Atomically Dispersed Cobalt 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 well-dispersed Co nanoparticles on graphene oxide, providing high surface area, enhanced conductivity, and robust electron-transfer pathways. The Co-GO 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⁺ and high sensitivities. The synergistic interaction between cobalt nanoparticles and graphene oxide facilitated improved adsorption and electron transfer, while minimal mutual interference between the two metal ions, thus enabling reliable simultaneous detection. 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 monitoring toxic heavy metals in environmental water bodies.