Preparation method and application of ZnIn2S4 nanosheet composite material modified by tungsten carbide quantum dots

Abstract

The invention provides a preparation method and application of a ZnIn2S4 nanosheet photocatalyst modified by tungsten carbide quantum dots. The tungsten carbide with the local surface plasmon resonance effect is introduced, so that the catalyst shows excellent photo-thermal and photocatalytic performance. The high-purity composite material has obvious light absorption in visible and near-infrared regions, and the separation efficiency and migration rate of photo-generated carriers of a catalyst are improved by multiple strategies such as Schottky junctions, surface defects and photothermal effects of the high-purity composite material, so that the generation rate of hydrogen is improved. Continuously generated low-concentration. OH and photogenerated holes attack an alpha C-H bond of benzyl alcohol, so that the conversion rate and selectivity of benzaldehyde are effectively improved. The technical synthesis steps are simple, no precious metal participates in, and the double functions of high-activity and selective benzyl alcohol oxidation for benzaldehyde preparation coupled with water decomposition for hydrogen production are achieved. Under a mild condition, solar energy is used as unique energy input to synchronously generate clean fuel and high-added-value fine chemicals, and the method has a wide application prospect.

Description

Technical Field

[0001] The present invention relates to functional material preparation technology and energy and environmental protection application fields, and specifically to a preparation method of a tungsten carbide quantum dot-modified ZnIn2S4 nanosheet composite material and its application in photocatalytic water decomposition for hydrogen production coupled with selective oxidation of benzyl alcohol. Background Art

[0002] Among the many hydrogen production technologies, solar-driven photocatalytic water splitting is known as the green holy grail technology and has attracted much attention from academia and industry. However, the oxygen evolution half-reaction of photocatalytic water splitting has high activation energy, slow reaction kinetics, low reaction value, and the generated hydrogen and oxygen are difficult to be effectively separated, which seriously restricts the entire photocatalytic process. In the past few decades, photocatalytic water splitting has mainly focused on the research of photocatalytic partial water splitting hydrogen production technology. Although this technology has a high hydrogen production rate, the catalytic process requires continuous supplementation of sacrificial agents to consume photogenerated holes, resulting in increased hydrogen production costs and the generation of by-products (such as CO2), which is not conducive to practical industrial applications. Therefore, how to achieve the effective consumption and utilization of photogenerated holes and explore the carbon-free green pathway for photocatalytic hydrogen production is still a frontier research field that urgently needs to be broken through. Photocatalytic water splitting based on semiconductor photocatalysts coupled with the selective oxidation of benzyl alcohol is one of the effective strategies to achieve efficient utilization of photogenerated holes and carbon-free characteristics in photocatalytic hydrogen production.

