Hydrothermal synthesis of NiCo2O4 Nanorods: A promising electrode material for supercapacitors with enhanced capacitance and stability

Abstract

NiCo₂O₄ nanorods were successfully synthesized via a cost-effective hydrothermal method and calcined at 400 °C for 3 h, exhibiting a highly crystalline structure with a 23 nm average crystallite size. FT-IR spectra confirmed NiO and CoO bond coordination, while FE-SEM revealed an aggregated porous nanorod morphology. EDS analysis verified the presence of Ni, Co, and O elements. Electrochemical studies showed a high specific capacitance (Cs) of 475 F g⁻¹ at 10 mV s⁻¹ scan rate, with a Cs of 435 F g⁻¹ at 1 A g⁻¹. Galvanostatic charge-discharge (GCD) analysis indicated a diffusion-controlled energy storage mechanism. Compared to MnCo₂O₄ nanocluster electrodes, NiCo₂O₄ nanorods exhibited superior electrochemical performance, with lower charge transfer resistance (Rct) as shown in Nyquist plots, attributed to their porous microstructure and large surface area. Additionally, the NiCo₂O₄ electrode demonstrated an 83.04 % capacitance retention after 5000 cycles, outperforming the 77.63 % retention of MnCo₂O₄ electrodes, confirming its potential as an efficient supercapacitor electrode.