Impact of Molecule–Molecule Interactions When Discerning Low-Concentration Hazardous Gas Mixtures

Gas sensor arrays are versatile and powerful tools for gas detection and analysis, enabling a wide range of applications across numerous industries. Critically, the accuracy and reliability of these arrays depend on the distinct gas sensing behavior or selectivity of the individual component gas sensors. However, studies of such arrays often consider only overly idealized scenarios, and the interaction between gas molecules is not typically considered in such studies. Here, based on first-principles calculations and direct experimental demonstrations, we show that interactions between gas molecules at the surface can play a significant role. We found that NO2 and NH3 molecules can be expected to align together to form dimers due to the strong interaction between NH3 and NO2 at the Fermi level, which enhances the adsorption capability and sensitivity of MoS2. Compared with the gas sensing performance of MoS2 for either NO2 or NH3 alone, a faster response is observed for sensing the NO2 and NH3 gas mixtures. Enhanced sensitivity, however, is achieved only at lower carrier densities with an appropriate concentration ratio between NO2 and NH3. These results not only provide evidence of the pronounced effect of gas molecule interactions but also suggest an approach for discerning gases.