Extended n-conjugated system in carbon nitride by incorporating pyridine rings and N vacancies for photocatalytic H2 evolution and H2O2 production

The extended n-conjugated system in polymer semiconductors holds a great potential in tuning the delocalized electrons for promoting photocatalytic efficiency. Herein, n-conjugate pyridine rings and nitrogen defects co-decorated polymer carbon nitride nanosheet (NCN-2AP-X) was constructed and applied in solar driven hydrogen (H2) and hydrogen peroxide (H2O2) production. Benefiting from synergistic effect of pyridine rings and N vacancies, the synthesized NCN-2AP photocatalyst with rich delocalized electrons indicates the extended light absorption range and improved carrier separation capability, particularly favoring the photocatalytic reactions. The optimal NCN-2AP-10 displayed an excellent H2 production rate of 2.55 mmol g-1 h-1 under visible-light irradiation with apparent quantum efficiency (AQE) of 9.79% at 420 nm. Moreover, a H2O2 production rate of 1.39 mmol L-1 h-1 was achieved by NCN-2AP-10 under monochromatic light (365 nm) irradiation. This work would provide a new view in designing the n-conjugated system incorporating metal-free photocatalysts for efficient H2 and H2O2 production.