Feasibility Study of Photoelectrochemical Sensing of Glucose and Urea Using BiVO₄ and BiVO₄/BiOCl Photoanodes

Mo-doped BiVO₄ demonstrated superior glucose and urea sensing with LOD of 0.173 µM and 0.656 µM, respectively. The formation of a BiVO₄/BiOCl heterojunction enhances photoelectrochemical activity; however, it also increases urea and glucose adsorption, raising LOD. Highlights: This study investigates the photoelectrochemical (PEC) performance of molybdenum-doped bismuth vanadate (Mo-doped BiVO₄) and its heterojunction with the BiOCl layer in glucose and urea sensing. Photoelectrochemical analyses, including cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), revealed that the formation of a heterojunction enhanced charge carrier separation. The impact of the interaction between the surface of the photoanode and analytes on sensing performance was systematically evaluated. Among the tested configurations, Mo-doped BiVO₄ exhibited superior glucose sensing with a limit of detection (LOD) of 0.173 µM, while BiVO₄/BiOCl demonstrated an LOD of 2.474 µM. In the context of urea sensing, Mo-doped BiVO₄ demonstrated an LOD of 0.656 µM, while BiVO₄/BiOCl exhibited an LOD of 0.918 µM. Notably, despite the enhanced PEC activity observed in heterostructured samples, Mo-doped BiVO₄ exhibited superior sensing performance, attributable to good interaction with analytes. The photocurrent response trends—an increase with glucose concentration and a decrease with urea concentration—were attributed to oxidation and adsorption phenomena on the photoanode surface. These findings underscore the critical role of photoanode surface engineering in advancing PEC sensor technology, paving the way for more efficient environmental and biomedical applications.