Surfactant-Assisted Synthesis of Bismuth-Based Nanoflowers and their Applications as Electrochemical Sensors

In this work we show 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). Generally, the reaction of bismuth chloride with water results in thin plate-like bismuth oxychloride structures primarily dominated by the 001 crystalline phase. We discovered that presence of surfactant sodium dodecyl sulfate was capable of crystallization behavior, encouraging the growth of 101 and 110 phases while reducing the 001 growth. The resulting structure was a uniform nanoflower material. This simple synthesis approach required no toxic materials for chemical reduction and proceeded immediately upon introduction of the salt into water, making it a highly scalable methodology. The as-synthesized nanoflowers were then suspended in Nafion solutions and deposited onto a glassy carbon electrode. Subsequent cyclic voltammetry analysis demonstrated the response to the analyte ions (Pb(II), Zn(II)), allowing for the detection of lead and zinc ions independently and simultaneously down to 1ppm. The implication of these results is the potential of bismuth-based structures for portable and accessible detection of heavy metal ions. Through parameter-focused structural optimization, we anticipate further improvements in sensitivity, paving the way for more effective monitoring of water quality and protection of public health. These results indicate the viability of bismuth-based nanoflower structures for portable, accessible detection of heavy metal ions, with enhanced sensitivity.