Emerging low-nuclearity supported metal catalysts with atomic level precision for efficient heterogeneous catalysis

Supported atomically dispersed metal catalysts (ADMCs) have received enormous attention due to their high atom utilization efficiency, mass activity and excellent selectivity. Single-atom site catalysts (SACs) with monometal-center as the quintessential ADMCs have been extensively studied in the catalysis-related fields. Beyond SACs, novel atomically dispersed metal catalysts (NADMCs) with flexible active sites featuring two or more catalytically centers including dual-atom and triple-atom catalysts have drawn ever-increasing attention recently. Owing to the presence of multiple neighboring active sites, NADMCs could exhibit much higher activity and selectivity compared with SACs, especially in those complicated reactions with multi-step intermediates. This review comprehensively outlines the recent exciting advances on the NADMCs with emphasis on the deeper understanding of the synergistic interactions among multiple metal atoms and underlying structure-performance relationships. It starts with the systematical introduction of principal synthetic approaches for NADMCs highlighting the key issues of each fabrication method including the atomically precise control in the design of metal nuclearity, and then the state-of-the-art characterizations for identifying and monitoring the atomic structure of NADMCs are explored. Thereafter, the recent development of NADMCs in energy-related applications is systematically discussed. Finally, we provide some new insights into the remaining challenges and opportunities for the development of NADMCs.