Accelerating directional charge separation via built-in interfacial electric fields originating from work-function differences

In this work, a hierarchical porous SnS2/rGO/TiO2 hollow sphere heterojunction that allows highly-efficient light utilization and shortening distance of charge transformation is rationally designed and synthesized. More importantly, an rGO interlayer is successfully embedded between the TiO2 hollow sphere shells and outermost SnS2 nanosheets. This interlayer functions as a bridge to connect the two light-harvesting semiconductors and acts as a hole injection layer in the tandem heterojunction. The induced built-in electric fields on both sides of the interface precisely regulate the spatial separation and directional migration of the photo-generated holes from the light-harvesting semiconductor to the rGO hole injection interlayer. These synergistic effects greatly prolong the lifetime of the photo-induced charge carriers. The optimized tandem heterojunction with a 2 wt% rGO loading demonstrate enhanced visible-light-driven photocatalytic activity for Rhodamine B (RhB) dye degradation (removal rate: 97.3%) and Cr(VI) reduction (removal rate: 97.09%). This work reveals a new strategy for the rational design and assembly of hollow-structured photocatalytic materials with spatially separated reduction and oxidation surfaces to achieve excellent photocatalytic performance. (C) 2021, Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.

Automated summary

In this study, a hierarchical porous SnS2/rGO/TiO2 hollow sphere heterojunction was designed and synthesized to enhance light utilization and charge transformation efficiency. The incorporation of an rGO interlayer acted as a bridge between the two semiconductors, improving photocatalytic performance for Rhodamine B dye degradation and Cr(VI) reduction. This work provides a new strategy for the rational design of hollow-structured photocatalytic materials with separated reduction and oxidation surfaces to achieve excellent photocatalytic activity.