A long-term stable iridium oxide pH electrode

In this work, a long-term stable pH electrode based on iridium oxide film is reported. A new method, i.e., a ‘carbonate melt oxidation’ method, has been developed to fabricate iridium oxide pH electrode. In this method, a uniform iridium oxide film is coated on the surface of an iridium metal wire through oxidation of the wire in a carbonate melt. The electrode made this way shows a “drift-free” behavior in pH buffer solutions. Calibration curves for the same electrode implied that the electrode is very stable over a long period of 2.5 years. Therefore, the present electrode is very suitable for continuous pH measurement without the need of frequent calibration.