Recent Advances in Single‐Atom Catalysis

Abstract As a new concept in catalysis, single‐atom catalyst (SAC) is becoming one of the hot topics in both homo‐ and heterogeneous catalysis, owing to its exactly identified active sites, unique electronic structure, and robust stability, selectivity, and activity in catalysis. Herein, we review the structural and electronic properties of SACs and summarize the theoretical and experimental results on a series of iron oxide–supported SACs of M 1 /FeO x (M = Pt, Ir, Au, Ni). We discuss the electronic nature of the high reactivity of SACs in catalyzing various important chemical reactions, including CO oxidation, the preferential oxidation of CO in H 2 (PROX), water gas shift (WGS) reactions, and chemoselective hydrogenation. As an extension of the SAC concept, two new types of SACs are also discussed, including singly dispersed bimetallic sites (SBMSs) of Rh 1 Co 3 on CoO support that have been shown to exhibit prominent catalytic activity for NO reduction by CO and the so‐called dynamic single‐atom catalysts (DSACs), where the dynamically formed transient monatomic species on supported gold nanoparticles are found to be the actual active sites for CO oxidation under reaction conditions. We emphasize that engineering the oxidation states of the supported transition metals is the key to achieve a high catalytic reactivity and selectivity of SACs. Finally, we summarize our understanding of the nature of SACs and provide a perspective viewpoint on the future development of SAC as a bridge of homogenous and heterogeneous catalysis.