Ammonia-treated biomass carbon for efficient charge storage: role of nitrogen doping in capacitance enhancement

Abstract

In this work, a nitrogen-doped activated carbon (N-NaOH-ACP) was synthesized via ammonia treatment of sodium hydroxide-activated carbon derived from pomegranate peel, a renewable and low-cost biomass waste. Comprehensive characterization using SEM, FTIR, XPS, Raman spectroscopy, EDS, XRD, and nitrogen adsorption-desorption analyses revealed that N-NaOH-ACP possessed a hierarchical porous structure and a high specific surface area of 2085 m2/g. Nitrogen incorporation significantly enhanced the electrochemical performance, delivering a specific capacitance of 338 F/g at 0.4 A/g in a 1 M KCl electrolyte-nearly three times higher than the undoped material. Furthermore, the symmetric supercapacitor device fabricated using N-NaOH-ACP electrodes exhibited excellent cycling durability, retaining 91.9 % of its initial capacitance after prolonged charge-discharge cycles. These findings highlight the beneficial effects of nitrogen doping on capacitive properties and underscore the potential of N-NaOH-ACP as a sustainable and efficient electrode material for advanced energy storage systems.