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

Hydrogen peroxide (H 2 O 2 ) levels have raised concerns about environmental pollution. However, reliable and low‐cost strategies for monitoring H 2 O 2 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 µg 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 H 2 O 2 oxidation, with a linear concentration range of 20–95 µM ( R 2 = 0.992), a sensitivity of 2.1 µA µM −1 cm −2 , and a low detection limit (LOD = 2.4 µM). When tested in seawater, the sensor maintained a linear response (10–70 µM, R 2 = 0.997) despite signal attenuation from matrix effects, demonstrating adequate robustness (sensitivity of 0.37 µA µM −1 cm −2 , LOD = 7.9 µM) in complex aqueous media. These findings highlight the potential of ZnONPs as effective electrocatalytic modifiers for low‐cost, disposable, and enzyme‐free H 2 O 2 sensing platforms.