Portal de Periódicos da CAPES

Biomass valorisation of marula nutshell waste into nitrogen-doped activated carbon for use in high performance supercapacitors

2023; Elsevier BV; Volume: 442; Linguagem: Inglês

10.1016/j.electacta.2023.141828

1873-3859

Bokome Shaku, Thapelo P. Mofokeng, Neil J. Coville, Kenneth I. Ozoemena, Manoko S. Maubane‐Nkadimeng,

Electrospun Nanofibers in Biomedical Applications

This study reports on the valorisation of marula nutshell waste into a valuable electrode material for supercapacitors. Marula nutshell waste, a brown hard residue from marula fruits was valorised into a nitrogen-doped activated carbon (N-ACs) by KOH treatment and using melamine as a nitrogen source. The microporous and mesoporous nature of N-ACs exhibited a high surface area of 1427 m² g−1 and pore volume of 0.31 cm3 g−1. Three electrode measurements were done in 6 M KOH and 2.5 M KNO3 aqueous electrolytes, to examine the materials in alkaline and neutral medium. The N-ACs exhibited a capacitance of 350 F g−1 in 6 M KOH and 248 F g−1 in 2.5 M KNO3 electrolyte. Due to low toxicity and wider operating voltage (∼1.8 V) of 2.5 KNO3, the material was further analysed in a symmetric device. The high surface area, the defects, and the high content of nitrogen (5.1%) revealed that the material produced an outstanding energy density of 17.2 Wh kg−1 and a power density of 448.7 W kg−1 in 2.5 M KNO3 electrolyte. The conversion of marula nuts waste into N-ACs thus provide a means of converting biomass waste into a useful energy storage material for supercapacitors.