ZIF-67/Pomelo Carbon Composite: Design and Application as an Electrochemical Sensor for Gallic Acid

Gallic acid (GA) is a natural polyphenol known for its significant biological activity and widespread presence in food, medicine, and various other fields. The accurate and rapid detection of GA is crucial for ensuring food quality control and conducting pharmaceutical analyses. In this study, we successfully developed a novel electrochemical sensor based on a ZIF-67/pomelo carbon (ZIF-67/PC) composite through a simple and environmentally friendly synthetic route. The results indicated that the glassy carbon electrode (GCE) modified with ZIF-67/PC exhibited remarkable electrocatalytic activity towards GA oxidation. The pore-like structure of ZIF-67/PC accelerates the diffusion of GA, the carbon matrix enhances electron transfer, and the Co-N-C sites catalyze the oxidation of GA, thereby achieving excellent detection performance. Under optimal conditions, the sensor demonstrated an extensive linear response range of 8–1000 μM for GA, accompanied by a low detection limit of 0.25 μM (S/N = 3). Furthermore, this sensor displayed excellent selectivity as well as good stability-retaining 91.27% current after 15 days and satisfactory reproducibility with a relative standard deviation below 2%. When applied to detect GA in green tea samples, recovery rates ranged from 95.2% to 102.1%, underscoring its practical application potential. This work presents a viable strategy for developing low-cost yet high-performance electrochemical sensors by integrating metal–organic frameworks with biomass-derived carbon materials.