Ionic Liquids: Promisingly Functional Mediators in Electrocatalysts for Water Splitting

A drastic demand for green energy has stimulated the development of H2 production from water electrolysis. So, the exploration of electrocatalysts for water splitting has become an intensive concerned issue. For decades, utilization of ionic liquids (ILs) in the research of electrocatalysts has gradually evolved to an important branch in the field of energy storage and conversion. The participation of ILs offers the catalyst with almost the highest catalytic activity for water splitting so far. In this review, we describe in detail the application of ILs as media and templates in the preparation of catalysts for hydrogen evolution reaction and oxygen evolution reaction. Different from ordinary organic solvents, ILs have the ability to control the growth direction of nanomaterials, adjust phases, morphologies, electronic structures, mass transfer process, etc. so they can enhance the performance of electrocatalysts. In summarizing the function of ILs in the preparation of nanomaterials, the relationship among reaction media, material structures and catalytic efficiencies of catalysts is paid intensive attention. We expect that this review will guide the readers to have a more systematic understanding on preparing electrocatalysts assisted by ILs, while stimulating new thoughts on the reasonable design and controllable preparation of IL-mediated catalysts for water electrolysis.