Adsorption behaviors of the Sc2C(OH)2 monolayer for small gas molecules: A first-principles study

We investigated the Sc2C(OH)2 monolayer adsorption properties for small gas molecules using the first-principles calculations. The nature of interactions is elucidated based on the calculated adsorption energies, charge transfer, band structure, densities of states, and charge density differences of the adsorption configura-tions. The adsorption stability on the Sc2C(OH)2 monolayer increases in the order: H2 < N2 < CO2 < CO < H2O < NO < N2O < C2N2 < BBr3 < SO2 < O2 < NO2. AsF5 and Br2 molecules are spontaneously dissociated into the Sc2C(OH)2 monolayer. Moreover, the electronic transport of the Sc2C(OH)2 monolayer has been computed based on the nonequilibrium Green's function formalism. Our results predicted that Sc2C(OH)2 monolayer-based sensor can detect NO2 gas with sensitivity to a NO2 molecule of up to 20% at the bias voltage of 0.5 V. However, oxygen is the interfering gas, which leads to the low selectivity of the NO2 sensor. In addition, Sc2C(OH)2 monolayer-based sensor is significantly affected by humidity, with a conductivity decrease of about 3% after H2O molecule adsorption.