Effects of gas adsorption on electronic and optical properties of palladium-doped graphene: First-principles study

The effects of O-2, CO, NO, N2O, NO2 and SO2 adsorbing on electronic and optical properties of graphene doped with palladium (PdG) were investigated using the first-principles calculation. Our investigation reveal that the six gas molecules chemically adsorb on PdG due to greater adsorption energy and smaller adsorption length; Gas adsorption can cause charge redistribution and the change of electronic properties for PdG. After O-2, NO2, and SO2 adsorption, PdG transforms from semiconductor to metal; CO@PdG and N-2 O@PdG have semiconducting property but the width of band gap declines in compare with that of PdG; NO@PdG shows half-metallic property. Gas adsorption can also lead to response of the PdG's work function, and its value depends on the orientation and quantity of charge transfer. In addition, gas adsorption can result in variation of optical absorption spectra of PdG. Different from PdG, new absorption peaks occur in the visible light region for O-2 @PdG, N2O@PdG and NO@PdG in case of E-perpendicular to polarization. The results obtained during this study can offer certain guiding significance for the design and application of highly sensitive and highly selective graphene based gas sensor.