Enhanced Free-Radical Generation on MoS₂/Pt by Light and Water Vapor Co-Activation for Selective CO Detection with High Sensitivity

Semiconductor-based gas sensors hold great promise for effective carbon monoxide (CO) detection. However, boosting sensor response and selectivity remains a key priority in moist conditions. In this study, a composite material, Pt quantum dots decorated MoS₂ nanosheets (MoS₂/Pt), is developed as a highly sensitive material for CO detection when facilitated with visible light. The MoS₂/Pt sensor shows a significantly improved response (87.4%) with impressive response/recovery kinetics (20 s/17 s), long-term stability (60 days), and good selectivity to CO at high humidity (≈60%). It is confirmed both experimentally and theoretically that the MoS₂/Pt surface lowers the activation energy to convert CO to CO₂ via the free radicals induced by the synergy of photochemical effects and water vapor. As a result, the MoS₂/Pt surface promotes both CO response and selectivity, providing fundamental clues to improve room-temperature semiconductor-based sensors for gas detection under extreme conditions.