The nature of phase separation in a Ru–Sn–O ternary oxide electrocatalyst

Abstract

A phase stability diagram of ruthenium–zirconium oxide (Ru–Sn–O) was constructed by a combination of ab initio density functional theory and thermodynamic calculations. Results suggest that the phase separation/segregation that has been reported in the literature for the RuO2–SnO2 system is through a typical spinodal decomposition mechanism. Ru0.45Sn0.55O2 films were prepared by thermal co-decomposition of precursors at 500 °C for varied duration. Quantitative phase analyses of the prepared films based on X-ray diffraction and high-resolution transmission electron microscopy confirmed the spinodal nature of the phase separation. The present fundamental study provides a theoretical guideline for the phase and microstructure design of Ru–Sn–O based mixed oxides for electrocatalysis applications.