Heteroatom-Doped Graphene Nanoribbons as High-Performance Electrodes for Lithium-Ion Hybrid Supercapacitors

Abstract

Electrochemical unzipping of multiwalled carbon nanotubes (MWCNTs6-40 nm) offers a controllable route to graphenic architectures with enriched edge sites, tuneable defect densities, and controllable functionality. Here, we report the room-temperature synthesis of pristine graphene nanoribbons (GNRs), fluorine-doped GNRs (F-GNRs), and boron, nitrogen, fluorine co-doped GNRs (B, N, F-GNRs) using protic acids, super-acids, and ionic liquids as electrolytes, respectively. A systematic structural and chemical analysis including TEM, PXRD, and FT-IR spectroscopy confirms complete longitudinal unzipping of MWCNTs and revealing significant heteroatom-induced lattice distortion, expanded interlayer spacing, and defect-rich ribbon morphologies. Electrochemical studies demonstrate that heteroatom engineering dramatically enhances the capacitive and faradaic contributions, while F-and B, N, F-GNRs exhibit superior cyclic voltametric responses, reduced charge-transfer resistance, and markedly improved Li-ion storage capability. In half-cell configuration, F-GNRs deliver a high reversible capacity of 342 mAh g⁻¹ with ~80% retention after 75 cycles, outperforming pristine GNRs and graphene. These findings reveal how unzipping pathways govern electronic structure, wettability, ionaccessible surface area, and reaction kinetics, establishing the promise of engineered GNR frameworks as high-performance electrode materials for next-generation lithium-ion hybrid supercapacitors.