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Prediction of a Kinetic Pathway for Fabricating the Narrowest Zigzag Graphene Nanoribbons on Cu(111)

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journal contribution
posted on 30.09.2021, 12:34 by Yifei Yang, Limei Wang, Zhenyu Zhang, Ping Cui
The narrowest zigzag graphene nanoribbons (nZGNRs) consisting of linearly fused benzene rings have distinctly superior electronic and spintronic properties; yet, to date, fabrication of nZGNRs via bottom-up self-assembly remains a daunting challenge. Here, based on first-principles calculations, we propose a kinetic pathway for growing nZGNRs on Cu(111) using 1,4-dibromo-2,5-bis­(bromomethyl)­benzene precursors. We show that such a precursor molecule can readily adsorb on Cu(111), accompanied by easy detachment of the four Br substituents. As building blocks for the formation of the nZGNRs, the resulting C8H6 radicals have high diffusional and rotational mobilities on the substrate. Two such radicals can fuse into an nZGNR-like dimer via covalent bond formation by overcoming a kinetic barrier of ∼1.00 eV, with the unsaturated C atoms properly located to allow additional C8H6 radicals to join and elongate the nZGNR. We further examine possible competing byproducts and find that the yields of nZGNRs can be enhanced with proper choices of the substrates. As a comparative study, the precursor molecule of 1,4-bis­(bromomethyl)­benzene has also been investigated and found to be less desirable in forming the nZGNRs. These findings provide a highly appealing route toward the fabrication of nZGNRs for potential applications in nanoelectronics and spintronics.