A theoretical study of gas adsorption on silicene nanoribbons and its application in a highly sensitive molecule sensor

Inspired by recent successes in the development of two-dimensional based gas sensors capable of single gas molecule detection, we investigate the adsorption of gas molecules (N-2, NO, NO2, NH3, CO, CO2, CH4, SO2, and H2S) on silicene nanoribbons (SiNRs) using density functional theory (DFT) and nonequilibrium Green's function (NEGF) methods. The most stable adsorption configurations, adsorption sites, adsorption energies, charge transfer, quantum conductance modulation, and electronic properties of gas molecules on SiNRs are studied. Our results indicate that NO, NO2, and SO2 are chemisorbed on SiNRs via strong covalent bonds, suggesting its potential application for disposable gas sensors. In addition, CO, NH3, and H2S are chemisorbed on SiNRs with moderate adsorption energy, alluding to its suitability as a highly sensitive gas sensor. The quantum conductance is detectably modulated by chemisorption of gas molecules which can be attributed to the charge transfer from the gas molecule to the SiNR. Other studied gases are physisorbed on SiNRs via van der Waals interactions. It is also found that the adsorption energies are enhanced by doping SiNRs with either B or N atoms. Our results suggest that SiNRs show promise in gas molecule sensing applications.