Asymmetric Enhancement of Hydrogen and Oxygen Evolution Reactions in a Bifunctional Fe0.5Rh0.5 Catalyst by Applying a Magnetic Field.

(FeRh) single-crystal thin-film catalyst and demonstrate distinct asymmetric activity improvement under a 13 kOe magnetic field, ∼40% enhancement for HER and ∼32% for OER. Density functional theory and spin-resolved electronic structure analysis reveal that the field raises spin polarization by 1.2%, enhances density of states near the Fermi level, and accelerates interfacial charge transfer. The asymmetric enhancement stems from a more significant Gibbs free energy reduction for H adsorption than for OH**. Moreover, FeRh follows the oxide pathway mechanism to avoid excessive surface oxyhydroxide passivation, ensuring a stable magneto-responsive catalysis. This work clarifies the fundamental mechanism of asymmetric magnetic field promotion and provides a rational design for magnetically enhanced bifunctional electrocatalysts.