Preparation method of defect hollow structure Zn3In2S6 photocatalyst and its application in co-production of hydrogen peroxide and benzaldehyde

Abstract

The present invention belongs to the field of photocatalysis and discloses a method for preparing a Zn3In2S6 photocatalyst with a defective hollow structure and its application in the co-production of hydrogen peroxide and benzaldehyde. The present invention synthesizes the Zn3In2S6 photocatalyst with a defective hollow structure by a solvent thermal method. Zinc sulfate heptahydrate, indium chloride tetrahydrate, thioacetamide, and ethylene glycol are uniformly mixed and then transferred to a polytetrafluoroethylene-lined autoclave for solvent thermal treatment to obtain the Zn3In2S6 photocatalyst with a defective hollow structure. The Zn3In2S6 photocatalyst with a defective hollow structure increases the specific surface area of ​​the material, while also increasing the number of active sites and improving reaction performance. The synthesized Zn3In2S6 photocatalyst with a defective hollow structure has the advantages of simple synthesis operation and being green and pollution-free. In addition, the catalyst has excellent photocatalytic co-production performance and stability for hydrogen peroxide and benzaldehyde.

Description

Technical Field

[0001] The present invention belongs to the field of photocatalyst preparation and application, and specifically relates to the preparation and application of a Zn3In2S6 photocatalyst. Background Art

[0002] With the rapid development of industrialization in the world, energy crisis and environmental pollution problems are becoming increasingly serious. H2O2 has attracted much attention due to its high commercial value, volumetric energy density and wide application in various industries. The most commonly used anthraquinone (AQ) oxidation industrial technology consumes a large amount of hydrogen and fossil fuels, while generating a large amount of organic waste. This requires cumbersome separation procedures to obtain high-purity H2O2 for use. Therefore, new green and efficient methods are urgently needed. In recent years, photocatalytic 2e - Oxygen reduction reaction (ORR) has been reported as a promising technology for H2O2 synthesis with low energy consumption and environmental friendliness, but it suffers from low H2O2 production rate and low carrier utilization. Although the oxidation barrier of H2O2 synthesis has been reduced by using sacrificial proton donors to increase the H2O2 production rate, the overall cost of H2O2 production has been pushed up. At the same time, the photogenerated holes (h + Therefore, exploring specific proton donors that can produce value-added chemicals in a highly selective manner, coupled with the promoted H2O2 production, is a very advantageous strategy to improve the economic significance of photocatalytic systems.

[0003] Different from most traditional semiconductor photocatalysts, the ternary metal sulfide Zn-In-S (general formula Zn m In2S 3+m m=1-5) has unique electronic and optical properties and has good prospects in photocatalytic applications. Among them, Zn3In2S6 has been widely used in various aspects such as photocatalytic hydrogen production, degradation of pollutants, and photocatalytic production of hydrogen peroxide due to its rich active sites. However, Zn3In2S6 still faces the problem of rapid photogenerated carrier recombination and low visible light response. In order to solve the above problems, researchers have made great efforts, including heterostructure construction, co-catalyst loading and morphology regulation, to improve the photocatalytic performance of Zn3In2S6. Among them, defect engineering plays an important role in enhancing photocatalytic hydrogen peroxide. It can act as an electron receiver to capture electrons generated by light, thereby extending the carrier lifetime. In addition, morphology regulation can help expose more active surface sites, thereby promoting the reaction.

[0004] Based on the above results, an idea is given as to whether it is possible to develop a new reaction, that is, to effectively utilize the system of photogenerated electrons and holes for the photocatalytic conversion of benzyl alcohol into benzaldehyde and the precipitation of H2O2 by controlling the defects and morphology of Zn3In2S6. Summary of the Invention

[0005] In order to solve the problems in the background technology, the purpose of the present invention is to provide a Zn3In2S6 photocatalyst containing a defective hollow structure and a preparation method thereof, and apply it to the coupled co-production of H2O2 and benzaldehyde, which has excellent photocatalytic performance.

[0006] The technical solution of the present invention is as follows: the present invention provides a Zn3In2S6 photocatalyst containing a defective hollow structure. The preparation method of the catalyst is as follows: zinc sulfate (ZnSO4·7H2O), indium chloride (InCl3·4H2O) and thioacetamide (TAA) are added to a solvent, mixed and stirred, and then transferred to a polytetrafluoroethylene-lined autoclave for solvent thermal reaction. After the reaction, the mixture is washed with deionized water and ethanol several times and then vacuum dried to obtain the Zn3In2S6 photocatalyst.

