Fundamentals and catalytic applications of single-atom alloys

Single-atom alloys that consist of a catalytically active metal atomically dispersed in a less-catalytic metal host have recently attracted significant concern from worldwide researchers. The unique geometric and electronic properties of single-atom alloys enable both facile dissociation of reactants and weak adsorption of intermediates on the surface, representing two highly desirable elements for efficient and selective catalysis. This review article provides an overview of recent progress in the synthesis and properties of single-atom alloys in heterogeneous catalysis. First, we summarize recent advances in the controllable synthesis of single-atom alloys with various metal combinations. Second, we introduce key characterization techniques, especially operando spectroscopic techniques for the identification of the geometric and electronic structures of diluted active metal atoms in single-atom alloys. Then, we discuss how these geometric and electronic properties of single-atom alloys affect their catalytic performances and thoroughly comprehend the reaction mechanism. Finally, insights into the current challenges and future prospects of single-atom alloys are provided.