Robust and highly mesoporous magnesium oxide and nitrogen atoms incorporated hierarchical porous carbon particles as electrode material for high-performance energy storage in acidic, neutral, and basic electrolytes

In this study, we propose a facile method for synthesizing hierarchical porous carbon particles incorporating magnesium oxide (MgO) and nitrogen (N) atoms. The process begins with the preparation of activated carbon from apricot kernel shell waste using potassium hydroxide (KOH) (ASAC). In the second step, nitrogen doping was performed via a hydrothermal method using nitric acid, yielding N-doped ASAC. Subsequently, MgO was integrated onto the N-doped ASAC through a hydrothermal process, resulting in the composite material designated as MgO@N-doped ASAC. The resulting composite was subsequently evaluated as an electrode material for supercapacitor applications. Comprehensive characterization of the samples was carried out using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS), nitrogen adsorption–desorption isotherms (BET analysis), and scanning electron microscopy (SEM). Electrochemical performance was investigated through electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), and galvanostatic charge–discharge (GCD) measurements. The specific capacitance values obtained for the MgO@N-doped ASAC supercapacitor were 274.07 F/g in acidic electrolyte, 32.09 F/g in neutral electrolyte, and 100.05 F/g in basic electrolyte. The supercapacitor demonstrated remarkable cycling stability, maintaining 86% efficiency after 5000 cycles in an acidic medium. Additionally, the maximum energy density and power density achieved in acidic electrolyte were 6.75 Wh/kg and 2603.57 W/kg, respectively. The resulting MgO@N-doped ASAC supercapacitor exhibits high specific capacitance, significant rate capabilities, and superior cycling performance in acidic electrolytes. © The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature 2025.