Hydrothermal synthesis of N-doped TiO2 nanowires and N-doped graphene heterostructures with enhanced photocatalytic properties

N-doped TiO2 nanowire/N-doped graphene (N-TiO2/NG) heterojunctions are fabricated by a simple hydrothermal method in a solution containing urea. In this hybrid structure, a three-dimensional hybrid photocatalyst was fabricated by using one-dimensional N-doped TiO2 nanowires penetrating through two-dimensional graphene nanosheets. Compared with TiO2 nanowire/graphene and N-doped TiO2 nanowire/graphene composites, the N-TiO2/NG heterostructures demonstrate a better photocatalytic performance for the degradation of methylene blue under visible light irradiations, as well as displaying a better recyclability. It is found that the nitrogen atoms originated from the decomposition of urea were not only entered into the lattice of TiO2 nanowires but also doped into the skeleton of graphene nanosheets. Results show that N doping expands the visible light absorption region of TiO2, and N-doped graphene additionally improves the separation and transportation of photogenerated electron-hole pairs plus generating a higher photocurrent, which plays a critical role for enhancing the photocatalytic activity.