C-I codoped porous g-C3N4 for superior photocatalytic hydrogen evolution

Porous C-I codoped carbon nitride materials were synthesized by in-situ codoping with iodized ionic liquid followed by post-thermal treatment in air. The effects of doping content of C-I codoping with different amounts of ionic liquid on the structural, optical and photocatalytic properties of the samples were investigated. Characterization results show that more compact interlayer sacking can be achieved by post-thermal treatment. Combined with C-I codoping by insertion of ionic liquids, much enlarged surface area but optimized sp(2) conjugated heterocyclic structure can be found in the catalysts. Optical and energy band analysis results evidence that the light absorptions especially in visible light region are significantly improved. Although the band gap of porous C-I codoped samples enlarge because of the generation of porous, the negatively shifted conduction band position thermodynamically supplies stronger motivation for water reduction. Photoelectricity tests reveal that the photo-induced electron density was increased after C-I codoping modification. Also, the recombination rate of electron-hole pairs is remarkably inhibited. The catalysts with moderate C-I codoing content perform sharply enhanced photocatalytic H-2 evolution activity under visible light irradiation. A H-2 evolution rate of 168.2 mu mol/h was achieved and it was more than 9.8 times higher than pristine carbon nitride. This study demonstrates a novel non-metal doping strategy for synthesis and optimization of polymer semiconductor with gratifying photocatalytic H-2 evolution performance from water hydrolysis. (C) 2018, Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.