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 MoS 2 nanosheets (MoS 2 /Pt), is developed as a highly sensitive material for CO detection when facilitated with visible light. The MoS 2 /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 MoS 2 /Pt surface lowers the activation energy to convert CO to CO 2 via the free radicals induced by the synergy of photochemical effects and water vapor. As a result, the MoS 2 /Pt surface promotes both CO response and selectivity, providing fundamental clues to improve room‐temperature semiconductor‐based sensors for gas detection under extreme conditions.