Boosting exciton dissociation and charge transfer in P-doped 2D porous g-C3N4 for enhanced H2 production and molecular oxygen activation

Graphite carbon nitride (g-C3N4) is regarded as a potential candidate to settle environmental and energy issues, but its activity remains unsatisfactory due to the huge exciton effect and delayed charge transfer. Herein, the effects of phosphorus-doping and two-dimensional (2D) porous structures on the transition among singlet excitons, triplet excitons, and carriers and consequently the regulation mechanism of reactive oxygen species have been intensively studied. The calculations of the density functional theory and experimental results confirmed that P-doping could induce a dual built-in electric field to provide a driving force (up to 0.3 eV) for exciton dissociation. The light response capability, exciton dissociation, and carrier migration efficiency were significantly enhanced by the synergistic effect of the dual electric field and 2D porous structure. The optimal sample exhibited excellent H2 evolution rate and tetracycline degradation rate under visible-light irradiation which were approximately 25 and 7.1 times higher than those of bulk g-C3N4, respectively. The improved photocatalytic activity can also be demonstrated by a 2.9-fold and 3.2-fold increase in ·O2– and H2O2 production, respectively. This work provides a new perspective and approach to improve the performance of polymer photocatalysts and the targeted regulation of active species using exciton engineering.