Enhancement of Oxygen Evolution Electrocatalysis via Magnetohydrodynamic Effect on Mass Transport

The sluggish kinetics of the oxygen evolution reaction (OER) significantly impede the industrial applications of water electrolysis and rechargeable metal-air batteries. Exploring magnetic field-assisted strategies to enhance the OER electrocatalytic activity has attracted extensive attention from researchers. Herein, a specially designed magnetoelectrochemical system has been employed to systematically investigate the influence of the magnetohydrodynamic (MHD) effect on the OER activity of magnetic and nonmagnetic current collectors in magnetic fields. The results demonstrate that the Lorentz force can effectively accelerate the bubbles to detach quickly under a high current in both magnetic and nonmagnetic current collectors. The OER performance of nonmagnetic copper foam (CF) is linearly and positively correlated with the projected area. In comparison with the nonmagnetic CF, the magnetic nickel foam (NF) benefits from the Kelvin force in the MHD effect, which can further optimize the electric double layer, accelerate the catalytic reaction kinetics, and enhance the oxygen evolution reaction activity. Through systematically integrating the Lorentz equation and the Kelvin equation, we establish a positive correlation between the projected magnetic field area and the Lorentz force response, as well as the positive enhancement effect of the perturbation of the Kelvin force─primarily on electric double layer enhancement─thereby improving the OER kinetics. Our findings advance the fundamental understanding of the role of magnetic fields in electrocatalysis and pave the way for the development of more effective and sustainable energy conversion technologies.