Manipulating Intermetallic Charge Transfer for Switchable External Stimulus-Enhanced Water Oxidation Electrocatalysis

Electrocatalytic processes involving the oxygen evolution reaction (OER) present a kinetic bottleneck due to the existence of linear-scaling relationships, which bind the energies of the different intermediates in the mechanism limiting optimization. Here, we offer a way to break these scaling relationships and enhance the electrocatalytic activity of a Co-Fe Prussian blue modified electrode in OER by applying external stimuli. Improvements of ~11% and ~57% were achieved under magnetic field (0.2 T) and light irradiation (100 mW.cm-2), respectively, when working at fixed overpotential, ƞ = 0.6 V at pH 7. The observed enhancements strongly tie in with the intermetallic charge transfer (IMCT) intensity between Fe and Co sites. Density Functional Theory simulations suggest that tuning the IMCT can lead to a change of the OER mechanism to an external stimuli-sensitive spin crossover-based pathway, which opens the way for switchable electrocatalytic devices.