Engineering the Electrochemical Interface of Oxygen Reduction Electrocatalysts with Ionic Liquids: A Review

Hydrogen fuel cells are a promising technology for the environmentally sustainable production of electricity. However, their commercialization is hindered by the sluggish kinetics of the oxygen reduction reaction and by the high cost of the state‐of‐the‐art platinum catalysts. To address these challenges, research has focused on the enhancement of the activity of platinum and platinum group metal (PGM)‐free electrocatalysts, by modifying their composition and topology. Recently, a new approach has emerged to boost the activity of ORR catalysts, based on engineering the electrochemical interface. Herein, the recent developments in the use of ionic liquids (ILs) to modify the triple‐point interface of ORR catalysts are summarized. In this review, the current understanding in the literature of the effect of IL layers is presented, along with the open questions and remaining challenges. A short perspective on the applicability of this simple and effective modification to other electrochemical reactions is discussed.