CdS-MSB photocatalytic composite material with selectively anchored crystal face as well as preparation method and application of CdS-MSB photocatalytic composite material

Abstract

The invention discloses a CdS-MSB photocatalytic composite material with selectively anchored crystal faces and a preparation method and application thereof, and belongs to the technical field of photocatalytic materials and new energy. A microwave-assisted solvothermal synthesis technology is adopted, MSB clusters are uniformly dispersed in a CdS precursor solution, nucleation and grain growth of CdS crystals are accelerated by means of a rapid polarization effect of a microwave field, meanwhile, through selective adsorption and coordination effects of the MSB clusters on a (002) crystal face of CdS, the growth kinetics process of the CdS crystals is regulated and controlled, preferred growth of CdS in the [001] crystal orientation is inhibited, and the CdS / MSB / CdS composite material is obtained. The directional adjustment of the ratio of the exposed crystal face of the CdS crystal is realized, so that the CdS-MSB photocatalytic composite material with a stable structure and controllable crystal face orientation is obtained. The photocatalytic composite material can be applied to the field of hydrogen production by photocatalytic water decomposition driven by solar energy, and shows relatively high catalytic activity and good stability.

Description

Technical Field

[0001] This invention belongs to the field of photocatalytic materials and new energy technology, specifically relating to a CdS-MSB photocatalytic composite material with selectively anchored crystal planes, as well as the preparation method of the material and its application in visible light-driven photocatalytic water splitting for hydrogen production. Background Technology

[0002] Photocatalytic water splitting for hydrogen production is considered one of the important ways to achieve efficient conversion of solar energy into chemical energy. Among them, cadmium sulfide (CdS) has received widespread attention in the field of photocatalytic hydrogen production due to its moderate band gap (about 2.4 eV), good response to visible light, and relatively mature preparation process. However, existing CdS photocatalytic materials still face the following key problems in practical applications: (1) the recombination rate of photogenerated electrons and holes is fast, and the quantum efficiency is low; (2) photocorrosion reaction is prone to occur under light conditions, resulting in rapid decay of catalytic activity; (3) traditional co-catalytic components are mostly loaded on the CdS surface in a random and non-selective manner, and the interfacial bonding mode is mainly physical adsorption, resulting in low interfacial charge transport efficiency and insufficient structural stability.

[0003] Recent studies have shown that specific crystal facets of semiconductors exhibit significant differences in surface atomic arrangement, electronic structure, and reactivity. If specific crystal facets of CdS can be selectively manipulated and a stable co-catalytic interface structure can be constructed on these facets, it will facilitate the directional migration and efficient separation of photogenerated carriers. However, current research on the selective loading of co-catalytic components onto CdS crystal facets remains limited, and a simple, controllable, and scalable technical solution is still lacking. Summary of the Invention

[0004] The purpose of this invention is to provide a CdS-MSB photocatalytic composite material with selectively anchored crystal planes. By introducing MSB clusters during the growth of CdS crystals, they are selectively anchored to the (002) crystal plane region of CdS, and a stable interfacial bonding structure is constructed between CdS and MSB clusters. This effectively regulates the crystal growth behavior of CdS, improves the separation and transport process of photogenerated carriers, enhances the photocatalytic hydrogen production activity, and strengthens the structural stability and resistance to photocorrosion of the material.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A crystal plane selectively anchored CdS-MSB photocatalytic composite material is composed of a hexagonal CdS semiconductor matrix and MSB clusters. The chemical formula of the MSB clusters is (NH4)2[Mo3S7(Br2)3]. The MSB clusters are loaded on the CdS surface and anchored to the (002) crystal plane region of CdS, thereby constructing a stable interfacial bonding structure between CdS and MSB clusters.

[0007] Furthermore, the MSB clusters remove Br - The coordination vacancies formed afterward and the cluster's own S 2- The sites are respectively related to the S on the surface of the CdS crystal. 2- Site and Cd 2+ The active sites undergo bidirectional coordination, forming S→Mo and S→Cd coordination bonds, thereby enabling the MSB clusters to be firmly anchored on the (002) crystal plane of CdS and constructing a stable interfacial bonding structure.

