In situ FTIR study of oxygen adsorption on nanostructured RuO2 thin-film electrode

In situ Fourier transform spectroscopy (FTIR) was used to study interactions of nanostructured ruthenium oxide (RuO₂) thin-film sensing electrode with O₂ at room temperature. RuO₂ nanostructures were pretreated at 1,000 °C for 1 h in order to obtain good crystallinity of amorphous RuO₂ nanoparticles. Morphology and properties of nanostructured RuO₂ were characterized by X-ray diffraction, thermo-gravimetric/differential thermal analysis, scanning electron microscopy, and FTIR. It was shown that pretreated RuO₂ is quite active for O₂ ⁻, O₂ ²⁻, and O²⁻ adsorption with clear 722 cm⁻¹ band for superoxide ions (O₂ ⁻) adsorption for the different oxygen concentrations. The results of in situ FTIR measurements revealed that the active sites for oxygen adsorption are not limited to the triple boundaries, but extended to surfaces of RuO₂ electrodes. Fundamental vibration frequencies of ruthenium–oxygen bond at a temperature of 23 °C as well as region above fundamental frequencies for the nanostructured RuO₂ were identified.