Magnetic Field-Induced Electrochemical Energy Storage and Oxygen Evolution Reaction of SrCO3 Nanoflakes

Abstract

The development of sustainable multifunctional electrode materials with tunable electrochemical properties is important for advanced energy-storage and energy-conversion applications. In this work, mesoporous SrCO₃ nanoflakes were synthesized through a sustainable Nerium oleander leaf extract-assisted green route and systematically investigated for supercapacitor and OER applications, including their response to an external magnetic field. XRD confirmed the formation of a highly crystalline orthorhombic SrCO₃ phase with a Pnma space group. SEM revealed flake-like agglomerated nanostructures with an average particle size of ~550 nm. FTIR and UV–Vis spectroscopy supported the formation of the structure, while XPS confirmed the oxidation states of Sr, C, and O. BET analysis indicated a mesoporous structure that provides accessible electrochemically active sites and facilitates electrolyte ion diffusion. Electrochemical measurements in 1 M KOH using a three-electrode system demonstrated a high specific capacitance of 1394.25 F g⁻¹ at 10 mV s⁻¹ with 75% capacitance retention after 10 000 cycles. The catalyst also exhibited efficient OER activity, with an overpotential of 237 mV at 10 mA cm⁻² and a Tafel slope of 70.9 mV dec⁻¹. Application of a 50 mT magnetic field resulted in a decrease in both charge-storage and OER performance, accompanied by changes in charge-transfer and ion-transport characteristics, demonstrating the system-dependent influence of magnetic fields on diffusion-controlled electrochemical processes. The novelty of this work lies in the integration of a sustainable plant-extract-assisted synthesis of mesoporous SrCO₃ nanoflakes with a systematic investigation of their magnetic-field-dependent supercapacitor and OER behavior, providing insights into the relationship between mesoporous architecture, ion transport, interfacial kinetics, and magnetic-field-induced electrochemical response.