H‐, N‐ and O‐Edge Passivation on AGNRs With Li, Mg, Ca, and Zn Adsorbents: A First‐Principles Study

ABSTRACT

Density functional theory (DFT) calculations were employed to systematically investigate the influence of H‐, N‐ and O‐edge passivation on adsorption, electronic structure, ion diffusion, and storage performance of Li, Mg, Ca, and Zn on armchair graphene nanoribbons (4‐AGNRs). The results demonstrate that the adsorption strength increases progressively from H‐ to N‐ and O‐passivated AGNRs owing to the increasing electronegativity of edge atoms with O‐passivation exhibiting strongest adsorption. Diffusion barrier reveals that N‐passivation significantly improves ion mobility, particularly for Li, Mg, and Zn whereas Ca exhibits a comparatively higher diffusion barrier. Projected density of states (PDOS) reveals enhanced orbital hybridization near Fermi level and semimetal metallic transitions upon adsorption. The charge‐density‐difference and Bader charge confirm significant electron transfer from adsorbed metal to AGNR particularly in N‐ and O‐passivated AGNRs. Further O‐passivated AGNRs deliver comparatively lower storage capacities because of highly localized metal–O interactions. In contrast, N‐passivation provides an optimum balance between adsorption strength, structural stability, ion mobility and suppression of localized metal aggregation leading to storage capacities of 1116, 2116, 1522 and 940 mAh g ^{− 1} for Li, Mg, Ca and Zn, respectively. Further, Mg exhibits the most favorable electrochemical performance, moderate adsorption, exceptionally low diffusion barrier, suppressed interactions, and high metal loading.