Preparation method and application of molybdenum disulfide / cadmium zinc sulfide composite photocatalyst
By coating the ultra-thin nanosheets of molybdenum disulfide disulfide nanorods on the zinc-cadmium sulfide nanorods, the problems of wide band gap and high photocarrier recombination rate of a single component photocatalyst are solved, and the photocatalytic hydrogen production performance and cycle stability are significantly improved.
Patent Information
- Application Number
- CN202411888044.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-20
- Publication Date
- 2025-05-06
AI Technical Summary
The wide band gap of a single-group photocatalyst and the high photogenerating electron-hole recombination rate limit their photocatalytic hydrogen production performance.
The zinc-cadmium sulfide nanorod is used as the substrate, and the outer layer is coated with molybdenum disulfide ultra-thin nanosheets to form a molybdenum disulfide/zin-cadmium sulfide composite photocatalyst. The composite photocatalyst was reacted through an autoclave for 24 hours, combined with ultrasonic dispersion and high-pressure reaction, and prepared a composite material with excellent photocatalytic properties.
The photocatalytic hydrogen production volume was significantly improved, and the photocatalytic hydrogen production volume reached 259.12 mmol·g-1 within 3 hours, and good cycle stability was maintained during the photocatalytic hydrogen production process.
Smart Images
Figure HDA0005199869980000011 
Figure HDA0005199869980000012 
Figure HDA0005199869980000013
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of photocatalysis, and in particular to a preparation method and application of a molybdenum disulfide / cadmium zinc sulfide composite photocatalyst. Background Art
[0002] Converting solar energy into hydrogen energy by photocatalytic water splitting is an effective and sustainable strategy to overcome the energy and environmental crisis. The development of efficient photocatalysts is the core of current research. Cadmium zinc sulfide photocatalysts have attracted widespread attention due to their excellent chemical stability, good band structure and visible light responsiveness. However, due to the high recombination rate of photogenerated carriers and severe photocorrosion, their practical applications are severely limited. Therefore, it is necessary to explore methods to improve their hydrogen evolution performance. Using two semiconductor materials to form a heterojunction is one of the common methods to improve the photocatalytic performance of photocatalysts. The formation of a heterojunction can promote the transfer of photogenerated carriers between the internal interfaces of the composite photocatalyst. Among many semiconductor materials, molybdenum disulfide nanosheets, as a typical two-dimensional material, have a large specific surface area, a narrow band gap and a high light energy utilization rate, and have therefore been widely studied.
[0003] Therefore, MoS2 nanosheets can be used to modify CdZnS to form heterojunction photocatalysts, thereby reducing the band gap, enhancing the light absorption capacity in the visible light region, and improving the ability to separate photogenerated electrons and holes, thereby effectively improving the photocatalytic hydrogen production performance of the photocatalyst.
[0004] In view of this, the present invention is proposed. Summary of the invention
[0005] In order to solve the problems of wide band gap of single-component photocatalyst and high recombination rate of photogenerated electrons and holes, the present invention provides a molybdenum disulfide / cadmium zinc sulfide composite photocatalyst obtained by using zinc cadmium sulfide nanorods as a substrate and coating an outer layer with molybdenum disulfide ultrathin nanosheets, and also provides a preparation method of the molybdenum disulfide / cadmium zinc sulfide composite photocatalyst and its application in photocatalytic hydrogen production.
[0006] The object of the present invention is to provide a method for preparing the above-mentioned molybdenum disulfide / cadmium zinc sulfide composite photocatalyst, which specifically comprises the following steps:
[0007] (1) Dissolve Zn(OAc)2·2H2O and Cd(OAc)2·2H2O in a mixed solution of deionized water and ethylenediamine, then add C2H5NS, stir evenly, and transfer to a high-pressure reactor to react for 24 hours. Centrifuge, wash, and dry in sequence to obtain zinc cadmium sulfide nanorods;
[0008] (2) Ultrasonic dispersion of the cadmium zinc sulfide in step (1) in deionized water, then dissolving Na2MoO4·2H2O and C2H5NS in the above solution, stirring evenly and transferring to a high-pressure reactor for reaction for 24 hours. After cooling to room temperature, the obtained product is centrifuged from the solution and washed several times with deionized water. Finally, the precipitate is dried to obtain a molybdenum disulfide / cadmium zinc sulfide composite photocatalyst.
