A Hexagonal Ag/Co/rGO Nanocomposite-Based Sensor for the Electrochemical Detection of Metronidazole

This study reports a sustainable and facile strategy for synthesizing hexagonal Ag/Co bimetallic nanoparticles uniformly anchored onto reduced graphene oxide (Ag/Co/rGO), where the graphene oxide precursor was derived exclusively from electronic waste (e-waste). The Ag/Co/rGO nanocomposites were synthesized by varying the ratio of GO while maintaining a constant 1:1 ratio of Ag and Co. Among the synthesized nanocomposites, the Ag/Co/rGO (1:1:3) composite exhibited a well-defined hexagonal crystal structure and was uniformly dispersed on the rGO surface without noticeable agglomeration. The Ag/Co/rGO (1:1:3) sensor showed excellent performance for metronidazole (MTZ) detection, with a low detection limit of 74 nM, wide linear range (2–600 μM), and high sensitivity (2870 μA·mM –1 ·cm –2 ). The sensor also exhibited excellent selectivity, reproducibility (relative standard deviation, RSD < 2%), and long-term stability (>95% signal retention after 8 days). Additionally, the developed sensor was also able to detect MTZ in real human urine samples with a high recovery rate of 88–103%. These findings suggest that the developed sensor has strong potential as a sensitive, practical, and cost-effective system for monitoring MTZ in water.