Nonenzymatic Electrochemical Detection of Hydrogen Peroxide at Zinc Oxide Nanoparticle-Modified Screen-Printed Electrodes

Hydrogen peroxide (H2O2) levels have raised concerns about environmental pollution. However, reliable and low-cost strategies for monitoring H2O2 levels remain limited. Herein, zinc oxide nanoparticles (ZnONPs) were synthesized via a simple, low-cost precipitation route followed by controlled calcination, producing a wurtzite hexagonal phase with nanorod morphology. ZnONPs were characterized by infrared spectroscopy, x-ray diffraction, atomic force, scanning and transmission electron microscopy, and electrochemical techniques. Screen-printed carbon electrodes (SPEs) were modified by drop-casting ZnONPs and coating the surface with a thin NAFION layer. Optimizing ZnONPs mass loading showed 37.5 & micro;g cm-2 gave the best electron-transfer behavior, confirmed by cyclic voltammetry. The SPE/ZnONPs/NAFION electrode displayed a rapid and well-defined anodic response toward H2O2 oxidation, with a linear concentration range of 20-95 & micro;M (R 2 = 0.992), a sensitivity of 2.1 & micro;A & micro;M-1 cm-2, and a low detection limit (LOD = 2.4 & micro;M). When tested in seawater, the sensor maintained a linear response (10-70 & micro;M, R 2 = 0.997) despite signal attenuation from matrix effects, demonstrating adequate robustness (sensitivity of 0.37 & micro;A & micro;M-1 cm-2, LOD = 7.9 & micro;M) in complex aqueous media. These findings highlight the potential of ZnONPs as effective electrocatalytic modifiers for low-cost, disposable, and enzyme-free H2O2 sensing platforms.