A simplified methodology: pH sensing using an in situ fabricated Ir electrode under neutral conditions

Herein, a simplified fabrication method for the producing of a pH-sensitive iridium electrode is developed. The in situ electrochemical fabrication of an iridium oxide film is optimized and shown to be achievable under neutral conditions rather than the acidic conditions hitherto employed. The formation of a pH sensitive Ir(III/IV) hydrous film is confirmed via XPS. The amperometric pH-sensing properties of this electrochemically generated material were investigated using square wave voltammetry. In the pH range 2-13, the iridium oxide redox signal has a pH dependency of 86.1 +/- 1.1 mV per pH unit for midpoint potentials with uncertainties being +/- 0.01-0.05 pH. Finally, the newly developed pH sensor was used to measure the pH of a natural water sample with excellent results as compared to a conventional glass pH probe.

Automated summary

This study developed a simplified method for producing a pH-sensitive iridium electrode and optimized the in situ electrochemical fabrication of an iridium oxide film under neutral conditions. The formation of a pH-sensitive Ir(III/IV) hydrous film was confirmed via XPS, and the electrochemically generated material showed good amperometric pH-sensing properties in the pH range 2-13. The newly developed pH sensor demonstrated excellent performance in measuring the pH of natural water samples compared to a conventional glass pH probe.