Trace-level methanol detection at room temperature enabled by single-atom Pd stabilized on defective 2D WS2

Conventional semiconducting gas sensors operating at high temperature (150-400 ℃) are unsuitable for detecting highly flammable methanol (CH 3 OH), thus necessitating room-temperature (RT) operation. However, most reported RT CH 3 OH sensors, hindered by low sensitivity, high detection limit, and poor stability, are impractical for precision gaseous analysis. This study presents a high-performance RT CH 3 OH sensor employing single-atom Pd stabilized onto defective WS 2 nanosheets (Pd SA@WS 2 NSs) as sensing material, overcoming the sensitivity, limit of detection, and stability limitations. Notably, 0.3   wt% Pd SA@WS 2 NSs-based RT sensor exhibited high response (33.7% to 100 ppb CH 3 OH), stable repeatability and low detection limit at 23 ℃, surpassing the reported RT CH 3 OH sensors. The enhanced gas-sensing performance is attributed to the synergistic effect of the highly catalytic activity of atomically dispersed Pd, and the high methanol adsorption at sulfur defects on the WS 2 surface. As a proof-of-concept, we constructed a portable real-time monitoring system using the as-prepared RT sensor, coupled with dynamic threshold alarm functionality that enables immediate indoor air quality assessment and early warning. This work establishes a new paradigm for CH 3 OH leakage monitoring.