Preparation ZnO-based Nanocomposite By Water Bath Method And Study On Their Photocatalytic Properties

Serious water pollution, air pollution, solid pollution pollution have donegrest harm to the development of the global economy and human life.Photocatalytic technology can clean up the environment using clean solar energy,it has a great advantage in the aspect of sewage purification. ZnO is used asphotocatalytic materials with high electron mobility, good stability, low cost andother advantages, has been a hot research topic for scientific researchers in thefield of photocatalysis. However, it has some shortcomings: Because of the largeband width, ZnO can only absorb visible light, which makes the ZnOphotocatalytic materials can not be full use of solar energy. Secondly, thephotogenerated electron hole pairs of ZnO semiconductor materials are easy totocomposite, which dose a bad effect on its photocatalytic activity. These defectshinder the development of ZnO in the field of photocatalysis. Scientists havebeen trying to study how to improve the photocatalytic activity of ZnOphotocatalyst. This study trys to improve the photocatalytic activity bycompouning with other semiconductor materials and modified by noble metalmodified. This thesis successfully prefabricated the ZnO/NiO heterojunction,Ag/ZnO heterojunction, Ag/ZnO/ZnSe heterojunction and Ag/ZnO/Cu2Oheterojunction. The structure and properties of the prepared samples investigated by XRD, SEM, TEM, PL. In addition, we degradated RhB by the reparedsamples and explained the principle. The main research contents of this thesisare as follows:(1)ZnO/NiO heterojunction was prefabricated by ultrasonic method withZnO which was synthesized by water bath method as the template. The resultsindicate that ZnO/NiO heterojunction consist of ZnO nanospheres coated byNiO nanoparticles. Comparing the photocatalytic performance of pure NiO, pureZnO and ZnO/NiO heterojunction, ZnO/NiO heterojunction has the highestphotocatalytic efficiency.(2)Ag nanowires were successfully prepared by microwave method, andthen Ag/ZnO heterojunction was synthesized with the Ag nanowires astemplates by ultrasonic method. Ag/ZnO heterojunction consist of Ag nanowirescoated by ZnO. Comparing the photocatalytic performance of pure Ag, pureZnO and Ag/ZnO heterojunction, the Ag/ZnO heterojunction has the highestphotocatalytic efficiency and its photocatalysis principle is discussed.(3)Ag/ZnO/ZnSe heterojunction was synthesized by water bath methodwith Ag/ZnO as template. It is proved that Ag/ZnO/ZnSe heterostructure wasconsisted with vermicular Ag/ZnO heterostructure coated by ZnSe nanoparticles.We degradated RhB under visible light by Ag/ZnO heterojunction andAg/ZnO/ZnSe heterojunction with different amount of adding hydrazine, thenanalyzed the photocatalytic principle, the result shows that the Ag/ZnO/ZnSeheterojunction added15mL hydrazine has the highest photocatalytic efficiency and its photocatalysis principle is discussed.(4)Ag/ZnO/Cu2O heterojunction was synthesized by water bath methodwith Ag/ZnO as template. It is proved that Ag/ZnO/ZnSe heterostructure wasconsisted with vermicular Ag/ZnO heterostructure coated by Cu2O. Wedegradated RhB under visible light by pure Cu2O, Ag/Cu2O heterojunction andAg/ZnO/Cu2O heterojunction, the result shows that the Ag/ZnO/Cu2Oheterojunction has the highest photocatalytic efficiency and its photocatalysisprinciple is discussed.