Ultrasmall Gold Nanoclusters-Enabled Fabrication of Ultrafine Gold Aerogels as Novel Self-Supported Nanozymes.

Metal aerogels represent an emerging type of functional porous materials with promising applications in diverse fields, but the fabrication of metal aerogels with specific structure and property still remains a challenge. Here, the authors report a new approach to fabricate metal aerogels by using ultrasmall metal nanoclusters (NCs) as functional building blocks. By taking D-penicillamine-stabilized gold NCs (AuNCs) with a diameter of 1.4 nm as an example, Au aerogels with ultrafine ligament size (3.5 nm) and good enzyme-mimic properties are synthesized. Detailed characterization shows that the obtained Au aerogels possess typical 3D self-supported porous network structure with high gold purity and surface area. Time-lapse spectroscopic and microscopic monitoring of the gelation process reveal that these ultrasmall AuNCs first grow into large nanoparticles before fusion into nanowire networks, during which both pH and the precursor concentration are identified to be the determining factor. Owing to their highly porous structure and abundant metal nodes, these self-supported Au aerogels display excellent peroxidase-like properties. This work provides a strategy for fabricating advanced metal aerogels by taking ultrasmall-sized metal NCs as building blocks, which also opens new avenues for engineering the structure and properties of metal aerogels for further advancing their applications.