Plasma surface treatment for enhanced supercapacitor and oxygen evolution reaction: Single-step preparation of carbon-coated nickel nanoparticles

Abstract

Developing porous electrode materials with highly conductive for advanced electrochemical energy storage and conversion devices poses significant challenges, particularly in achieving single-step, impurity-free large-scale production for commercialization. This study investigates a method for synthesizing carbon-coated metallic nickel nanoparticles directly in the gas phase, using the plasma arc discharge method in an argon-methane atmosphere. The study meticulously examines the developed samples' phase, crystal type, morphology, elemental presence, and chemical state. The synthesized C@Ni NPs exhibit a core-shell morphology with high surface area, as confirmed by TEM and BET analysis. The C@Ni electrode underwent surface modification to enhance its electrochemical performance. In this context, the original C@Ni electrode and a plasma-treated version (C@Ni PT) were extensively investigated for their suitability in supercapacitor and oxygen evolution reaction applications. The C@Ni PT electrode demonstrated remarkable performance characteristics. In supercapacitor tests, it achieved a significantly higher specific capacitance of 313 F/g at a current density of 1 A/g, coupled with superior cyclic stability. It exhibited outstanding electrocatalytic activity for the OER, requiring only 312 mV of overpotential to reach a current density of 20 mA cm−2. The reduced overpotential and increase in specific capacitance suggest that C@Ni PT electrodes as promising materials for both OER and supercapacitor applications. Further, the plasma arc discharge method and dielectric barrier discharge are suitable for the large-scale production of nanoparticles and surface modification.