# NO2 Gas Sensor Based on WO3/SiNWs Composite Structure

## TL;DR

A new NO2 gas sensor using a WO3/SiNWs composite structure shows high sensitivity at low temperatures due to improved charge separation and surface adsorption.

## Contribution

A novel WO3/SiNWs heterojunction sensor design that achieves high sensitivity at low operating temperatures.

## Key findings

- The sensor shows a response of 238 toward 1 ppm NO2 at 127 °C.
- Response and recovery times are 14.8 s and 99.2 s, respectively.
- The heterojunction enhances charge carrier separation and surface adsorption sites.

## Abstract

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.