First-principles study on N2, H2, O2, NO, NO2, CO, CO2, and SO2 gas adsorption properties of the Sc2CF2 monolayer

In this work, we systematically investigated the gas adsorption properties of N2, H2, O2, NO, NO2, CO, CO2, and SO2 on the MXene Sc2CF2 monolayer using first-principles calculations. We determined structural geometries, adsorption energies, bandgap, charge transfer, density of states, and charge density difference of adsorption systems. We found that all N2, H2, O2, CO, CO2, SO2, NO, and NO2 molecules are physisorbed on the Sc2CF2 monolayer. The adsorption energies show that the Sc2CF2 monolayer exhibits low adsorption selectivity in respect of the studied gas molecules. Spin-polarized DOS indicates the transitions of non-magnetic pristine MXene Sc2CF2 to magnetic systems after O2, NO and NO2 adsorptions. Especially, we observed the semiconductor-to-semimetal transition of the Sc2CF2 monolayer by NO adsorption, while the adsorptions of CO, CO2, H2, N2, SO2, NO2 and O2 molecules do not change the conductive behavior of the Sc2CF2 monolayer. Our results suggest that the Sc2CF2 monolayer is a novel potential sensing nanomaterial for detecting NO gas.