[0009] Preferably, in step (1), the molar ratio of Zn(OAc)2·2H2O to Cd(OAc)2·2H2O is 1:(1-9).
[0010] Preferably, in step (1), the molar ratio of metal ions to C2H5NS is 1:(1.25-2.5).
[0011] Preferably, in step (1), the heating temperature of the reaction is 220° C., and the heating rate is 5° C. / min.
[0012] Preferably, in step (2), the content of cadmium zinc sulfide nanorods is 0.5-1 g / L.
[0013] Preferably, in the step (2), the mass ratio of Na2MoO4·2H2O to C2H5NS is 1:2.
[0014] Preferably, in step (2), the heating temperature of the reaction is 180-220° C., and the heating rate is 5° C. / min.
[0015] Another object of the present invention is to provide the use of the above-mentioned molybdenum disulfide / cadmium zinc sulfide composite photocatalyst in photocatalytic water splitting to produce hydrogen. The photocatalytic water splitting to produce hydrogen test is carried out in an all-glass automatic online trace gas analysis system (Labsolar-6A), wherein the light source is a 300W xenon lamp (MICROSOLAR300), the sacrificial agents are anhydrous Na2SO3 and Na2S·9H2O, the molybdenum disulfide / cadmium zinc sulfide composite photocatalyst is dispersed in the system as a photocatalyst, and the hydrogen evolution content is determined by online gas chromatography (GC-7806).
[0016] Compared with the prior art, the raw materials used in the preparation method of the molybdenum disulfide / cadmium zinc sulfide composite photocatalyst provided by the present invention are easy to obtain, the production cost is low, and the preparation process is simple. The molybdenum disulfide / cadmium zinc sulfide composite photocatalyst prepared by the present invention was subjected to a photocatalytic hydrogen production experiment, and its photocatalytic hydrogen production was significantly improved, and the photocatalytic hydrogen production in 3 hours could reach 259.12mmol·g -1 , and the material can maintain good cycle stability during photocatalytic hydrogen production. BRIEF DESCRIPTION OF THE DRAWINGS
[0017] Figure 1 This is a scanning electron microscope photograph of the zinc cadmium sulfide nanorods prepared in Example 1.
[0018] Figure 2 This is a scanning electron microscope photograph of the molybdenum disulfide / cadmium zinc sulfide composite photocatalyst prepared in Example 3.
[0019] Figure 3 This is the X-ray diffraction pattern of the molybdenum disulfide / cadmium zinc sulfide composite photocatalyst prepared in Example 3.
[0020] Figure 4 The photocatalytic hydrogen production of the catalyst materials prepared in Examples 1, 2 and 3. DETAILED DESCRIPTION
[0021] The present invention will be further described below in conjunction with specific embodiments:
[0022] Example 1
[0023] This embodiment provides a method for preparing zinc cadmium sulfide nanorods, comprising the following steps:
[0024] 18mmol Cd(OAc)2·2H2O and 2mmol Zn(OAc)2·2H2O were dissolved in a mixed solution of 30mL deionized water and 30mL ethylenediamine, and then 25mmol C2H5NS was added and stirred for 30min. The mixed solution was then transferred to a high-pressure reactor and reacted at 220°C for 24h with a heating rate of 5°C / min. After cooling to room temperature, the mixture was centrifuged, washed, and dried in sequence to obtain the zinc cadmium sulfide nanorods.
[0025] Example 2
[0026] This embodiment provides a method for preparing molybdenum disulfide nanosheets, comprising the following steps:
[0027] 0.045 g Na2MoO4·2H2O and 0.09 g C2H5NS were dissolved in 20 mL deionized water, stirred evenly, transferred to a high-pressure reactor, and reacted at 220° C. for 24 h at a heating rate of 5° C. / min. After cooling to room temperature, centrifugation, washing, and drying were performed in sequence to obtain the molybdenum disulfide nanosheets.
