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

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 (VIn) In2S3 with atomic p–n homojunction through a one-pot preparation strategy. Positron annihilation spectroscopy and electron paramagnetic resonance reveal existence of VIn in the prepared photocatalysts. Mott–Schottky plots and surface photovoltage spectra prove rich VIn In2S3 can form atomic p–n homojunction. It is validated that p–n homojunction can effectively separate carriers combined with photoelectrochemical tests. VIn decreases carrier transport activation energy (CTAE) from 0.64 eV of VIn-poor In2S3 to 0.44 eV of VIn-rich In2S3. The special structure endows defective In2S3 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 In2S3 composite catalysts. Therefore, such a compositional strategy and mechanistic study are expected to offer new insights for designing highly efficient photocatalysts through defect engineering.