Chemically complex oxides have the ability to readily exchange oxygen with a surrounding gas atmosphere, especially at high temperatures and when driven by electrochemical polarization. As the transformation of an oxygen molecule in the gas phase to an oxide anion in the solid involves cleavage of bonds and multiple electron transfers, the mechanism of such an oxygen intercalation reaction tends to be complex. With spectroscopic techniques such as X-Ray absorption and photoemission spectroscopy (XAS and XPS) rapidly advancing from requiring UHV to functioning well in actual reaction conditions with respect to pressure and temperature, insights into the surface chemistry of a working electrode of a solid oxide electrochemical cell (SOC) are more readily available. Here we will discuss the oxygen exchange of the prototypical SOC material family (La,Sr)(Co,Fe,Ti)O3-δ of the perovskite structure, and how operando XAS and XPS can help understand how the cation chemistry impacts the electronic and ionic properties of the materials on an atomistic level. Even though these materials show single phase solid solution behavior in many aspects, some choices of transition metal cation composition show surprising emerging properties, such as electron trapping for example in the Co/Ti substituted perovskites, which in turn show a profound impact on transport properties.

High temperature oxygen intercalation studied by operando X-ray spectroscopy

2019 Fall National Meeting

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.