Gas Sensing by Metal and Nonmetal Co-Doped Graphene on a Ni Substrate

Gas sensors based on graphene are gaining more and more attention. The unique properties of the single-atom-thick, flexible, robust, and quanta-sensitive graphene make it an excellent candidate for sensors. However, its characteristics can be modified to suit specific applications by means of metal and nonmetal doping. In this systematic and detailed study, with the aid of density functional theory (DFT)-based simulations, we investigate the gas sensing capabilities of trapped transition-metal (TM) atoms at the graphene double vacancy (2VG). Eight different gas molecules, ranging from electron acceptors (Lewis acids) to donor species (Lewis bases), are investigated, namely, O-2, NO2, NO, CO2, SO2, H2O, NH3, and CO. Four TM atoms Fe, Co, Ni, and Cu are considered as active sites for gas sensing. The effects of N-doping and the Ni(111) substrate are also examined. The performance of these systems in terms of stability, sensitivity, selectivity, and reusability is discussed for practical applications.