Enhancement in hazardous gas detection capabilities of MoS2 monolayer-based devices through defect engineering and photonic activation

The gas-sensing potential of transition metal dichalcogenides (TMDs) drew attention owing to their high surface sensitivity and tunable optoelectronic features. Among the TMDs, monolayer MoS₂ stands out as a promising material for advanced gas sensors. However, TMDs-based gas sensors still require considerable improvement in room temperature sensitivity, response times, and stability, which may be achievable through alterations in kinetics. Herein, we report a highly sensitive NH₃ gas sensor based on monolayer MoS₂, whose sensing performance is greatly enhanced by defect engineering and photonic activation. Intestinally induced sulfur vacancies create chemically active adsorption sites, increasing adsorption energy and enhancing charge transfer between NH₃ molecules and MoS₂. On the other hand, visible-light illumination stimulates photoresponsivity by generating electron-hole pairs to speed up desorption and recovery time. With these combined stimuli, very large modulations to the electronic band structure occur, thus enhancing the gas-surface interaction dynamics and hence sensing performance. Thus, this study highlights the potential of defect-engineered and photonic-activated monolayer MoS₂ as a strong candidate for advanced gas detection and presents a scalable pathway for next-generation sensor development, meeting the demands of environmental and industrial monitoring.