Building a direct Z-scheme heterojunction photocatalyst by ZnIn2S4 nanosheets and TiO2 hollowspheres for highly-efficient artificial photosynthesis

Facing the requirement of modern industrial development, selective reduction of 4-nitroaniline (4-NA) into p-phenylenediamine (PPD) via a facile, economic and eco-friendly photocatalysis technique has attracted more and more attention in recent years. In this study, ZnIn2S4 (ZIS) nanosheets grew in-situ on the surface of TiO2 hollowspheres through a hydrothermal method and formed a direct Z-scheme heterojunction composite, which exhibited exceedingly better photocatalytic 4-NA reduction performance than bare ZIS and TiO2. Such enhancement was mainly attributed to the dissimilar dimensionalities, intimate contact, and matchable band edge positions between ZIS and TiO2 semiconductors. Moreover, the substantial mechanism for the photocatalytic reaction in the ZIS/TiO2 system was reasonably proposed. Inspired by recent applications of the Z-scheme heterostructured materials in solar energy conversion and artificial photosynthesis, this work would arouse an increasing interest in designing more Z-scheme photocatalyst systems with high efficiency and extensive applications.