Study On Preparation And Properties Of Graphene/Titanium Oxide Composite Photocatalysts

With rapid industrialization and poor management of energy, there are issues that threaten human health and global environment. Among them, the discharge of wastewater and the release of CO2 are major concerns. Since the first discovery of Fujishima and Honda in 1972 on the photocatalytic splitting of water over TiO2 electrodes under ultraviolet irradiation, clean and low-cost photocatalysts are used to tackle energy crisis and environmental contamination simultaneously. Now although there are many reports on photocatalytic oxidation of organic pollutants and reduction of CO2, there is no report on the combination of these two issues for one-pot conversion of organic pollutants to useful organic compounds. It is urgent to develop new catalysts that can fulfill simultaneous photocatalytic oxidation and reduction. In this article, we studied the rGO/SrTi1-x FexO3-δ and a new GQDs/V-TiO2 heterostructured photocatalyst for one-pot conversion of organic pollutants to methanol and ethanol.We tried to prepare photocatalysts of rGO/SrTi0.95Fe0.05O3-δ via combining Fe-doping and graphene loadings. According to the experimental results revealed that the Fe-doping and graphene loadings have effects on the SrTiO3 photocatalytic performance. The as-obtained 1%rGO/Sr Ti0.95Fe0.05O3-δ catalyst exhibits good photocatalytic performance of one-pot conversion of RhB to useful hydrocarbons with a product rate of CH3 OH and C2H5 OH of 10.76 and 6.14 μmol·g-1·h-1, respectively.GQDs are graphene fragments that have more “molecule-like” character. GQDs show many advantages, such as ease of preparation, good visible light absorption and electro-optic properties of quantum dots. In view of the electron acceptor and transporter, photosensitizer and upconversion properties of GQDs, we try to combine GQDs with Vanadium doped TiO2(V-TiO2) in a composite system to use the full spectrum of sunlight and effectively separate photo-generated electrons and holes.According to the experimental results We have successfully combined GQDs with V-doped TiO2 mesoporous material to the prepared GQDs/V-TiO2 composites with a facile solution method. And the 5%GQDs/V-TiO2 has the best photocatalytic activity and the product rates of CH3 OH and C2H5 OH are 13.24 and 5.65 μmol·g-1·h-1,respectively. The one-pot conversion of MB into hydrocarbons was demonstrated by a series of experiments. The photocatalytic mechanisms of one-pot conversion of MBinto hydrocarbons were proposed to explain the detailed photocatalytic process. These works provides an ideal scenario that couples the photodegradation of organic pollutants with photoreduction of CO2 and opens a new avenue to realize the degradation and recycling of organic pollutants.