Synergistic Effects of Photoactivation and Photothermal in MXene Heterostructures for the Enhanced H2S Detection Capability

Abstract

Semiconductor-based H2S gas sensors offer promising applications in human health detection, food monitoring, and industrial safety. Designing novel sensitive materials and coupling regulation mechanisms is crucial to achieving excellent response and response/recovery speed for room-temperature gas sensors. Herein, MXene/PbS heterostructures dual-modulated by visible-light activation and photothermal catalysis are proposed. Under near-infrared light activation, MXene/PbS sensor achieves a significant response value (90%, threefold higher than in dark conditions) for 10 ppm H2S, which also demonstrates rapid response/recovery kinetics (2 s/89 s), broad detection range (10 ppb–50 ppm), long-term stability (60 days), and excellent selectivity. Experimental and theoretical calculations reveal that the enhanced sensing performance of MXene/PbS arises from improved near-infrared light absorption and efficient photogenerated carrier separation by the constructed heterostructures, which promotes the dynamic generation of reactive radicals (·O2−, ·OH) on the sensitive material, and reduces the activation energy of H2S. Further, the self-generated photothermal effectively promotes the response and recovery speeds of the MXene/PbS sensor. Eventually, an intelligent monitoring system integrating MXene/PbS sensors and deep learning algorithms is successfully applied to human oral health diagnosis and egg spoilage warning, providing novel strategies for gas sensing mechanisms and practical applications of room-temperature semiconductor gas sensors.