalytic hydrogen production performance of ZnIn2S4. However, related research is still very rare.

[0004] Based on the above analysis, this invention designs a Cu method that is simple to operate and highly controllable. + Doping and leaching strategy: Using this strategy, atoms containing both metallic Cu single atoms and Cu... + ZnIn2S4 photocatalysts with S vacancies and Cu / In / S vacancies can efficiently perform photocatalytic water splitting to produce hydrogen, showing great promise for practical applications. Summary of the Invention

[0005] The purpose of this invention is to provide a single-atom Cu composite of metallic Cu. + Preparation method of ZnIn2S4 doped photocatalyst.

[0006] The objective of this invention is achieved through the following technical solution: (1) Dissolve CuCl, Zn(CH3COO)2·2H2O and InCl3 in a mixture of N,N-dimethylformamide and ethylene glycol, and then add thioacetamide to the above solution and stir until dissolved. The volume ratio of N,N-dimethylformamide and ethylene glycol is 1:1, and the molar ratio of Cu, Zn, In and S is 0.08~0.10:1:2:8. (2) Transfer the solution obtained in step (1) to the reaction vessel, heat it to 180°C and keep it at that temperature for 10 hours. After cooling, centrifuge, wash and dry the product. (3) Add the product obtained in step (2) to a NaBH4 concentration of 5~20 mmol·L −1 The concentration of NaOH is 0.2 mol·L⁻¹ –1 The product was ultrasonicated for 1 h and stirred for 6 h in an alkaline NaBH4 solution, followed by centrifugation, washing, and drying to obtain a single-atom Cu composite of metallic Cu. + ZnIn2S4 doped photocatalyst. Attached Figure Description

[0007] Figure 1 The single-atom Cu composite metal prepared in Example 1 + Scanning electron microscope (SEM) image of a ZnIn2S4 photocatalyst; Figure 2 The single-atom Cu composite metal prepared in Example 1 + Energy-dispersive X-ray (EDX) spectrum of ZnIn2S4 photocatalyst; Figure 3 The single-atom Cu composite metal prepared in Example 1 + Aberration-corrected electron microscopy (AC-TEM) image of a ZnIn2S4 photocatalyst; Figure 4 The single-atom Cu composite metal prepared in Example 1 + Photocatalytic water splitting rate for hydrogen production using a ZnIn2S4 doped photocatalyst; Figure 5 The single-atom Cu composite metal prepared in Example 2 + The rate of hydrogen production from water splitting using a ZnIn2S4 photocatalyst. Figure 6 The single-atom Cu composite metal prepared in Example 3 + The rate of hydrogen production from water splitting using a ZnIn2S4 photocatalyst. Detailed Implementation

[0008] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. However, the accompanying drawings and specific embodiments are merely examples and do not limit the scope of the present invention in any way.

[0009] Example 1 (1) Dissolve 0.04 mmol CuCl, 0.5 mmol Zn(CH3COO)2·2H2O, and 1 mmol InCl3 in a mixture of 15 mL N,N-dimethylformamide and 15 mL ethylene glycol. Then add 4 mmol thioacetamide and stir until dissolved. Transfer the solution to a reaction vessel and place the vessel in an oven. Set the temperature program to 180℃ and the holding time to 10 h for the reaction. After the reaction is complete and cooled to room temperature, centrifuge to separate the precipitate. Wash the precipitate with deionized water and ethanol. Finally, dry the precipitate in a 60℃ drying oven to obtain metallic Cu single-atom composite Cu. + ZnIn2S4 doped photocatalyst.

[0010] (2) Weigh 0.1 g of the precipitate obtained in step (1) and add it to 20 mL of NaBH4 with a concentration of 5 mmol·L⁻¹. −1 The NaOH concentration is 0.2 mol·L⁻¹ –1 The precipitate was ultrasonicated for 1 hour and then magnetically stirred for 6 hours in an alkaline solution. Afterwards, it was centrifuged, and the precipitate was washed several times with deionized water until the supernatant became neutral. Finally, the precipitate was dried in a 60℃ drying oven to obtain metallic Cu single-atom composite Cu. + ZnIn2S4 doped photocatalyst. Its SEM image is shown in the attached diagram in the instruction manual. Figure 1 As can be seen, the photocatalyst exhibits a flower-like microstructure assembled from nanosheets. Its EDX spectrum is shown in the attached figure in the specification. Figure 2 As can be observed from the figure, in addition to Zn, In, and S, characteristic peaks of Cu are also observed. The AC-TEM image is shown in the attached figure in the instruction manual. Figure 3 The figure shows the simultaneous presence of single Cu atoms, Cu-doped atoms, S vacancies, and vacancy clusters. These characterization results demonstrate that single Cu atoms are composites with Cu... + A ZnIn2S4 doped photocatalyst was successfully prepared.

