The interaction of NO2 gas with functionalized 2D WSe2 was investigated in this study. The liquid exfoliated pristine 2D WSe2 was functionalized with Au and Pt nanoparticles through reduction of respective metal salts at room temperature. The catalytic effect of nanoparticle functionalization was observed in gas sensing experiments. The results revealed the enhancement in sensing response upon decoration (R% = 170% for Au-decoration and 220% for Pt-decoration at 5 ppm NO2) at room temperature and most importantly, the recovery of the sensor was improved to less than 5 min for Au decorated WSe2. This work, therefore, successfully addressed the known bottleneck of recovery in 2D material-based NO2 sensors without utilizing any external energy stimulus. In fact, the response was found to be stable and reproducible while the sensor was subjected to repeated testing. The sensing characteristics and the underlying sensing mechanism have been explained in detail.
