Modulator-driven pore engineering of tunable and scalable ternary ZIF-8/ZnO/Ag2O nanocomposite for electrochemical sensing of catechol oxidation marker in tea samples.

Reliable on-site detection of trace amounts of catechol, a toxic oxidation product of tea catechins, remains challenging due to sensor instability and fouling. Herein, the porous electrocatalytic interface ZIF-8/ZnO/Ag2O nanocomposite, with HCOONa-tuned pore expansion from ∼3.4 to ∼4.1 Å, provides size-selective preconcentration of catechol while maintaining high microporosity. This pore engineering offers a novel strategy to overcome matrix interference and achieve high sensitivity in complex food samples such as tea. The electrochemical sensor exhibits a linear range of 0.1 nM to 1 μM with LOD = 0.579 nM, excellent reproducibility (RSD = 2.3%), 35-day stability (86.3%), and 30-s regeneration, outperforming most non-enzymatic sensors. Real-sample analysis in tap water, black tea, and green tea via standard addition yields 96.0-104.4% recovery with RSD < 3.17%, confirming tolerance to matrix interference and practical applicability. This scalable, regenerable platform offers a promising engineering solution for catechol monitoring as an oxidation marker in tea quality control and food safety.