Electrostatic self-assembly to form unique LiNbO3/ZnS core-shell structure for photocatalytic nitrate reduction enhancement

Abstract

Photocatalytic NO3– reduction in water has been regarded as a promising route due to its high efficiency and green feature. Several limiting factors, such as lack of catalytic sites, insufficient light collection, and spatial charge separation capacity photocatalytic denitrification, still need to be overcome for the practical applications. Herein, an innovative LiNbO3/ZnS heterojunction with a unilateral opening core–shell structure was constructed. ZnS was tightly anchored on the surface of LiNbO3 by modified electrostatic self-assembly method. High nitrate removal rate (98.84%) and N2 selectivity (98.92%) were achieved with a molar ratio of LiNbO3 and ZnS of 1:5 (1:5L-ZS) using formic acid as a hole scavenge. The LiNbO3/ZnS degradation kinetics of NO3– was corresponding to the first-order kinetics equation. The nitrate removal rate and N2 selectivity remained stable after three cycles in such photocatalytic NO3– reduction. The outstanding photocatalyst performance can be ascribed to the improved surface active sites, the well-matched band structure, and the unique core–shell structure. It provides an effective strategy for controllable fabrication of core–shell photocatalyst with strong light-harvesting ability and charge separation efficiency to enhance the removal rate of nitrate in water.