Electric Double Layer Charging, a New Framework for Optimizing Electrocatalyst Design and Performance

Electrochemical reactions occur at charged interfaces where the accumulation and redistribution of charge within the electric double layer (EDL) fundamentally govern the reaction kinetics. Despite its ubiquity, the mechanistic connection between EDL charging and electrocatalytic activity remains underexplored. This Perspective highlights recent theoretical and experimental advances─focusing on studies from our group and others─that link the degree of EDL charging, characterized by the surface charge density (σ), to catalytic activity. We categorized the types of charge accumulated in the EDL as space charge, ionic charge, and pseudocapacitive charge and discussed how these components mechanistically influence electrocatalytic activity. Together, these insights suggest σ as a key descriptor that representatively captures the microenvironment effect of the EDL, bridging interfacial charge dynamics and catalytic performance and thereby suggesting new opportunities for the rational design of high-performance electrochemical interfaces.