The modulation of g-C3N4 energy band structure by excitons capture and dissociation

Abstract The nitrogen vacancy g-C3N4 obtained by the thermal polymerization urea possessed the largest exciton binding energy, and the nitrogen vacancies would capture excitons and promote them to dissociate into the free electrons and the holes at energy disordered areas. The accumulation of numerous free electrons in the nitrogen vacancy g-C3N4 led to raise its Fermi level, which meant that the conduction band potential of nitrogen vacancy g-C3N4 would be more negative. Additionally, the enhancement of the confinement effect endowed it a more positive valence band potential. Eventually, it gave nitrogen vacancy g-C3N4 the widest band gap (2.62 eV) and the strongest redox ability (ECB: -1.260 V, EVB: 1.360 V).