Preparation of TiO₂/graphene oxide and their photocatalytic properties at room temperature

TiO₂/GO with different graphene oxide (GO) composite ratios were prepared by hydrothermal method and characterized by SEM, TEM, XRD, UV-vis, XPS, Raman and photocurrent. The results show that both TiO₂ and GO/TiO₂ crystal are anatase type. Part of GO is reduced to the reduced graphene oxide (RGO), properties of which are closer to that of graphene, when GO is prepared by hydrothermal reaction with butyl titanate. And such transformation is conducive to photoelectron transfer. Compared with pure TiO₂, the composite TiO₂/GO catalyst has a smaller grain size and a higher ratio of adsorbed oxygen/lattice oxygen, which is beneficial to the oxidation of NO. Moreover, lower band gap enhances the abilities of absorbing visible light and the photoelectron response over TiO₂/GO catalyst. Therefore, the catalyst exhibits more excellent photocatalytic performance. The photocatalytic denitration performance of the composites was evaluated under visible light. When the GO composite ratio is 1.5%, the catalyst possesses the optimal photocatalytic denitration performance. When the ratio of ammonia to nitrogen is 1:1, the denitration efficiency can reach as high as 88.6%, which is 30% higher than that of self-made unmodified TiO₂ and 40% higher than that of V-Ti-W catalyst. The anti-interference ability is significantly stronger than that of commercial V-Ti-W catalysts. It is concluded, from the mechanism analysis, that the oxidation rate of NO plays a key role in the process of photocatalytic denitration, and the presence of ammonia can accelerate the reduction of NO₂.