Facile preparation of In ₂ O ₃ –In ₂ S ₃ core–shell composites for the enhanced photoelectric activity

Abstract This study examines In ₂ S ₃ concentration to the photo‐induced current density of particulate In ₂ O ₃ –In ₂ S ₃ composite heterostructures under visible light irradiation. A self‐templated approach involving hydrothermal sulfidation of In ₂ O ₃ nanofibers with thioacetamide (TAA) in water produces the In ₂ O ₃ –In ₂ S ₃ core–shell structure at a moderate temperature. The In ₂ S ₃ fraction is readily tunable by adjusting the TAA concentration. Incorporating In ₂ S ₃ (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 In ₂ O ₃ –In ₂ S ₃ composites consist of 45 wt.% In ₂ S ₃ , to which the photocurrent intensity is more significant than 0.1 mA⋅cm ⁻² at 0.8 V in 0.1 M Na ₂ SO ₄ solution compared to less than 0.01 mA⋅cm ⁻² for the rest of the In ₂ O ₃ –In ₂ S ₃ 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.