A first-principles study of gas adsorption on germanene

Abstract

The adsorption of common gas molecules (N₂, CO, CO₂, H₂O, NH₃, NO, NO₂, and O₂) on germanene is studied with density functional theory. The results show that N₂, CO, CO₂, and H₂O are physisorbed on germanene via van der Waals interactions, while NH₃, NO, NO₂, and O₂ are chemisorbed on germanene via strong covalent (Ge–N or Ge–O) bonds. The chemisorption of gas molecules on germanene opens a band gap at the Dirac point of germanene. NO₂ chemisorption on germanene shows strong hole doping in germanene. O₂ is easily dissociated on germanene at room temperature. Different adsorption behaviors of common gas molecules on germanene provide a feasible way to exploit chemically modified germanene.