The nature of phase separation in Ir-Sn-O ternary oxide electrocatalyst

Phase diagram of iridium-tin oxide (Ir-Sn-O) was calculated by a combination of ab initio density functional theory (DFT) and thermodynamic calculations. Results suggested that the phase separation that had been reported in literature for Ir-Sn-O was through a typical spinodal decomposition mechanism. Ir0.534Sn0.466O2 was prepared by a thermal co-decomposition method at 320 and 450 °C. Quantitative phase analyze based on DFT, X-ray diffraction and high-resolution transmission electron microscopy confirmed the spinodal nature of the phase separation. The present fundamental study is an important reference for phase and microstructure design of Ir-Sn-O for various electrocatalysis applications. The DFT-assisted quantitative phase analysis has provided peer researchers with a novel reliable phase analysis approach for complex compounds.