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.