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

Abstract

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.