Synthesis Of Au-CdS Nanocomposites And Their Photocatalytic Properties Research

Heterogeneous photocatalysis had started a new era since Fujishima and Honda discovered that the TiO₂ semiconductor electrode can decompose water into hydrogen in 1972.Many experts in chemistry,physics and materialogy have worked hard to understand the basic processes of semiconductor photocatalysis,and develop new photocatalytic materials,that make rapid development of materials based on semiconductor photocatalysis.At present,the photocatalytic research is divided into hydrogen production by water splitting,large-scale sewage treatment,carbon dioxide reduction,photocatalytic organic and inorganic chemical reactions.In recent years,photocatalytic research and application in environmental purification has become the most active field,and made exciting results in the practical application.The emergence of composite functional materials has attracted a large number of scholars'attention and developed into a new field of scientific research.The properties of nanocomposites are mainly determined by the composition,structure and morphology.In order to improve the property of material,composition of nanocomposites should be rational designed,and the material morphology should be precise controlled according to the application.?-VI semiconductor nanocrystals and their heterogeneous nanocrystals formed with metals have unique optical and electrical properties.They have a wide range in application and scientific research value in the efficiently use of solar energy,such as in photovoltaic devices,photocatalytic decomposition of water system,LED,high efficiency fluorescence aspects.In this paper,we mainly research metal-semiconductor nanocomposites and their photocatalytic activity.We improve the conversion efficiency of solar energy by constructing metal-semiconductor heterojunction and controlling the shape of the material.Two kinds of composite structures were synthesized through different methods,they had the same composition,different morphology and high photocatalytic activity.Their morphology,structure and properties were tested by XRD,SEM,TEM,UV-vis,SERS,PL spectra and other means.The main research contents and results are as follows:?1?Three kinds of Au nanoparticles with different particle size were prepared by sodium citrate reduction method.The structure,morphology and optical properties were tested and characterized by XRD,SEM,UV-vis absorption spectrum.Au nanoparticles monolayer film had higher surface-enhanced Raman scattering properties which could be used to research the relationship between SERS signals intensity and the SERS substrate.?2?Au@CdS core-shell nanoparticles were prepared by hydrothermal method.The incorporation of precious metals into the semiconductor could improve the solar conversion efficiency,for one reason,they have higher visible light absorption capacity,for another,the metal-semiconductor heterojunction could improve the photo-induced charge separation and migration.The photocatalytic degradation of Rhodamine 6G experiments confirmed that Au@CdS core-shell nanoparticles had high photocatalytic activity.Combined with Au nanoparticle monofilm,rhodamine 6G were investigated by SERS and the result showed that R6G molecules structure changed in the photocatalytic degradation process.?3?In order to further improve the solar conversion efficiency of Au@CdS nanoparticles,CdS nanorods were epitaxially grown on the shells of Au@CdS core-shell nanoparticles by stepwise method to synthesize flower-like Au@CdS nanoparticles.Au@CdS nanoflowers with three-dimensional heterostructures have stronger visible light capture capability,photo-induced charge separation properties,and also have large specific surface areas,which make them highly efficient solar conversion efficiency.Their photocatalytic properties significantly improved compared with the previous core-shell nanoparticles.