Green-synthesized ZnO nano-crystallites as an electrochemical sensor for efficient detection of heavy metal

Green-synthesized nanomaterials have garnered increased interest in mitigating the issue of freshwater scarcity worldwide. So, focusing on this issue, bay leaf extract (Laurus nobilis) was employed to synthesize ZnO NPs, which were able to detect the heavy metal (Cd²⁺) in aqueous solution. The synthesized material was characterized by XRD, FTIR spectroscopy, FE-SEM equipped with EDX, and TGA. The structure of ZnO (hexagonal wurtzite) was assured from the X-ray diffractogram, and the determined crystallite size was within 4-127 nm depending on several model equations such as the Sahadat-Scherrer Method, Monshi-Scherrer Method, Linear Straight-line Method of Scherrer's equation, Halder-Wagner method, Williamson-Hall plots, and size-strain plot. TGA revealed the weight loss (three stages), whereas the SEM micrograph confirmed the presence of small spherical particles. The EDX assured the presence of Zn (84.45 wt%) and O (15.55 wt%). A glassy carbon working electrode fabricated with ZnO NPs was able to detect heavy metal (Cd) through the DPASV electrochemical technique with a linear range of 0.1-7 ppm.