[0007] The molar ratio of ZnSO4·7H2O, InCl3·4H2O and TAA is 3:2:6~18.

[0008] Preferably, the molar ratio of ZnSO4·7H2O, InCl3·4H2O, and TAA is 3:2:12; and the mixture is stirred vigorously for 30 minutes to mix uniformly.

[0009] The solvent thermal reaction temperature is 140 ~ 180 ° C, and the reaction time is 10 ~ 14 h.

[0010] Preferably, the solvent thermal reaction temperature is 160° C. and the reaction time is 12 h.

[0011] The solvent is ethylene glycol, deionized water, or a mixture of ethylene glycol and deionized water at a volume ratio of 0.15 to 6:1. The amount of solvent used is not specifically limited as long as it does not affect the reaction.

[0012] Preferably, the solvent is ethylene glycol; the dosage of zinc sulfate and ethylene glycol is 3 mmol / 60 ~ 100 mL.

[0013] The above preparation method is applied to the photocatalytic co-production of hydrogen peroxide and benzaldehyde. Specifically, the method involves adding a zinc-indium-sulfur photocatalyst to a solution containing benzyl alcohol, ultrasonically dispersing the catalyst to uniformity, bubbling the suspension with oxygen until the oxygen in the reaction solution fills the reaction vessel, and then co-producing hydrogen peroxide and benzaldehyde under light conditions. The hydrogen peroxide concentration is measured using an ultraviolet spectrophotometer, and the benzaldehyde production is measured using gas chromatography.

[0014] Furthermore, acetonitrile is used as a solvent in the benzyl alcohol-containing solution, i.e., the acetonitrile solution containing benzyl alcohol, and preferably the volume ratio of acetonitrile to benzyl alcohol is 1:0.004 to 0.014.

[0015] Furthermore, the amount of Zn3In2S6 catalyst used relative to benzyl alcohol is 3 mg / 20-70 μL, and more preferably 3 mg / 50 μL.

[0016] Furthermore, light irradiation refers to subjecting the mixed solution to a photocatalytic reaction under simulated sunlight (55W xenon lamp).

[0017] The technical effects achieved by the present invention are:

[0018] (1) The present invention uses ethylene glycol as a solvent, zinc sulfate as a zinc source, indium chloride as an indium source, and thioacetamide as a sulfur source, and synthesizes a defective hollow structure Zn3In2S6 photocatalyst via a solvothermal method. By optimizing the solvent type, reaction time, and temperature, a Zn3In2S6 photocatalyst with optimal performance is obtained. The lattice symmetry of the synthesized Zn3In2S6 is reduced, and the material defects are increased. Defect engineering plays an important role in enhancing the photocatalytic evolution of hydrogen peroxide. It can act as an electron receiver to capture electrons generated by light, thereby extending the lifetime of photogenerated carriers.

[0019] (2) The Zn3In2S6 photocatalyst provided by the present invention has a hollow nanoflower structure, which can increase the exposure of active sites, promote the full contact between the reactants and the catalyst, thereby promoting the reaction and improving the photocatalytic performance of the catalyst.

[0020] (3) The defective hollow structure Zn3In2S6 photocatalyst provided by the present invention has excellent photocatalytic performance and is pioneered in the reaction of benzyl alcohol to produce hydrogen peroxide and benzaldehyde. The defective hollow structure Zn3In2S6 provides 41.58 mmol h-1 of H2O2 and benzaldehyde, respectively. -1 g -1 and 75.97 mmol h -1 g -1 high yield. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 XRD patterns of Zn3In2S6 catalysts were obtained for Example 1, Comparative Example 1, Example 10, Example 11, and Comparative Example 4;

[0022] Figure 2 (a) is the SEM image of Comparative Example 1, Figure 2 (b) is the SEM image of Example 1;

[0023] Figure 3 The EDS-Mapping spectrum of the Zn3In2S6 catalyst prepared in Example 1;

[0024] Figure 4The performance graphs of hydrogen peroxide and benzaldehyde production in Examples 2, 3, 4, 5, 6, and 7 are shown;

[0025] Figure 5 The performance graphs of hydrogen peroxide and benzaldehyde production of Example 1, Comparative Example 1, Example 10, Example 11, Example 12 and Comparative Example 2 are shown;

[0026] Figure 6 is the EPR spectrum of Example 1;

[0027] Figure 7 Figure 2 is a reaction mechanism diagram of the present invention. DETAILED DESCRIPTION

[0028] The present invention further illustrates the technical features of the present invention with the following examples, but the protection scope of the present invention is not limited to the following examples.