[0003] Two-dimensional layered ZnIn2S4 is a semiconductor with a narrow band gap and a wide spectral response. It can effectively absorb and utilize sunlight in the visible and near-infrared regions, and its suitable valence band position can also effectively prevent the further oxidation of benzyl alcohol in water, thereby improving the selectivity of benzyl alcohol oxidation. In addition, two-dimensional layered ZnIn2S4 has the characteristics of adjustable electronic and energy level structure, designable non-stoichiometric defect sites and surface states, and has great potential in the coupling of photocatalytic water decomposition and hydrogen production with the selective oxidation of benzyl alcohol. At present, the photocatalyst based on ZnIn2S4 nanosheets mainly constructs S-type and Z-type heterojunctions, and improves the separation and transmission efficiency of photogenerated carriers through strong interfacial electric fields. However, this configuration makes the catalyst have strong reducing ability while also showing strong oxidizing ability, which will lead to excessive oxidation of benzyl alcohol and is not conducive to the selectivity of the product. The suitable valence band position of ZnIn2S4 nanosheets gives it a mild oxidizing ability, which can effectively prevent the further oxidation of benzaldehyde, so the retained oxidizing ability is necessary. In addition, full d orbitals are the basic characteristics of Zn and In atoms (3d 10), so the 2p orbital of the C or O atom in benzyl alcohol and the d orbital of the Zn and In atoms are weakly bonded. This weak interaction makes the efficiency of the photocatalytic selective oxidation reaction of benzyl alcohol by ZnIn2S4-based heterojunction catalyst still unsatisfactory. The present invention uses carbide quantum dots with metal-like properties to modify defective ZnIn2S4 nanosheets, and successfully prepares defective ZnIn2S4 / tungsten carbide quantum dot Schottky junction composite materials (ZnIn2S4 / WC). The surface plasmon resonance effect of tungsten carbide makes the composite material show good photothermal performance, which can effectively promote carrier mobility and reduce the energy barrier of the catalytic reaction. In addition, S vacancies and WC move the d-band center of the catalyst upward, thereby enhancing the interaction between the adsorbed benzyl alcohol and the catalyst, and reducing the energy barrier of the adsorption / activation / oxidation of benzyl alcohol on the catalyst surface. In summary, the ZnIn2S4 nanosheet composite modified by WC quantum dots shows excellent water decomposition hydrogen production and benzyl alcohol selective oxidation activity and selectivity. This strategy not only achieves efficient water splitting to produce hydrogen, but also provides an efficient and green synthetic route for the synthesis of industrially relevant chemicals. Summary of the invention

[0004] The main purpose of the present invention is to propose a method for preparing a tungsten carbide quantum dot-modified ZnIn2S4 nanosheet photocatalyst and its application in photocatalytic water decomposition for hydrogen production coupled with benzyl alcohol selective oxidation performance. The ZnIn2S4 / WC composite material was prepared by solvothermal and high-temperature calcination methods. The wide spectral response, Schottky junction and photothermal effect of the material enable the catalyst to exhibit efficient hydrogen production rate and excellent benzyl alcohol conversion rate and selectivity.

[0005] The present invention is implemented through the following technical scheme.

[0006] The XRD data of ZnIn2S4 / WC composites show peaks at 21.59, 27.69, 30.45, 39.78, 47.18, and 52.44 at 2-Theta, corresponding to the (006), (102), (104), (108), (110), and (116) crystal planes of ZnIn2S4, among which WC exhibits weaker peak intensity due to its smaller size and less content in the composite.

[0007] The present invention provides a method for preparing a tungsten carbide quantum dot-modified ZnIn2S4 nanosheet photocatalyst, the method comprising the following steps: (1) Preparation of tungsten carbide quantum dots: A certain proportion of ammonium metatungstate and dicyandiamide are mixed, and tungsten carbide quantum dots are obtained by long-term grinding and high-temperature calcination.

[0008] In step (1), the mass ratio of ammonium metatungstate to dicyandiamide is 0.3-5.0, and the physical grinding time is 15-25 min. The calcination conditions are: firstly, starting from room temperature and heating at 1-2 °C min -1 The heating rate is heated to 300-400 ℃, and then 5-10 ℃ min -1 The heating rate is heated to 800-900 ℃.

[0009] In some cases, the mass ratio of ammonium metatungstate to dicyandiamide can change the phase state and particle size of tungsten carbide. The phase state and particle size are related to the conductivity of the material and the contact area with the substrate. In order to obtain tungsten carbide with appropriate conductivity and particle size, different mass ratios are used for grinding in the experiment.

[0010] The grinding time is adjusted according to the mass ratio of ammonium metatungstate to dicyandiamide until the two are ground into powder and fully mixed, which is conducive to the formation of a single-phase product during the high-temperature process.

[0011] (2) Preparation of ZnIn2S4 nanosheets: Zinc chloride and indium chloride tetrahydrate were added to anhydrous methanol solution, and after ultrasonic dispersion, thioacetamide was added and stirred evenly. ZnIn2S4 nanosheets were obtained after solvothermal reaction.

