Silver metavanadate composite cadmium sulfide photocatalytic material, preparation method thereof and application thereof in photocatalytic hydrogen production

Abstract

The application belongs to the field of photocatalytic materials, and particularly relates to a silver metavanadate composite cadmium sulfide photocatalytic material, a preparation method thereof and application thereof in photocatalytic hydrogen production. The preparation method comprises the following steps: taking a sulfur source and a cadmium source, adding ethylenediamine, stirring and uniformly mixing; transferring to a hydrothermal reaction kettle for reaction; after the reaction is completed, taking the obtained suspension, centrifuging, washing and drying to obtain cadmium sulfide powder; adding water to the cadmium sulfide, adding a silver source and a vanadium source under stirring, stirring, transferring to a reaction kettle for hydrothermal reaction, then centrifuging, washing and drying to obtain the silver metavanadate composite cadmium sulfide photocatalytic material. The photocatalytic material has a relatively obvious catalytic effect in photocatalytic hydrogen production reaction. Under the irradiation of a xenon lamp and under the condition of a set reaction system, the hydrogen production rate of the photocatalyst reaches 228.8 micromoles per gram per hour, which is obviously superior to that of a pure cadmium sulfide catalyst.

Description

Technical Field

[0001] This invention belongs to the field of photocatalytic materials, and specifically relates to a silver metavanadate composite cadmium sulfide photocatalytic material, its preparation method, and its application in photocatalytic hydrogen production. Background Technology

[0002] Since the advent of photocatalysis research, titanium dioxide (TiO2) has been considered the most suitable catalyst in this field due to its advantages such as good stability, ease of preparation, and low toxicity. It has thus been dubbed a "classic semiconductor material in photocatalysis." However, with in-depth research, it has been found that despite its many advantages, titanium dioxide also has significant drawbacks. For example, TiO2 has a relatively large band gap of approximately 3.20 eV, which means it only responds to ultraviolet light. Furthermore, the rapid recombination of photogenerated carriers in TiO2 greatly limits its photocatalytic activity. Therefore, designing a photocatalyst with high efficiency and long lifespan has become a key task for researchers. In recent years, with the development of physics, chemistry, and materials science, various methods have been developed to modify catalysts to improve their photocatalytic activity. Common methods include elemental doping, surface modification of catalysts, microstructure control of catalysts, and the preparation of semiconductor heterojunctions. The application fields of photocatalysis have also been widely expanded, such as: photocatalytic degradation of organic waste and dyes; photocatalytic reduction of carbon dioxide and heavy metal ions in wastewater; and photocatalytic hydrogen production. Different degrees of progress have been made in each of these fields.

[0003] With the increasing depletion of Earth's resources, photocatalytic water splitting for hydrogen production using sunlight is attracting growing attention, offering a novel approach to the development of renewable energy. Besides the titanium dioxide photocatalyst mentioned above, many other excellent photocatalytic materials have been developed for various photocatalytic reactions. Cadmium sulfide (CdS) is an important semiconductor material with advantages such as a good band gap and strong visible light response, making it considered one of the most promising photocatalysts. To date, numerous modifications have been made to CdS to improve its photocatalytic performance. In addition, silver metavanadate (AgVO3) also possesses high visible light absorption performance and is another candidate material for photocatalysis. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing a catalytic composite material of silver metavanadate and cadmium sulfide.

[0005] The technical solution adopted in this invention is: a silver metavanadate composite cadmium sulfide photocatalytic material, the preparation method of which includes the following steps:

[0006] 1) Place the sulfur source and cadmium source in a beaker, add ethylenediamine, and stir vigorously to mix the three together.

[0007] 2) Then the mixture is transferred to a hydrothermal reactor for reaction. After the reaction is complete, the resulting suspension is taken, centrifuged, washed, and dried to obtain cadmium sulfide powder.

[0008] 3) Place the synthesized cadmium sulfide in a beaker, add water, and stir for 30 minutes. Then, add silver and vanadium sources while stirring, and stir for 3-4 hours before transferring to a reactor for hydrothermal reaction. After the reaction is complete, centrifuge, wash and dry to obtain the composite catalyst.

[0009] In the above-mentioned silver metavanadate composite cadmium sulfide photocatalytic material, in step 1), the source and the sulfur source are respectively: cadmium acetate dihydrate and thiourea.