[0028] Example 3
[0029] This embodiment provides a method for preparing a molybdenum disulfide / cadmium zinc sulfide composite photocatalyst, comprising the following steps:
[0030] (1) 18 mmol Cd(OAc)2·2H2O and 2 mmol Zn(OAc)2·2H2O were dissolved in a mixed solution of 30 mL deionized water and 30 mL ethylenediamine, and then 25 mmol C2H5NS was added and stirred for 30 min. The mixed solution was then transferred to a high-pressure reactor and reacted at 220°C for 24 h at a heating rate of 5°C / min. After cooling to room temperature, the mixture was centrifuged, washed, and dried in sequence to obtain the zinc cadmium sulfide nanorods.
[0031] (2) 0.01 g of cadmium zinc sulfide nanorods were ultrasonically dispersed in 20 mL of deionized water, and then 0.045 g of Na2MoO4·2H2O and 0.09 g of C2H5NS were dissolved in the above solution, stirred for 15 min, and then transferred to a high-pressure reactor, reacted at 220°C for 24 h, and the heating rate was 5°C / min. After cooling to room temperature, the obtained product was centrifuged from the solution and washed several times with deionized water. Finally, the precipitate was dried to obtain the molybdenum disulfide / cadmium zinc sulfide composite photocatalyst.
[0032] The zinc cadmium sulfide nanorods prepared in Example 1 were tested by scanning electron microscopy. The test results are shown in Figure 1 As shown in the figure, cadmium zinc sulfide has a smooth rod-like structure with an average length of 1648.9nm and an average diameter of 92.7nm.
[0033] The molybdenum disulfide / cadmium zinc sulfide composite photocatalyst prepared in Example 3 was tested by scanning electron microscope. The test results are shown in Figure 2 , petal-shaped MoS2 nanosheets are uniformly coated on the surface of ZnCdS nanorods.
[0034] The cadmium zinc sulfide, molybdenum disulfide and molybdenum disulfide / cadmium zinc sulfide composite photocatalysts prepared in Examples 1, 2 and 3 were subjected to X-ray diffraction tests. Figure 3 As shown in the figure, in the X-ray diffraction spectrum of the MoS2 / CdZnS composite photocatalyst, diffraction peaks belonging to CdZnS and MoS2 were observed respectively, and no other impurity peaks were observed, indicating that CdZnS and MoS2 were successfully composited, and the coating of MoS2 had no effect on the crystal structure of CdZnS.
[0035] The photocatalytic hydrogen production performance of the catalyst materials prepared in Examples 1, 2 and 3 was tested. The specific method was as follows: 10 mg of photocatalyst was added to 100 mL of deionized water containing 0.35 M Na2S·9H2O and 0.25 M Na2SO3, and after complete ultrasonic dispersion, it was loaded into a 250 mL glass reactor. A 300 W xenon lamp was used as the light source, and the closed test system was evacuated for 30 minutes before irradiation to remove oxygen. In the photocatalytic hydrogen production test, the hydrogen production was determined by a gas chromatograph (GC-2014), and the photocatalytic hydrogen production rate was calculated based on the standard curve. The results are shown in Figure 4 , as shown in the figure:
[0036] 1. When the zinc cadmium sulfide prepared in Example 1 was used as the photocatalyst, the photocatalytic hydrogen production within 3 hours was 55.85 mmol·g -1 ;
[0037] 2. When the molybdenum disulfide prepared in Example 2 was used as the photocatalyst, the photocatalytic hydrogen production within 3 hours was 78.60 mmol·g -1 ;
[0038] 3. When the molybdenum disulfide / cadmium zinc sulfide prepared in Example 3 was used as the photocatalyst, the photocatalytic hydrogen production was significantly increased within 3 hours and reached 259.12 mmol·g -1 .
[0039] The above experimental results show that after the surface of cadmium zinc sulfide is modified with molybdenum disulfide, the photocatalytic hydrogen production yield is significantly improved, proving that the composite of cadmium zinc sulfide and molybdenum disulfide can effectively enhance the photocatalytic hydrogen production performance.
