J–V Decoupling: Independent Control over Current and Potential in Electrocatalysis

This report details an approach for circumventing the current–potential coupling constraints present in traditional electrochemical voltammetry. Specifically, a light-dependent method for expanding the region of testable electrochemical conditions from merely the current–voltage coordinates lying on an electrocatalyst’s polarization curve, to a two-dimensional surface defined by the integral of the polarization curve, is introduced. Validation and applicability of the concept are investigated by testing the utility of current density–potential (J–V) decoupling in steering the fate of reactants in electrochemical CO2 reduction toward CO versus H2. Current density and potential are shown to serve as independent handles for controlling electrocatalyst reactivity, rather than codependent quantities. Demonstration of this concept is then used to refine Faradaic yields for CO evolution in a photo-driven electrochemical device operating at steady state. Finally, an explication of J–V decoupling as the light-dependent analog of a biophysical principle governing electron transfers and catalysis in redox-active enzymes, is put forth.