The Preparation Of Doped Zno/heterogeneous Type Photocatalyst And Their Photocatalytic Performance Of The Research

ZnO is an important n-type semiconductor, and has the characteristics of its abundant source, non-toxic, and low cost. It has the band gap of3.2eV. Under the irradiation of ultraviolet light, ZnO will can produce photogenerated electron-hole pairs, and further transform to generate the high active groups such as·OH and·O2-with strong oxidization and reduction abilities, which can be used for the degradation of the organic pollutants such as dyes. Now, it gradually attracts great attention of the domestic and foreign photocatalytic researchers. However, Compared with the already commercialized TiO2photocatalyst, ZnO has its disadvantage due to its lower photocatalytic activity and photocatalytic stability. Low photocatalytic activity is caused by the high recombination rate of the photogenerated electron-hole pairs. Low photocatalytic stability was resulted by the photochemistry corrosion. These disadvantages limites its large-scale industrial utilization.Therefore, it is a research focus to improve its photocatalytic activity and stability by design the composition and structure of ZnO in the photocatalytic field.In view of the photocatalytic shortcomings of ZnO as a photocatalyt, the effects of elment doping and the formation of heterojunction on the physical struture and photocatalytic performance of ZnO were investigated. The photocatalytic activity of the samples was evaluated by the photodegradation of acid orange Ⅱ or methylene blue. The relationship between the composition,structure of ZnO and photocatalytic properties were discussed. The major research contents are as follows:1. The effects of doing typical rare earth metal ions and transition metal ions on the structure and photocatalytic property of ZnO were investigated. The influences of the donging content of Ce and Sn and the preparation conditions on the structure property such as the crystal, optical absorption and photocatalytic performance of ZnO were explored. The influence of the structure and photocatalytic performance resulting form Zr-Al codoped ZnO was also discussed. Results showed that the surface property of ZnO was modified and more surface hydroxyl groups could produce. The doping could effectively promote the separation of electron-hole pairs, which contribute to a big improvement of photocatalytic performance.2. The effects of the formation of heterojunction structure over ZnO by coupling with the typical semiconductor on the structures and photocatalytic performance of ZnO were investigated. Firstly, the influence of WO3/ZnO heterojunction structure on the structure, surface properties and photocatalytic performaces of ZnO was investigated. It is found that the presence of WO3could effectively inhibit the growth of ZnO crystal and increase its specific surface area and the surface hydroxyl groups. The recombination of photoindured electrons and holes is also effectively inhibited by the heterojunction structure. Secondly, the role of the formation of heterojunction of metal salt semiconductor Bi2WO6(BiOCl)/ZnO on the structure and photocatalytic activity of ZnO was explored. Results showed that the formation of Bi2WO6/ZnO and BiOCl/ZnO heterojunction could significantly decrease the recombination rate of the photogenerated electron-hole pairs and improve the surface properties of ZnO photocatalyst. The content of Bi2WO6and hydrothermal temperature had a great impact on ZnO photocatalytic performance. Moveover, the formation of BiOCl/ZnO heterojunction structure could give3.4times of photocatalytic activity of pure ZnO.3. Based on the the discovered role of heterojunction, for further improving the photocatalytic properties of ZnO photocatalyst, using precious metal to capture the excited electrons to further promote the separation of photoinduced electron-hole pairs was further investigated.The above research results indicated that the doping of suitable elements and the formation of semiconductor heterojunction could improve the surface properties, crystal structure, and photo-absorption ability of ZnO and promote the separation of photogenerated electron-hole pairs, then greatly improving the photocatalytic properties of ZnO.