Adsorption Mechanism of SO2 on Transition Metal (Pd, Pt, Au, Fe, Co and Mo)-Modified InP3 Monolayer

Using the first-principles theory, this study explored the electronic behavior and adsorption effect of SO2 on an InP3 monolayer doped with transition metal atoms (Pd, Pt, Au, Fe, Co and Mo). Through calculation and analysis, the optimum doping sites of TM dopants on the InP3 monolayer were determined, and the adsorption processes of SO2 by TM-InP3 monolayers were simulated. In the adsorption process, all TM-InP3 monolayers and SO2 molecules were deformed to some extent. All adsorption was characterized as chemical adsorption, and SO2 acted as an electron acceptor. Comparing Ead and Qt, the order of the SO2 adsorption effect was Mo-InP3 > Fe-InP3 > Co-InP3 > Pt-InP3 > Pd-InP3 > Au-InP3. Except for the Au atom, the other five TM atoms as dopants all enhanced the adsorption effect of InP3 monolayers for SO2. Furthermore, the analysis of DCD and DOS further confirmed the above conclusions. Based on frontier orbital theory analysis, it is revealed that the adsorption of SO2 reduces the conductivity of TM-InP3 monolayers to different degrees, and it is concluded that Pd-InP3, Pt-InP3, Fe-InP3 and Mo-InP3 monolayers have great potential in the application of SO2 resistive gas sensors. This study provides a theoretical basis for further research on TM-InP3 as a SO2 sensor.