Catharanthus r oseus ‐Assisted Synthesis of Zirconia Nanoparticles for Electrochemical Determination of Nitrobenzene

Nitrobenzene (NB) is a toxic, persistent pollutant widely used in manufacturing pesticides, dyes, explosives, and preservatives, and its detection demands sensitive and reliable analytical methods. Electrochemical techniques are attractive for NB detection owing to their low cost, simplicity, and ease of operation. Herein, we report a simple and green synthesis of zirconia nanoparticles (ZrO 2 NPs) assisted by Catharanthus roseus (CR) flower extract. Structural characterization by X‐ray diffraction, Fourier transform infrared spectroscopy, X‐ray photoelectron spectroscopy, scanning electron microscopy, and transmission electron microscopy confirmed the formation of monoclinic‐phase CR‐ZrO 2 NPs with particle sizes of 20–25 nm. The electrochemical performance of the CR‐ZrO 2 ‐modified glassy carbon electrode (CR‐ZrO 2 /GCE) toward NB reduction was evaluated using cyclic voltammetry, differential pulse voltammetry, and electrochemical impedance spectroscopy. Under optimized conditions, the sensor exhibited good electrocatalytic activity toward NB reduction via a four‐electron/four‐proton transfer mechanism, with a detection range of 1–150 µM and a limit of detection of 0.51 µM. The sensor also showed good selectivity, precision, and storage stability, along with satisfactory practical applicability for river water sample analysis. These findings highlight the promising potential of CR‐ZrO 2 NPs for electrochemical monitoring of environmental pollutants.