Insight into the effect of B-doping on electronic structure and photocatalytic H2 evolution performance of C3N5 nanosheets

Graphitized carbon nitride (g-C3N4) is a star polymer for photochemical H2 production, but its broad bandgap and severe charge recombination usually limit its practical application. Herein, a novel B-doped N-rich carbon nitride (C3N5) material (BCN) is prepared through a one-pot thermal polymerization method, whereby C3N5 contains heptazine rings connected by two N-rich triazole terminal units with different structures, and the incorporated B-atoms replace the C-sites of heptazine rings. These structural features make C3N5 and BCN have larger conjugated structure, smaller electronic bandgap and more effective charge separation than g-C3N4. Moreover, B-doping can further significantly promote the photogenerated charge carrier separation and modulate the electronic energy bands of C3N5, and 1.3 wt% BCN delivers an apparent quantum yield of 12.5 % at 420 nm. The present results provide a promising strategy to improve the solar H2 production performance of carbon nitride by altering component and incorporating heteroatoms.