Microwave Synthesis And Properties Of Gypsum - Semiconductor Composite Photocatalyst

With the rapid development of society, the problems of environmental pollution become increasingly serious. As a green and environmental friendly technology, photocatalytic has known as one of the most promising technology in energy and environment area. TiO2 and CdS are of the most widely used semiconductor catalysis in the field of photocatalysis. However, there are also many shortcomings in the process of catalytic application, such as light response in a narrow range, fast recombination of photogenerated electron-hole pairs, easy to clusters for nanoparticles, etc. To prepare type â…¡ semiconductor hetero structured nanocomposites and graphene/semiconductor were effective methods to improve photocatalytic performance of semiconductor catalysis. In this paper, we have prepared RGO/TiO2 with exposed{001} surface, RGO/CdS and RGO/CdS/TiO2 nanocomposites via microwave solvothermal process. And the morphology, structure and photocatalytic property of the nanocomposites were characterized. The main research contents and results are listed as follows:RGO/TiO2 nanocomposites with exposed{001} surface and RGO/CdS were successfully synthesized via microwave solvothermal process. TiO2 in RGO/TiO2 was square-shaped nanocrystals with exposed high-energy{001} facets and TiO2 nanoparticles were uniformly distributed on the surface of RGO. Compared to pure TiO2, RGO/TiO2 shows an enhanced absorption intensity in visible light region, and a gradual red shift of absorption edge. The composite samples showed the MB phtotodegradation rate of 94.25% in 90 min, but pure TiO2 only shows MB phtotodegradation rate of 68.72% in the same conditions. The enhanced photocatalytic activity indicating the presence of RGO can accelerate the separation of the photo-induced electrons-hole pairs, thus enhancing the photocatalytic performance.CdS nanoparticles in RGO/CdS were uniformly distributed on the surface of RGO and the particle size is smaller than pure CdS. Morever, the introduction of graphene enhanced the absorption of CdS toward visible light and reduce the band gaps of CdS sample. The composite samples showed the MB phtotodegradation rate of 87.96% in 90 min, but pure CdS only shows MB phtotodegradation rate of 68.72% in the same conditions. Recombination with graphene enhancing the photocatalytic performance of the CdS.Considering low utilization of visible light and poor stability of RGO/CdS and RGO/TiO2, we have successfully synthesized RGO/CdS/TiO2 composites using the microwave solvothermal method.The introduction of TiO2 enhances the absorption intensity of RGO/CdS in visible light region and reduce its band gaps. When the weight ratio of TiO2 is 10%, RGO/CdS/TiO2 material shows the optimal photodegradation activity with 99.70% in 50 min, which higher than RGO/CdS and RGO/TiO2. The enhanced photocatalytic activity of RGO/CdS/TiO2 due to the electron transfer of CdS/TiO2 heterostructure, in the same time the introduction of RGO provides transport channels for samples.The synergistic effect of TiO2 and RGO can accelerate the separation of the photo-induced electrons-hole pairs, thus enhancing the photocatalytic performance.