[0029] Example 1: Hollow structure double-defect Zn3In2S6 was prepared by a one-step solvothermal method.

[0030] 0.8656 g (3 mmol) of ZnSO₄·7H₂O, 0.5865 g (2 mmol) of InCl₃·4H₂O, and 12 mmol of TAA were sequentially dissolved in 70 mL of ethylene glycol and stirred continuously for approximately 30 minutes. After mixing thoroughly, the mixture was transferred to a 100 mL polytetrafluoroethylene-lined stainless steel autoclave and maintained at 160°C for 12 hours. After cooling to room temperature, the precipitate was collected by centrifugation, washed several times with distilled water and ethanol, and dried in a vacuum oven at 60°C to obtain hollow-structured double-defect Zn₃In₂S₆.

[0031] 1. Application method

[0032] The photocatalytic reaction was carried out in a constant-temperature circulating water system, where the reaction system temperature was maintained at 25°C. For a typical reaction, 3 mg of the photocatalyst was dispersed in a mixture of 5 mL of acetonitrile and 50 μL of benzyl alcohol. After ultrasonic treatment for 2 minutes, the suspension was bubbled with oxygen for 2 minutes. The mixture was then illuminated by a 55 W xenon lamp simulating sunlight for 30 minutes. The yields of hydrogen peroxide and benzaldehyde in the reaction solution were determined to be 41.58 mmol h-1, respectively. -1 g -1 and 75.97 mmol h -1 g -1 .

[0033] 2. Stability test

[0034] 3 mg of the photocatalyst was dispersed in a mixture of 20 mL of acetonitrile and 200 μL of benzyl alcohol. After ultrasonic treatment for 2 minutes, the suspension was bubbled with oxygen for 2 minutes. The mixed solution was then illuminated by a 55 W xenon lamp simulating sunlight for 30 minutes. The reaction solution was ultrasonicated again for 2 minutes and bubbled with oxygen for 2 minutes, and then illuminated by a 55 W xenon lamp simulating sunlight for another 30 minutes. This operation was repeated a total of four times, and the yields of hydrogen peroxide (H2O2) and benzaldehyde (Ph-CHO) in the reaction solution were determined to be 40.76 mmol h-1 and 40.76 mmol h-1, respectively. -1 g -1 and 70.26 mmol h -1 g -1 .

[0035] from Figure 1 It can be seen from the XRD that the hollow structure Zn3In2S6 catalyst prepared in Example 1 is well reduced to the hexagonal phase of Zn3In2S6 (intracellular parameters are a = b = 3.85 Å, c = 21.79 Å, JCPDS No. 24-1453). The broad diffraction peaks are located at 20.7°, 27.0°, 28.4°, 47.2°, 51.9°, 56.2° and 76.3°, corresponding to the (005), (100), (102), (110), (115), (203) and (213) crystal planes of hexagonal Zn3In2S6, respectively. This shows that the Zn3In2S6 catalyst was successfully prepared. At the same time, from Figure 2 (b) SEM shows that Zn3In2S6 has a good nanoflower structure and a hollow structure. Figure 3 The EDS-Mapping spectrum showed three elements, Zn, In and S, confirming the successful preparation of the hollow structure Zn3In2S6 catalyst.

[0036] Example 2: Compared with Example 1, the difference is that during the preparation process, the molar ratio of ZnSO4·7H2O, InCl3·4H2O, and TAA is changed to 3:2:6. The other operations are the same as in Example 1 to prepare a Zn3In2S6 catalyst.

[0037] The application method was the same as in Example 1, and the yields of hydrogen peroxide and benzaldehyde were 34.02 mmol h -1 g -1 and 37.74 mmol h -1 g -1 .

[0038] Example 3: Compared with Example 1, the difference is that during the preparation process, the molar ratio of ZnSO4·7H2O, InCl3·4H2O, and TAA is changed to 3:2:18. The other operations are the same as in Example 1 to prepare a Zn3In2S6 catalyst.

