A New Type of Nitrate Potentiometric Sensor Prepared Using Hybrid Metal Oxide/Metal Nanoparticles

In this study, for the first time, ZnO nanoparticles doped with noble metals (Pt, Ag, Au) were employed as a solid contact in nitrate ion-selective electrodes based on a glassy carbon internal electrode, and their performance was described and studied. Nanoparticles were synthesized by pulsed laser ablation in liquid. They were placed as an intermediate layer between the inner electrode and the ion-selective membrane. The impact of nanoparticle type on electrode performance was assessed by analyzing their analytical and electrical parameters using both potentiometry and electrochemical impedance spectroscopy. It was found that the determined properties of hybrid nanoparticles, as well as their effectiveness as a solid contact, depend significantly on the type of metal doping. Doping ZnO nanoparticles with metals increases their electrical capacity and reduces contact angles. The best results were obtained for the electrode modified with platinum-doped zinc oxide nanoparticles, characterized by the largest electric capacitance and the most hydrophobic properties among the hybrid nanoparticles. This electrode has been successfully used for the potentiometric determination of nitrate content in soil.