In situ FTIR investigation of adsorption properties of sub-micron Cu2O-doped RuO2 sensing electrode of planar potentiometric pH sensor

In situ Fourier transform infrared spectroscopy (FTIR) was used to study adsorption properties of 20?mol% Cu₂O-doped RuO₂ sensing electrode (SE) screen-printed on the platinised alumina substrate of the planar electrochemical pH sensor and subsequently sintered at 800?°C. Morphology and properties of developed SEs were characterized by X-ray diffraction, scanning electron microscopy, atomic force microscopy and FTIR techniques. It was shown that both Cu₂O doping and changes in the sintering condition of the SE affected morphology and adsorption spectra of 20?mol% Cu₂O-doped RuO₂. Fundamental vibration frequencies of ruthenium?Coxygen bond at a temperature of 23?°C as well as region above fundamental frequencies for the sub-micron 20?mol% Cu₂O-doped RuO₂-SE were identified.