Effect of conjugation degree and delocalized Π-system on the photocatalytic activity of single layer g-C₃N₄

Single layer g-C₃N₄ could be obtained from a protonic acid treatment of g-C₃N₄ or a new sandwich-like orientation growth of melamine. Through the self-assembly of melamine and polyacrylamide by hydrogen bonds and electrostatic interactions, g-C₃N₄, with extended planarized atomic single layer, exhibits superiority in both photocatalytic hydrogen evolution and photocatalytic degradation under visible light irradiation. Besides low efficiency, the acid exfoliation will destroy the delocalized π-system by inducing O atoms. The decrease of conjugation degree increases the optical gaps, making it hard for g-C₃N₄ to capture photons. On the contrary, the facile sandwich-like orientation growth of melamine highly keeps the conjugation degree of g-C₃N₄ and extends its delocalized π-system. Such single layer g-C₃N₄ is more active even better than N-doped TiO₂ under visible light irradiation.