Green Light-Driven Ultraselective Trimethylamine Detection Using In₂S₃ Nanoflakes at Room Temperature for Fish Quality Monitoring

Visible light-activated chemoresistive gas sensors offer low power consumption, room-temperature operation, minimal material degradation, and human safety. While extensive research has focused on NO₂ detection due to its high electron affinity, detecting volatile organic compounds or amine gases by light activation remains challenging because of the high activation energy required for interactions with sensing materials. Here, we report the first demonstration of green-light-activated trimethylamine (TMA) detection using β-In₂S₃ nanoflakes (NFs) corresponding to the bandgap energy of green wavelength. Photoabsorbed β-In₂S₃ NFs exhibit a TMA response 55 times greater than that in dark condition, with a rapid detection and ultrahigh selectivity. Density functional theory calculations highlight the role of the intrinsic defective structure of β-In₂S₃ in gas interactions. The β-In₂S₃ sensors were successfully applied for real-time fish quality monitoring under humid room-temperature conditions. Our findings provide a material strategy that achieves selective detection of specific gas molecules under wavelength-controlled light activation.