Evaluation of iridium oxide electrodes formed by potential cycling as pH probes

Abstract

Iridium oxide electrodes formed by potential cycling in dilute acids were investigated for their use as pH sensors. It was shown that both the short- and long-term stabilities of such sensors were adequate for applications where an accuracy of ±0.2 pH is acceptable. It was also found that thicker oxide films which give responses of up to about 80 mV pH–1 are to be preferred in order to ensure reproducible behaviour. As potentiometric probes either for direct monitoring of pH or for following typical acid-base titrations, these electrodes give comparable results to those obtained with glass electrodes. Several basic concepts relating to the practical management of potential-cycled iridium oxide electrodes are discussed.