Preparation And Photocatalytic Studies Of Graphene/CdS Nanoparticles Hybrid Structure

Graphene with atomically thin and two-dimensional conjugated structure, exhibits high conductivity as well as thermal, chemical, mechanical, and optical stability and a high specific surface area. CdS is an important II-VI semiconductor, it can be potentially applied in many fields such as light-emitting diodes, thin film transistors, solar cells, and photocatalysts. The narrower bandgap of CdS facilitates the utilization of visible light, which makes CdS a competitive candidate as photocatalyst. Disadvantageously, the rapid recombination of the excited electronhole pairs is an obstacle limiting the photocatalytic activity of catalysts. The ways to delay the electron-hole pair recombination of CdS include the hybrid of CdS with other semiconductors, noble metals, or loaded CdS on support materials with high surface areas or combining CdS with conductive supports. The nanocomposites composed of CdS and graphene showed significantly improved properties in electrocatalysis, supercapacitor, high-performance lithium ion batteries, etc. In the thesis, the applications of hybrid structures of graphene-CdS (G/CdS) and G/CdS/Pt as the adsorbent for the extraction of organic pollutants were investigated. The thesis includes three parts as followed:1. Preparation of graphene oxide (GO):GO is prepared by improved Hummers method.2. Preparation and characterization of G/CdS nanaocomposites:GO/CdS is synthesized by hydrothermal method. The results show that the CdS particles were formed uniformly on the graphene sheets. Rhodamine B (Rh.B) was selected as model organic pollutant in this work. The results exhibit that the G/CdS composites possesses very efficient adsorption and photodegradation ability and the absorption rate gets to 96.6%.3. Preparation of G/CdS/Pt composite and photocatalytic performance:we prepared G/Pt, G/CdS, G/CdS/Pt hybrid composites. The structure and morphology of the composites were characterized. Under the fluorescent lamp irradiation, the composite materials has the ability on the photocatalytic degradation of rhodamine B solution. The results show that the photocatalytic performance of G/CdS/Pt is the best in these materials.