Silicene as a highly sensitive molecule sensor for NH3, NO and NO2

Abstract

On the basis of first-principles calculations, we demonstrate the potential application of silicene as a highly sensitive molecule sensor for NH₃, NO, and NO₂ molecules. NH₃, NO and NO₂ molecules chemically adsorb on silicene via strong chemical bonds. With distinct charge transfer from silicene to molecules, silicene and chemisorbed molecules form charge-transfer complexes. The adsorption energy and charge transfer in NO₂-adsorbed silicene are larger than those of NH₃- and NO-adsorbed silicones. Depending on the adsorbate types and concentrations, the silicene-based charge-transfer complexes exhibit versatile electronic properties with tunable band gap opening at the Dirac point of silicene. The calculated charge carrier concentrations of NO₂-chemisorbed silicene are 3 orders of magnitude larger than intrinsic charge carrier concentration of graphene at room temperature. The results present a great potential of silicene for application as a highly sensitive molecule sensor.