▎ 摘　　要

The letter presents the adsorption properties of CO, NH3, CH4, SO2, and H2S molecules over niobium doped graphene sheet (Nb/G). Using density functional theory, the optimum configuration and orientation of adsorbent molecules over the Nb/G surface are geometrically optimized, and adsorption energy, adsorption distance, Hirshfeld charge transfer, electron localization function, and the work function of Nb/G-molecule systems are calculated. CO and SO2 molecules over Nb/G show chemisorption, hence they have high reactivity towards Nb/G. Adsorption of NH3, CH4, and H2S on Nb/G shows physisorption as they are weakly adsorbed. The adsorption of these molecules indicates the suitability of Nb/G as a sensor. To understand the superiority of Nb/G over pristine graphene, comparison of adsorption properties was made between the two systems. The work function of Nb/G with adsorbed molecule suggests that the Fermi level of Nb/G surface may be controlled by the selection of appropriate adsorbent molecules. Therefore, Nb/G could be a good candidate for gas sensing application.