Phenyl-doped graphitic carbon nitride: photoluminescence mechanism and latent fingerprint imaging

The photoluminescence (PL) emission mechanism of graphitic carbon nitride (g-C₃N₄) is still ambiguous and the application of PL g-C₃N₄ powder as a solid sensing platform has not been explored. Herein we highlight a strategy to prepare g-C₃N₄ powder with strong green PL by doping phenyl groups in a carbon nitride network. Compared with pristine g-C₃N₄, doping of phenyl groups greatly enhances the PL efficiency and Stokes shift. Theoretical calculations based on density function theory indicate that phenyl groups change the electronic structure of the carbon nitride network and have an obvious contribution to the LUMO of phenyl-doped g-C₃N₄, which may be the main reason for the enhancement of the PL efficiency and Stokes shift. Taking advantage of the high PL efficiency, large Stokes shift and high photo-stability, phenyl-doped g-C₃N₄ powder shows promising application for the imaging of latent fingerprints.