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Whether Corrugated or Planar Vacancy Graphene-like Carbon Nitride (g-C₃N₄) Is More Effective for Nitrogen Reduction Reaction?

Ren, Chunjin, Zhang, Yongli, Li, Yanli, Zhang, Yongfan, Huang, Shuping, Lin, Wei, Ding, Kaining
Journal of physical chemistry 2019 v.123 no.28 pp. 17296-17305
Gibbs free energy, absorption, carbon nitride, density functional theory, models, nitrogen, nitrogen fixation, photocatalysis, spectral analysis
Different conformations, including planar, corrugated, as well as the deficient structure of the two-dimensional materials, play a relevant role in determining their catalytic reaction performances. Here, we systematically investigated the stabilities, electronic properties, and nitrogen activities capacity of various vacancy-modified g-C₃N₄ considering two different conformations (planar and corrugated) to explore the effects of nitrogen vacancy (NV) and conformations on the photocatalytic performance of g-C₃N₄ by means of density functional theory computations. Our results found that not only can the nitrogen vacancy (NV) promote separation efficiency of the photoinduced carriers in g-C₃N₄ but also the distortion conformation can activate more n → π* transitions of NV g-C₃N₄, resulting in a red shift of optical absorption spectra. More importantly, our results reveal that the corrugation configuration structure, compared to planar conformation, is much more favorable to photocatalytic nitrogen fixation reaction from the aspects of nitrogen absorption capacity and free-energy change, in which corrugation model with N₂C vacancy has the smallest onset potential (1.32 V) for the most difficult step through the alternating pathway.