The gas-sensing performance of a core–shell SnO2-based chemiresistive MEMS sensor for H2S detection under vacuum

Abstract

Current semiconductor gas sensors often fail to operate in low-temperature and high-vacuum environments, making it challenging to detect gases in space. Herein, a core–shell structured SnO₂@Ag₂O composite with a high proportion of an effective interface was designed and developed into a MEMS gas sensor. Utilizing the selective adsorption of H₂S gas by SnO₂ microspheres, the direct reaction between Ag₂O nanoparticles and H₂S gas adsorbed on the surface of SnO₂ microspheres was achieved. The gas sensor achieved a fast response and high selectivity to H₂S gas under −20 °C and 1 × 10⁻⁵ Pa, with a response time of 15.3 s and a response value of 7.6 for 1 ppm H₂S gas. The present study has clarified surface chemisorbed oxygen ion roles and the deactivation of semiconductor gas sensors under high-vacuum. The “adsorption coupled with reaction” concept for gas sensing reactions was introduced, which could potentially be utilized in gas detection for deep space exploration.