Oxygen self-doped g-C3N4 with tunable electronic band structure for unprecedentedly enhanced photocatalytic performance

Abstract

As a fascinating conjugated polymer, graphitic carbon nitride (g-C₃N₄) has attracted much attention for solving the worldwide energy shortage and environmental pollution. In this work, for the first time we report oxygen self-doping of solvothermally synthesized g-C₃N₄ nanospheres with tunable electronic band structure via ambient air exposure for unprecedentedly enhanced photocatalytic performance. Various measurements, such as XPS, Mott–Schottky plots, and density functional theory (DFT) calculations reveal that such oxygen doping can tune the intrinsic electronic state and band structure of g-C₃N₄via the formation of C–O–C bond. Our results show that the oxygen doping content can be controlled by the copolymerization of the precursors. As a consequence, the oxygen doped g-C₃N₄ shows excellent photocatalytic performance, with an RhB photodegradation rate of 0.249 min⁻¹ and a hydrogen evolution rate of 3174 μmol h⁻¹ g⁻¹, >35 times and ∼4 times higher than that of conventional thermally made pure g-C₃N₄ (0.007 min⁻¹ and 846 μmol h⁻¹ g⁻¹, respectively) under visible light. Our work introduces a new route for the rational design and fabrication of doping modified g-C₃N₄ photocatalyst for efficient degradation of organic pollutants and H₂ production.