Creating distortion in g-C3N4 framework by incorporation of ethylenediaminetetramethylene for enhancing photocatalytic generation of hydrogen

Relatively narrow visible light responsive region and high recombination probability of photogenerated charge carriers are the main barriers that limit the photocatalytic activity of graphitic carbon nitride (g-C 3 N 4 ). In this study, modified g-C 3 N 4 was synthesized by adding minor amount of ethylenediaminetetraacetic acid (EDTA) into urea as precursors for subsequent thermal polymerization. The thermal intermediate product ethylenediaminetetramethylene (EDTM) during decarboxylation of EDTA was grafted to the framework of g-C 3 N 4 by connecting adjacent 3,s-triazine units. The special chelate structure of EDTA leads to the distortion of g-C 3 N 4 to a nonplanar structure, which is responsible for extending the light harvesting around 500   nm, and consequently promoting the generation, separation and transfer of charge carriers. The H 2 evolution rate on an optimized EDTM-grafted g-C 3 N 4 photocatalyst (UCN-10) reaches 116.4   μmol   h −1 , which is about 3.5 times of that on the pristine g-C 3 N 4 (UCN). The formation process of the grafted structure and the mechanism for the enhanced photocatalytic H 2 evolution over UCN-10 were proposed based on experimental results.