Fabrication of graphene wrapped ZnIn2S4 microspheres heterojunction with enhanced interfacial contact and its improved photocatalytic performance

Abstract

Due to their build-in electric fields locating at interfaces of different materials, heterojunctions have shown excellent carrier separation ability and received wide attention in photocatalysis and photovoltaics. In general, larger interface area and smoother carrier transfer pathway are favorable for heterojunctions to achieve larger active area of build-in electric fields and longer photogenerated charge lifetime, respectively, and sequentially the heterojunctions may show optimized separation ability. However, there is hardly any report about this topic. In this paper, we design a new heterojunction material where a graphene (Gr) layer is close-fitting as the surface of the ZnIn₂S₄ microspheres (ZnIn₂S₄@Gr) in virtue of the electrostatic interaction between the functional groups of GO and the amino groups of ZnIn₂S₄ microspheres. Benefiting from the effective contact of Gr and ZnIn₂S₄ at their interface as well as the superior charge transfer ability of Gr, this structure displays good photocatalytic capability. The kinetic constant of phenol degradation on ZnIn₂S₄@Gr was 3.03 h⁻¹, which was 8.4-fold and 1.5-fold higher than those on ZnIn₂S₄ and ZnIn₂S₄–Gr composites, respectively. Furthermore, the excellent performance was stable according to the result of the consecutive cycling experiment. These experimental results demonstrated that the large interface area and smooth carrier transfer pathway were significant for heterojunction materials to provide better photogenerated charge separation properties.