[0008] Furthermore, the coordination anchoring interface structure formed between the CdS and MSB clusters facilitates the electron transport interface for the migration of photogenerated electrons from CdS to MSB clusters.

[0009] Furthermore, when the MSB clusters are selectively anchored to the (002) crystal plane of CdS, the preferred growth of CdS crystals along the

[001] crystal orientation is suppressed.

[0010] Another objective of this invention is to provide a method for preparing a CdS-MSB photocatalytic composite material with selectively anchored crystal planes. First, microwave-assisted solvothermal synthesis technology is used to uniformly disperse MSB clusters in a CdS precursor solution. The rapid polarization effect of the microwave field accelerates the nucleation and grain growth of CdS crystals. At the same time, the selective adsorption and coordination of MSB clusters on the (002) crystal plane of CdS regulates the growth kinetics of CdS crystals, inhibits the preferred growth of CdS along the

[001] crystal direction, and realizes the directional adjustment of the proportion of exposed crystal planes of CdS crystals, thereby obtaining a CdS-MSB photocatalytic composite material with stable structure and controllable crystal plane orientation.

[0011] Furthermore, the preparation method includes the following steps:

[0012] (1) Preparation of (NH4)2[Mo3S7(S2)3] clusters (MS):

[0013] Weigh 25.2 g of sulfur powder and add it to 120 mL of (NH4)2S solution, dissolving it under stirring. Then, slowly add the solution to 30 mL of a solution with a concentration of 0.2 g / mL. -1 (NH4)6Mo7O 24The reaction mixture was obtained in an aqueous solution; the reaction mixture was placed at 90 °C for 20 h; after the reaction was completed, the precipitate was collected, washed and dried to obtain (NH4)2[Mo3S7(S2)3] clusters, denoted as MS;

[0014] (2) Preparation of (NH4)2[Mo3S7(Br2)3] cluster (MSB):

[0015] Weigh 6 g of the MS cluster and add it to 50 mL of hydrobromic acid solution. React under reflux for 3 h. Filter the resulting reaction mixture into a container containing 6 g of tetraethylammonium bromide and let it stand at 4 °C for 12 h. Wash and dry the precipitate obtained by filtration to obtain (NH4)2[Mo3S7(Br2)3] cluster, denoted as MSB.

[0016] (3) Preparation of photocatalytic composite materials:

[0017] 0.4 mmol of cadmium acetate dihydrate and 1.0 mmol of thiourea were dissolved in deionized water and magnetically stirred for 30 min to obtain a clear precursor solution. Then, 0.1 mL of ethylenediamine was slowly added dropwise and stirring was continued for 5 h to allow the system to fully complex. 30–90 mg of MSB cluster powder was dispersed in 3 mL of DMF and sonicated for 30 min to form a uniform MSB dispersion. The MSB dispersion was added dropwise to the above complexed system solution and stirring was continued for 5 h. The mixed solution was placed in a microwave synthesizer for reaction. After the reaction was completed, the mixture was washed and dried to obtain the CdS-MSB photocatalytic composite material.

[0018] As a preferred technical solution of the present invention, the microwave reaction power in step (3) is 200 W, the reaction temperature is 90℃, and the reaction time is 15~30 min.

[0019] In addition, this invention also proposes an application of the CdS-MSB photocatalytic composite material in visible light-driven photocatalytic water splitting for hydrogen production.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0021] (1) By leveraging the coordination anchoring behavior of MSB clusters on specific crystal planes of CdS, the co-catalytic components can be stably bonded to the CdS(002) crystal plane, thus avoiding random distribution and agglomeration;

[0022] (2) A stable coordination anchoring interface structure is formed between CdS and MSB clusters, which provides an effective channel for photogenerated electrons to migrate from CdS to MSB clusters and improves the utilization efficiency of photogenerated carriers.

[0023] (3) MSB clusters play a regulatory role in the growth behavior of CdS crystals, which helps to suppress the preferential growth of CdS along specific crystal orientations and obtain CdS matrix structures with controllable crystal orientation.

