Fe-Au-Ni/GDC enhanced performance under short-term Accelerated rSOC operation: Electrochemical and physicochemical investigation on the impact of Au

The presented study is a thorough investigation on the highly enhancing effect that is induced by the interaction of Fe-Au with Ni/GDC, in SOCs under accelerated reversible operation. There was also clarification of the Au impact on the Ni/GDC physicochemical properties in relation to the rSOC performance and determination of its optimum content. A series of electrocatalysts was prepared via the scalable deposition-co precipitation method and cells were compared by means of i-V and EIS measurements upon rSOC cycling at 900 °C in harsh pH 2 O/pH 2 = 9 mixture. Physicochemical characterization took place with BET, XRD, SEM, TEM, H 2 -TPR and “quasi” in-situ H 2 - or H 2 O-XPS. All Fe-Au-Ni/GDC electrodes exhibited remarkably enhanced and stable rSOC performance, compared to Ni/GDC, during short-term accelerated rSOC operation. Fe-Au addition decreased the R ohm and most importantly the R pol values, particularly for the SOE reaction, through enhancement of the corresponding Ni/GDC charge transfer processes in the intermediate frequencies region. Formation of Fe-Au-Ni solution improved the Ni/GDC MIEC properties and varied the amount of surface Ce 3+ . However, the Au wt.% content increase affected negatively the electrochemical and redox properties of the samples. The 0.5Fe-0.5Au-Ni/GDC fuel electrode exhibited the best rSOC activity, having the highest extent of Ce 3+ , while being less susceptible to H 2 O-oxidation. The results highlight directions for the development of highly performing and potentially stable modified Ni-based rSOC fuel electrodes with minimized Au content.