One step to synthesize the nanocomposites of graphene nanosheets and N-doped titania nanoplates with exposed {001} facets for enhanced visible-light photocatalytic activity

Abstract

Due to large particle size, low specific surface area, and the high recombination rate of the photo-generated electron–hole pairs, micrometer-sized N-doped TiO2 plates (NTP) with {001} facets generally present lower visible-light photocatalytic activity. In order to solve these problems, the nanocomposite photocatalysts consisted of graphene nanosheets (GR) and N-doped TiO2 nanoplates (NTNP) with exposed {001} facets were synthesized by a sol–gel process for the first time. The physical and chemical properties of the resultant nanocomposites (NTNP/GR) were studied in detail, and their photocatalytic activities were investigated by the photocatalytic decoloration of methylene blue solution under visible-light irradiation (λ > 420 nm). Owing to smaller particle size (about 25 nm) and higher specific surface area in comparison with micrometer-sized NTP, the photocatalytic activity of NTNP was improved effectively. Due to the effective charge anti-recombination of graphene, the photocatalytic activity of nanocomposite NTNP/GR was further improved. Due to the competition for light absorption between graphene and NTNP, there was an optimal ratio (1.0 %, the weight percentage of graphene to TiO2) between graphene and NTNP for the maximum of visible-light photocatalytic activity.