Materials design of edge-modified polymeric carbon nitride nanoribbons for the photocatalytic CO2 reduction reaction

Nanoribbon construction and modification with functional groups are important methods to improve the performance of photocatalysts. In this paper, density functional theory (DFT) calculations are applied to assess the electron absorption capacity of different model structures in the photocatalytic CO2 reduction reaction (CO2RR), i.e., melon-based carbon nitride nanoribbons (MNRs) and edge-modified melon-based carbon nitride nanoribbons (X-MNRs, X = NO2, CF3, CN, CHO, F, Cl, CCH, OH, SH, CH3, and H). It is found that X-MNRs (X = NO2, CN, CHO, CCH, OH, and H) have a significantly reduced band gap. Meanwhile, the VBM and CBM are effectively separated with the same optical absorption wavelength range, agreeing with the experimental observations. More importantly, the Gibbs free energy difference of the CO2RR rate-determining step is greatly reduced in MNRs, CHO-MNRs, CN-MNRs etc. with the formation of CO or HCOOH. The mechanism investigation indicates that the materials design via edge-group modification can optimize the CO2RR process.