Outer Space H2S Detection: CuO-Based Thin Film Gas Sensors Powered by UV-LED in Vacuum

Toxic gas sensors are widely used on Earth, but few are developed for their applications in outer space. Conventional metal oxide semiconductor (MOS) sensors are commonly operated at high temperatures (>100 ℃), which hinder their capabilities for detecting many toxic and explosive gases. Additionally, operating at elevated temperatures compromises their energy efficiency and long-term reliability, especially in space environment (approximately 10−12 Pa). Herein, we developed a p-n heterojunction-based MOS thin film gas sensor, assisted with an ultraviolet light emitting diode (UV-LED) irradiation method, operated at room temperature and vacuum condition (around 10−3 Pa). SnO2-CuO and ZnO-CuO thin films for detecting hydrogen sulfide (H2S) gas were chosen as examples in this study. The UV-LED (365 nm) enhanced chemical reactions between H2S and CuO significantly improved sensor performance, and the developed H2S sensor exhibited a remarkable sensitivity, with a response of 9799 for 25 ppm H2S. The sensor demonstrated good selectivity in the presence of various interfering gases such as CO, H2, and NO2, and showed its great potential for future space exploration applications.