Enhanced acidic gas adsorption performance of arsenene by Pt mediation

Based on first-principle calculations, we have theoretically investigated the effect of Pt mediation (doping and embedding) on the adsorption behavior of the arsenene monolayer (As-ML) for several acidic gas molecules (H2S, SO2, and NO2). We find that the shape and orientation of each gas molecule in the most stable adsorption configuration are changeable depending upon the type of substrate used; however, the changing trend for adsorption energy is well correlated with the adsorption distance. The results reveal that Pt-embedded As-ML is more sensitive to all gas molecules than Pt-doped As-ML due to its larger adsorption energy. The gas molecules interact with Pt-embedded As-ML via weak chemical bonds, which induces a significant change in the bandgap of the adsorption system. Charge transfer occurs from the substrate to gas molecules, and the gas molecule acts as an electron acceptor, which will affect the change in the charge carrier concentration, thereby reflecting a change in the electrical conductance of the arsenene system. However, taking into account the feasibility of the desorption process, Pt-doped As-ML is more suitable as an H2S sensor compared to Pt-embedded As-ML. Overall, this work will help to guide scientists to develop fabricating arsenene-based gas sensors in the future.