Interface Engineering: Enhanced Catalysis Through Precise Control of Metal Nanocluster Transformation.

Atomically precise metal nanoclusters (NCs) have garnered significant interest due to their unique atomic stacking structures, the effect of quantum confinement, and enriched active sites but suffer from thermal- or light-induced poor instability and self-aggregation, together with in situ self-conversion to conventional metal nanoparticles (NPs). How to effectively harness the generic detrimental self-transformation property of metal NCs has so far not garnered immense attention within the realm of catalysis. In this work, we develop a layer-by-layer assembly technology to accurately anchor metal NCs to the metal oxide matrix. Then, the anchoring of metal NCs to metal NPs is triggered by a simple thermal treatment that enables precise control over the interface structure, resulting in a hollow core-shell heterostructure with a metal core (Au, Ag) encapsulated by a metal oxide (CeO, FeO, SnO) shell. Benefiting from the synergistic interplay between metal NPs and the metal oxide substrate, such self-assembled metal NPs@metal oxide heterostructures display excellent catalytic activities and stability in the reduction of aromatic nitro compounds. The detailed catalytic mechanism is elucidated. Our work offers fresh impetus for the judicious utilization of the inherent instability of metal NCs for catalytic selective organic transformation.