Untangling the Mechanisms in Magneto-Electrocatalytic Oxygen Evolution

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 H₂ 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 (Co₃O₄/BaFe₁₂O₁₉ 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 Co₃O₄ systems display minimal orientation dependence, indicating spin-polarization domination. Introducing BaFe₁₂O₁₉ 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.