NO₂ Gas Sensor Based on WO₃/SiNWs Composite Structure

Although tungsten oxide (WO₃)-based NO₂ sensors have been extensively studied, achieving high sensitivity at low operating temperatures remains a significant challenge. To address this limitation, we designed a WO₃/SiNWs heterojunction-based sensor, fabricated through metal-assisted chemical etching followed by hydrothermal synthesis. Structural and morphological analyses confirm the uniform integration of WO₃ nanorods onto SiNWs and the establishment of an effective p-n junction. The optimized sensor exhibits a response of 238 toward 1 ppm NO₂ at 127 °C with a response/recovery times of 14.8 s/99.2 s. The improved performance stems from the heterojunction-driven enhancement of charge carrier separation and surface adsorption sites, offering a viable route for developing low-power, high-performance gas sensors.