[0039] The application method was the same as in Example 1, and the yields of hydrogen peroxide and benzaldehyde were 22.36 mmol h -1 g -1 and 23.68 mmol h -1 g -1 .

[0040] Example 4: Compared with Example 1, the difference is that the solvent thermal reaction temperature during the preparation process is 140° C. Other operations are the same as in Example 1 to prepare a Zn3In2S6 catalyst.

[0041] The application method was the same as in Example 1, and the yields of hydrogen peroxide and benzaldehyde were 27.69 mmol h -1 g -1 and 24.64 mmol h -1 g -1 .

[0042] Example 5: Compared with Example 1, the difference is that the solvent thermal reaction temperature during the preparation process is 180° C. Other operations are the same as in Example 1 to prepare a Zn3In2S6 catalyst.

[0043] The application method was the same as in Example 1, and the yields of hydrogen peroxide and benzaldehyde were 32.99 mmol h -1 g -1 and 26.17 mmol h -1 g -1 .

[0044] Example 6: Compared with Example 1, the difference is that the solvent thermal reaction time in the preparation process is 10 h. Other operations are the same as in Example 1 to prepare a Zn3In2S6 catalyst.

[0045] The application method was the same as in Example 1, and the yields of hydrogen peroxide and benzaldehyde were 17.70 mmol h -1 g -1 and 17.61 mmol h -1 g -1 .

[0046] Example 7: Compared with Example 1, the difference is that the solvent thermal reaction time in the preparation process is 14 hours. Other operations are the same as in Example 1 to prepare a Zn3In2S6 catalyst.

[0047] The application method was the same as in Example 1, and the yields of hydrogen peroxide and benzaldehyde were 25.24 mmol h -1 g -1 and 28.21 mmol h -1 g -1 .

[0048] Example 8: The preparation method of the hollow structure Zn3In2S6 catalyst is the same as that of Example 1.

[0049] The application method is different from that of Example 1 in that 3 mg of the photocatalyst is dispersed in a mixed solution of 5 mL of acetonitrile and 20 μL of benzyl alcohol. The yields of hydrogen peroxide and benzaldehyde are 29.24 mmol h -1 g -1 and 14.33 mmol h -1 g -1 .

[0050] Example 9: The preparation method of the hollow structure Zn3In2S6 catalyst is the same as that of Example 1.

[0051] The application method is different from that of Example 1 in that 3 mg of the photocatalyst is dispersed in a mixed solution of 5 mL of acetonitrile and 70 μL of benzyl alcohol. The yields of hydrogen peroxide and benzaldehyde are 36.13 mmol h -1 g -1 and 42.33 mmol h -1 g -1 .

[0052] Example 10: 0.8656 g (3 mmol) of ZnSO₄·7H₂O, 0.5865 g (2 mmol) of InCl₃·4H₂O, and 12 mmol of TAA were sequentially dissolved in a mixture of 60 mL of deionized water and 10 mL of ethylene glycol. Stirring was continued for approximately 30 minutes. After mixing thoroughly, the mixture was transferred to a 100 mL Teflon-lined stainless steel autoclave and maintained at 160°C for 12 hours. After cooling to room temperature, the precipitate was collected by centrifugation, washed several times with distilled water and ethanol, and dried in a vacuum oven at 60°C.

[0053] The application method was the same as in Example 1, and the yields of hydrogen peroxide and benzaldehyde were 16.73 mmol h -1 g -1 and 19.7 mmol h -1 g -1 .

[0054] Example 11: 0.8656 g (3 mmol) of ZnSO₄·7H₂O, 0.5865 g (2 mmol) of InCl₃·4H₂O, and 12 mmol of TAA were sequentially dissolved in a mixture of 40 mL of deionized water and 30 mL of ethylene glycol. Stirring was continued for approximately 30 minutes. After mixing thoroughly, the mixture was transferred to a 100 mL Teflon-lined stainless steel autoclave and maintained at 160°C for 12 hours. After cooling to room temperature, the precipitate was collected by centrifugation, washed several times with distilled water and ethanol, and dried in a vacuum oven at 60°C.

[0055] The application method was the same as in Example 1, and the yields of hydrogen peroxide and benzaldehyde were 24.26 mmol h -1 g -1 and 29.61 mmol h -1 g -1 .

