From sugarcane bagasse pulp into electroactive materials: Carboxymethyl cellulose/reduced graphene oxide/nickel oxide composites as high-performance supercapacitor components

We report bio-sourced electrically conductive materials derived from sugarcane bagasse cellulose. First, the cellulose was chemically transformed into carboxymethyl cellulose (CMC). Acrylamide (AM) and 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS) were co-polymerized with CMC, and the resulting material was cross-linked with N,N`-methylenebisacrylamide (MBA) to improve its mechanical properties. To further enhance the electrical performance, the materials were modified with reduced graphene oxide (rGO), nickel oxide (NiO) nanoparticles and rGO@NiO composites. The nanocomposites were then used as electrodes for solid-state supercapacitors. To evaluate the electrochemical properties of these materials, cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), and electrochemical impedance spectroscopy (EIS) were performed. These results demonstrate enhanced electrochemical performance of the composite material modified with both rGO and NiO NPs. CV profiles exhibited well-defined redox peaks indicative of reversible faradaic processes, confirming high pseudocapacitance contributions. The optimized sample X_GNi2.5 exhibited a high specific capacitance of 497.8 F g^-1 at 0.5 A g^-1, outstanding cycling stability with 91 % capacitance retention after 5000 cycles, and a maximum energy density of 44.2 Wh kg^-1 at a power density of 226.2 W kg^-1. EIS revealed low charge transfer resistance and efficient ion transport. These results underscore the potential of CMC/rGO/NiO composites as sustainable, high-performance electrode materials for next-generation supercapacitors.