Rich Indium‐Vacancies In ₂ S ₃ 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 ) In₂ S₃ 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 In₂ S₃ 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 In₂ S₃ to 0.44 eV of VIn -rich In₂ S₃ . The special structure endows defective In₂ S₃ 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 In₂ S₃ composite catalysts. Therefore, such a compositional strategy and mechanistic study are expected to offer new insights for designing highly efficient photocatalysts through defect engineering.