Performance of surface renewable pH electrodes based on RuO2–graphite–epoxy composites

Abstract

In this work, surface renewable pH electrodes comprising RuO₂–graphite–epoxy composites were developed. Three electrode types with different composite ratios were fabricated and their performance was investigated in detail by the potentiometric method. The experimental results show that the RuO₂ based pH sensors exhibit sub-Nernstian responses of 40–50 mV pH⁻¹ in the pH range 2–12 and the one with the highest amount of RuO₂ shows the best performance. It is found that the properties of electrodes would change as they are aged in pH 7 buffer, and 10 days seem to be enough to get a stable result. The pH sensing mechanism is discussed on the basis of electrochemical impedance measurements. Finally, renewability of the pH electrodes is discussed and it is found that the electrodes exhibit stable pH sensitivity.