ZIF‐8‐Derived Zn Single‐Atom Nanozyme with High Oxidase Activities for Highly Sensitive Colorimetric Detection of Tannic Acid in Tea

This work demonstrates that Zn single atoms exhibit intrinsic oxidase‐like activity. Zn single‐atom nanozymes (Zn‐SAs/NC) were synthesized via direct pyrolysis of ZIF‐8 at 1000 °C under N 2 atmosphere, which retains a rhombic dodecahedral morphology with atomically dispersed Zn sites. Crucially, Zn‐SAs/NC exhibited pronounced oxidase‐like activity, efficiently catalyzing the oxidation of 3,3′,5,5′‐tetramethylbenzidine (TMB) to blue oxTMB without exogenous H 2 O 2 . Control experiments with metal‐free NC confirmed that the catalytic activity originated specifically from the Zn single atoms, challenging the traditional view of Zn's catalytic inertness. The Zn‐SAs/NC‐catalyzed TMB oxidation system was exploited for colorimetric detection of tannic acid (TA) based on TA's inhibitory effect, achieving high sensitivity (LOD = 0.016 µM) and selectivity. Successful application in real tea samples validated the method's practicality, establishing Zn single atoms as a novel nanozyme platform.