[0010] In the above-mentioned silver metavanadate composite cadmium sulfide photocatalytic material, in step 1), the molar ratio of the source and the sulfur source is 1:1.

[0011] In step 2) of the aforementioned silver metavanadate composite cadmium sulfide photocatalytic material, the hydrothermal reaction is carried out at 160°C for 20–28 hours.

[0012] In step 2) of the above-mentioned silver metavanadate composite cadmium sulfide photocatalytic material, the drying method is vacuum drying at 60°C.

[0013] In step 3) of the aforementioned silver metavanadate composite cadmium sulfide photocatalytic material, the silver source and vanadium source are silver nitrate and ammonium metavanadate, respectively.

[0014] In step 3) of the aforementioned silver metavanadate composite cadmium sulfide photocatalytic material, the hydrothermal reaction is carried out at 180°C for 20–28 h.

[0015] In step 3) of the aforementioned silver metavanadate composite cadmium sulfide photocatalytic material, the drying method is to dry overnight at 80°C.

[0016] The above-mentioned silver metavanadate composite cadmium sulfide photocatalyst material is used in photocatalytic hydrogen production.

[0017] The above application is carried out using the following method: a photocatalytic sealed reaction tank is used as the reactor, a mixed solution of acetonitrile, water and triethanolamine is used as the reaction medium, a xenon lamp is used as the light source, simulated sunlight is used as the radiation light, and silver metavanadate composite cadmium sulfide is used as the catalyst for photocatalytic hydrogen production.

[0018] Preferably, in the above-described applications, triethanolamine is used as a hole sacrificial agent.

[0019] The beneficial effects of this invention are as follows: This invention uses a green and simple hydrothermal method to prepare silver metavanadate composite cadmium sulfide photocatalysts. The silver metavanadate composite cadmium sulfide photocatalyst provided by this invention has significant catalytic effects. Under xenon lamp irradiation, with the set reaction system conditions, the water splitting hydrogen production rate of the photocatalyst reached 228.8 μmol / g / h, which is significantly better than that of pure cadmium sulfide catalysts. Attached Figure Description

[0020] Figure 1 This is a scanning electron microscope image of the AgVO3 / CdS composite photocatalyst material.

[0021] Figure 2 This is a transmission electron microscope (TEM) image of the AgVO3 / CdS composite photocatalytic material.

[0022] Figure 3 This is the energy spectrum of the AgVO3 / CdS composite photocatalytic material.

[0023] Figure 4 This is the X-ray diffraction (XRD) pattern of the AgVO3 / CdS composite photocatalyst material.

[0024] Figure 5 This is the solid-state ultraviolet absorption spectrum of the AgVO3 / CdS composite photocatalytic material.

[0025] Figure 6 This is a graph showing the photocatalytic hydrogen production performance of the AgVO3 / CdS composite photocatalytic material. Detailed Implementation

[0026] To better understand the technical solution of the present invention, specific embodiments are provided for further explanation, but the solution is not limited thereto.

[0027] Example 1: Preparation method of silver metavanadate composite cadmium sulfide photocatalytic material (I) is as follows:

[0028] 1. Preparation of CdS:

[0029] Add 0.1 mol of cadmium acetate dihydrate and 0.1 mol of thiourea to a beaker, add 60 mL of ethylenediamine and mix. Stir for 30 min until homogeneous. Transfer the mixture to a reaction vessel and hydrothermally heat at 160 °C for 1 day. After cooling, centrifuge, wash, and vacuum dry at 60 °C overnight.

[0030] 2. Preparation of AgVO3 / CdS photocatalytic materials

[0031] Weigh 0.1 g of CdS into a beaker, add 70 mL of water, and stir to obtain a suspension. Then add 11.9 mg of silver nitrate powder and stir for 30 min, followed by 8.2 mg of ammonium metavanadate powder and stir for 3 h. Afterward, perform a hydrothermal reaction at 180 °C for 1 day. After cooling, centrifuge, wash, and dry overnight at 80 °C to obtain the AgVO3 / CdS photocatalytic material.

