A novel pH potentiometric sensor based on electrochemically synthesized polybisphenol A films at an ITO electrode

A polymer-based pH electrode has been successfully fabricated via a simple electropolymerization of bisphenol A (BPA) on an indium tin oxide (ITO) electrode using repetitive voltammetric sweeping. A combination of voltammetry, electrochemical impedance spectroscopy and X-ray photoelectron spectroscopy revealed that polybisphenol A (PBPA) films with benzoquinonyl and hydroquinonyl groups not only showed basically reversible redox activities, but also exhibited the mixed ionic–electronic conductivity. The redox peak potential and open circuit potential using the PBPA/ITO electrode as a pH sensor presented response slopes of −58.6 ± 1.4 mV/pH and −56.7 ± 1.6 mV/pH, respectively. The potentiometric signals were stable in electrolyte solutions and displayed a wide response range for the detection of pH. Compared with the commercial glass pH electrode, the PBPA-based electrode showed several advantages including easy fabrication, low cost, high stability and selectivity.