[0012] In step (2), the mass ratio of zinc chloride, indium chloride tetrahydrate and thioacetamide is 10-15:45-70:30-35.

[0013] The solvent thermal temperature is 60-180 °C, and the solvent thermal time is 20-200 min. After the solvent thermal reaction is completed, deionized water and ethanol are used for alternating washing, the washing times are 2 times with deionized water and 3 times with ethanol, and then the product is dried in a vacuum drying oven at 40-60 °C to obtain a yellow-green powder product.

[0014] (3) Preparation of tungsten carbide quantum dot modified ZnIn2S4 nanosheet photocatalyst: First, tungsten carbide quantum dots were uniformly dispersed in anhydrous methanol by ultrasound, and then zinc chloride and zinc chloride tetrahydrate were added and stirred. After sufficient stirring, thioacetamide was added and stirred evenly, and then a solvothermal reaction was performed to obtain tungsten carbide quantum dot modified ZnIn2S4 nanosheet photocatalyst.

[0015] The mass ratio of tungsten carbide nanoparticles, zinc chloride, indium chloride tetrahydrate, and thioacetamide described in step (3) is 2-6:10-15:50-60:30-35. The solvent thermal temperature is 60-180 °C, and the solvent thermal time is 20-200 min. After the solvent thermal reaction is completed, the product needs to be washed with deionized water and anhydrous ethanol for 2-3 times respectively, and dried in a vacuum drying oven at 40-60 °C to obtain a yellow-green powder product. Deionized water and ethanol are used for alternating washing, the washing times are 2 times with deionized water and 3 times with ethanol, and then vacuum dried at 40-60 °C to obtain the product.

[0016] Another technical solution of the present invention is the application of ZnIn2S4 nanosheets modified with tungsten carbide quantum dots in the photocatalytic water decomposition to produce hydrogen coupled with the selective oxidation performance of benzyl alcohol.

[0017] A xenon lamp is used as a light source, and the prepared ZnIn2S4 / WC photocatalyst is dispersed in a quartz reactor to carry out water decomposition to produce hydrogen coupled with benzyl alcohol selective oxidation reaction. The reactor contains deionized water and benzyl alcohol. The mixed liquid is degassed before xenon lamp irradiation to ensure that the reactor is in a negative pressure state.

[0018] The performance of photocatalytic water splitting for hydrogen production coupled with benzyl alcohol selective oxidation was carried out on a fully automatic online analytical nanomaterial test system, using a xenon lamp with a power of 300 W and equipped with an AM1.5G filter as the light source. The photocatalyst was ultrasonically dispersed in an aqueous solution containing benzyl alcohol. Before the reaction, the air in the reactor mixed solution and the test glass system was removed by a vacuum pump to make the system under negative pressure, and the temperature of the reactor was maintained at 298 K by a circulating condensation system. The amount of hydrogen produced was detected by gas chromatography (GC7920-TF2A, Au light, China) every hour, and monitored quantitatively by a thermal conductivity detector (TCD). After the reaction, the reaction solution was detected by high performance liquid chromatography (Waters2695, Water Company, USA), and the results were compared with the standard peak time, and the amount of benzaldehyde generated was analyzed with a standard curve.

[0019] The amount of catalyst used is 5-100 mg, and the content of benzyl alcohol is 0.1-10 mL. In the preferred embodiment, the amount of catalyst used is 20 mg, and the content of benzyl alcohol is 7 mL.

[0020] Another object of the present invention is to provide a catalyst for photocatalytic oxidation of benzyl alcohol to generate benzaldehyde and coupled hydrogen production, including the catalyst, or the catalyst prepared by the method.

