Small‐Scale Big Science: From Nano‐ to Atomically Dispersed Catalytic Materials

The emergence of nanomaterials (NMs) has made everyone more aware of the close relationship between the size and performance of materials. Especially, the catalytic properties of materials may change dramatically when the macroscopic size of matter goes from bulk to nanometer to atomic level. It is very firmly believed that “Small size determines macroproperties, contains big science.” Therefore, as chemists hope, it is very essential to rationally tune and characterize the size of materials and deeply understand the relationship between macroscopic catalytic properties and small structures. Herein, the recent progress in both multi‐scale materials from nanoscale, sub‐nano, clusters to atomic scale for various catalytic reactions is focused. Specifically, the catalytic reaction on the microstructures and the relationship between the small scale and big science are comprehensively summarized and discussed. This review systematically spans dimensions to reveal the catalytic performances of materials at different scales with a unique effect. This is crucial for rationally understanding the composition of materials and exploring their catalytic activity. Current opportunities, future challenges, and outlooks for the application of multiscale materials (NMs, sub‐nano, cluster, and atomically dispersed materials) in catalysis, energy and environmental protection, etc. are summarized and outlined.