Single-Atom Catalysts for Hydrogen Evolution Reaction

Single-atom catalysts (SACs) have sparked rapidly emerging research interest in industrial water-splitting electrolysis for sustainable hydrogen production. Downsizing the metal nanoparticles to SACs anchored on solid support reveals extraordinary reaction kinetics compared to bulk counterparts due to the distinct merits of atomically monodispersed catalytically active sites, tunable coordination environment, and greater atom utilization. Moreover, strong metal-support bonding favors swift charge transfer at the interface, which modulates the electronic structure towards remarkable and unique catalytic activity. In this regard, consistent efforts have been devoted to designing low-cost, durable, and highly effective SACs for hydrogen evolution reaction (HER). In this chapter, we present different innovative synthesis routes and focus on a combination of analytical characterization techniques to highlight the successful synthesis and determine the optimal SAC concentration, vital for high HER efficiency. Further, we elaborate on recent advancements and electrochemical characteristics of SACs towards HER applications. After this, we aim to provide a comprehensive understanding and in-depth analysis of electronic structure transformation and subsequent increase in a number of accessible surface active HER sites upon SAC introduction. Finally, current key challenges in SACs are briefly addressed and future outlooks for developing intriguing SACs for exceptionally high activity and stability are proposed.