Magnetic Field-Assisted Low-Temperature Electrodeposition of Fe-CoP for Magnetic Field-Promoted OER Catalysis

Abstract Oxygen evolution reaction (OER) is a key half-reaction for electrochemical water splitting, while its sluggish kinetics and high overpotential seriously limit the development of efficient energy conversion technologies. To address this issue, a low-temperature magnetic field synergistic electrodeposition strategy was proposed for the preparation of Fe–CoP catalysts toward the oxygen evolution reaction (OER). Fe–CoP catalysts with high structural regularity and optimized electronic structures were successfully fabricated by controlling the electrodeposition process at 0 °C and under a static magnetic field of 300 mT. Electrochemical tests in the 1.0 M KOH electrolyte showed that the obtained catalysts exhibited an overpotential of 280 mV at 100 mA cm–2, demonstrating significantly enhanced OER activity compared with the catalysts prepared at room temperature without a magnetic field. Characterizations, including SEM, TEM, XPS, Raman spectra, and magnetic property measurements, verified that the synergistic effect of low temperature and magnetic field effectively optimized the morphology, crystal structure, and elemental chemical states of the catalysts, and promoted the selective enrichment of Fe3+ and the formation of highly active Co–P species. Theoretical calculations further revealed that the magnetic field applied during the reaction could accelerate interfacial electron transfer, regulate the electronic configuration and spin states of active sites, and tune the adsorption–desorption energy barriers of reaction intermediates, thus boosting OER kinetics. In addition, this work clarified the critical roles of low temperature and a magnetic field in the synthesis of transition metal phosphide catalysts, and unveiled the multistage regulation effect of the magnetic field during electrocatalysis, which realizes the remarkable improvement of OER activity via multidimensional optimization of catalyst structure and microenvironment. This study provides an effective strategy for the design and construction of high-performance OER electrocatalysts.