Magnetic Field‐Induced Electrochemical Energy Storage and Oxygen Evolution Reaction of SrCO 3 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 SrCO 3 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 SrCO 3 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 SrCO 3 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.