Ordered layered N-doped KTiNbO5/g-C3N4 heterojunction with enhanced visible light photocatalytic activity

Abstract

A facile one-step calcination approach for the synthesis of ordered layered N-doped KTiNbO5/g-C3N4 (NTNO/CN) heterojunction composites was developed. It was found that KTiNbO5 layers were in-situ doped by nitrogen atoms to form N-KTiNbO5 and two-layered g-C3N4 nanosheets were formed within the interlayers of N-KTiNbO5 due to the space-confined effects. The photocatalytic performance of the resulted composites was evaluated by the degradation of rhodamine B (RhB) and bisphenol A (BPA) under visible light irradiation. N-KTiNbO5 coupled with a proper amount of g-C3N4 exhibited an excellent photocatalytic performance due to the synthetic effects of N doping and layered heterojunction, leading to the high efficiency of light harvesting and charge separation. Especially, the in-situ intercalated two-layered g-C3N4 nanosheets can significantly increase the contact area with N-KTiNbO5 layers for efficient charge transfer across the interface, showing a much greater effect on the enhanced photocatalytic activity than those on the pure surface of N-KTiNbO5. It is expected that such a layered heterojunction can greatly speed up the separation and efficient transfer of photogenerated charge carriers. The active species of O2− played a leading role in the photocatalytic process while h+ contributed to a lesser extent during the photocatalytic degradation of RhB over NTNO/CN-1, as determined by the active species capture experiment and ESR spectra. This work provides a new insight into the preparation of layered heterojunction hybrids with ordered alternative layered structure, and thus opens up the possibility of ‘design-and-build’ 2D layered heterojunctions for large-scale theoretical exploration and practical applications.