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

• Published in: Molecular catalysis 2017-05, Vol.432, p.64-75
• Main Authors: Su, Feng-Yun, Zhang, Wei-De
• Format: Article
• Language: English
• Subjects: EDTA; g-C3N4; Grafting; Hydrogen evolution; Photocatalysis
• ISSN: 2468-8231; 2468-8231
• DOI: 10.1016/j.mcat.2017.02.011

g-C3N4 with distorted framework was prepared by thermal polymerization of EDTA-modified melamine. The obtained photocatalysts display high and stable activity for photocatalytic generation of hydrogen through water splitting. [Display omitted] •EDTM-modified g-C3N4 was synthesized.•Extending the light harvesting.•Effective separation and transfer of charge carriers.•High visible light photocatalytic activity for H2 evolution. 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-C3N4). In this study, modified g-C3N4 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-C3N4 by connecting adjacent 3,s-triazine units. The special chelate structure of EDTA leads to the distortion of g-C3N4 to a nonplanar structure, which is responsible for extending the light harvesting around 500nm, and consequently promoting the generation, separation and transfer of charge carriers. The H2 evolution rate on an optimized EDTM-grafted g-C3N4 photocatalyst (UCN-10) reaches 116.4μmolh−1, which is about 3.5 times of that on the pristine g-C3N4 (UCN). The formation process of the grafted structure and the mechanism for the enhanced photocatalytic H2 evolution over UCN-10 were proposed based on experimental results.