Universal Covalent Functionalization of Two-Dimensional Transition Metal Dichalcogenides for Sarin Simulant Detection

The detection of chemical warfare agents such as sarin is essential for public security, yet conventional sensors lack sufficient sensitivity for trace-level vapor detection. To address this, we developed a universal covalent functionalization approach for two-dimensional transition metal dichalcogenides (including MoS2, MoSe2, WS2, WSe2, and In2Se3), enabling highly sensitive detection of dimethyl methylphosphonate (DMMP), a sarin simulant. Using a custom-synthesized diazonium salt (4-HFBD) with KI assistance, we rapidly graft acidic groups onto inert TMD surfaces while enhancing their n-type semiconductor characteristics. This design leverages directional hydrogen bonding between the functionalized surface and DMMP, resulting in exceptional room-temperature sensitivity. The optimized MoS2 sensor achieves selective and reversible DMMP detection with a low detection limit of 42 ppb and a fast response time of 4.6 s, surpassing most reported analogues. This work provides a versatile and tunable platform for trace chemical threat detection, representing a major advance in sensing technology.