Phosphorus and sulfur codoped g-C3N4 as an efficient metal-free photocatalyst

In this study, the photocatalytic activity of graphitic carbon nitride (g-C3N4) was improved by codoping S and P on the interstitial and carbon sites of its aromatic heptazine units, respectively. X-ray photoelectron spectra and X-ray diffraction measurements demonstrated that P covalently bonded with N because of the substitution of C with P and that S was located at the interstitial sites with relatively weak bonding with N in the heptazine units of the g-C3N4 structure. The samples of g-C3N4 codoped with P and S (PSCN) displayed low photoluminescence emission intensity, suggesting suppressed recombination of photogenerated charges, and thus increased photocatalytic degradation activity. In particular, PC (C replaced by P) and Si (interstitial doping of S) doping on g-C3N4 was prominently able to enhance the charge transfer through the N-S-N-C-N-P pathway to cross the heptazine units for the photocatalytic reaction, making PSCN a highly visible-active and effective metal-free photocatalyst. (C) 2017 Elsevier Ltd. All rights reserved.