Size-Controlled TiO2 nanocrystals with exposed {001} and {101} facets strongly linking to graphene oxide via p-Phenylenediamine for efficient photocatalytic degradation of fulvic acids

Photocatalytic degradation is one of the most promising methods for removal of fulvic acids (FA), which is a typical category of natural organic contamination in groundwater. In this paper, TiO 2 /graphene nanocomposites (N-RGO/TiO 2 ) were prepared via simple chemical functionalization and one-step hydrothermal method for efficient photodegradation of FA under illumination of a xenon lamp as light source. Here, p -phenylenediamine was used as not only the linkage chemical agent between TiO 2 nanocrystals and graphene, but also the nitrogen dopant for TiO 2 nanocrystals and graphene. During the hydrothermal process, facets of TiO 2 nanocrystals were modulated with addition of HF, and sizes of TiO 2 nanocrystals were controlled by the contents of graphene oxide functionalized with p -phenylenediamine (RGO-NH 2 ). The obtained N-RGO/TiO 2 nanocomposites exhibited a much higher photocatalytic activity and stability for degradation of methyl blue (MB) and FA compared with other TiO 2 samples under xenon lamp irradiation. For the third cycle, the 10wt%N-RGO/TiO 2 catalyst maintains high photoactivity (87%) for the degradation of FA, which is much better than the TiO 2 -N/F (61%) in 3   h. This approach supplies a new strategy to design and synthesize metal oxide and graphene oxide nanocomposites with highly efficient photocatalytic performance.