Acetamide- or Formamide-Assisted In Situ Approach to Carbon-Rich or Nitrogen-Deficient Graphitic Carbon Nitride for Notably Enhanced Visible-Light Photocatalytic Redox Performance.

Acetamide- or formamide-assisted in situ strategy is designed to synthesize carbon atom self-doped g-C N (AHCN ) or nitrogen vacancy-modified g-C N (FHCN ). Different from the direct copolymerization route that suffers from the problem of mismatched physical properties of acetamide (or formamide) with urea, the synthesis of AHCN (or FHCN ) starts from a crucial preorganization step of acetamide (or formamide) with urea via freeze drying-hydrothermal treatment so that the chemical structures as well as C-doping level in AHCN and N-vacancy concentration in FHCN can be precisely regulated. By using various structural characterization methods, well-defined AHCN and FHCN structures are proposed. At the optimal C-doping level in AHCN or N-vacancy concentration in FHCN , both AHCN and FHCN exhibit remarkably improved visible-light photocatalytic performance in oxidation of emerging organic pollutants (acetaminophen and methylparaben) and reduction of proton to H in comparison of unmodified g-C N . Combination of the experimental results with theoretical calculations, it is confirmed that AHCN and FHCN show different charge separation and transfer mechanisms, while the enhanced visible-light harvesting capacity and the localized charge distributions on HOMO and LUMO are responsible for this excellent photocatalytic redox performance of AHCN and FHCN .