Covalently bonded 2D/2D O-g-C3N4/TiO2 heterojunction for enhanced visible-light photocatalytic hydrogen evolution

Visible-light photocatalytic hydrogen evolution is a key step towards utilizing solar energy. Here we constructed covalently bonded oxidized graphitic C 3 N 4 /TiO 2 (O-g-C 3 N 4 /TiO 2 ) heterostructure with high surface area via an in-situ solvothermal synthetic strategy. The edge-anchoring of two-dimensional (2D) TiO 2 on 2D O-g-C 3 N 4 was evidenced by the HAADF-STEM EDS mapping, EELS and XPS analysis. Density functional theory computations suggest strong affinity between TiO 2 and O-g-C 3 N 4 2D structures through N O Ti covalent bonding, which drastically enhances the synergetic effect of the light absorption of O-g-C 3 N 4 and high surface area of TiO 2 . The as-formed heterojunction can remarkably boost the visible-light photocatalytic activity for H 2 evolution by 6.1 times compared to physical mixture of TiO 2 nanosheets (NS) and O-g-C 3 N 4 .