Photoactivated Mixed In-Plane and Edge-Enriched p-Type MoS₂ Flake-Based NO₂ Sensor Working at Room Temperature

Toxic gases are produced during the burning of fossil fuels. Room temperature (RT) fast detection of toxic gases is still challenging. Recently, MoS₂ transition metal dichalcogenides have sparked great attention in the research community due to their performance in gas sensing applications. However, MoS₂ based gas sensors still suffer from long response and recovery times, especially at RT. Considering this challenge, here, we report photoactivated highly reversible and fast detection of NO₂ sensors at room temperature (RT) by using mixed in-plane and edge-enriched p-MoS₂ flakes (mixed MoS₂). The sensor showed fast response with good sensitivity of ∼10.36% for 10 ppm of NO₂ at RT without complete recovery. However, complete recovery was obtained with better sensor performance under UV light illumination at RT. The UV assisted NO₂ sensing showed improved performance in terms of fast response and recovery kinetics with enhanced sensitivity to 10 ppm NO₂ concentration. The sensor performance is also investigated under thermal energy, and a better sensor performance with reduced sensitivity and high selectivity toward NO₂ was observed. A detailed gas sensing mechanism based on the density functional theory (DFT) calculations for favorable NO₂ adsorption sites on in-plane and edge-enriched MoS₂ flakes is proposed. This study revealed the role of favorable adsorption sites in MoS₂ flakes for the enhanced interaction of target gases and developed a highly sensitive, reversible, and fast gas sensor for next-generation toxic gases at room temperature.