Nanoarchitectonics for sustainable supercapacitor electrodes via the upcycling of waste cardboard into graphitic porous carbon

Abstract

In this work, highly porous activated carbon was synthesized from waste cardboard through a single-step pyrolytic route at 600, 700, and 800 °C, and systematically evaluated as an electrode material for aqueous supercapacitors. Structural analysis confirmed the coexistence of graphitic domains and residual CaCO3, with progressive carbon ordering and CaCO3 decomposition at higher temperatures. FESEM and BET measurements revealed a transition from fibrous structures to fragmented, pore-rich carbon, accompanied by a substantial rise in specific surface area at 800 °C. XPS confirmed rich oxygenated functionalities, supporting improved wettability and charge-storage behaviour. Electrochemical studies in a three-electrode configuration demonstrated superior capacitive performance for the 800 °C sample, delivering 688.1 F g−1 at 5 mV s−1 and stable cycling over 5000 cycles. A symmetric two-electrode device further achieved 163.4 F g−1, retained 92.5% capacitance after 1000 cycles and delivered a maximum energy density of approximately 13.6 Wh kg−1 at a power density of 710 W kg−1. Practical demonstrations, including LED illumination and powering a watch, validate its application potential. These findings establish waste cardboard-derived carbon as a sustainable and efficient electrode material for high-performance energy-storage devices. © 2026 Elsevier Masson SAS. All rights are reserved, including those for text and data mining, AI training, and similar technologies.