| Popis: |
Density functional theory calculations are performed here to evaluate changes in band structure, density of states, adsorption energy and charge transfer of monolayer SnO about adsorption of multifarious gas molecules, including CH4, CO, CO2, H2, H2O, NH3, N2, NO2, NO and O2. The optimum binding position between gas molecules and monolayer SnO is confirmed by calculating the adsorption energy. The calculation shows that monolayer SnO has the strongest adsorption capacity for NO, NO2 and O2 among these gas molecules, illustrating that SnO is prone to select above three molecules. The adsorbability of these three molecules is attributed to the shorter distance of critical adsorption, the larger charge transfer and greater sensitivity to electron band structure. The adsorption energy of O2 is as high as 1.69 eV, and furthermore, the average electron obtained by each O¬2 from the base is high up to 1 e-. However, the adsorption energy and charge transfer of other molecules are almost negligible. The selectivity and sensitivity indicate that monolayer SnO can be considered as a possible gas sensor material to detect the concentration of above-mentioned three gases in the mixed gases. Moreover, the valence band and the conduction band of monolayer SnO are not obviously changed after adsorbing CH4, CO, CO2, H2, H2O, NH3 or N2; in contrast, impurity levels appear in the band gap when NO, NO2 or O2 is adsorbed, and they could obviously reduce the band gap. |
