Spin‐Polarization Strategy for Enhanced Acidic Oxygen Evolution Activity

Abstract Spin‐polarization is known as a promising way to promote the anodic oxygen evolution reaction (OER), since the intermediates and products endow spin‐dependent behaviors, yet it is rarely reported for ferromagnetic catalysts toward acidic OER practically used in industry. Herein, the first spin‐polarization‐mediated strategy is reported to create a net ferromagnetic moment in antiferromagnetic RuO 2 via dilute manganese (Mn 2+ ) ( S = 5/2) doping for enhancing OER activity in acidic electrolyte. Element‐selective X‐ray magnetic circular dichroism reveals the ferromagnetic coupling between Mn and Ru ions, fulfilling the Goodenough–Kanamori rule. The ferromagnetism behavior at room temperature can be well interpreted by first principles calculations as the interaction between the Mn 2+ impurity and Ru ions. Indeed, Mn‐RuO 2 nanoflakes exhibit a strongly magnetic field enhanced OER activity, with the lowest overpotential of 143 mV at 10 mA cm geo −2 and negligible activity decay in 480 h stability (vs 200 mV/195 h without magnetic field) as known for magnetic effects in the literature. The intrinsic turnover frequency is also improved to reach 5.5 s −1 at 1.45 V RHE . This work highlights an important avenue of spin‐engineering strategy for designing efficient acidic oxygen evolution catalysts.