The Effect of Anionic and Cationic Charge Carriers on the Supercapacitive Behavior of Graphene Nanoribbons

As worldwide energy consumption continues to increase, so too does the demand for improved energy storage technologies. Supercapacitors have attracted a lot of attention due to their quick charging/discharging rate, high power density, and long-term cycling stability in comparison to conventional batteries. 1 Graphene nanoribbons (GNRs) with ultrathin two-dimensional structures and unique properties received a lot of attention recently as potential materials for electrochemical energy storage and specifically supercapacitors. 2,3 GNRs maintain graphene’s unique lattice structure in one dimension and provide more open-edge structures compared to graphene, thus allowing faster ion diffusion, which makes GNRs highly promising for energy storage systems. 2,3 GNRs have unique characteristics such as exceptional electrical conductivity, a highly modifiable surface area, strong chemical stability, low toxicity, great mechanical behavior, and the ability to tune properties for the desired application. This presentation provides an overview of the production of GNRs from carbon nanotubes and their application in supercapacitors. The physical/chemical structure of GNRs was evaluated using XRD, TEM, FT-IR, Raman spectroscopy, and XPS. Since the selection of the cation and anion has been reported to have a dramatic effect on the specific capacitance of the studied materials, 4 the supercapacitive behavior of GNR was thoroughly investigated in various media (H 2 SO 4 , KOH, K 2 SO 4 ), using different loadings and different evaluation systems (three and two-electrode systems). GNRs, in all of the tested media, showed good stability (retained 95% of their capacitance over 10,000 cycles at a high current density of 10 A/g), a wide potential window (up to 1.7 V), and a relatively high capacitance (≈ 400-800 F/g). The best medium for GNRs highest supercapacitance in correlation with their surface chemical structure will be discussed. References: E. A. Worsley, S. Margadonna, and P. Bertoncello, Nanomaterials , 12 , 3600 (2022). Z. Liu et al., Advanced Functional Materials , 32 , 2109543 (2022). Twinkle et al., Materials Today: Proceedings , 50 , 1511–1515 (2022). B. Pal, S. Yang, S. Ramesh, V. Thangadurai, and R. Jose, Nanoscale Adv. , 1 , 3807–3835 (2019).