Photocatalytic properties of a new Z-scheme system BaTiO3/In2S3 with a core–shell structure

Abstract

It's highly desired to design and fabricate an effective Z-scheme photo-catalyst with excellent charge transfer and separation, and a more negative conduction band edge (ECB) than O2/·O2− (−0.33 eV) and a more positive valence band edge (EVB) than ·OH/OH− (+2.27 eV) which provides high-energy redox radicals. Herein, we firstly designed and synthesized a core–shell-heterojunction-structured Z-scheme system BaTiO3@In2S3 (BT@IS, labelled as BTIS) through a hydrothermal method, where commercial BT was used as the core and In(NO3)3·xH2O together with thioacetamide as the precursor of IS was utilized as the shell material. In this system, the shell IS possesses a ECB of −0.76 eV and visible-light-response Eg of 1.92 eV, while the core BT possesses a EVB of 3.38 eV, which is well suited for a Z-scheme. It was found that the as-prepared BTIS possesses a higher photocatalytic degradation ability for methyl orange (MO) than commercial BT and the as-prepared IS fabricated by the same processing parameters as those of BTIS. Holes (h+) and superoxide radicals (·O2−) were found to be the dominant active species for BTIS. In this work, the core–shell structure has inhibited the production of ·OH because the shell IS has shielded the OH− from h+. It is assumed that if the structure of BTIS is a composite, not a core–shell structure, ·OH could be produced during photocatalysis, and therefore a higher photocatalytic efficiency would be obtained. This current work opens a new pathway for designing Z-scheme photocatalysts and offers new insight into the Z-scheme mechanism for applications in the field of photocatalysis.