Development of low-cost metal oxide pH electrodes based on the polymeric precursor method.

In this work, the polymeric precursor method was used to prepare low-cost solid-state sensors for pH determination based on iridium oxide as the main pH sensitive material. The iridium content was reduced with addition of TiO(2), forming the binary system IrO(x)-TiO(2), whose electroanalytical properties were evaluated in comparison with a commercial glass pH electrode. The minimum iridium content which gave suitable results was 30mol%, and the electrode presented Nernstian and fast response in the pH range from 1 to 13, with no hysteresis effect observed. Besides, the electrode showed high selectivity in the presence of alkali ions as Li(+), Na(+) or K(+). The amount of iridium in the prepared electrodes was very small (<0.1mg), supporting the efficiency of this method on the simple preparation of functional low-cost pH electrodes.