Emerging Applications of Solid Catalysts with Ionic Liquid Layer Concept in Electrocatalysis

Abstract The concept of solid catalysts with ionic liquid layer (SCILL) originates from the field of heterogeneous catalysis, where it offers a unique way to regulate both the catalytic activity and selectivity. In recent years, applying this concept in electrocatalysis represented a new, exciting, and growing research field. Herein, emerging applications of the SCILL concept in the context of electrocatalysis for key energy storage/conversion processes such as oxygen reduction, oxygen evolution, and CO 2 reduction reactions are comprehensively reviewed. Alongside case studies highlighting the history, development and latest progress of the SCILL concept, mechanistic underpinnings on the roles of ILs in each application are critically discussed. At the same time, the key challenges and future opportunities in fully leveraging the SCILL concept for either regulating the performance of electrocatalysts or gaining mechanistic understandings for those electrocatalytic processes with complex reaction pathways are outlined.