One-Pot Dual-Phytochemical Synthesis of Nickel Oxide Nanoparticles from Eclipta prostrata and Ocimum tenuiflorum as a Green Electrode for High-Performance Pseudo-Capacitor

Nanomaterials synthesis for energy storage often involves toxic chemicals, high
temperatures, and non-renewable resources harming the environment. To address
this, eco-friendly green electrodes must be developed for sustainable energy
solutions. In this context, we have synthesized nickel oxide nanoparticles
(NiO-NPs) using a dual-phytochemical approach, leveraging the bioactive
compounds derived from Eclipta prostrata and Ocimum tenuiflorum extracts.
The synthesized NiO-NPs exhibited homogeneous spherical morphology and
revealed a crystalline nature with the approximate particle size of 18.3 nm. The
combined plant extract-derived NiO-NPs exhibit a half-cell gravimetric capacitance
of 525 F/g. The fabricated asymmetric supercapacitor device with the asprepared
NiO-NPs as cathode and commercial activated carbon as anode
delivered a full-cell gravimetric capacitance of � 101.35 F/g, an energy density
of 106 Wh/kg at 1 A/g and a power density of 10,440 W/kg at 10 A/g. This device
operates effectively up to 1.45 V in an alkaline medium. The device also delivered
a maximum columbic efficiency of 92.59% over 12,000 cycles in ambient
condition. Hence, the synergistic effects on the phytochemicals improved the
electrochemical properties, making the NiO-NPs suitable as an electrochemical
energy electrode. Thus, this work highlights the potential of dual-phytochemical
synthesis in advancing the development of sustainable and efficient electrode
materials for next-generation supercapacitors.