Pd, Ag decorated MoSi2N4 monolayer: A potential material for reusable CO and NO gas-sensitive material with high sensitivity

Abstract

Recently, a novel MoSi2N4 monolayer has been successfully synthesized (Science 369, 670, 2020) and exhibits excellent photoelectric property. Motivated by this, the adsorption characteristics and sensing properties of four toxic gases (CO, NO, NO2, SO2) on the Pd and Ag doped MoSi2N4 (Pd-MSN and Ag-MSN) monolayers were systematically investigated by DFT computations, which aims to explore their feasibility as a potential gas-sensitive material. The studied results show that the Pd-MSN and Ag-MSN monolayers possess high stability due to the large binding strength. The SO2 molecule is physically adsorbed on the Pd-MSN and Ag-MSN surface with Eads of −0.43 and −0.45 eV. However, the chemisorption of CO, NO, NO2 on the surface can be found with the Eads of −0.73 eV ∼ −1.24 eV, and the strong surface bonding force is mainly contributed by the significant hybridizations between N-p orbital of Pd/Ag-MSN and p orbitals of CO, NO, NO2. Moreover, the Pd-MSN and Ag-MSN monolayers are highly sensitive to CO and NO molecules due to their great change in electrical conductivity and work function. Additionally, the recovery time of NO and CO in Pd-MSN system is respectively predicted to be 0.03 and 0.12 s at room temperature, whereas the rapid desorption of NO and CO from Ag-MSN surface requires the help of high temperature. Therefore, the Pd-MSN monolayer can be a promising gas-sensitive material with excellent sensitivity for the detection of CO and NO. Those studied results can provide a theoretical guidance for the designing of MoSi2N4 based gas sensors.