rGO/ZnO/Nafion nanocomposite as highly sensitive and selective amperometric sensor for detecting nitrite ions (NO2⁻)

The coupling between inorganic semiconductor metal oxide and nanocarbon material is a proper route to fabricate efficient electrochemical sensors. Herein, the electrocatalytic oxidation, detection of nitrite ions (NO2−) is investigated using reduced graphene oxide/mesoporous zinc oxide (rGO/ZnO) nanocomposite-modified glassy carbon electrode (GCE). The mesoporous ZnO and rGO were prepared via a modified sol-gel in presence of F127 structural template agent and modified Hummers’ methods, respectively. The rGO/ZnO nanocomposite was then produced via a simple ultrasonication and characterized using various analytical techniques to examine the morphology, structure and chemical constituents. The newly-developed rGO/ZnO/Nafion nanocomposite exhibited remarkable sensing response towards NO2− oxidation compared to bare GCE or ZnO/Nafion/GCE. The rGO/ZnO/Nafion/GCE sensor demonstrated a linear dynamic range between 200 and 4000 µM for linear sweep voltammetry (LSV) and 20 to 520 µM (for amperometry). Remarkable sensitivity and low limit of detection (LOD: at S/N = 3) were projected to be 0.3156 μAμM−1cm−2 and 1.18 μM for LSV, whereas values of 0.2754 μAμM−1cm−2 and 1.36 µM were obtained using the amperometric technique. The modified electrocatalyst demonstrated excellent operational stability, reproducibility and anti-interfering ability towards several common active species. The developed rGO/ZnO/GCE electrode represents a favorable strategy for efficient detection and quantification of NO2− by the electrochemical approach.