Electrochemical performance of spray-pyrolyzed CNT@NiO electrodes for supercapacitor applications

Abstract

In this study, spray pyrolysis was employed to fabricate pristine NiO and a CNT@NiO composite electrode at 350 °C for supercapacitor electrodes. The structural and morphological properties of both materials were characterized by X-ray diffraction, Fourier-transform infrared spectroscopy, Brunauer-Emmett-Teller analysis, and scanning electron microscopy. Electrochemical performance was evaluated by cyclic voltammetry, galvanostatic charge-discharge, and electrochemical impedance spectroscopy in 2 M KOH over a potential window of 0 to 0.7 V vs. SCE. BET analysis showed that CNT incorporation increased the specific surface area from 29.55 to 46.51 m 2 g -1 and the mean pore diameter from 6.10 to 27.37 nm. The 350-CNT@NiO electrode delivered a specific capacitance of 472.4 F g -1 at 2 A g -1 , exceeding that of 350-NiO (18.92 F g -1 ), with a rate capability of 68.8% compared to 13.6% for 350-NiO. After 1,000 cycles at 2 A g -1 , 350-CNT@NiO retained 93.3% of its initial capacitance compared to 81.5% for 350-NiO, with both electrodes maintaining 100% Coulombic efficiency. The results demonstrate that 350-CNT@NiO is a promising electrode material for supercapacitor applications and that spray pyrolysis is a low-cost, scalable fabrication route suitable for energy storage electrode preparation.