[0011] (3) Weigh 10 mg of metallic Cu single-atom complex Cu + The ZnIn2S4 photocatalyst was ultrasonically dispersed in 100 mL of ascorbic acid to a concentration of 0.1 mol·L⁻¹. −1The reaction solution was prepared by dissolving the sample in an aqueous solution. The reaction solution was then poured into a 250 mL photocatalytic reactor. The reactor was evacuated and circulating cooling water was introduced to maintain the temperature of the reaction solution at 5°C. A 300 W Xe lamp equipped with a 420 nm cutoff filter was then used as the light source to irradiate the reaction solution from the top of the reactor, initiating the photocatalytic water splitting to hydrogen production reaction. Samples were taken from the system every 30 minutes and injected into a gas chromatograph for analysis. Based on the peak area and standard curve of the chromatogram, the water splitting to hydrogen production rate of this photocatalyst can be calculated (see the attached instruction manual). Figure 4 It can be seen that as the illumination time increases, the number of Cu single-atom composites per unit mass of metallic Cu increases. + The hydrogen production of the ZnIn2S4 photocatalyst gradually increased, with an average hydrogen production rate of 70.58 mmol·g over 2 hours. −1 ·h −1 .

[0012] Example 2 (1) Dissolve 0.05 mmol CuCl, 0.5 mmol Zn(CH3COO)2·2H2O and 1 mmol InCl3 in a mixture of 15 mL N,N-dimethylformamide and 15 mL ethylene glycol, then add 4 mmol thioacetamide and stir until dissolved. Then, transfer the solution to a reaction vessel and place the reaction vessel in an oven, set the program temperature to 180℃ and the holding time to 10 h, and carry out the reaction. After the reaction is completed and cooled to room temperature, centrifuge to separate the precipitate, wash the precipitate with deionized water and ethanol, and finally dry the obtained precipitate in a drying oven at 60℃.

[0013] (2) Weigh 0.1 g of the precipitate obtained in step (1) and add it to 20 mL of NaBH4 with a concentration of 10 mmol·L⁻¹. −1 The NaOH concentration is 0.2 mol·L⁻¹ –1 The precipitate was ultrasonicated for 1 hour and then magnetically stirred for 6 hours in an alkaline solution. Afterwards, it was centrifuged, and the precipitate was washed several times with deionized water until the supernatant became neutral. Finally, the precipitate was dried in a 60℃ drying oven to obtain metallic Cu single-atom composite Cu. + ZnIn2S4 doped photocatalyst.

[0014] (3) Perform the photocatalytic water splitting hydrogen production performance test according to step (3) in Example 1. The resulting water splitting hydrogen production performance graph is shown in the appendix of the instruction manual. Figure 5 .from Figure 5 As can be seen, the average hydrogen production rate from water splitting of this photocatalyst reached 68.3 mmol·g over 2 hours. −1 ·h −1 .

[0015] Example 3 (1) Dissolve 0.04 mmol CuCl, 0.5 mmol Zn(CH3COO)2·2H2O and 1 mmol InCl3 in a mixture of 15 mL N,N-dimethylformamide and 15 mL ethylene glycol, then add 4 mmol thioacetamide and stir until dissolved. Then, transfer the solution to a reaction vessel and place the reaction vessel in an oven, set the program temperature to 180℃ and the holding time to 10 h, and carry out the reaction. After the reaction is completed and cooled to room temperature, centrifuge to separate the precipitate, wash the precipitate with deionized water and ethanol, and finally dry the obtained precipitate in a drying oven at 60℃.

[0016] (2) Weigh 0.1 g of the precipitate obtained in step (1) and add it to 20 mL of NaBH4 with a concentration of 20 mmol·L⁻¹. −1 The NaOH concentration is 0.2 mol·L⁻¹ –1 The solution was sonicated for 1 hour and then magnetically stirred for 6 hours. Afterwards, it was centrifuged, and the precipitate was washed several times with deionized water until the supernatant became neutral. Finally, the obtained precipitate was dried in a 60℃ drying oven to obtain metallic Cu single-atom composite Cu. + ZnIn2S4 doped photocatalyst.

[0017] (3) Perform the photocatalytic water splitting hydrogen production performance test according to step (3) in Example 1. The resulting water splitting hydrogen production performance graph is shown in the appendix of the instruction manual. Figure 6 .from Figure 6 As can be seen, the average hydrogen production rate from water splitting of this photocatalyst reached 62.54 mmol·g over 2 hours. −1 ·h −1 .

[0018] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made within the scope of the claims of the present invention should be included in the scope of the present invention.

Claims

1. A single-atom composite Cu of metallic Cu + A method for preparing a ZnIn2S4 doped photocatalyst, characterized in that... Includes the following steps: (1) Dissolve CuCl, Zn(CH3COO)2·2H2O and InCl3 in a mixture of N,N-dimethylformamide and ethylene glycol, and then add thioacetamide to the above solution and stir until dissolved. The volume ratio of N,N-dimethylformamide to ethylene glycol is 1:1, and the molar ratio of Cu, Zn, In and S is 0.08 to 0.10:1:2:

8. (2) Transfer the solution obtained in step (1) to the reaction vessel, heat it to 180°C and keep it at that temperature for 10 hours. After cooling, centrifuge, wash and dry the product. (3) Add the product obtained in step (2) to a NaBH4 concentration of 5~20 mmol·L −1 The NaOH concentration is 0.2 mol·L⁻¹ –1 The product was ultrasonicated for 1 h and stirred for 6 h in an alkaline NaBH4 solution, followed by centrifugation, washing, and drying to obtain a single-atom Cu composite of metallic Cu. + ZnIn2S4 doped photocatalyst.

2. The preparation method according to claim 1, characterized in that, The prepared metallic Cu single-atom composite Cu + The ZnIn2S4 photocatalyst exhibited a photocatalytic hydrogen production rate of 62.54–70.58 mmol·g under visible light irradiation. ‒1 ·h ‒1 .

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