In Situ Grown ZnIn₂S₄@ZnWO₄ Heterojunction for Highly Sensitive Photoelectrochemical Detection of Chlorogenic Acid

Chlorogenic acid (CA) is a phenolic acid compound with broad biological activity. In this study, a high-performance photoelectrochemical sensor based on in situ grown ZnIn₂S₄@ZnWO₄ heterojunctions was developed for the sensitive detection of CA. ZnWO₄ nanocrystals were successfully grown on the surface of flower-like ZnIn₂S₄ through a one-step hydrothermal method, resulting in a tightly coupled heterojunction structure that effectively promoted photo-induced charge separation and enhanced photocurrent response. Experimental results demonstrated that the sensor exhibited excellent analytical performance for CA, with a good linear relationship within a concentration range of 20-800 nM, a detection limit as low as 5 nM (S/N = 3), and high selectivity, stability, and reproducibility. Density functional theory (DFT) calculations revealed the charge transfer mechanism at the heterojunction interface and the interaction between CA and the material surface. Practical sample analysis showed that the sensor was successfully applied to accurately determine CA content in coffee, eucommia ulmoides oliver and lonicera japonica thunb, with recovery rates ranging from 97.08 to 103.56%. This study provides a new method for CA detection and offers fresh insights into the design of efficient photoelectrochemical sensors.