[0021] The embodiment of the present invention provides a tungsten carbide quantum dot modified ZnIn2S4 nanosheet and its preparation method and application. The specific beneficial effects of the material are as follows: The present invention synthesizes ZnIn2S4 nanosheet material modified by tungsten carbide quantum dots for the first time. First, tungsten carbide quantum dots are prepared by high-temperature calcination. Then, the tungsten carbide quantum dots are subjected to a solvothermal reaction with zinc chloride, indium chloride tetrahydrate and thioacetamide to obtain a ZnIn2S4 nanosheet material modified by tungsten carbide quantum dots with good stability. The defect structure on the surface of the ZnIn2S4 nanosheet in the composite material can not only significantly improve the separation efficiency of photogenerated carriers, but also facilitate the adsorption of benzyl alcohol. In addition, tungsten carbide quantum dots can form a Schottky junction with ZnIn2S4, so that the photogenerated electrons are immediately transferred to the surface of tungsten carbide quantum dots, further improving the separation efficiency of photogenerated carriers. The photogenerated electrons generated by the photoexcitation of the ZnIn2S4 nanosheets participate in the photocatalytic proton reduction process together with the hot electrons generated by the LSPR effect of the carbide quantum dots. The photogenerated holes with mild oxidation ability in the valence band of ZnIn2S4 and the continuously generated low concentration of ·OH directly and quickly attack the αC-H bond of benzyl alcohol, thereby improving the conversion rate of benzyl alcohol and the selectivity of benzaldehyde. Finally, the photothermal effect of tungsten carbide quantum dots can accelerate the migration of photogenerated carriers by increasing the surface temperature of the material, reduce the barrier of the catalytic reduction reaction, and thus improve the photocatalytic activity and selectivity. ZnIn2S4 / WC composite material photocatalytic water decomposition hydrogen production (12.58 mmol g -1 h -1 ) coupled with the selective oxidation of benzyl alcohol to generate benzaldehyde (10.53 mmol g -1 h -1 ) is more than 40 times that of pure ZnIn2S4, and the selectivity of benzaldehyde is as high as over 90%. This method is simple to operate and has broad application prospects.

[0022] The prepared tungsten carbide quantum dot modified ZnIn2S4 nanosheet material has a wide range of raw material sources and does not contain precious metals, so it is inexpensive. The prepared tungsten carbide quantum dot modified ZnIn2S4 nanosheet material has good light absorption in the visible light and near-infrared regions, is environmentally friendly, and fully utilizes photogenerated electrons and photogenerated holes, and is suitable for large-scale industrial applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 In the figure, a is the TEM image of tungsten carbide quantum dots; b is the TEM image of ZnIn2S4 nanosheets; c is the TEM image of ZnIn2S4 nanosheet material modified with tungsten carbide quantum dots; d is the HRTEM image of ZnIn2S4 nanosheet material modified with tungsten carbide quantum dots.

[0024] Figure 2 This is the XRD pattern of ZnIn2S4 nanosheet material modified with tungsten carbide quantum dots.

[0025] Figure 3This is the UV-visible diffuse reflectance absorption spectrum of ZnIn2S4 nanosheet material modified with tungsten carbide quantum dots.

[0026] Figure 4 This is a diagram of the photothermal conversion characteristics of ZnIn2S4 nanosheet material modified with tungsten carbide quantum dots.

[0027] Figure 5 This is the performance diagram of photocatalytic hydrogen evolution and benzaldehyde conversion of ZnIn2S4 nanosheet material modified with tungsten carbide quantum dots.

[0028] Figure 6 Benzyl alcohol conversion rate and selectivity diagram of ZnIn2S4 nanosheet material modified with tungsten carbide quantum dots.

[0029] Figure 7 This is a diagram showing the photocatalytic hydrogen evolution cycle effect of ZnIn2S4 nanosheet material modified with tungsten carbide quantum dots. DETAILED DESCRIPTION

[0030] Embodiments of the present invention are described in detail below. Examples of the embodiments are shown in the accompanying drawings. The described examples are exemplary and are only used to explain the present invention, and should not be understood as limiting the present invention.

[0031] With reference to the following description and drawings, it will be clear that the experimental methods and detection methods described in the embodiments of the present invention are conventional methods unless otherwise specified; the reagents and materials described are all commercially available unless otherwise specified.

