Simultaneous N-doping of reduced graphene oxide and TiO2 in the composite for visible light photodegradation of methylene blue with enhanced performance

The nitrogen-doped P90 TiO2 (N-P90), nitrogen-doped reduced graphene oxide (N-RGO) and their composite were synthesized via a one-step annealing treatment process under NH3 atmosphere using commercial P90 TiO2 and GO as starting materials. The as-prepared N-P90, N-RGO and N-P90/N-RGO composite were characterized by field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and ultraviolet-visible diffuse reflectance spectroscopy (DRS). The results indicated that both the reduction of graphene oxide and the incorporation of nitrogen into both RGO and TiO2 matrices were accomplished simultaneously in the facile process. The photocatalytic activity of the as-prepared samples was evaluated using the degradation of methylene blue (MB) under visible light irradiation. N-P90/N-RGO composites showed a significantly enhanced photocatalytic performance compared with P90 TiO2, N-P90 and N-P90/RGO composites. The higher photocatalytic activity of N-P90/N-RGO composites can be ascribed to the more efficient separation of the photogenerated charges resulting from the improved electrical conductivity of the N-RGO sheets, as well as the enhanced absorption in the visible light region. Overall, this work demonstrated a facile approach of incorporating nitrogen into commercial TiO2 and RGO simultaneously and a novel strategy of fabricating a visible light-active photocatalyst with improved efficiency for mass application.