Hydrophobic Effects in Heterogeneous Electrocatalysis

Inducing hydrophobicity at solid–liquid interfaces has emerged as an effective tool for enhancing heterogeneously catalyzed electrochemical reactions. This Perspective highlights the current understanding of the so-called hydrophobic effects in heterogeneous electrocatalysis, as well as the future efforts necessary to elucidate their role—enabling rational design of interfacial environments that optimize electrocatalytic performance. Common strategies to create hydrophobic interfaces include organic and polymer coatings on catalyst surfaces, the formation of composites with hydrophobic materials, physical structuring of catalysts, and the use of additives in the liquid. They have led to enhancements in activity and selectivity for a wide range of electrocatalytic reactions, including the electroconversion of CO 2, CO, N 2, and O 2 . The primary mechanisms discussed in the field are interfacial water displacement, suppressing water-based side reactions (e.g., hydrogen evolution), and a hydrophobic interface providing a favorable environment to enrich reactants near catalyst surfaces. However, recent studies have highlighted the complexity of hydrophobic interfaces and how they can alter other aspects of the interface, such as the structure of interfacial water molecules. Future efforts are necessary to address key fundamental questions and optimize hydrophobic effects, including understanding their impact on reaction kinetics—via altered intermediate states and reaction pathways—as well as their surface-dependent nature, alongside the development of advanced methods to finely tune interfacial hydrophobicity.