Incorporation of π-conjugated molecules as electron donors in g-C3N4 enhances photocatalytic H2-production

Abstract Reinforcing migration of charge carrier in g-C3N4 photocatalytic system is critical for photocatalytic H2 evolution. Herein, we constructed a benzene-ring-incorporated g-C3N4 by copolymerization of urea with N-phenylthiourea. A π electron donor-acceptor conjugated structure is formed in which benzene ring is the donor while triazine ring is the acceptor. It is noteworthy that ultrafast transient absorption spectroscopy and density functional theory calculation were applied to gain more insight into the properties of the benzene ring with g-C3N4 as the electron donor in the triazine ring. As expected, the introduction of the benzene ring into triazine ring of the g-C3N4 displayed extraordinarily aggrandized hydrogen evolution, which not only crucially modified the π electronic structures and promote π-electron availability, but also played the role of a donor to improve the electron-hole separation. This study revealed that the photocatalytic H2 evolution of the donor-acceptor system can be further improved by inserting suitable π-conjugated as one of the units.