Enhanced oxygen evolution by magnetic exchange coupling modulation of high‑entropy spinel oxides

Abstract

Magnetic field-assisted electrocatalysis provides a contactless strategy for improving the water splitting performance, yet the origin of the composition-dependent magnetic-field response in high-entropy oxides remains insufficiently understood. Herein, with Fe3O4-based high-entropy spinel oxides as model catalysts, we reveal how cation configuration regulates the magnetic field-enhanced oxygen evolution reaction (OER) kinetics. It is found that incorporation of Zn significantly changes the local Co-O coordination environment, thus tuning the magnetic exchange coupling. Interestingly, the enhancement degree of OER activity under the magnetic field is closely related to the saturation magnetization of the high-entropy spinel oxides. In situ Raman spectroscopy reveals reversible potential-dependent evolution of the local coordination environment while preserving the spinel framework, with (FeCrMnCoZn)3O4 exhibiting the strongest local structural evolution. Density functional theory (DFT) calculations indicate that Zn-Co-containing configuration induces the largest redistribution of Co-centered d-orbital states, suggesting more flexible Co-O coordination and stronger modulation of M-O-M magnetic exchange interactions. This work provides new insight into the rational design of magnetic-field-responsive electrocatalysts through local coordination engineering in high-entropy oxides.