Superior supercapacitance behavior of oxygen self-doped carbon nanospheres: a conversion of Allium cepa peel to energy storage system

• Published in: Biomass conversion and biorefinery 2021-08, Vol.11 (4), p.1311-1323
• Main Authors: Ali, Gomaa A. M., Supriya, S., Chong, Kwok Feng, Shaaban, Essam R., Algarni, H., Maiyalagan, T., Hegde, Gurumurthy
• Format: Article
• Language: English
• Subjects: Biotechnology; Carbon; Chemical synthesis; Electrochemical analysis; Energy; Energy storage; Flux density; Morphology; Nanospheres; Original Article; Pyrolysis; Renewable and Green Energy; Supercapacitors
• ISSN: 2190-6815; 2190-6823
• DOI: 10.1007/s13399-019-00520-3

Mesoporous carbon nanospheres are produced from biowaste, Allium cepa peels, well known as “onion” dry peels using the catalyst-free pyrolysis method. The synthesis process involves an unusable bio-precursor that is accumulated in millions of tons per year. The obtained materials show nanosphere morphology with particles size of 63–66 nm and surface area up to 2962 m 2 g −1 . After pyrolysis at 800, 900, and 1000 °C, the carbon nanospheres are directly applied for supercapacitance study without further activation processes. The electrochemical studies show promising results such as high electrode capacitance of 189.4 at 0.1 A g −1 in 3 M KOH. Moreover, full cell symmetrical supercapacitor is fabricated and further investigated under a wide potential window up to 1.6 V. An excellent electrochemical behavior is observed for the supercapacitor in terms of high energy density of 22.1 Wh kg −1 at a power density of 39.6 W kg −1 , high cyclic stability of 78%, and high coulombic efficiency of 90% over 4500 cycles at 0.5 A g −1 . These studies support carbon nanospheres obtained from Allium cepa wastes to be used as promising materials for supercapacitor application. Graphical abstract