In the present work, we have studied the interaction of different closed-shell and openshell gas molecules with the ZGNRs. With the adsorption of these molecules on ZGNRs, we intend to break the spin degeneracy of the ZGNR. More importantly, our objective is to understand the interaction of the different gas molecules with the ZGNRs and how this interaction will affect the spin current of pristine ZGNRs. We choose closed-shell N 2 , CO, CO 2 and open-shell O 2 , N O and N O 2 gas molecules and hydrogen-passivated ZGNR that has four carbon atoms along the width (4ZGNRH). The ab initio modeling results suggest that the gas molecules are either physisorbed or chemisorbed on ZGNRs depending upon the adsorption site and nature of gas molecules. Further, the spin-polarized electron transport and spin-current characteristics are investigated with a non-equilibrium Green's function (NEGF) based approach using density functional theory(DFT). The charge transfer and transmission pathways (bond current) are used to interpret the spin-current of gas molecules deposited ZGNRs.