Facile synthesis of spinel nickel-zinc ferrite nanoparticles and their dual functionality for supercapacitor and oxygen evolution reaction applications

Spinel nickel-zinc ferrite (ZNF) nanoparticles were successfully synthesised via a facile coprecipitation method, and their performance as an electrode material for a supercapacitor was evaluated. The physicochemical characterisation revealed that the ZNF nanoparticle exhibits a crystallite size of 43.2 nm and a spherical morphology (average particle size of ⁓23 ± 0.5 nm). The nitrogen adsorption–desorption isotherm revealed a mesoporous texture with a high specific surface area of 78.4 m 2 g −1 , providing abundant electroactive sites for ion transport. The electrochemical study revealed the coexistence of electric double-layer and pseudocapacitive charge-storage mechanisms. The ZNF electrode achieved a specific capacitance of 273 F g −1 at a current density of 2 A g −1 . The ZNF electrode demonstrates excellent cyclic stability after 6000 cycles. On the other hand, studies of the electrocatalytic oxygen evolution reaction (OER) revealed that the ZNF electrocatalyst exhibits appreciable OER activity, requiring an overpotential of 421 mV to reach a current density of 10 mA cm −2 . Besides, the electrocatalyst exhibits a Tafel slope of ⁓114 mV dec −1 , indicating favourable reaction kinetics governed by surface-adsorbed intermediates. The moderate electrochemical performance of ZNF nanoparticles is attributed to the high surface area, mesoporous framework, cation redistribution, and modified electronic interactions within the spinel ferrite framework.