Solid Migration to Assemble a Flower-like Nanozyme with Highly Dense Single Copper Sites for Specific Phenol Oxidation

Nanozymes with high catalytic stability and sustainability have emerged as powerful competitors to natural enzymes for diverse biocatalytic applications. However, constructing a nanozyme with high specificity is one of their biggest challenges. Herein, we develop a facile solid migration strategy to access a flower-like single copper site nanozyme (Cu SSN) via direct transformation of copper foam activated by 2-methylimidazole. With highly clustered CuN₃ sites whose local structure is similar to that of natural polyphenol oxidase, the Cu SSN exhibits excellent activity and specificity to oxidize phenols without peroxidase-like activity. Furthermore, the Cu SSN shows high sensitivity in the colorimetric detection of epinephrine with a low detection limit of 0.10 μg mL^–1, exceeding that of most previously reported enzyme-mimicking catalysts. This work not only provides a simple method for the large-scale preparation of high-performance nanozymes but also offers an inspiration for the design of highly specific nanozymes by mimicking the synergy among sites in natural enzymes.