Near-infrared light-activated g-C3N4 with effective n → π* electron transition for H2O2 production.

The synergistic effect of sodium and oxygen expands π-conjugated aromatic rings and distortion of the heptazine skeleton, enhancing the intrinsic π→π* electron transition and the effective n→π* electron transition. [Display omitted] • A sodium and oxygen co-doped g-C 3 N 4 (NaOCN) is prepared by facile microwave synthesis, in which Na as a charge transport channel promotes the separation efficiency of photogenerated carriers. • The as-prepared NaOCN exhibits the NIR absorption extended to 1400 nm and the apparent quantum yield (AQY) can keep 26.9% at 420 nm and still maintain 7.2 % at 600 nm, which shows strong NIR response range. • The intrinsic π → π* electron transition and active the n → π* electron transition generated by the synergistic effect of Na and O atoms are the main factor to promote the NIR response of NaOCN. Efficient utilization of near-infrared light (NIR) is critical to optimize the performance of photocatalysts. Herein, an ultrafast process is employed to co-condensation of melamine and NaCl by microwave-assist heating. The fabricated sodium and oxygen co-doped g-C 3 N 4 (NaOCN) shows extended π-conjugated aromatic rings and distortion of the heptazine skeleton, which can enhance the intrinsic π → π* electron transition and active the n → π* electron transition. The robust n → π* excitation of NaOCN leads to a narrowed bandgap of 2.73 eV with the NIR absorption extending to 1400 nm. The apparent quantum yield (AQY) for NaOCN can still keep 7.2 % at 600 nm. This work provides a promising way for the application of NIR-based carbon nitride in photocatalytic H 2 O 2 production. [ABSTRACT FROM AUTHOR]