Exploration of Half Metallicity in Edge-Modified Graphene Nanoribbons

A Systematic Study of various edge modified graphene nanoribbons (GNRs) have been performed using a density functional theory method. Particular attention is placed oil the possibility of achieving half-metallicity in the graphene nanostructures. Six chemical functional groups, namely, OH, NH2, N(CH3)(2), SO2, NO2, and CN, are considered for the edge modification. Density functional theory (DFT) calculations with Perdew-Burke-Ernzerhof (PBE) functional Suggest that half-metallicity call be realized ill zigzag-edged GNRs (ZGNRs) when one edge of the graphene is fully decorated with the OH group while the other edge is decorated with either NO2 or SO2 functional group. Moreover, DFT/PBE calculations Suggest that the half-metallicity call be realized via modification of one edge with hybrid X groups (X = SO2, NO2, or CN) and hydrogen (H) atoms. Two mechanisms call lead to half-metallicity ill ZGNRs, (1) chemical-potential mechanism, that is, to create a difference in chemical potential between the two edges by decorating one edge with electron-donating groups and another with electron-accepting groups, which can lead to spin-polarized states in the electronic band gap, and (2) impurity-state mechanism, that is, to introduce a Spin-polarized impurity state at the Fermi level through partial modification of one edge with isolated SO2 groups. More specifically, fora narrow ZGNR, both DFT/PBE and DFT/hybrid Heyd-Scuseria-Ernzerhof calculations show that the impurity-state mechanism call be realized with hybrid SO2 and H decorated edge. To Our knowledge, the second mechanism has not been reported ill the literature. A major advantage of the Impurity-state mechanism is its insensitivity to the chemical potential difference between the two edges of a ZGNR. As such, the opposing edge to the SO2-decorated edge can be decorated by;I variety Of functional groups (e.g., F, H, or OH) to meet the needs for nanoelectronic applications by design.