In-situ photoelectron microspectroscopy during the operation of a single-chamber SOFC

This paper reports the first in-situ synchrotron-based scanning photoelectron microscopy study of an operating YSZ-supported single-chamber SOFCwith Au–MnO2 composite cathode and NiO anode, fedwith 10−5 mbar 1:1 mixture of CH4 fuel and O2 at 650 °C.We employed a YSZ-supported cell with Au–MnO2 composite cathode and NiO anode. The chemical imaging and micro-XPS results were complemented with simultaneous electrochemical measurements, open circuit potential, potentiostatic and impedance spectrometry. The cell was operated under two conditions: (i) with fully oxidized electrodes and (ii) after in-situ reductive activation of the anode. The current delivered by the cell after in-situ reduction was about one order of magnitude higher. The chemical states of Ni and Mn were affected by the in-situ reduction process but they were not modified by the fuel-cell operation. Notwithstanding the absence of chemical state transformations of the electrode materials during the prolonged fuel-cell operation, cell aging brings about morphological change, accompanied by a decrease of the extracted current.