A novel route to porous N-doping carbon grafted carbon nitride for enhanced photocatalytic activity on CO2 reduction

Abstract Bulk graphitic carbon nitride (g-C3N4) shows inferior photocatalytic performance on CO2 conversion due to low CO2 capture and severe charge carriers recombination. In this work, a porous nitrogen-doping carbon grafted carbon nitride (N-doping carbon / CN) has been fabricated via the temperature-programmed thermal polymerization of urea with carboxyl functionalized polystyrene (HOOC-PS) nanospheres as template and carbon source. A series of characterizations including XRD, XPS, FE-SEM, TEM, BET-BJH and CO2-TPD have been investigated. It is found that, in comparison of bulk g-C3N4 synthesized by direct thermopolymerization of urea, N-doping carbon / CN presents pronounced nanopores, larger surface area and increased basic sites, which result in a high CO2 adsorption of about 5.5 times that on bulk g-C3N4. In addition, XPS results uncover N-doping carbon units have been grafted into g-C3N4 matrix through chemical interactions, which accelerate electron transport on N-doping carbon / CN. As a result, porous N-doping carbon / CN exhibits prominent photocatalytic activity on CO2 reduction with water vapor under visible light. The average CO production rate reaches 15.4 μmol· g-1· h-1, about 7.0 times that on bulk g-C3N4 (2. 2 μmol· g-1· h-1).