Engineering Single Atom Catalysts to Tune Properties for Electrochemical Reduction and Evolution Reactions

Electrocatalysis is important to the conversion and storage of renewable energy resources, including fuel cells, water electrolysers, and batteries. Engineering metal-based nano-architectures and their atomic-scale surfaces is a promising approach for designing electrocatalysts. Single metal atom interactions with substrates and reaction environments crucially modulate the surface electronic properties of active metal centers, yielding controllable scaling relationships and transitions between different reaction mechanisms that improve catalytic activity. Single-atom catalysts (SACs) allow activity and selectivity tuning while maintaining relatively consistent morphologies. SACs have well-defined configurations and active centers within homogeneous single-atom dispersions, producing exceptional selectivities, activities, and stabilities. Furthermore, SACs with high per-atom utilization efficiencies, well-controlled substrate compositions, and engineered surface structures develop single atom active sites for molecular reactions, enhancing mass activities. Recent developments in different metal-based SAC nanostructures are discussed to explain their remarkable bi-functional electrocatalytic activities and high mechanical flexibility, especially in the oxygen evolution reaction, oxygen reduction reaction, carbon dioxide reduction reaction, hydrogen evolution reaction, and in battery applications. Existing barriers to and future insights into improving SAC performance are addressed. This study develops practical and fundamental insights on single atom electrocatalysts directed towards tuning their electrocatalytic activities and enhancing their stabilities.