The adsorption of closed-shell molecules does not result in any significant changes in the transmission spectra of pristine 4ZGNRH near the Fermi level. For example, the adsorption of N 2 shows a transmission dip near E -E f = 3.0eV for both spin-up and spin-down transmission spectra. The step behavior of transmission spectra of pristine 4ZGNRH discussed in supporting information (Section S2 and in our previous work ) remains preserved after the adsorption of closed-shell molecules. On the other hand, the open-shell molecules result in spin non-degenerate transmission spectra and a decrease in transmission spectra in the form of transmission dips. In O 2 -4ZN-upper configuration, transmission dips at -1.475eV , -1.305eV and 0.595eV energy positions are observed for spin-up transmission spectra. For spin-down transmission spectra, the transmission dips at -0.995eV and 0.955eV energy positions are observed. In O 2 -4ZN-middle configuration, we observed the dip at -1.625eV (0.485eV ) for spin-up (spin-down) transmission spectra. Thus the interaction of O 2 molecule with 4ZGNRH results in non-degenerate transmission dips for spin-up and spin-down. Such transmission dips arise due to interference between the localized and a continuum of extended states. We have analyzed the partial density of states (PDOS) of the adsorbed molecules and 4ZGNRH (shown in Figure ), which reveals that PDOS of adsorbed molecules corresponds to the position of the transmission dips in the transmission This decrease in the transmittance step size near the Fermi level is associated with the broken edge spin symmetry of the ZGNRs. The calculated spin-filtering efficiency (SF E) at zero bias voltage using equation 5 is