Untangling the Mechanisms in Magneto‐Electrocatalytic Oxygen Evolution

Abstract External magnetic fields emerge as a promising method for enhancing the electrocatalytic oxygen evolution reaction (OER), yet the underlying magneto‐electric (ME) mechanisms are not well understood. The slow kinetics of OER make it a key challenge in electrocatalytic water‐splitting, a promising technique for sustainable H 2 fuel production. Herein, a systematic approach is presented to analyzing the ME mechanisms governing OER, using metallic‐plate (Ni foam, Ni sheet, and Pt sheet) and powder‐based (Co 3 O 4 /BaFe 12 O 19 on carbon paper) electrodes. Through controlled experiments using varying magnetic field strengths and orientations, Lorentz force and spin‐polarization mechanisms are separated. For metallic electrodes, the effects are orientation‐dependent, indicating domination by Lorentz force. Magnetic flux density about the electrode surface is shown to govern the Lorentz force behavior. Interestingly, a “pseudo” effect is discovered which results from the relative position of the reference electrode, highlighting the importance of experimental design. The Co 3 O 4 systems display minimal orientation dependence, indicating spin‐polarization domination. Introducing BaFe 12 O 19 as a magnetic co‐catalyst further amplifies the ME effect, marking the first demonstration of magnetic co‐catalyst enhancement in magneto‐electrocatalysis. This work provides key insights into ME mechanisms, linking electrode composition, magnetism, and geometry to performance, offering new pathways for optimizing future magneto‐electrocatalytic systems.