Controlling carbon self-doping site of g-C3N4 for highly enhanced visible-light-driven hydrogen evolution

By Yuanyong Huang, Di Li, Zhenyuan Fang, Ruijie Chen, Bifu Luo, Weidong Shi. Applied Catalysis B: Environmental, 2019

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Abstract Nowadays, the C-substitution for N in g-C3N4 can promote π-electron availability and thus considerably increase its photocatalytic properties. However, the replacement of N in triazine ring of g-C3N4 by carbon atom represents a huge challenge on account of the higher electronegativity of N over C. Herein, we firstly report a simple and effective strategy for skillfully replacing one nitrogen with carbon atom by copolymerizing π-electrons-rich uracil with dicyandiamide via a facile Schiff-base reaction. The results show that direct incorporation C4N2 ring into the framework not only maintains the structural features of g-C3N4 and narrows its bandgap from 2.75 to 2.58 eV, but also effectively boosts the dissociation of photogenerated excitons. Consequently, C-incorporated g-C3N4 could harvest more solar light (λ = 750 nm). As expected, the photocatalytic hydrogen evolution rate of the optimal C self-doped g-C3N4 is almost as high as 13 and 20 times that of bare g-C3N4 under the visible-light exposure and the blue light illumination, respectively. Most importantly, the optimal sample also shows excellent performance under the green (λ = 500 nm) and yellow (λ = 550 nm) light illumination (94.07 and 28.47 μmol g−1 h−1, respectively). This work sheds light on a subtle molecular-tailored protocol for controlling carbon self-doping site of the g-C3N4 to optimize the intrinsic electronic properties and photoactivity.

Subfields: Electrical and Electronic Engineering, Materials Chemistry, Renewable Energy, Sustainability and the Environment

View Paper: https://www.semanticscholar.org/paper/1ac01200c7214439a8dc5c5bd280e4cf3e84e2b3