Stability and spinodal decomposition of the solid-solution phase in the ruthenium–cerium–oxide electro-catalyst

Abstract

The phase diagram of Ru-Ce-O was calculated by a combination of ab initio density functional theory and thermodynamic calculations. The phase diagram indicates that the solubility between ruthenium oxide and cerium oxide is very low at temperatures below 1100 K. Solid solution phases, if existing under normal experimental conditions, are metastable and subject to a quasi-spinodal decomposition to form a mixture of a Ru-rich rutile oxide phase and a Ce-rich fluorite oxide phase. To study the spinodal decomposition of Ru-Ce-O, Ru0.6Ce0.4O2 samples were prepared at 280 °C and 450 °C. XRD and in situ TEM characterization provide proof of the quasi-spinodal decomposition of Ru0.6Ce0.4O2. The present study provides a fundamental reference for the phase design of the Ru-Ce-O electro-catalyst.

Decoupling the Impacts of Engineering Defects and Band Gap Alignment Mechanism on the Catalytic Performance of Holey 2D CeO2−x‐Based Heterojunctions

“…For Ru doping, the calculated RuO 2 -CeO 2 phase diagram is dominated by high-temperature spinodal decomposition; studies confirm substantial Ru solid solubility in the range 450 to 600 °C. [25,26] CeO 2−x nanosheets have been applied for different catalytic applications, including thermocatalysis (CO oxidation), [27] electrocatalysis (hydrogen evolution reaction, HER), [28] and photocatalysis (air purification). [29] Improvements in the catalytic performance have been achieved through doping and hetero junction formation, [30,31] which modify the electronic band structure, thereby addressing the shortcomings of wide band gaps and short recombination times.…”

“…For Ru doping, the calculated RuO 2 ‐CeO 2 phase diagram is dominated by high‐temperature spinodal decomposition; studies confirm substantial Ru solid solubility in the range 450 to 600 °C. [ 25,26 ]…”

Low- and high-temperature oxidation of Mn1.5Al1.5O4in relation to decomposition mechanism and microstructure

“…At 450 °C, the driving force for spinodal decomposition is released and Ru 0.6 Ce 0.4 O 2 decomposes into rutile-like Ru-rich and fluorite-like Ce-rich phases. 46 As for oxidative decomposition, the Mn 1.5 Al 1.5 O 4 spinel example having a composition close to the centerline of the This journal is © Royal Society of Chemistry 2016 miscibility gap shows that different types of nanostructured materials can be produced due to different decomposition mechanisms depending on the Mn 2+ oxidation temperature.…”

“…Let us consider nonoxidative decomposition of two mixed oxides having compositions close to the centerline of the miscibility gap. 45,46 Phase separation of Co 1.7 Fe 1.3 O 4 occurs at temperatures below 900 °C. Spinodal decomposition was confirmed at 600 °C by X-ray diffraction and transmission electron microscopy studies.…”