Magnetic regulation of anodic oxygen evolution in alkaline water electrolysis: Flux-density and orientation responses with multiscale bubble dynamics

Quantitative relationships between magnetic field parameters and anodic oxygen evolution reaction (OER) performance in alkaline water electrolysis remain insufficiently established. This study examines OER responses across 13 magnetic flux densities and eight orientations using nickel-foam electrodes. Current-density gains follow a reproducible S-shaped flux-density dependence and an asymmetric quasi-sinusoidal angular response at stronger fields, with enhancement near 90° and suppression near 270°. Wavelet analysis identifies multiple characteristic timescales in representative bubble-associated current fluctuations, informing a qualitative multiscale interpretation of interfacial dynamics. Marginal OER enhancement diminishes at higher fields, with most high-field gains achieved near 308 mT under three-electrode conditions. Complementary HER measurements reveal a distinct cathodic response. Tests on a miniature industrial-type electrolyzer demonstrate approximately 6.0% lower cell-level specific energy consumption at 297 mT, 90°, and 350 mA cm −2 . These findings advance the quantitative understanding of magnetic flux-density and orientation effects on anodic OER.