Room-temperature NO2 detection using visible light-responsive SnO2-In2O3 heterostructures

Metal-oxide-semiconductor (MOS)-based gas sensors are promising platforms for NO 2 detection, yet their high operating temperatures and sluggish response-recovery times hinder practical applications. We report a hollow SnO 2 -In 2 O 3 heterostructure prepared through a hydrothermal route, followed by milling and calcination, enabling visible-light-activated NO 2 detection at room temperature. The sensor exhibits an exceptional response of 324.67–10 ppm NO 2 with rapid response/recovery times of 21/18 s and outstanding stability over 42 days. These remarkable properties arise from an increased number of active sites, a reduced band gap, and accelerates interfacial electron transfer. The well-engineered heterostructure facilitates efficient charge separation, enabling highly sensitive and low-power NO 2 sensing at room temperature. This work provides a heterostructure-engineering strategy for developing low-power MOS-based gas sensors for environmental NO 2 monitoring.