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

Abstract

The invention belongs to the field of photocatalytic materials, and particularly relates to a silver metavanadate composite cadmium sulfide photocatalytic material as well as a preparation method and application thereof in photocatalytic hydrogen production. The preparation method comprises the following steps: taking a sulfur source and a cadmium source, adding ethylenediamine, and uniformly stirring and mixing; transferring the mixture into a hydrothermal reaction kettle for reaction, after the reaction is finished, obtaining turbid liquid, and centrifugally washing and drying the turbid liquid to obtain cadmium sulfide powder; the preparation method comprises the following steps: adding water into cadmium sulfide, adding a silver source and a vanadium source under a stirring condition, stirring, transferring into a reaction kettle, carrying out a hydrothermal reaction, centrifuging, washing and drying to obtain the silver metavanadate composite cadmium sulfide photocatalytic material. The photocatalytic material disclosed by the invention has a relatively obvious catalytic effect in a 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 water decomposition of the photocatalyst reaches 228.8 mu mol / g / h, which is obviously superior to that of a pure cadmium sulfide catalyst.

Description

Technical Field

[0001] The invention belongs to the field of photocatalytic materials, and particularly relates to a silver metavanadate composite cadmium sulfide photocatalytic material and a preparation method thereof and application thereof in photocatalytic hydrogen production. Background Art

[0002] Since the emergence of photocatalytic research, titanium dioxide has been considered the most suitable catalyst in this field because of its advantages such as good stability, easy preparation and low toxicity. Therefore, titanium dioxide is dubbed the "classic semiconductor material in the field of photocatalysis". However, with the deepening of research, people have found that even though titanium dioxide has many advantages, its disadvantages cannot be ignored. For example: the band gap of TiO2 is relatively large, about 3.20eV, which leads to titanium dioxide only responding to ultraviolet light; in addition, the photogenerated carriers of TiO2 itself recombine quickly, which greatly limits its photocatalytic activity. Therefore, designing a photocatalyst with high photocatalytic efficiency and long service life has become a key task for researchers. In recent years, with the development of physics, chemistry, and materials science, people have studied a variety of methods to transform catalysts in order to improve their photocatalytic activity. Common methods include: element doping, surface modification of catalysts, micromorphology regulation of catalysts, preparation of semiconductor heterojunctions, etc. 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; photocatalytic production of hydrogen, etc. All of the above fields have achieved development results to varying degrees.

[0003] With the increasing depletion of earth resources, the use of sunlight for photocatalytic water decomposition to produce hydrogen has attracted more and more attention. Its emergence has provided a new idea for the development of renewable energy. In addition to the titanium dioxide photocatalyst mentioned above, people have also developed many excellent photocatalytic materials for different photocatalytic reactions. Cadmium sulfide (CdS) is an important semiconductor material with advantages such as good band gap and strong visible light response ability. Therefore, CdS is considered to be one of the most promising photocatalysts. So far, people have made many modifications to cadmium sulfide to improve its photocatalytic performance. In addition, silver metavanadate (AgVO3) also has high visible light absorption performance and is also one of the candidate materials for photocatalysis. Summary of the invention

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

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

[0006] 1) Put the sulfur source and cadmium source in a beaker, add ethylenediamine, and stir vigorously to mix the three evenly;

[0007] 2) then transferring to a hydrothermal reactor for reaction, after the reaction is completed, taking the obtained suspension, centrifuging, washing, and drying to obtain cadmium sulfide powder;

[0008] 3) The synthesized cadmium sulfide is placed in a beaker, water is added, and the mixture is stirred for 30 minutes. Then, the silver source and the vanadium source are added under stirring. The mixture is then stirred for 3 to 4 hours and transferred to a reactor for a hydrothermal reaction. After the reaction is completed, the mixture is centrifuged, washed, and dried to obtain a composite catalyst.

[0009] In the above-mentioned silver metavanadate composite cadmium sulfide photocatalytic material, in step 1), the barrier 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 isolation source to the sulfur source is 1:1.

[0011] In the above-mentioned silver metavanadate composite cadmium sulfide photocatalytic material, in step 2), the hydrothermal reaction is carried out at 160° C. for 20 to 28 hours.

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

[0013] In the above-mentioned silver metavanadate composite cadmium sulfide photocatalytic material, in step 3), the silver source and vanadium source are silver nitrate and ammonium metavanadate.

[0014] In the above-mentioned silver metavanadate composite cadmium sulfide photocatalytic material, in step 3), the hydrothermal reaction is carried out at 180° C. for 20 to 28 hours.

[0015] In the above-mentioned silver metavanadate composite cadmium sulfide photocatalytic material, in step 3), the drying method is drying at 80° C. overnight.

[0016] Application of the above-mentioned silver metavanadate composite cadmium sulfide photocatalytic material in photocatalytic hydrogen production.

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

[0018] Preferably, in the above application, triethanolamine is used as the hole sacrificial agent.

[0019] The beneficial effects of the present invention are as follows: the present invention adopts a green and simple hydrothermal method to prepare a silver metavanadate composite cadmium sulfide photocatalyst. The silver metavanadate composite cadmium sulfide photocatalytic material provided by the present invention has a significant catalytic effect. Under the irradiation of a xenon lamp and with the set reaction system as the condition, the water decomposition hydrogen production rate of the photocatalyst reaches 228.8 μmol / g / h, which is significantly better than that of a pure cadmium sulfide catalyst. BRIEF DESCRIPTION OF THE DRAWINGS

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

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

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

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

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

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

[0026] In order to better understand the technical solution of the present invention, a specific embodiment is given to further illustrate it, but the solution is not limited thereto.

