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 (WS₂) nanosheets through surface functionalization using Ag nanowires (NWs). Large-area WS₂ nanosheets were synthesized through atomic layer deposition of WO₃ followed by sulfurization. The pristine WS₂ gas sensors exhibited a significant response to acetone and NO₂ but an incomplete recovery in the case of NO₂ sensing. After AgNW functionalization, the WS₂ gas sensor showed dramatically improved response (667%) and recovery upon NO₂ exposure. Our results establish that the proposed method is a promising strategy to improve 2D TMDC gas sensors.