Photoluminescence And Photocatalytic Properties Of Au/ZnO Nanoparticles

Photocatalytic degradation can convert organic pollutants into water, carbon dioxide and other inorganic substances, has playing a important role in the remediation of environmental pollution, owing to its simple process, easy operation, low cost, etc. In recent years, the photocatalytic properties of Zn O nanomaterials has attracted widespread attention, especially noble metals modification such as Au nanoparticles, has been proved to effectively improve the photocatalytic properties of Zn O nanomaterials, however the photocatalytic properties optimization of Au/Zn O system and the related physical mechanisms deserve some further investigation. Obviously, the research in photoelectrical field has important scientific significance and value. In this thesis, based on the above background, the controlled preparation and photocatalytic properties of Au/Zn O nanomaterials have been studied extensively. Through careful analysis of the relationship between the photocatalytic and photoluminescence properties of Au/Zn O nanomaterials, we have investigated the impact of the morphologies of Au /Zn O nanoparticles on their photocatalytic performance, the role of charge transfer between Au and Zn O and the other related mechanisms. The research content is as follows:First, uniform and well-dispersive Au nanoparticles with the average particle size of ~17nm have been prepared,. The n, these Au nanoparticles were used as nucleaion sites to prepare Au/Zn O nanoparticles with different morphologies and compositions by employing a hydrothermal method.Secondly, we used Rhodamine B degradation as a model reaction to study the photocatalytic properties of Au/Zn O nanomaterials under UV irradiation. The results show that: the photocatalytic performance of Au/Zn O nanoparticles is significantly better than pure Zn O samples, and the material preparation conditions and compositions, e.g. the growth temperature of Zn O and the Au content, have important fluence on the photocatalytic properties of Au/Zn O nanoparticles.Finally, we explored optical properties of Au/Zn O nanoparticles and discussed the relationship between the photocatalytic and the photoluminescence properties of the samples. It was revealed that the Au nanoparticles can modify the crystalline quality and sizes of the Zn O nanoparticles, and promote electron-hole separation in Zn O. All these three factors can contribute to the enhanced p hotocatalytic properties of Au/Zn O nanoparticles. Most importantly, a new mechanism for the enhanced p hotocatalytic properties of Au/Zn O nanoparticles has been proposed, i.e. the strong visible emission in green light region of the small Zn O nanocrystallines enables an internal bidirectional electron transfer between Au and Zn O, including the transfer from the defect level of Zn O to the Fermi level of Au, and the excited electrons in Au through surface plasmon resonance absorption of the Zn O green emission to the conduction band of Zn O.This study may have provided a deeper understanding on the mechanisms and property optimization of metal-semiconductor nanostructures for photocatalytic applications.