Research paperEffect of conjugation degree and delocalized π-system on the photocatalytic activity of single layer g-C3N4

- Chemical exfoliation changes the surface electricity of g-C3N4.
- The partial destruction occurred during acid exfoliation.
- High conjugation degree was kept in g-C3N4-PAM.
- Delocalized π-system was extended in g-C3N4-PAM.
- g-C3N4-PAM exhibits higher photocatalytic activity.

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.

201Because of the superiority on conjugation degree and delocalized π-system, single layer g-C3N4-PAM exhibits excellent photocatalytic activity not only on organic degradation but also on H2 evolution.