Ordered and carbon-doped porous polymeric graphitic carbon nitride nanosheets toward enhanced visible light absorption and efficient photocatalytic H2 evolution

Abstract

An effective and rational pathway to tune the electronic bandstructure and visible light absorption properties of low-cost organic graphitic carbon nitride (g-C₃N₄, GCN) photocatalysts is still very challenging. Here, an efficient strategy is validated to tailor the bandstructure of g-C₃N₄ and C-doping can be regulated by polymerizing melamine with malonic acid, which can greatly extend the photoresponse range to 900 nm. The optimized GCN exhibits an improved photocatalytic hydrogen production rate of 663.6 μmol g⁻¹ h⁻¹ under visible light irradiation and an apparent quantum yield of 11% at 420 nm, which is three times higher than that of traditional bulk g-C₃N₄. This superior performance is derived from the unique ordered and porous structure of GCN, which effectively improves its light absorption and provides a larger specific surface area. In addition, the introduction of malonic acid into melamine and the subsequent thermal polymerization reaction further optimize the band structure of GCN, extend its light absorption via C-doping, and improve the photoinduced charge separation, resulting in high photocatalytic performance. This strategy provides a novel platform to design highly efficient GCN-based photocatalysts with precisely tunable operation windows and enhanced charge separation.