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

Abstract 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.