[0056] Example 12: 0.8656 g (3 mmol) of ZnSO₄·7H₂O, 0.5865 g (2 mmol) of InCl₃·4H₂O, and 12 mmol of TAA were sequentially dissolved in a mixture of 20 mL of deionized water and 50 mL of ethylene glycol. Stirring was continued for approximately 30 minutes. After uniform mixing, the mixture was transferred to a 100 mL Teflon-lined stainless steel autoclave and maintained at 160°C for 12 hours. After cooling to room temperature, the precipitate was collected by centrifugation, washed several times with distilled water and ethanol, and dried in a vacuum oven at 60°C.

[0057] The application method was the same as in Example 1, and the yields of hydrogen peroxide and benzaldehyde were 34.91 mmol h -1 g -1 and 44.10 mmol h -1 g -1 .

[0058] Comparative Example 1: 0.8656 g (3 mmol) of ZnSO₄·7H₂O, 0.5865 g (2 mmol) of InCl₃·4H₂O, and 12 mmol of TAA were dissolved sequentially in 70 mL of deionized water and stirred continuously for approximately 30 minutes. After mixing thoroughly, the mixture was transferred to a 100 mL Teflon-lined stainless steel autoclave and maintained at 160°C for 12 hours. After cooling to room temperature, the precipitate was collected by centrifugation, washed several times with distilled water and ethanol, and dried in a vacuum oven at 60°C.

[0059] The application method was the same as in Example 1, and the yields of hydrogen peroxide and benzaldehyde were 8.47 mmol h -1 g -1and 10.31 mmol h -1 g -1 .

[0060] Comparative Example 2: 0.8656 g (3 mmol) of ZnSO₄·7H₂O, 0.5865 g (2 mmol) of InCl₃·4H₂O, and 12 mmol of TAA were dissolved sequentially in 70 mL of deionized water with continuous stirring for approximately 30 minutes. 0.65 g of CTAB was then slowly added with stirring. After stirring for 30 minutes, the mixture was transferred to a 100 mL Teflon-lined stainless steel autoclave and maintained at 160°C for 12 hours. After cooling to room temperature, the precipitate was collected by centrifugation, washed several times with distilled water and ethanol, and dried in a vacuum oven at 60°C.

[0061] The application method was the same as in Example 1, and the yields of hydrogen peroxide and benzaldehyde were 33.29 mmol h -1 g -1 and 40.18 mmol h -1 g -1 .

[0062] Comparative Example 3: The preparation method of the hollow structure Zn3In2S6 catalyst is the same as that of Example 1.

[0063] The application method is different from that of Example 1 in that 3 mg of the photocatalyst is dispersed in a mixed solution of 5 mL of deionized water and 50 μL of benzyl alcohol. The yields of hydrogen peroxide and benzaldehyde are 14.96 mmol h -1 g -1 and 7.53 mmol h -1 g -1 .

Claims

1. Application of a defective hollow structure Zn3In2S6 photocatalyst in photocatalytic co-production of hydrogen peroxide and benzaldehyde, characterized in that: The defective hollow structure Zn3In2S6 photocatalyst was added to a solution containing benzyl alcohol, dispersed evenly by ultrasonication, and oxygen was introduced. Under sunlight illumination, H2O2 and benzaldehyde were co-produced. The benzyl alcohol-containing solution is a mixed solution of benzyl alcohol and acetonitrile; acetonitrile is used as the solvent, and the volume ratio of acetonitrile to benzyl alcohol is 1:0.004 to 0.014; The Zn3In2S6 photocatalytic preparation method comprises: adding zinc sulfate, indium chloride, and thioacetamide to a solvent, mixing and stirring, and then transferring the mixture to an autoclave for a solvothermal reaction at a reaction temperature of 140 to 180°C for 10 to 14 hours. After the reaction, the solid is collected, washed, and dried to obtain the Zn3In2S6 photocatalyst. The molar ratio of zinc sulfate, indium chloride, and thioacetamide is 3:2:12; and the solvent is ethylene glycol.

2. The application according to claim 1, characterized in that The reaction temperature of the solvothermal reaction was 160 °C and the reaction time was 12 h.

3. The use according to claim 1, characterized in that The amount of Zn3In2S6 catalyst used relative to benzyl alcohol is 3 mg / 20-70 μL.

4. The use according to claim 3, characterized in that The amount of Zn3In2S6 catalyst used relative to benzyl alcohol was 3 mg / 50 μL.

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