Humidity-mediated room-temperature NO2 sensing using 2D SnS2 nanoplates

Abstract

Two-dimensional (2D) materials are promising candidates for room-temperature gas sensing because their ultrathin channels enable surface band bending to modulate a large fraction of the conduction current. Despite extensive material and device engineering, most 2D-based sensors still suffer from incomplete signal recovery and baseline drift. Here, we present a humidity-mediated gas-sensing strategy based on randomly oriented two-dimensional SnS2 nanoplates grown by atomic layer deposition. The sensing mechanism is proposed as a cascade process involving proton conduction through hydrogen-bonded networks on the SnS2 surface, analyte-induced disruption of these pathways, and water-assisted signal recovery. Experimental results demonstrate ideal NO2 sensing performance at relative humidity levels above 40%, with an excellent detection limit of 114.8 ppt and rapid recovery within 1 min at room temperature. Joint modulation of electrical bias and humidity enables tunable NO2 responses and maintains signal variation within ±5% of the mean over a relative humidity range of 40–80% as the bias is adjusted from 0.5 to 3 V. The sensor also exhibits excellent selectivity toward NO2, with minimal responses to interfering gases. These results suggest that humidity-mediated sensing offers a practical and effective pathway for developing high-performance room-temperature gas sensors.