Atomically precise control in the design of low-nuclearity supported metal catalysts

Low-nuclearity catalysts incorporating supported metal atoms or small clusters on appropriately tailored carriers are growing in diversity and have great potential in catalysis. This Review examines progress in their synthesis and characterization towards the atomically precise design of high-performing new architectures. Nanostructured catalysts incorporating supported metal atoms or small clusters of defined size and chemical composition attract considerable attention because of their potential to maximize resource efficiency. When optimally assembled, all the metal nuclei can participate in the catalytic cycle with properties tailored to deliver high specific activity and stable performance. Over the past decade, both the number and diversity of reported systems have exploded as researchers attempted to control the nanostructure with increasing atomic precision. Nonetheless, spatially resolving the architecture and properties of supported low-nuclearity catalysts using existing analytical methods remains challenging. After identifying general structural features of this advanced family of catalytic materials, including their composition, nuclearity, coordination environment and location, as well as dynamic effects in reactive environments, this Review critically examines progress in their control and understanding. State-of-the-art experimental and theoretical approaches for their characterization are explored, addressing strengths and limitations through recent case studies. Finally, we outline directions for future work that will cross frontiers in the design of catalytic materials, which will be indispensable for developing high-performing new architectures for sustainable technologies.