[0024] (4) The obtained photocatalytic composite material exhibits high catalytic activity and good structural stability in the photocatalytic water splitting hydrogen production process, and is suitable for solar-driven photocatalytic hydrogen production systems. Attached Figure Description

[0025] Figure 1 The X-ray diffraction (XRD) patterns of pure CdS, CdS-MSB-x with different MSB additions (a), and MSB samples (b) are used to characterize the crystal structure features and the changes in crystal plane diffraction peaks of the materials.

[0026] Figure 2 Scanning electron microscope (SEM) images of pure CdS (a) and CdS-MSB-3 sample (b) are used to compare the morphological characteristics of the materials before and after the introduction of MSB.

[0027] Figure 3 The images show transmission electron microscopy (TEM) images and elemental distribution maps of the CdS-MSB-3 sample. Images (a), (b), and (c) are TEM images at different magnifications, image (d) is a scanning transmission electron microscopy image under dark field conditions, and images (e), (f), (g), and (h) are the elemental distribution maps of Cd, S, Mo, and Br, respectively, used to characterize the distribution of MSB clusters on the CdS surface and the interfacial bonding state.

[0028] Figure 4 The photocatalytic hydrogen production performance test results are shown for MSB, pure CdS, and CdS-MSB composites with different component ratios. (a) is the curve of hydrogen production as a function of reaction time, and (b) is the corresponding comparison graph of hydrogen production rate. Detailed Implementation

[0029] The present invention will be further described in detail below with reference to the embodiments and accompanying drawings.

[0030] Example 1

[0031] (1) Preparation of (NH4)2[Mo3S7(S2)3] clusters (MS)

[0032] 25.2 g of sulfur powder was weighed and added to 120 mL of (NH4)2S solution. The solution was dissolved under stirring to obtain a bright red solution. Then, the solution was slowly added to 30 mL of a solution with a concentration of 0.2 g / mL. -1 hot (NH4)6Mo7O 24In aqueous solution, the system rapidly turns deep red. The resulting reaction mixture was reacted at 90 °C for 20 h. After the reaction was complete, the mixture was cooled to room temperature, and the resulting red precipitate was collected and washed successively with deionized water, anhydrous ethanol, carbon disulfide, and diethyl ether. Finally, the washed product was dried in air at 60 °C to obtain a red powder, which is the (NH4)2[Mo3S7(S2)3] cluster, denoted as MS.

[0033] (2) Preparation of (NH4)2[Mo3S7(Br2)3] cluster (MSB)

[0034] 6 g of the MS cluster was weighed and added to 50 mL of hydrobromic acid solution. The mixture was reacted under reflux for 3 h to obtain a red reaction mixture. The resulting reaction mixture was filtered into a container containing 6 g of tetraethylammonium bromide and stored at 4 °C. After 12 h, it was filtered again to obtain an orange precipitate, which was repeatedly washed with deionized water. Finally, the product was dried under vacuum at 60 °C to obtain an orange powder, which is the (NH4)2[Mo3S7(Br2)3] cluster, denoted as MSB.

[0035] (3) Preparation of photocatalytic composite materials

[0036] 0.4 mmol of cadmium acetate dihydrate and 1.0 mmol of thiourea were dissolved in 50 mL of deionized water and magnetically stirred for 30 min to obtain a clear precursor solution. Then, 0.1 mL of ethylenediamine was slowly added dropwise, and stirring continued for 5 h to allow for complete complexation. Simultaneously, 30 mg of MSB powder was dispersed in 3 mL of DMF and sonicated for 30 min to form a homogeneous dispersion. The MSB dispersion was added dropwise to the complexed solution, and stirring continued for 5 h. The mixture was then transferred to a microwave synthesizer and microwaved at 200 W power and 90 °C for 15 min. After the reaction, the mixture was allowed to cool naturally to room temperature and washed three times, sequentially with anhydrous ethanol and deionized water (8000 rpm, 7 min), by centrifugation to remove residual impurities. The final product was dried in a vacuum oven at 60 °C for 8 h to obtain the CdS-MSB-1 photocatalytic composite material.

