Oxidase‐Like Nanozyme Activity of Ultrathin Copper Metal–Organic Framework Nanosheets With High Specificity for Catechol Oxidation

Abstract In nature, catechol oxidase catalyzes the oxidation of o ‐diphenol to o ‐quinone to produce a series of highly important polyphenolic natural products. Although mimicking the functionality of natural enzyme using a nanozyme was found to be beneficial, attaining a high specificity is challenging. Herein, we have explored the thickness‐dependent oxidase activity and specificity of Cu‐metal‐organic framework (MOF) nanosheets. The unique synthetic method offers control over the thickness of the Cu‐MOF nanosheets. The ultrathin (4 nm) Cu‐MOF (Cu‐UMOF) nanosheets as an oxidase nanozyme exhibit high specificity for catechol oxidation without having any peroxidase activity. Interestingly, the thicker (20–30 nm) Cu‐MOF nanosheets showed poor catechol oxidase and peroxidase activity. The binuclear Cu‐center, coordinative, and electronic unsaturation tuned electronic structure in Cu‐UMOF, resulting in higher specificity for catechol oxidation than thicker Cu‐MOF.