Recent advances in single-atom catalysts and single-atom alloys: opportunities for exploring the uncharted phase space in-between

Single-atom catalysts (SACs) have gained significant worldwide attention for exhibiting distinct reactivity and selectivity for important reactions, while utilizing precious metals at the ultimate limit of efficiency. SACs involving reducible oxide supports are good catalysts for oxidation reactions, and metalacid site pairs enable C-C bond formation, but SACs can deactivate by sintering under reducing conditions. On the other hand, single-atom alloys (SAAs) are robust towards sintering and exhibit exceptional catalytic performance for a wide range of reactions under reducing conditions but can deactivate under oxidizing environments. Therefore, there is tremendous opportunity to explore and exploit catalytic reactivity between the SAC and SAA extremes. This paper focuses on recent advances in both fields and highlights prospects for future research.