Copper oxide nanostructure-based sensitive amperometric detection of sulfite from wastewater

In the current study, we synthesized copper oxide nanostructures (CuO NSs) via a facile hydrothermal procedure. We characterized them with the help of scanning electron microscopy (SEM) and X-ray diffractometry (XRD). SEM study revealed that CuO NSs inherited nanoneedles-based flowering geometry with a porous nature, while XRD proved the crystalline nature of these NSs. When deposited on a glassy carbon electrode (GCE), these nanostructures are displayed as a sensitive sulfite detection tool in the sample matrix. The results showed that sodium hydroxide, with pH 10.0, was the best-supporting electrolyte among all electrolytes studied. The as-prepared sulfite sensor performed well in a linear working range of 10–100 µM sulfite with the low detection limit (LOD) of the amperometry technique used to evaluate the analytical performance of the electrode, such as a limit of 1.12 µM. The developed sensor was highly stable and reproducible, showing a relative standard deviation of 2.17% for 10 cycles. The sensor also exhibited more selectivity for sulfite in the presence of probable interfering species, including cyanide, sulfate, chloride, and nitrate. The findings further proved the CuO/GCE-Nafion-based sensor as a sensitive diagnostic tool for quantifying or monitoring health-hazardous sulfite in the environmental sample matrices.