[0037] Example 2

[0038] (1) Preparation of (NH4)2[Mo3S7(S2)3] clusters (MS)

[0039] 25.2 g of sulfur powder was weighed and added to 120 mL of (NH4)2S solution. The solution was dissolved under stirring to obtain a bright red solution. Then, the solution was slowly added to 30 mL of a solution with a concentration of 0.2 g / mL. -1 hot (NH4)6Mo7O24 In aqueous solution, the system rapidly turns deep red. The resulting reaction mixture was reacted at 90 °C for 20 h. After the reaction was complete, the mixture was cooled to room temperature, and the resulting red precipitate was collected and washed successively with deionized water, anhydrous ethanol, carbon disulfide, and diethyl ether. Finally, the washed product was dried in air at 60 °C to obtain a red powder, which is the (NH4)2[Mo3S7(S2)3] cluster, denoted as MS.

[0040] (2) Preparation of (NH4)2[Mo3S7(Br2)3] cluster (MSB)

[0041] 6 g of the MS cluster was weighed and added to 50 mL of hydrobromic acid solution. The mixture was reacted under reflux for 3 h to obtain a red reaction mixture. The resulting reaction mixture was filtered into a container containing 6 g of tetraethylammonium bromide and stored at 4 °C. After 12 h, it was filtered again to obtain an orange precipitate, which was repeatedly washed with deionized water. Finally, the product was dried under vacuum at 60 °C to obtain an orange powder, which is the (NH4)2[Mo3S7(Br2)3] cluster, denoted as MSB.

[0042] (3) Preparation of photocatalytic composite materials

[0043] 0.4 mmol of cadmium acetate dihydrate and 1.0 mmol of thiourea were dissolved in 50 mL of deionized water and stirred magnetically for 50 min to obtain a clear precursor solution. Then, 0.1 mL of ethylenediamine was slowly added dropwise, and stirring continued for 5 h to allow the system to fully complex. Simultaneously, 50 mg of MSB powder was dispersed in 3 mL of DMF and sonicated for 30 min to form a homogeneous dispersion. The MSB dispersion was added dropwise to the complexed system solution, and stirring continued for 5 h. The mixture was then transferred to a microwave synthesizer and microwaved at 200 W power and 90 °C for 15 min. After the reaction, the mixture was allowed to cool naturally to room temperature and washed three times, sequentially with anhydrous ethanol and deionized water (8000 rpm, 7 min), by centrifugation to remove residual impurities. The final product was dried in a vacuum drying oven at 60 °C for 8 h to obtain the CdS-MSB-2 photocatalytic composite material.

[0044] Example 3

[0045] (1) Preparation of (NH4)2[Mo3S7(S2)3] clusters (MS)

[0046] 25.2 g of sulfur powder was weighed and added to 120 mL of (NH4)2S solution. The solution was dissolved under stirring to obtain a bright red solution. Then, the solution was slowly added to 30 mL of a solution with a concentration of 0.2 g / mL. -1hot (NH4)6Mo7O 24 In aqueous solution, the system rapidly turns deep red. The resulting reaction mixture was reacted at 90 °C for 20 h. After the reaction was complete, the mixture was cooled to room temperature, and the resulting red precipitate was collected and washed successively with deionized water, anhydrous ethanol, carbon disulfide, and diethyl ether. Finally, the washed product was dried in air at 60 °C to obtain a red powder, which is the (NH4)2[Mo3S7(S2)3] cluster, denoted as MS.

[0047] (2) Preparation of (NH4)2[Mo3S7(Br2)3] cluster (MSB)

[0048] 6 g of the MS cluster was weighed and added to 50 mL of hydrobromic acid solution. The mixture was reacted under reflux for 3 h to obtain a red reaction mixture. The resulting reaction mixture was filtered into a container containing 6 g of tetraethylammonium bromide and stored at 4 °C. After 12 h, it was filtered again to obtain an orange precipitate, which was repeatedly washed with deionized water. Finally, the product was dried under vacuum at 60 °C to obtain an orange powder, which is the (NH4)2[Mo3S7(Br2)3] cluster, denoted as MSB.

