Electrical Double Layer in Electrocatalysis: Definitions, Characterization, and Influencing Factors

Electrical double layer (EDL) at the interface between electrode and electrolyte dominates the electrochemical reaction progress and determines the performance of electrochemical devices. Recent findings of solvation effect, selective adsorption of ions, and product evolution at the interface pose the challenge to the understanding of classical EDL─the proposed nonclassical EDL tries to involve these aspects, and emerging measurements have been used to uncover its previously unexplored properties. These advances will reshape the strategy for designing the electrochemical devices, catalyst synthesis, and electrolyte engineering. Clarifying the features of the EDL and its characterization can be beneficial for the development of electrochemistry. In the present review, the features and characteristics of EDL will be redefined and proposed. Diverse methods used to determine and quantify the EDL are summarized to provide a clear framework for understanding the structure and behavior of the EDL. In addition, factors that affect the EDL are reviewed in diverse electrochemical reactions. This review can accelerate innovation in the field of electrochemical catalysis.