Constructing oxygen-doped g-C3N4 nanosheets with an enlarged conductive band edge for enhanced visible-light-driven hydrogen evolution

Doping protocols have been widely investigated due to their effectiveness in tuning the energy band gaps of photocatalysts for improved photocatalytic activity. Here, we demonstrated the efficient and facile hydrogen peroxide-assisted hydrothermal reforming of melamine to synthesize a new oxygen (O)-doped precursor that was then transferred to O-doped g-C3N4 nanosheets, with an increased conductive band edge compared to bulk g-C3N4, via direct thermal polymerization. Owing to synergistic interaction between the 2D ultrathin nanosheet structure with large surface area and the enhanced conductive band edge caused by appropriate oxygen doping, the as-synthesized O-doped g-C3N4 nanosheets showed highly enhanced photocatalytic hydrogen evolution activity, about 10.7 times higher than pristine C3N4 under visible light irradiation, achieving an apparent quantum yield of 13.04% at 420 nm. Significantly, this precursor pre-doping strategy might provide a promising pathway for preparing heteroatom-doped g-C3N4.