[0032] Example 1 (1) Preparation of tungsten carbide quantum dots Weigh 100 mg of ammonium metatungstate and 300 mg of dicyandiamide in a mortar and grind thoroughly for 20 minutes. Put the mixed solid powder into a magnetic boat and stir at 2° min under N2 atmosphere. -1 The temperature was heated to 400 °C at a rate of 5 °C min -1 The sample was heated to 800 °C at a heating rate of 100 °C and kept at that temperature for 5 h. After cooling to room temperature, black tungsten carbide quantum dots were obtained.

[0033] Figure 1 -a is a TEM image of tungsten carbide quantum dots, from which it can be seen that the particle size of tungsten carbide quantum dots is 2-5nm.

[0034] (2) Preparation of ZnIn2S4 nanosheets 136 mg of zinc chloride and 586 mg of indium chloride tetrahydrate were weighed and added to 20 mL of anhydrous methanol solution. After stirring evenly, 310 mg of thioacetamide was added and the mixture was continued to be stirred for one hour. The mixture was then transferred to a 50 mL stainless steel high-pressure reactor lined with polytetrafluoroethylene and heated to 120 °C in an oil bath while stirring for 2 h. After the product was cooled to room temperature, the precipitated product was collected by centrifugation and washed twice with deionized water and three times with anhydrous ethanol. Finally, it was vacuum dried at 60 °C overnight to obtain ZnIn2S4 nanosheet material.

[0035] Figure 1 -b is the TEM image of ZnIn2S4 nanosheets. It can be seen from the picture that ZnIn2S4 presents a two-dimensional flake morphology.

[0036] (3) Preparation of ZnIn2S4 / WC composites 50 mg of tungsten carbide black powder was weighed and added to 20 mL of anhydrous methanol solution, then ultrasonicated for half an hour, and then stirred, and 136 mg of zinc chloride, 586 mg of indium chloride tetrahydrate and 310 mg of thioacetamide were added thereto. After stirring for 60 min, the mixture was transferred to a 50 mL stainless steel high-pressure reactor lined with polytetrafluoroethylene, and heated to 120 °C in an oil bath while stirring for 2 h. After the product was cooled to room temperature, the precipitated product was collected by centrifugation and washed twice with deionized water and three times with anhydrous ethanol, and finally dried overnight at 60 °C in vacuum to obtain a ZnIn2S4 / WC composite material.

[0037] Attached Figure 1 -c is the TEM image of ZnIn2S4 / WC composite material, from which it can be seen that tungsten carbide quantum dots are dispersed on the surface of ZnIn2S4 nanosheets. Figure 1 -d is the HRTEM image of the ZnIn2S4 / WC composite material, in which the lattice fringes with a lattice spacing of 0.32 nm belong to the (102) crystal plane of ZnIn2S4; the tungsten carbide nanoparticles are magnified, and the lattice fringes with a lattice spacing of 0.24 nm in the inset belong to WC 1-x The (111) crystal plane also proves that the crystal phase of ZnIn2S4 and tungsten carbide will not change after being composited.

[0038] Example 2 20 mg of the photocatalyst prepared in Example 1, 80 mL of deionized water and 104 μL of benzyl alcohol were mixed evenly and placed in a photocatalytic reactor. The reactor was evacuated for 20 min until vacuum was achieved and then condensed water was passed through to maintain 298 K. A 300 W xenon lamp equipped with an AM1.5G filter was used as a light source to start the photocatalytic reaction.

