Enhancement of intramolecular charge transfer in carbon nitride by attaching 2,4,5-Trichlorophenoxyacetic acid as electron acceptor units

Abstract

[EN] The photocatalytic activity of polymeric carbon nitride (CN) can still be improved by increasing the separation efficiency of photogenerated electron-hole pairs. Herein, we successfully anchored onto the framework of CN 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) as electron acceptor moiety through thermal copolymerization to assist photoinduced charge separation. The influence of chlorine groups as electron-withdrawing substituents made 2,4,5-T an electron-deficient molecule, able to act as shallow electron traps and favoring charge carrier separation respect to pristine CN. The energy levels introduced by 2,4,5-T effectively narrow the band gap in the 2,4,5-T-derivatized CN, leading to better light harvesting. The nanotube structure of CN-(2,4,5-T)0.25 induced larger specific surface area, providing larger number of active sites. As result, CN-(2,4,5-T)0.25 displayed an excellent photocatalytic H2 evolution of 1845 ¿mol g-1h¿1, 10.2 fold higher than that of CN. The methodology reported herein for the preparation of CN-(2,4,5-T) can be expanded to the rational design of efficient advanced CN nanomaterials exhibiting improved photocatalytic hydrogen production.