Harnessing magnetic fields to accelerate oxygen evolution reaction

The challenge of overcoming the bottleneck in water electrolysis can potentially be addressed by utilizing permanent magnets without extra energy consumption, but the underlying mechanism of magnetic field effects is still puzzling despite increasing efforts in last few years. In this work, by dip-coating a superhydrophilic γ-Fe2O3 layer onto different electrode substrates, their surface wettability and magnetism are modified, so the ever-tangled effects of magnetic field are separated and identified. It is determined that the primary contribution of magnetic fields at the high current density was due to additional Lorentz force and Kelvin force exerted on oxygen gas bubble, with the former being dependent on the external magnetic field's geometry and the latter closely tied to the electrodes' magnetism. Strategies to maximize effects of magnetic field as well as the overall efficiency of water electrolysis is proposed.