[0039] The catalyst prepared in Example 1 was subjected to XRD test, and the results were as follows: Figure 2 As shown, the prepared ZnIn2S4 nanosheets and carbide quantum dots have high purity and good crystallinity; the XRD data of the ZnIn2S4 / WC composite material have peaks at 21.59, 27.69, 30.45, 39.78, 47.18, and 52.44 at 2-Theta, corresponding to the (006), (102), (104), (108), (110), and (116) crystal planes of ZnIn2S4. The ZnIn2S4 / WC composite material is the same as ZnIn2S4, and no diffraction peak of tungsten carbide can be seen, which is due to the small size and small loading of tungsten carbide quantum dots. The prepared ZnIn2S4 / WC composite material has no impurity peaks, indicating that the present invention successfully and stably obtains the ZnIn2S4 / WC composite material.

[0040] The light absorption characteristics of the prepared photocatalyst were tested, and the results were as follows: Figure 3 As shown in the figure, pure ZnIn2S4 nanosheets only absorb light in the ultraviolet and visible regions. After loading tungsten carbide nanoparticles, the light absorption of ZnIn2S4 / WC composite materials in the visible and near-infrared regions is significantly enhanced. The photothermal conversion properties of the prepared photocatalyst were tested, and the results are shown in Figure 4 As shown in the figure, under the conditions of simulated sunlight, the surface temperature of the ZnIn2S4 / WC composite material can reach 96 °C, which is significantly higher than that of pure ZnIn2S4 nanosheets. This result shows that tungsten carbide with LSPR effect has a strong photothermal effect, which can increase the local temperature of the catalyst in a short time under light conditions, thereby improving the photocatalytic performance of the composite material.

[0041] The photocatalytic decomposition of water to produce hydrogen coupled with the selective oxidation of benzyl alcohol of the prepared catalyst was tested, and the specific steps included: Step 1, add deionized water into the photocatalytic reactor, then add the ZnIn2S4 nanosheet photocatalyst modified with tungsten carbide quantum dots, and then add benzyl alcohol, the catalyst dosage is 20 mg, the benzyl alcohol content is 7 mL, and ultrasonic dispersion is performed evenly; Step 2, sealing and degassing the reactor to ensure that the reactor is in a negative pressure state; Step 3: Use a xenon lamp equipped with an AM1.5G filter to illuminate the reactor. Use a 300 W xenon lamp equipped with an AM1.5G filter as a light source, and add an agitator and condensed water to prepare benzaldehyde and hydrogen.

[0042] The results are as follows Figure 5As shown in Figure 2, under simulated sunlight conditions, the rates of hydrogen production and benzaldehyde production by photocatalytic water decomposition of ZnIn2S4 / WC composites were 12.58 and 10.53 mmol g -1 h -1 , much higher than pure ZnIn2S4 nanoparticles (1.43 and 0.98mmol g -1 h -1 ).and Figure 6 The conversion rate and selectivity of benzaldehyde of ZnIn2S4 / WC composite material are as high as 85.34% and 96.53%. The improvement factor and selectivity of the present invention are higher than those of most ZnIn2S4-based composite materials. The prepared ZnIn2S4 / WC composite material is subjected to a cycle test, and the result is shown in Figure 7. In the test of 5 cycles with one cycle every 3 hours, the photocatalytic activity of ZnIn2S4 / WC composite material does not decrease significantly during the cycle, which proves that it has good photocatalytic stability and is suitable for large-scale application.

[0043] The above contents are only preferred examples of the present invention, but the present invention should not be limited to the contents disclosed in the examples. Therefore, any equivalent or modified contents completed without departing from the spirit disclosed in the present invention shall fall within the scope of protection of the present invention.

Claims

1. A tungsten carbide quantum dot modified ZnIn2S4 nanosheet photocatalyst, characterized in that: Using ZnIn2S4 nanosheets as the main catalyst and tungsten carbide quantum dots as co-catalysts, hydrothermal synthesis was used to achieve uniform loading of tungsten carbide quantum dots on the surface of ZnIn2S4 nanosheets to form a ZnIn2S4 / WC photocatalyst. The XRD data of the ZnIn2S4 / WC photocatalyst had peaks at 2-Theta of 21.59, 27.69, 30.45, 39.78, 47.18, and 52.

44.

