Advancements in monolayer TMD-based gas sensors: Synthesis, mechanisms, electronic structure engineering, and flexible wearable sensors for real-world applications and future prospects

Sensors are gaining attention as promising options for advanced detection technologies due to their higher sensitivity and faster response times, despite certain challenges related to stability and scalability. However, to meet the growing demand for even greater selectivity and flexibility, it is crucial to explore innovative materials that can enhance sensor device efficiency. Recent research has focused on investigating various materials for use in gas sensors, with particular attention given to monolayer transition metal dichalcogenides (TMDs). Monolayer TMDs exhibit immense potential for gas sensing due to their unique characteristics, including high carrier mobility, strong adsorption sites, efficient charge transfer, work function modulation, tunable bandgap, high surface-to-volume ratio, and low resistance. This comprehensive review explores a diverse array of topics related to the latest advancements in monolayer TMD-based sensors. It encompasses discussions on different synthesis methods for monolayer TMD materials, sensor structures, and the underlying gas sensing mechanisms, while elucidating the interplay between surface interactions and charge carrier dynamics that underpin their sensing capabilities. Additionally, a thorough overview of monolayer TMD-based materials focusing on their structural properties and gas sensing performance. This review also highlights electronic structure engineering strategies for monolayer TMDs-based sensors, which have shown promise in enhancing gas sensing performance. Furthermore, the advantages and limitations of monolayer TMD-based sensors are examined, offering a comprehensive understanding of their strengths and challenges. Additionally, the review discusses the applications of monolayer-based flexible sensors in real-world scenarios, particularly in daily human life. Finally, it addresses the challenges and future directions for the use of monolayer TMDs in gas sensing applications, offering valuable perspectives for the advancement of next-generation gas sensor devices.