A MXene-based multiple catalyst for highly efficient photocatalytic removal of nitrate.

ABSTRACT

Photocatalytic removal of nitrate in wastewater has attracted wide attention because of its simple operation and environmental protection. However, the preparation of photocatalysts with high efficiency and high nitrogen selectivity is still a challenge. In this paper, TiO2 is grown in situ on Ti3C2 MXene by a simple calcination method and modified with silver particles. The presence of Ti3C2 reduces the recombination rate of photogenerated electrons and generates more photogenerated electrons. At the same time, the silver particles also increase the photoelectron density and further improve the carrier separation of the catalyst. Due to its unique structure and optical properties, the prepared photocatalyst shows an excellent nitrate removal rate under a high-pressure mercury lamp. At 500 mgN/L, the nitrate removal rate reaches 96.1%, and the nitrogen selectivity reaches 92.6%. Even after 5 cycles, the prepared photocatalyst still maintains a high nitrate photocatalytic removal efficiency (89%). The electron transfer path is verified by density functional theory calculations.