[0040] Example 4
[0041] This embodiment provides a method for preparing a molybdenum disulfide / cadmium zinc sulfide composite photocatalyst, comprising the following steps:
[0042] (1) 10 mmol Cd(OAc)2·2H2O and 10 mmol Zn(OAc)2·2H2O were dissolved in a mixed solution of 30 mL deionized water and 30 mL ethylenediamine, and then 25 mmol C2H5NS was added and stirred for 30 min. The mixed solution was then transferred to a high-pressure reactor and reacted at 220°C for 24 h at a heating rate of 5°C / min. After cooling to room temperature, the mixture was centrifuged, washed, and dried in sequence to obtain the zinc cadmium sulfide nanorods.
[0043] (2) 0.01 g of cadmium zinc sulfide nanorods were ultrasonically dispersed in 20 mL of deionized water. Then, 0.045 g of Na2MoO4·2H2O and 0.09 g of C2H5NS were dissolved in the above solution, stirred for 15 min, and then transferred to a high-pressure reactor for reaction at 220°C for 24 h at a heating rate of 5°C / min. After cooling to room temperature, the obtained product was centrifuged from the solution and washed several times with deionized water. Finally, the precipitate was dried to obtain the molybdenum disulfide / cadmium zinc sulfide composite photocatalyst.
[0044] Example 5
[0045] This embodiment provides a method for preparing a molybdenum disulfide / cadmium zinc sulfide composite photocatalyst, comprising the following steps:
[0046] (1) 18 mmol Cd(OAc)2·2H2O and 2 mmol Zn(OAc)2·2H2O were dissolved in a mixed solution of 30 mL deionized water and 30 mL ethylenediamine, and then 50 mmol C2H5NS was added and stirred for 30 min. Subsequently, the mixed solution was transferred to a high-pressure reactor and reacted at 220°C for 24 h at a heating rate of 5°C / min. After cooling to room temperature, the mixture was centrifuged, washed, and dried in sequence to obtain the zinc cadmium sulfide nanorods.
[0047] (2) 0.02 g of cadmium zinc sulfide nanorods were ultrasonically dispersed in 20 mL of deionized water. Then, 0.045 g of Na2MoO4·2H2O and 0.09 g of C2H5NS were dissolved in the above solution, stirred for 15 min, and then transferred to a high-pressure reactor, reacted at 220°C for 24 h, with a heating rate of 5°C / min. After cooling to room temperature, the obtained product was centrifuged from the solution and washed several times with deionized water. Finally, the precipitate was dried to obtain the molybdenum disulfide / cadmium zinc sulfide composite photocatalyst.
[0048] Example 6
[0049] This embodiment provides a method for preparing a molybdenum disulfide / cadmium zinc sulfide composite photocatalyst, comprising the following steps:
[0050] (1) 12 mmol Cd(OAc)2·2H2O and 10 mmol Zn(OAc)2·2H2O were dissolved in a mixed solution of 30 mL deionized water and 30 mL ethylenediamine, and then 30 mmol C2H5NS was added and stirred for 30 min. The mixed solution was then transferred to a high-pressure reactor and reacted at 220°C for 24 h at a heating rate of 5°C / min. After cooling to room temperature, the mixture was centrifuged, washed, and dried in sequence to obtain the zinc cadmium sulfide nanorods.
[0051] (2) 0.01 g of cadmium zinc sulfide nanorods were ultrasonically dispersed in 20 mL of deionized water. Then, 0.045 g of Na2MoO4·2H2O and 0.09 g of C2H5NS were dissolved in the above solution, stirred for 15 min, and then transferred to a high-pressure reactor for reaction at 220°C for 24 h at a heating rate of 5°C / min. After cooling to room temperature, the obtained product was centrifuged from the solution and washed several times with deionized water. Finally, the precipitate was dried to obtain the molybdenum disulfide / cadmium zinc sulfide composite photocatalyst.
