In-situ surface monitoring of charge transfer during oxidation of zirconia at elevated temperatures

This work considers the reactivity at the gas/solid interface for energy conversion systems based on ZrO2, such as solid oxide fuel cells, SOFCs, and the related charge transfer. We consider the effect of a quasi-isolated surface structure, QISS, on the reactivity of yttria-stabilized zirconia, YSZ, with oxygen at elevated temperatures. The charge transfer associated with oxidation of both YSZ and Nb-doped YSZ in the range 973 K - 1173 K was determined by in situ surface monitoring using work function, WF, measurements. We show that the reactivity at the O2/YSZ interface can be enhanced by incorporation of pentavalent cations, such as Nb5+ ions, into the QISS that exhibits the functions of both fast ionic oxygen conductor and metallic electrode. It has been documented that surface doping of YSZ with niobium results in removal of oxygen chemisorption-related surface potential barrier that prevents oxygen incorporation into the lattice of YSZ. This finding paves the way for the development of novel materials for energy conversion devices, such as SOFCs, with enhanced performance through surface processing.