Improvement of Gas-Sensing Performance of Large-Area Tungsten Disulfide Nanosheets by Surface Functionalization

Semiconducting two-dimensional (2D) transition metal dichalcogenides (TMDCs) are promising gas-sensing materials due to their large surface-to-volume ratio. However, their poor gas-sensing performance resulting from the low response, incomplete recovery, and insufficient selectivity hinders the realization of high-performance 2D TMDC gas sensors. Here, we demonstrate the improvement of gas-sensing performance of large-area tungsten disulfide (WS 2 ) nanosheets through surface functionalization using Ag nanowires (NWs). Large-area WS 2 nanosheets were synthesized through atomic layer deposition of WO 3 followed by sulfurization. The pristine WS 2 gas sensors exhibited a significant response to acetone and NO 2 but an incomplete recovery in the case of NO 2 sensing. After AgNW functionalization, the WS 2 gas sensor showed dramatically improved response (667%) and recovery upon NO 2 exposure. Our results establish that the proposed method is a promising strategy to improve 2D TMDC gas sensors.