Edge-enriched porous graphene nanoribbons for high energy density supercapacitors†
A simple solution-based oxidative process and subsequent chemical activation combination method has been developed to prepare edge-enriched porous graphene nanoribbons (GNRs) as a high-performance electrode material for supercapacitors. The precursor aligned carbon nanotubes are cut longitudinally and unzipped by a modified Brodie method to form tube-like GNRs with abundant edges. The intermediate GNRs were subsequently chemically activated using KOH to generate a suitable porosity and create more edge sites. These edge sites contribute a larger capacitance than the basal plane of graphene and the nanopores facilitate the fast immigration of ions. As a result, the edge-enriched GNRs exhibit a capacitance uptake per specific surface area almost two times higher than that of conventional activated graphene sheets, which gives rise to the high energy density of the porous GNR electrode. The highly efficient utilization of the edge planes and easy, low-cost scale-up production will make porous GNRs potentially applicable to high-performance supercapacitors.