Harnessing magnetic fields for oxygen electrocatalysis enhancement

Magnetic fields offer a non-invasive strategy to modulate oxygen electrocatalysis, but a clear and unified understanding of the underlying mechanisms still remains challenging. This review provides a systematic classification of magneto-electrocatalytic effects, including gas management engineering and reaction rate acceleration, and summarizes the latest research advancements in the field. In addition, this review offers a critical evaluation of prevailing mechanistic theories. Specifically, we highlight the inability of the magnetoresistance effect to account for the pronounced pH dependency of magnetic enhancement. Furthermore, we discuss in depth the ongoing debate surrounding the electron spin selectivity effect, questioning its universal validity. We also emphasize some key breakthroughs, particularly the relationship between domain wall elimination and enhanced catalytic activity. This review also addresses the critical experimental challenges of decoupling coexisting magnetic effects, emphasizing the necessary experimental procedures designed to distinguish macroscopic, magnetohydrodynamic-driven convection from intrinsic, spin-mediated kinetic enhancements. Finally, the future progresses are proposed, hinging on the strategic integration of magnetic fields with other external fields, like electric, photonic, or thermal fields, to unlock the novel catalytic pathways and precisely steer reaction selectivity and efficiency.