Preparation method and application of Ag/ZnO/CdS composite photocatalyst

Abstract

The invention belongs to the field of nanomaterial preparation and environmental protection, and discloses a preparation method of a composite photocatalyst Ag / ZnO / CdS. The method comprises the following steps: 1) subjecting cadmium salt, sulfide and polyvinylpyrrolidone to reacting under a high-temperature condition to prepare a hexagonal crystal phase CdS crystal; 2) respectively dissolving sodium hydroxide and zinc acetate into absolute ethyl alcohol, and conducting mixing to obtain ZnO sol; 3) respectively dissolving zinc nitrate and hexamethylenetetramine in deionized water, and conducting mixing to obtain a ZnO solution; 4) dispersing the CdS crystal into the ZnO sol, carrying out a water-bath reaction in the ZnO solution to obtain a dispersion liquid containing ZnO / CdS, and carrying out centrifuging, washing and drying to obtain ZnO / CdS; and 5) dispersing the ZnO / CdS powder in an aqueous triethanolamine solution, then adding a silver nitrate solution, and performing stirring under the irradiation of a light source to obtain the composite photocatalyst Ag / ZnO / CdS. The preparation method is mild in conditions and simple in materials, and the composite photocatalyst is uniform in particle, high in stability, high in photocatalytic activity, excellent in antibacterial property and good in application prospect.

Description

technical field [0001] The invention relates to the field of semiconductor photocatalyst material preparation, more specifically, to a preparation method of a nanocomposite photocatalyst Ag / ZnO / CdS, the composite photocatalyst thus prepared and its application in photocatalytic degradation of organic matter and antibacterial. Background technique [0002] With the rapid development of the economy, environmental pollution, especially water pollution, has become increasingly prominent. The removal of dissolved organic pollutants in polluted water and sterilization and disinfection treatment are important and necessary links in the process of water resource regeneration and resource utilization. As a new environmental protection technology that can directly use solar energy to realize energy conversion, pollutant degradation, sterilization and disinfection, semiconductor photocatalysis technology has very broad development and application prospects. Generally, semiconductors a...

AI Technical Summary

Problems solved by technology

The conduction band potential of CdS is about -0.6V, which is higher than (O 2 / ·O 2 - ) conversion potential, however, since its valence band potential is about 1.8V, lower than (H 2 O / ·OH) transformation potential, therefore, CdS can only generate ·O 2 - Active oxygen groups, but cannot produce .OH active oxygen groups, which is not conducive to the improvement of photocatalytic activity and sterilization performance to a certain extent

[0006] The above two examples show that the contradictory problems faced in the design and preparation of single-component photocatalysts are: lowering the band gap energy can improve the utilization rate of visible light, but the conduction band and valence band potential are too low to simultaneously generate O 2 - and OH and other active oxygen groups; on the contrary, increasing the conduction band and valence band potential can generate more active oxygen groups, but the band gap energy will increase accordingly

However, in the existing reports, most of the ZnO nanorods are prepared first, and then the CdS nanocrystals are attached or embedded on the surface of the ZnO nanorods, that is, the CdS is located in the shell or outer layer, and the light absorption and light absorption are mainly performed by CdS. Catalytic reaction, while the inner layer ZnO only plays the role of electron transfer

This strategy can solve the problem of too high band gap energy, but the CdS valence band potential is too low to produce O 2 - At the same time, CdS located in the outer layer of the composite material will also cause the problem of CdS nanocrystal shedding, and the biological toxicity caused by the dispersion or dissolution of Cd ions in water cannot be ignored.

However, the preparation of CdS into crystals with a certain structure and morphology, and the examples of attaching ZnO nanorods to the surface of CdS have hardly been reported.

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