Electrochemical detection of zinc oxide nanoparticles in water contamination analysis based on surface catalytic reactivity

An electroanalytical method for determining the concentration of ZnO nanoparticles (< 50 nm) in aqueous dispersion has been developed. The nanoparticles are first allowed to coat a screen-printed electrode by air-drying, which provides a significant magnification of the reduction current for KCl electrolyte at negative potentials. Phenol is next added as a chemical probe for electrochemical analysis by cyclic voltammetry. Measurement of the reduction current at an applied potential of − 0.3 V provides adequate sensitivity for the indirect quantification of ZnO nanoparticles down to a low concentration of 0.1 mg/mL. Other nanoparticles such as TiO₂ and CeO₂ do not produce any similar reduction peak. Furthermore, the irreversible oxidation peak at + 0.6 V and the charge storage capacity are both linearly proportional to ZnO concentrations (below 0.2 mg/mL) and can afford a detection limit of 0.01 mg/mL nanoparticles. Hence, the new method comprising three simultaneous measurements is good for both the identification and quantification of ZnO nanoparticles.