2. The tungsten carbide quantum dot modified ZnIn2S4 nanosheet photocatalyst according to claim 1, characterized in that: The mass percentage of the tungsten carbide is 7% to 20%.

3. A method for preparing a tungsten carbide quantum dot modified ZnIn2S4 nanosheet photocatalyst, characterized in that: The method comprises the following steps: Step 1, preparation of tungsten carbide quantum dots: a certain proportion of ammonium metatungstate and dicyandiamide are mixed, and tungsten carbide quantum dots are obtained by long-term grinding and high-temperature calcination; Step 2, preparation of ZnIn2S4 nanosheet photocatalyst modified with tungsten carbide quantum dots: first, uniformly disperse the tungsten carbide quantum dots in anhydrous methanol by ultrasound, then add zinc chloride and zinc chloride tetrahydrate and stir, add thioacetamide after sufficient stirring, stir evenly, and then perform a solvothermal reaction to obtain the ZnIn2S4 nanosheet photocatalyst modified with tungsten carbide quantum dots.

4. The method for preparing a tungsten carbide quantum dot modified ZnIn2S4 nanosheet photocatalyst according to claim 3, characterized in that: In step 1, the mass ratio of ammonium metatungstate to dicyandiamide is 0.3-5.0; the physical grinding time is 15-25 min; the calcination conditions are: first, starting from room temperature at 1-2 ° C min -1 The heating rate is heated to 300-400 ℃, and then 5-10 ℃ min -1 The heating rate is heated to 800-900 ℃.

5. The method for preparing a tungsten carbide quantum dot modified ZnIn2S4 nanosheet photocatalyst according to claim 3, characterized in that: In step 3, the mass ratio of the tungsten carbide nanoparticles, zinc chloride, indium chloride tetrahydrate, and thioacetamide is 2-6:10-15:50-60:30-35.

6. The method for preparing a tungsten carbide quantum dot modified ZnIn2S4 nanosheet photocatalyst according to claim 2, characterized in that: In step 3, the ultrasonic power is 200-500 W, the ultrasonic time is 20-40 min, the oil bath temperature is 90-150 ° C, the vigorous stirring time under constant temperature conditions is 90-150 min, and the product is obtained after vacuum drying.

7. An application of a ZnIn2S4 nanosheet photocatalyst modified with tungsten carbide quantum dots prepared by the method according to any one of claims 1 to 2 or claims 3 to 6 in a photocatalytic reaction.

8. The use of the tungsten carbide quantum dot-modified ZnIn2S4 nanosheet photocatalyst in a photocatalytic reaction according to claim 7, characterized in that: The tungsten carbide quantum dot-modified ZnIn2S4 nanosheet photocatalyst is used for photocatalytic oxidation of benzyl alcohol to generate benzaldehyde and coupled hydrogen production.

9. The use of the tungsten carbide quantum dot-modified ZnIn2S4 nanosheet photocatalyst in a photocatalytic reaction according to claim 7, characterized in that: The specific steps of using the tungsten carbide quantum dot-modified ZnIn2S4 nanosheet photocatalyst for photocatalytic water decomposition to produce hydrogen coupled with selective oxidation of benzyl alcohol include: Step 1, adding a certain amount of water into a photocatalytic reactor, then adding ZnIn2S4 nanosheet photocatalyst modified with tungsten carbide quantum dots, and then adding benzyl alcohol, and uniformly dispersing by ultrasonication; Step 2, sealing and degassing the reactor to ensure that the reactor is in a negative pressure state; Step 3: Use a xenon lamp equipped with an AM1.5G filter to illuminate the reactor, and add an agitator and condensed water to prepare benzaldehyde and hydrogen.

10. A catalyst for photocatalytic oxidation of benzyl alcohol to generate benzaldehyde coupled with hydrogen production, characterized in that: The invention comprises the catalyst according to claim 1 or 2, or the catalyst prepared by the method according to any one of claims 3 to 7.

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