[0032] (II) Testing

[0033] 1. Figure 1 , Figure 2 The images are scanning electron microscope (SEM) and transmission electron microscope (TEM) images of the prepared AgVO3 / CdS photocatalytic material, respectively. Figure 1 As can be seen, the prepared composite catalyst has a stacked rod-like structure. Figure 2 The transmission electron microscopy (TEM) images further confirmed this conclusion. In addition, AgVO3 and CdS were observed separately in the TEM images, confirming that we successfully prepared the AgVO3 / CdS photocatalytic material.

[0034] 2. Figure 3 This is the energy spectrum of the prepared AgVO3 / CdS photocatalytic material, from... Figure 3 As can be seen, corresponding elements belonging to AgVO3 and CdS were observed in the energy spectrum, which further confirms the successful preparation of AgVO3 / CdS photocatalytic material.

[0035] 3. Figure 4 This is the X-ray diffraction (XRD) pattern of the prepared AgVO3 / CdS photocatalytic material, from... Figure 4 It can be observed that the XRD pattern of the AgVO3 / CdS photocatalytic material shows diffraction peaks corresponding to both AgVO3 and CdS, which demonstrates the successful preparation of the AgVO3 / CdS photocatalytic material.

[0036] 4. Figure 6 The image shows the solid-state UV absorption spectrum of the prepared AgVO3 / CdS photocatalyst. As can be seen, after combining AgVO3 and CdS, the absorbance of the AgVO3 / CdS photocatalyst significantly increases in the long-wavelength direction, and the absorption band edge also shifts. This also reflects the improved catalyst performance.

[0037] Example 2: Application of silver metavanadate composite cadmium sulfide photocatalytic material in photocatalytic hydrogen production.

[0038] Xenon lamps from Zhongjiao Jinyuan were used to test the photocatalytic hydrogen production performance of the catalyst.

[0039] The method is as follows: A photocatalytic sealed reaction tank is used as the reactor. Before the reaction, the gas is exhausted with inert gas. A mixed solution of 6 mL acetonitrile, 4 mL water and 2 mL triethanolamine is used as the reaction medium. A xenon lamp is used as the light source and simulated sunlight is used as the radiation light. 0.01 g silver metavanadate composite cadmium sulfide is used as the catalyst for photocatalytic hydrogen production.

[0040] like Figure 6 The image shows the photocatalytic hydrogen production effect of the silver metavanadate-cadmium sulfide composite photocatalyst. As can be seen from the image, after combining AgVO3 and CdS, the hydrogen production rate of the silver metavanadate-cadmium sulfide composite photocatalyst is significantly improved compared to the pure CdS catalyst, reaching a hydrogen production rate of 228.8 μmol / g / h. This indicates that the addition of AgVO3 helps improve the photocatalytic hydrogen production performance of CdS. The performance improvement of the silver metavanadate-cadmium sulfide composite photocatalyst is due to the increased absorbance of the composite material after modifying CdS with AgVO3, allowing the material to absorb more light and generate more photogenerated carriers. These carriers can participate in the reaction, thereby improving the photocatalytic performance and increasing the hydrogen production.

Claims

1. The application of a silver metavanadate composite cadmium sulfide photocatalytic material in photocatalytic hydrogen production, characterized in that, The method is as follows: a photocatalytic sealed reaction tank is used as the reactor, a mixed solution of acetonitrile, water, and triethanolamine is used as the reaction medium, a xenon lamp is used as the light source, simulated sunlight is used as the radiation light, and silver metavanadate composite cadmium sulfide is used as the catalyst for photocatalytic hydrogen production. The preparation method of silver metavanadate composite cadmium sulfide photocatalytic material includes the following steps: 1) According to the molar ratio, place thiourea and cadmium acetate dihydrate in a beaker, add ethylenediamine, and stir vigorously to mix the three evenly; 2) Then transfer it to a hydrothermal reactor and react at 160°C for 20-28 hours. After the reaction is complete, take the obtained suspension, centrifuge and wash it, and vacuum dry it at 60°C to obtain cadmium sulfide powder. 3) Place the synthesized cadmium sulfide in a beaker, add water, and stir for 30 minutes. Then, add silver nitrate and ammonium metavanadate while stirring. After stirring for 3-4 hours, transfer the mixture to a reaction vessel and carry out a hydrothermal reaction at 180°C for 20-28 hours. After the reaction is complete, centrifuge the mixture, wash it, and dry it overnight at 80°C to obtain the silver metavanadate composite cadmium sulfide photocatalytic material.

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