[0049] (3) Preparation of photocatalytic composite materials

[0050] 0.4 mmol of cadmium acetate dihydrate and 1.0 mmol of thiourea were dissolved in 50 mL of deionized water and magnetically stirred for 50 min to obtain a clear precursor solution. Then, 0.1 mL of ethylenediamine was slowly added dropwise, and stirring continued for 5 h to allow the system to fully complex. Simultaneously, 70 mg of MSB powder was dispersed in 3 mL of DMF and sonicated for 30 min to form a homogeneous dispersion. The MSB dispersion was added dropwise to the complexed system solution, and stirring continued for 5 h. The mixture was then transferred to a microwave synthesizer and microwaved at 200 W power and 90 °C for 15 min. After the reaction, the mixture was allowed to cool naturally to room temperature and washed three times, sequentially with anhydrous ethanol and deionized water (8000 rpm, 7 min), by centrifugation to remove residual impurities. The final product was dried in a vacuum drying oven at 60 °C for 8 h to obtain the CdS-MSB-3 photocatalytic composite material.

[0051] Example 4

[0052] (1) Preparation of (NH4)2[Mo3S7(S2)3] clusters (MS)

[0053] 25.2 g of sulfur powder was weighed and added to 120 mL of (NH4)2S solution. The solution was dissolved under stirring to obtain a bright red solution. Then, the solution was slowly added to 30 mL of a solution with a concentration of 0.2 g / mL.-1 hot (NH4)6Mo7O 24 In aqueous solution, the system rapidly turns deep red. The resulting reaction mixture was reacted at 90 °C for 20 h. After the reaction was complete, the mixture was cooled to room temperature, and the resulting red precipitate was collected and washed successively with deionized water, anhydrous ethanol, carbon disulfide, and diethyl ether. Finally, the washed product was dried in air at 60 °C to obtain a red powder, which is the (NH4)2[Mo3S7(S2)3] cluster, denoted as MS.

[0054] (2) Preparation of (NH4)2[Mo3S7(Br2)3] cluster (MSB)

[0055] 6 g of the MS cluster was weighed and added to 50 mL of hydrobromic acid solution. The mixture was reacted under reflux for 3 h to obtain a red reaction mixture. The resulting reaction mixture was filtered into a container containing 6 g of tetraethylammonium bromide and stored at 4 °C. After 12 h, it was filtered again to obtain an orange precipitate, which was repeatedly washed with deionized water. Finally, the product was dried under vacuum at 60 °C to obtain an orange powder, which is the (NH4)2[Mo3S7(Br2)3] cluster, denoted as MSB.

[0056] (3) Preparation of photocatalytic composite materials

[0057] 0.4 mmol of cadmium acetate dihydrate and 1.0 mmol of thiourea were dissolved in 50 mL of deionized water and magnetically stirred for 50 min to obtain a clear precursor solution. Then, 0.1 mL of ethylenediamine was slowly added dropwise, and stirring continued for 5 h to allow the system to fully complex. Simultaneously, 90 mg of MSB powder was dispersed in 3 mL of DMF and sonicated for 30 min to form a homogeneous dispersion. The MSB dispersion was added dropwise to the complexed system solution, and stirring continued for 5 h. The mixture was then transferred to a microwave synthesizer and microwaved at 200 W power and 90 °C for 15 min. After the reaction, the mixture was allowed to cool naturally to room temperature and washed three times, sequentially with anhydrous ethanol and deionized water (8000 rpm, 7 min), by centrifugation to remove residual impurities. The final product was dried in a vacuum drying oven at 60 °C for 8 h to obtain the CdS-MSB-4 photocatalytic composite material.

[0058] Table 1. Hydrogen production performance of CdS-MSB photocatalytic composite material under different MSB addition levels.

