Surfactant-Assisted Synthesis of Bismuth Oxychloride Nanoflowers for Electrochemical Sensing of Heavy Metal Ions

Heavy metal ion contamination of drinking water is a significant, invisible threat to public health which requires active and decentralized monitoring with high sensitivity, accuracy and reliability. The government and regulatory agencies actively survey and maintain established limits on heavy metal contamination, but generally prioritizing localized hotspots in high-risk communities. Their characterization techniques are typically expensive and inaccessible to the public, requiring specialized training and extended sample shipping times, with a purview restricted to public infrastructure. As plumbing systems corrode and contaminants leach into drinking water systems, independent means of oversight are becoming increasingly vital in effectively identifying and mitigating toxic exposure. In this work we propose the development and application of a high surface area bismuth oxychloride nanoflower for the electrochemical detection of zinc and lead ions in drinking water. The flower structure was synthesized via hydrolysis of bismuth chloride salt in a micellar environment of sodium dodecyl sulfate, followed by aqueous chemical reduction and transformation to metallic bismuth. The size and uniformity of the synthesized nanoflower was characterized with scanning electron microscopy (SEM), and the composition and microstructure were investigated using energy dispersive x-ray spectroscopy (EDS) analysis and x-ray diffraction (XRD). The nanoflowers were deposited onto a glassy carbon electrode and coated with a protective Nafion layer, prior to cyclic voltammetry analysis of analyte ion reactivity, achieving detection of lead and zinc ions in buffer and practical drinking water samples. These results indicate the viability of bismuth-based nanoflower structures for portable, accessible detection of heavy metal ions, with enhanced sensitivity.