Rich Indium‐Vacancies In2S3 with Atomic p–n Homojunction for Boosting Photocatalytic Multifunctional Properties

Abstract Design and development of highly efficient photocatalytic materials are key to employ photocatalytic technology as a sound solution to energy and environment related challenges. This work aims to significantly boost photocatalytic activity through rich indium vacancies (V In ) In 2 S 3 with atomic p–n homojunction through a one‐pot preparation strategy. Positron annihilation spectroscopy and electron paramagnetic resonance reveal existence of V In in the prepared photocatalysts. Mott–Schottky plots and surface photovoltage spectra prove rich V In In 2 S 3 can form atomic p–n homojunction. It is validated that p–n homojunction can effectively separate carriers combined with photoelectrochemical tests. V In decreases carrier transport activation energy (CTAE) from 0.64 eV of V In ‐poor In 2 S 3 to 0.44 eV of V In ‐rich In 2 S 3 . The special structure endows defective In 2 S 3 with multifunctional photocatalysis properties, i.e., hydrogen production (872.7 µmol g −1 h −1 ), degradation of methyl orange (20 min, 97%), and reduction in heavy metal ions Cr(VI) (30 min, 98%) under simulated sunlight, which outperforms a variety of existing In 2 S 3 composite catalysts. Therefore, such a compositional strategy and mechanistic study are expected to offer new insights for designing highly efficient photocatalysts through defect engineering.