Visible Light-Driven Heterojunction Array Based on Type-I In₂S₃/In₂O₃ for Selective Multi-Gas Discrimination

Visible light-activated chemoresistive gas sensors offer a promising solution for minimizing power consumption, preventing material degradation, and enabling room temperature operation. However, their lower photon energy compared to UV light results in slower recovery and reduced sensitivity to NO₂, while detecting gases like volatile organic compounds and amines remains challenging. This work presents a visible light-driven gas sensor array based on type-I In₂S₃/In₂O₃ heterostructure. The In₂S₃ layer is uniformly deposited on In₂O₃ nanorods, forming type-I band alignment. Under blue light illumination, photoexcited electron-hole pairs migrate to the In₂S₃ surface, enhancing surface reactivity and enabling 56 times higher NO₂ response than pristine In₂O₃, with excellent selectivity, reliability, and humidity stability. Noble metal (Pd, Pt, and Au) decoration on the In₂S₃-In₂O₃ array also allows truly selective detection of NO₂, NH₃, C₂H₅OH, and H₂, which has not been reported previously for light-activated gas sensors. This work introduces a new strategy to optimize visible light-driven gas detection, advancing electronic nose technologies.