Structure–Property Relationships in the Y2O3–ZrO2Phase Diagram: Influence of the Y-Content on Reactivity in C1 Gases, Surface Conduction, and Surface Chemistry

Abstract

The C1 chemistry of Y-doped ZrO2 samples (3, 8, 20, and 40 mol % Y2O3; 3-YSZ, 8-YSZ, 20-YSZ, and 40-YSZ) was comparatively studied with respect to the correlation of electrochemical properties and surface chemistry in CH4, CO, and CO2 atmospheres by electrochemical impedance (EIS) and spectroscopic (FT-IR) methods up to 1273 K to unravel the influence of the Y-doping level. A consistent picture with respect to qualitative and quantitative surface modifications as a function of temperature and gas-phase composition evolves by performing highly correlated operando/in situ measurements. A detailed study of carbon deposition in CH4 and CO and adsorption of CO and CO2, but also proof of the strong influence of the surface chemistry, is included. Carbon deposition during treatment in CH4 and CO at temperatures T ≥ 1023 K is a common feature on all materials, irrespective of the Y content. On the 40-YSZ sample, the thinnest, but at the same time fully percolated, carbon layer was generated, and hence, “metallic”...