Facile preparation of In2O3–In2S3 core–shell composites for the enhanced photoelectric activity.

This study examines In2S3 concentration to the photo‐induced current density of particulate In2O3–In2S3 composite heterostructures under visible light irradiation. A self‐templated approach involving hydrothermal sulfidation of In2O3 nanofibers with thioacetamide (TAA) in water produces the In2O3–In2S3 core–shell structure at a moderate temperature. The In2S3 fraction is readily tunable by adjusting the TAA concentration. Incorporating In2S3 (45–82 wt.%) leads to a decreased bandgap from 3.1 to ca. 2.3 eV, enabling the harvest of partial visible‐light energy to create charged carriers efficiently. The photocurrent is particularly pronounced when the In2O3–In2S3 composites consist of 45 wt.% In2S3, to which the photocurrent intensity is more significant than 0.1 mA⋅cm−2 at 0.8 V in 0.1 M Na2SO4 solution compared to less than 0.01 mA⋅cm−2 for the rest of the In2O3–In2S3 counterparts. This is attributable to the enhanced electron–hole separation at the semiconducting heterojunction and the more efficient use of the light spectrum due to the narrowing bandgap. [ABSTRACT FROM AUTHOR]