[0027] Example 1 Silver metavanadate composite cadmium sulfide photocatalytic material (I) The preparation method is as follows:

[0028] 1. Preparation of CdS:

[0029] Add 0.1 mol of cadmium acetate dihydrate and 0.1 mol of thiourea into a beaker, add 60 mL of ethylenediamine and mix, then stir for 30 min. After mixing evenly, transfer the mixture into a reactor, hydroheat at 160°C for 1 day, cool, centrifuge, wash, and vacuum dry at 60°C overnight.

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

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

[0032] (II) Testing

[0033] 1. Figure 1 , Figure 2 The scanning electron microscope and transmission electron microscope images of the prepared AgVO3 / CdS photocatalytic material are shown in Figure 2. Figure 1 It can be seen that the prepared composite catalyst is a stacked rod-like structure. Figure 2 The transmission electron microscope image further confirmed this conclusion. In addition, AgVO3 and CdS were observed from the transmission electron microscope image, which confirmed that we successfully prepared the AgVO3 / CdS photocatalytic material.

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

[0035] 3. Figure 4 is the X-ray diffraction spectrum (XRD) of the prepared AgVO3 / CdS photocatalytic material. Figure 4 It can be observed that in the XRD spectrum of AgVO3 / CdS photocatalytic material, there are both diffraction peaks corresponding to AgVO3 and diffraction peaks corresponding to CdS. This result also illustrates the successful preparation of AgVO3 / CdS photocatalytic material.

[0036] 4. Figure 6 This is the solid ultraviolet absorption diagram of the prepared AgVO3 / CdS photocatalytic material. From the figure, we can see that after the AgVO3 and CdS are compounded, the absorbance of the AgVO3 / CdS photocatalytic material in the long-wave direction increases significantly, and the absorption band edge also moves. This also indirectly reflects the reason for the improvement of catalyst performance.

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

[0038] The xenon lamp of Zhongjiao Jinyuan was used to test the photocatalytic hydrogen production performance of the catalyst.

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

[0040] like Figure 6 The photocatalytic hydrogen production effect diagram of silver metavanadate composite cadmium sulfide photocatalyst material is shown. It can be seen from the figure that after AgVO3 and CdS are compounded, the hydrogen production rate of silver metavanadate composite cadmium sulfide photocatalyst material is significantly improved compared with the pure CdS catalyst, and the hydrogen generation rate reaches 228.8μmol / g / h. This shows that the addition of AgVO3 helps to improve the photocatalytic hydrogen production performance of CdS. The reason for the performance improvement of silver metavanadate composite cadmium sulfide photocatalyst material is that after AgVO3 is modified on CdS, the absorbance of the composite material increases, causing the material to absorb more light to generate more photogenerated carriers. These carriers can participate in the reaction, thereby improving the photocatalytic performance and increasing the amount of hydrogen produced.

Claims

1. A silver metavanadate composite cadmium sulfide photocatalytic material, characterized in that: The preparation method comprises the following steps: 1) Put the sulfur source and cadmium source in a beaker, add ethylenediamine, and stir vigorously to mix the three evenly; 2) then transferring to a hydrothermal reactor for reaction, after the reaction is completed, taking the obtained suspension, centrifuging, washing, and drying to obtain cadmium sulfide powder; 3) The synthesized cadmium sulfide is placed in a beaker, water is added, and the mixture is stirred for 30 minutes. Then, a silver source and a vanadium source are added under stirring, and the mixture is stirred for 3 to 4 hours and then transferred to a reactor for a hydrothermal reaction. After the reaction is completed, the mixture is centrifuged, washed, and dried to obtain a silver metavanadate composite cadmium sulfide photocatalytic material.

2. The silver metavanadate composite cadmium sulfide photocatalytic material according to claim 1, characterized in that: In step 1), the isolation source and the sulfur source are cadmium acetate dihydrate and thiourea respectively.

3. The silver metavanadate composite cadmium sulfide photocatalytic material according to claim 1, characterized in that: In step 1), the molar ratio of the isolation source to the sulfur source is 1:

1.

4. The silver metavanadate composite cadmium sulfide photocatalytic material according to claim 1, characterized in that: In step 2), the hydrothermal reaction is carried out at 160° C. for 20 to 28 hours.

5. The silver metavanadate composite cadmium sulfide photocatalytic material according to claim 1, characterized in that: In step 2), the drying method is vacuum drying at 60°C.

6. The silver metavanadate composite cadmium sulfide photocatalytic material according to claim 1, characterized in that: In step 3), the silver source and vanadium source are silver nitrate and ammonium metavanadate.

7. The silver metavanadate composite cadmium sulfide photocatalytic material according to claim 1, characterized in that: In step 3), the hydrothermal reaction is carried out at 180° C. for 20 to 28 hours.

8. The silver metavanadate composite cadmium sulfide photocatalytic material according to claim 1, characterized in that: In step 3), the drying method is drying at 80° C. overnight.

9. Use of the silver metavanadate composite cadmium sulfide photocatalytic material according to any one of claims 1 to 8 in photocatalytic hydrogen production.

10. The use according to claim 9, characterized in that: The method is as follows: a photocatalytic sealed reaction pool is used as a reactor, a mixed solution of acetonitrile, water and triethanolamine is used as a reaction medium, a xenon lamp is used as a light source, simulated sunlight is used as radiation light, and silver metavanadate composite cadmium sulfide is used as a catalyst for photocatalytic hydrogen production.

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