Voltammetrically Measuring pH of Strong Basic Solution on Au Electrode Modified with Ag3PO4 Shell@Ag Core Nanoparticles

Abstract Precise determination of pH values of strong basic solution is appealing and challenging. Herein, a voltammetric method for measuring pH of strong basic solution was developed using Ag 3 PO 4 shell@Ag core nanoparticles as a pH indicator. Ag nanoparticles (AgNPs) were electrodeposited on Au electrode surface and then were electrochemically oxidized to form Ag + . A layer of Ag 3 PO 4 was in‐situ formed on the surface of AgNPs by precipitation with PO 4 3− in solution. As an electroactive species, Ag 3 PO 4 can undertake an electrochemical redox reaction and its reduction peak potential is linear with pH values of solution in the range of 10–14. The slope of the linear equation is about −0.0196, which is consistent with that calculated by the Nernst equation. The resultant AgNPs/Ag 3 PO 4 modified electrode has been successfully applied in the determination of pH of strong basic solution. The proposed voltammetic method for measuring pH value overcomes the shortcoming of pH glass electrode under strong basic environments.