SnO2 promoted carrier separation in superior thin g-C3N4 nanosheets for enhanced photocatalytic degradation and H2 generation

The construction of heterostructures is an efficient approach to improve the photocatalystic performance of semiconductors. In this paper, SnO2-g-C3N4 (SnO2–CN) nanocomposites were created via thermal polymerization using SnO2 nanoparticles and layered g-C3N4 nanosheets. A mechano-chemical pre-reaction and the second thermal polymerization of bulk g-C3N4 play important roles for the formation of SnO2/g-C3N4 heterostructures with improved interface nature. The heterostructures with an optimized SnO2 weight ratio of 10% was obtained by adjusting parameters for enhanced photocatalytic reactions in visible light region. Hydrogen generation and the degradation of rhodamine B (Rh B) were tested to characterize the photocatalytic performance of the SnO2–CN nanocomposites. The degradation of a 20 mg/L Rh B solution was finished within 15 min, in which the degradation rate was about twice compared with superior thin g-C3N4 nanosheets prepared by a two-step polymerization procedure. The SnO2–CN nanocomposite with 10% SnO2 revealed a H2 generation rate of 2569.5 μmol g−1L−1. The enhanced photocatalytic performance is ascribed to a type II heterostructure formed and improved interface properties between g-C3N4 and SnO2. In addition, the improved conductivity of SnO2 promoted the photogenerated carrier separation and transfer. The result provided a new idea for the construction of g-C3N4 heterostructures with improved interface characterization and the improvement of photocatalytic properties.