Photocatalytic properties of a new Z-scheme system BaTiO 3 /In 2 S 3 with a core-shell structure.

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 ( E _CB ) than O ₂ /·O ₂ ^- (-0.33 eV) and a more positive valence band edge ( E _VB ) 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 BaTiO ₃ @In ₂ S ₃ (BT@IS, labelled as BTIS) through a hydrothermal method, where commercial BT was used as the core and In(NO ₃ ) ₃ · x H ₂ O together with thioacetamide as the precursor of IS was utilized as the shell material. In this system, the shell IS possesses a E _CB of -0.76 eV and visible-light-response E _g of 1.92 eV, while the core BT possesses a E _VB 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 (·O ₂ ^- ) 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.
Competing Interests: There are no conflicts to declare.
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