Electrospun CuO-ZnO nanohybrid: Tuning the nanostructure for improved amperometric detection of hydrogen peroxide as...

Hydrogen peroxide (H₂O₂) is a by-product of some biochemical processes which is catalyzed by enzymes such as glucose oxidase (GOx), cholesterol oxidase (ChoOx), etc and its overproduction in living cells can trigger cancer growth and various diseases. Therefore, H₂O₂ sensing is of great importance in the determination of diseases as well as industries and environmental health plans. We produced ZnO-CuO nanofibers by electrospinning method for non-enzymatic electrochemical H₂O₂ sensing. The sensing properties of the carbon paste electrode (CPE) modified with ZnO (0.3 wt%)/CuO (0.7 wt%) nanofibers (named as ZnO3-CuO7) for detection of H₂O₂ were explored in phosphate-buffered saline (PBS) at pH ∼ 7.4 solution. The ZnO3-CuO7 nanofiber exhibited the lowest charge transfer resistance and the highest electrocatalytic performance among other modified electrodes for detection of H₂O₂ and considered as an optimized sample. The effect of scan rate and H₂O₂ concentration in the reduction process were also investigated by cyclic voltammetry (CV) and the mechanism for the electrochemical reaction of H₂O₂ at the surface of the optimized electrode was studied. The diffusion coefficient of H₂O₂ and the catalytic rate constant were evaluated by chronoamperometry as 1.65 × 10^-5 cm² s^-1 and 6 × 10³ cm³ mol^-1 s^-1, respectively. Furthermore, amperometric detection of H₂O₂ with a low detection limit of 2.4 µM and a wide linear range of 3 to 530 µM were obtained. Meanwhile, the optimized electrode displayed no recognizable response towards some biomolecules such as ascorbic acid, uric acid, dopamine and glucose. The obtained results confirmed that the modified electrode shows high sensitivity and selectivity as a H₂O₂ biosensor with improved reproducibility and stability.