High-Performance Holmium Pyrochlore/h-BN Composite for Ultrasensitive Electrochemical Sensing of Phenazopyridine Hydrochloride

The proliferation of pharmaceutical drugs has had critical impacts on ecosystems. Phenazopyridine hydrochloride (PAP) is one of the well-known medications used to treat urinary tract infections (UTIs) which is excreted into the environment through human waste. With the increasing global concern over pharmaceutical contamination in water and environmental monitoring, this work contributes by providing a novel electrochemical sensing platform using the rare-earth pyrochlore-type oxide Ho₂Sn₂O₇ (HSO) incorporated with hexagonal boron nitride (h-BN). The combination of HSO nanoparticles and h-BN nanoplatelets on the surface of GCE enriches the active sites and facilitates faster charge transfer. This state-of-the-art modified electrode demonstrates excellent electrochemical performance with a broad linear range of 0.1–241.5 μM and the lowest detection limit of 0.003 μM. The proposed sensor demonstrates exceptional selectivity and sensitivity for PAP, even in complex urine samples that contain various potential interferents such as glucose, uric acid, and electrolytes. Our experimental data show a clear 31% increase in peak current, demonstrating enhanced detection capabilities, and we present a comparative analysis with existing detection methods, highlighting the superior sensitivity and response time of our approach. Remarkably, our constructed nanocomposite material established exceptional selectivity against a series of interfering molecules. Furthermore, the practical accessibility of the HSO/h-BN sensor for detecting PAP in real-world samples has been evaluated with an outstanding recovery range of 78.99% to 99.15%.