[0059] Sample number MSB addition amount (mg) <![CDATA[H2 rate (mmol·g -1 ·h -1 )]]> The improvement factor compared to pure CdS Pure CdS 0 0.11 1.0 CdS-MSB-1 30 1.25 11.4 CdS-MSB-2 50 2.0 24.5 CdS-MSB-3 70 4.62 42.0 CdS-MSB-4 90 3.85 35.0

[0060] As shown in Table 1, the hydrogen production performance of the prepared CdS-MSB photocatalytic composite material first increases and then decreases with the increase of MSB addition. Among them, the sample prepared under the appropriate MSB addition conditions exhibits the best photocatalytic hydrogen production activity.

[0061] Analysis of structural characterization results:

[0062] The crystal structure of the prepared CdS-MSB photocatalytic composite material was analyzed by X-ray diffraction (XRD). Figure 1 The results show that the diffraction peaks of each sample are consistent with the standard diffraction characteristics of CdS, and no new impurity phase diffraction peaks were observed, indicating that the introduction of MSB clusters did not disrupt the main crystal structure of CdS. Compared with pure CdS, the intensity of the (002) crystal plane diffraction peak of CdS in the CdS-MSB sample was significantly weakened, indicating that MSB clusters had a significant regulatory effect on the crystal growth behavior of CdS during the growth process. During the formation of CdS crystals, MSB clusters preferentially act on the (002) crystal plane region of CdS, inhibiting the growth of CdS. 2+ With S 2- The continuous stacking along the direction of the crystal plane restricts the preferential growth of CdS along the

[001] direction, resulting in a reduction in crystal size and a redistribution of the crystal plane exposure ratio, so that the (002) crystal plane is in a stable exposed or surface passivated state.

[0063] The morphological characteristics of the prepared CdS-MSB photocatalytic composite material were observed using scanning electron microscopy (SEM). Figure 2 The results show that the CdS-MSB photocatalytic composite material prepared in Example 3 has a relatively uniform particle distribution and no obvious severe agglomeration. Transmission electron microscopy (TEM) and elemental distribution analysis results are as follows: Figure 3 Further evidence shows that MSB clusters are uniformly distributed on the CdS surface and maintain close contact with the CdS matrix, with no obvious phase separation observed, indicating that a stable interfacial bonding structure is formed between the MSB clusters and CdS.

[0064] Performance description of photocatalytic hydrogen production:

[0065] The photocatalytic hydrogen production performance of the prepared CdS-MSB photocatalytic composite material was tested. Figure 4 The results show that, compared with pure CdS material, the CdS-MSB photocatalytic composite material with introduced MSB clusters exhibits significantly improved hydrogen production activity. This performance improvement is mainly attributed to the crystal-plane selective anchoring of MSB clusters on the CdS surface and their synergistic regulation of interface structure and crystal growth behavior.

[0066] In summary, the innovative aspects of the crystal-plane-selectively anchored CdS-MSB photocatalytic composite material proposed in this invention are reflected in the following aspects:

[0067] (1) The photocatalytic composite material includes a CdS semiconductor matrix and MSB clusters, wherein the MSB clusters are selectively anchored to the (002) crystal plane region of CdS through chemical interaction during the material preparation process, forming a stable interface bonding structure between CdS and MSB clusters.

[0068] (2) Removal of Br from the MSB cluster - The coordination vacancies formed afterward and the cluster's own S 2- The sites are respectively related to the S on the surface of the CdS crystal. 2- Site and Cd 2+ The active sites undergo bidirectional coordination, forming S→Mo and S→Cd coordination bonds, thereby enabling the MSB clusters to be firmly anchored on the (002) crystal plane of CdS.

[0069] (3) The introduction of the MSB cluster can regulate the crystal growth behavior of CdS, suppress its preferential growth along the

[001] direction, change the exposure ratio of CdS crystal plane, and help form a CdS matrix with stable structure and higher surface activity.

Claims

1. A crystal-plane selectively anchored CdS-MSB photocatalytic composite material, characterized in that, The CdS-MSB photocatalytic composite material consists of a hexagonal CdS semiconductor matrix and MSB clusters. The chemical formula of the MSB clusters is (NH4)2[Mo3S7(Br2)3]. The MSB clusters are loaded on the CdS surface and anchored to the (002) crystal plane region of CdS, thereby constructing a stable interfacial bonding structure between CdS and MSB clusters.

