Cobalt nanoparticles anchored on graphene oxide for ultra-sensitive simultaneous detection of Pb2+ and Cd2+ by square-wave anodic stripping voltammetry

Lead and cadmium remain critical environmental contaminants despite regulatory restrictions, necessitating sensitive and reliable detection methods. Herein, a cobalt–graphene oxide (Co-GO) nanocomposite was synthesised and employed as an electrocatalyst for the electrochemical detection of Cd2+ and Pb2+. Structural and morphological characterisation confirmed the formation of cobalt nanoparticles uniformly dispersed on graphene oxide, providing high surface area, enhanced conductivity, and robust electron-transfer pathways. The CoGO modified glassy carbon electrode (GCE/Co-GO) demonstrated excellent performance for both individual and
simultaneous detection using square-wave anodic stripping voltammetry (SWASV), achieving detection limits of 0.610 nM for Cd2+ and 0.481 nM for Pb2+, with good sensitivity and a wide linear range response. The synergistic interaction between cobalt nanoparticles and graphene oxide facilitated enhanced adsorption of metal ions and efficient electron transfer during the stripping process. While simultaneous detection resulted in reduced sensitivity due to competitive adsorption and intermetallic interactions, the linear calibration behaviour was preserved. The practical applicability was confirmed using tap water recovery experiments (91–106%). These results establish GCE/Co-GO as a robust, ultra-sensitive platform for electrochemical monitoring of toxic heavy metals in aqueous systems.