Graphene-TiO2 mesoporous spheres assembled by anatase and rutile nanowires for efficient NO photooxidation

We design and synthesize a novel graphene embedded orient-assembled TiO2 mesoporous spheres composite (OATMS/GP) evidenced by SEM, TEM and optical spectra. Mesoporous structure, characteristics of single-crystal-like TiO2, mixed phases of anatase and rutile and embedding of graphene have been integrated into a composite system to investigate the structure-property relationship for enhancing photocatalytic activity. Three-dimensional (3D) open mesoporous TiO2 microspheres were well-constructed by the radially oriented self-assembly of single-crystal-like TiO2 nanowires. The aggregation of nanowires leads to the formation of 3D hierarchical microsphere including mesopores that is convenient for light harvesting and adsorption of reaction molecules. Especially, the phase ratio of anatase and rutile in the composite is readily tunable by the change of reaction agents. The incorporation of graphene accelerates the electron transfer and further prolongs the lifetime of the photoinduced electron-hole pairs. This unique structure makes the composite ideal be an efficient photocatalyst for the removal of pollutants. The OATMS/GP composite for degradation of Nitric Oxide (NO) shows an excellently photocatalytic activity and stability during photocatalytic reaction. The results presented here are expected to make a contribution to preparing delicately photocatalytic nanocomposites toward the promising applications for air purification and solar energy utilization.