Multiple effects driven by AC magnetic field for enhanced electrocatalytic oxygen evolution in alkaline electrolyte

The slow kinetics of Oxygen evolution reaction (OER) restricts the large-scale application of water electrolysis technology. It is reported that magnetic field can improve OER activity, but it is not clear how the AC magnetic field affects OER. Here, a series of NiCoFe-MOF-74 are reported, and it is found AC magnetic field can significantly enhance the alkaline OER activity at low current densities, but reduce the alkaline OER activity at high current densities, due to spin conservation, MHD effect, and induced electric field induced by AC magnetic field. In particular, when an AC magnetic field of 5.184 mT is applied, the overpotential at 10 mA cm−2 of NiCoFe-MOF-74 and carbon paper was reduced by 36.7% and 17.6%, respectively, but the overpotential at 40 mA cm−2 increased by 27.8% and 39.9%, respectively. This discovery provides a promising strategy for introducing an AC magnetic field to adjust the process of electrocatalytic reactions.