In this research, the effects of the Ni-doped, single vacancy (SV), double vacancy (DV), stone wells (STV) defects and electric-field (EF) on the adsorption of NH3 molecules on the surface of graphene are investigated by using the first-principles calculation. For this purpose, at first step we consider different configurations models, and then all selected models are optimized for this study. From optimized structures the adsorption energies, interaction distances, geometric and electronic parameters and partial density of states (PDOS) for all adsorbed models are calculated and all calculated results are analyzed. The calculated results demonstrate that the adsorption energy of NH3 molecule on the surface of the pristine, SV; Ni-doped in presence of EF (+0.02Z)are ‒27.4202, ‒27.2062, ‒93.9150and ‒36.9352Kcal/mol, respectively. Inspection of results reveals that the SV-defected and Electric-filed are not very much sensitivity to NH3 molecule adsorption. The order of increasing of the Eads values for all studied systems are Ni-doped>EF (+0.02Z)>SV-defected >DV-defects>EF(‒0.02Z)>EF(+0.01Z)>STV defects>EF (‒0.01Z)Graphene/NH3. The density of state (DOS), partial density of states (PDOS) and the electron concentration of the adsorption systems suggested a strong interaction between NH3 molecules and Ni-doped, SV-defected graphene and electric-filed (0.02Z). Therefore, the Ni-doped graphene, SV-defected graphene and Electric-filed (0.02Z) have potential capacities to make the sensors for graphene molecule detecting.

Keywords: Density functional theory (DFT), graphene, partial density of states (PDOS), Ni-doped, electrical effect, NH3 adsorption