2. The CdS-MSB photocatalytic composite material with selectively anchored crystal planes as described in claim 1, characterized in that, The MSB clusters remove Br - The coordination vacancies formed afterward and the cluster's own S 2- The sites are respectively related to the S on the surface of the CdS crystal. 2- Site and Cd 2+ The active sites undergo bidirectional coordination, forming S→Mo and S→Cd coordination bonds, thereby enabling the MSB clusters to be firmly anchored on the (002) crystal plane of CdS and constructing a stable interfacial bonding structure.

3. The CdS-MSB photocatalytic composite material with selectively anchored crystal planes as described in claim 1 or 2, characterized in that, The coordination anchoring interface structure formed between the CdS and MSB clusters facilitates the electron transport interface for the migration of photogenerated electrons from CdS to MSB clusters.

4. The CdS-MSB photocatalytic composite material with selectively anchored crystal planes as described in claim 1 or 2, characterized in that, When the MSB clusters are selectively anchored to the (002) crystal plane of CdS, the preferred growth of CdS crystals along the [001] crystal orientation is suppressed.

5. A method for preparing the CdS-MSB photocatalytic composite material as described in any one of claims 1 to 4, characterized in that, First, microwave-assisted solvothermal synthesis technology is used to uniformly disperse MSB clusters in CdS precursor solution. The rapid polarization effect of microwave field accelerates the nucleation and grain growth of CdS crystals. At the same time, the selective adsorption and coordination of MSB clusters on the (002) crystal plane of CdS regulates the growth kinetics of CdS crystals, inhibits the preferred growth of CdS along the [001] crystal direction, and realizes the directional adjustment of the exposed crystal plane ratio of CdS crystals. In this way, a CdS-MSB photocatalytic composite material with stable structure and controllable crystal plane orientation is obtained.

6. The preparation method according to claim 5, characterized in that, Includes the following steps: (1) Preparation of (NH4)2[Mo3S7(S2)3] clusters (MS): Weigh 25.2 g of sulfur powder and add it to 120 mL of (NH4)2S solution, dissolving it under stirring. Then, slowly add the solution to 30 mL of a solution with a concentration of 0.2 g / mL. -1 (NH4)6Mo7O 24 The reaction mixture was obtained in an aqueous solution; the reaction mixture was placed at 90 °C for 20 h; after the reaction was completed, the precipitate was collected, washed and dried to obtain (NH4)2[Mo3S7(S2)3] clusters, denoted as MS; (2) Preparation of (NH4)2[Mo3S7(Br2)3] cluster (MSB): Weigh 6 g of the MS cluster and add it to 50 mL of hydrobromic acid solution. React under reflux for 3 h. Filter the resulting reaction mixture into a container containing 6 g of tetraethylammonium bromide and let it stand at 4 °C for 12 h. Wash and dry the precipitate obtained by filtration to obtain (NH4)2[Mo3S7(Br2)3] cluster, denoted as MSB. (3) Preparation of photocatalytic composite materials: 0.4 mmol of cadmium acetate dihydrate and 1.0 mmol of thiourea were dissolved in deionized water and magnetically stirred for 30 min to obtain a clear precursor solution. Then, 0.1 mL of ethylenediamine was slowly added dropwise and stirring was continued for 5 h to allow the system to fully complex. 30–90 mg of MSB cluster powder was dispersed in 3 mL of DMF and sonicated for 30 min to form a uniform MSB dispersion. The MSB dispersion was added dropwise to the above complexed system solution and stirring was continued for 5 h. The mixed solution was placed in a microwave synthesizer for reaction. After the reaction was completed, the mixture was washed and dried to obtain the CdS-MSB photocatalytic composite material.

7. The preparation method according to claim 6, characterized in that, In step (3), the microwave reaction power is 200 W, the reaction temperature is 90 ℃, and the reaction time is 15~30 min.

8. The application of the CdS-MSB photocatalytic composite material as described in any one of claims 1 to 4 in visible light-driven photocatalytic water splitting for hydrogen production.

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