Utilizing graphene as a spin-selective transport material in spintronics applications has raised broad interest due to its weak spin-orbit coupling and long spin relaxation time. The zig-zag edged graphene nanoribbons (GNRs) are of particular interest in this regard due to their low-bandgap and magnetic semiconducting nature with antiferromagnetic (AFM) coupling between the opposite edges. GNRs having different widths and edge structures can be experimentally synthesized using lithography and bottom-up chemical synthesis using molecular precursors. Ruffieux et al. have demonstrated that precise zigzag-edged GNRs can be synthesized using surface-assisted polymerization and cyclodehydrogenation of molecular precursor monomers. Wang et al. have demonstrated the tunability of the edge states of the bilayer zig-zag graphene nanoribbons (ZGNRs) with the twist angle and stacking offset. There are a lot of studies on the effect of molecule adsorption on the electronic structure of pristine and doped graphene, armchair and zig-zag graphene nanoribbons. Hou et al. reported that the edge functionalization of ZGNRs with a radical can result in gapped ferromagnetic (FM) ZGNRs which can be further controlled by the doping of B or N atoms in the coupling pathway. The electronic structure of molecules adsorbed systems provides a good estimate of the induced spin polarization. However, the electronic states of the adsorbed molecules can result in different phenomena in the device, such as quantum interference (QI) effects and scattering. Thus, an understanding of the spin-polarized quantum transport properties of such systems is required. Saraiva-Souza et al. reported that the presence of an imidazole donor group to the polyacetylene chain connected to the ZGNR electrodes can result in destructive quantum interference (DQI) features in the electron transmission spectrum. The edge magnetism in zigzag graphene nanoflakes and quantum interference effects can result in spin-polarized quantum interference antiresonances. The literature discusses different methods to utilize graphene nanoribbons for various applications, but the development of quantum spin transport-based sensing devices is still lacking. It has been reported that the edge-dopped zig-zag graphene nanoribbons show high sensitivity towards N O 2 and SO 3 gas molecules. Suman et al. shown that the ZGNRs are more sensitive towards H 2 S detection compared to armchair GNRs. This sensing response can be further enhanced with cobalt doping in ZGNR. However, most of the related studies ignored the fact that ZGNRs possess anti-ferromagnetic spin densities on the edges.