[0052] Example 7
[0053] This embodiment provides a method for preparing a molybdenum disulfide / cadmium zinc sulfide composite photocatalyst, comprising the following steps:
[0054] (1) 18 mmol Cd(OAc)2·2H2O and 2 mmol Zn(OAc)2·2H2O were dissolved in a mixed solution of 30 mL deionized water and 30 mL ethylenediamine, and then 25 mmol C2H5NS was added and stirred for 30 min. The mixed solution was then transferred to a high-pressure reactor and reacted at 220°C for 24 h at a heating rate of 5°C / min. After cooling to room temperature, the mixture was centrifuged, washed, and dried in sequence to obtain the zinc cadmium sulfide nanorods.
[0055] (2) 0.015 g of cadmium zinc sulfide nanorods were ultrasonically dispersed in 20 mL of deionized water. Then, 0.045 g of Na2MoO4·2H2O and 0.09 g of C2H5NS were dissolved in the above solution, stirred for 15 min, and then transferred to a high-pressure reactor, reacted at 180°C for 24 h, with a heating rate of 5°C / min. After cooling to room temperature, the obtained product was centrifuged from the solution and washed several times with deionized water. Finally, the precipitate was dried to obtain the molybdenum disulfide / cadmium zinc sulfide composite photocatalyst.
[0056] The above is only a preferred embodiment of the present invention, and does not limit the present invention in other forms. Any technician familiar with the profession may use the above disclosed technical content to change or modify it into an equivalent embodiment with equivalent changes. However, any simple modification, equivalent change and modification made to the above embodiment according to the technical essence of the present invention without departing from the technical solution of the present invention is still covered by the protection scope of the technical solution of the present invention.
Claims
1. A method for preparing a molybdenum disulfide / cadmium zinc sulfide composite photocatalyst, characterized in that: The following steps are involved: (1) Dissolve Zn(OAc)2·2H2O and Cd(OAc)2·2H2O in a mixed solution of deionized water and ethylenediamine, then add C2H5NS, stir evenly, and transfer to a high-pressure reactor to react for 24 hours. Centrifuge, wash, and dry in sequence to obtain zinc cadmium sulfide nanorods; (2) Ultrasonic dispersion of the cadmium zinc sulfide in step (1) in deionized water, then dissolving Na2MoO4·2H2O and C2H5NS in the above solution, stirring evenly and transferring to a high-pressure reactor for reaction for 24 hours. After cooling to room temperature, the obtained product is centrifuged from the solution and washed several times with deionized water. Finally, the precipitate is dried to obtain a molybdenum disulfide / cadmium zinc sulfide composite photocatalyst.
2. The method for preparing the molybdenum disulfide / cadmium zinc sulfide composite photocatalyst according to claim 1, characterized in that: In the step (1), the molar ratio of Zn(OAc)2·2H2O to Cd(OAc)2·2H2O is 1:(1-9).
3. The method for preparing the molybdenum disulfide / cadmium zinc sulfide composite photocatalyst according to claim 1, characterized in that: In the step (1), the molar ratio of metal ions to C2H5NS is 1:(1.25-2.5).
4. The method for preparing the molybdenum disulfide / cadmium zinc sulfide composite photocatalyst according to claim 1, characterized in that: In the step (1), the heating temperature of the reaction is 220° C., and the heating rate is 5° C. / min.
5. The method for preparing the molybdenum disulfide / cadmium zinc sulfide composite photocatalyst according to claim 1, characterized in that: In the step (2), the content of zinc cadmium sulfide nanorods is 0.5-1 g / L.
6. The method for preparing the molybdenum disulfide / cadmium zinc sulfide composite photocatalyst according to claim 1, characterized in that: In the step (2), the mass ratio of Na2MoO4·2H2O to C2H5NS is 1:
2.
7. The method for preparing the molybdenum disulfide / cadmium zinc sulfide composite photocatalyst according to claim 1, characterized in that: In the step (2), the heating temperature of the reaction is 180-220° C., and the heating rate is 5° C. / min.
8. Use of the molybdenum disulfide / cadmium zinc sulfide composite photocatalyst as claimed in claim 1 in photocatalytic water decomposition to produce hydrogen.