Bottom-Up Redox State Engineering of Ni/GDC Thin-Film Anodes for Carbon Tolerant Syngas-Fueled SOFCs

Abstract

Syngas-fueled solid oxide fuel cells (SOFCs) offer an efficient route for converting carbon-rich feedstock into electricity. However, it introduces critical challenges, such as carbon deposition on the anode, which significantly hinders performance and durability. This issue necessitates the use of precise cell fabrication engineering. In this study, we utilize a co-sputtered thin-film anode architecture as a bottom-up platform to systematically tune the initial surface ceria redox state through GDC content control and effectively mitigate carbon deposition. Electrochemical testing under syngas conditions reveals that an intermediate GDC composition window exhibits the best resistance to early/intermediate degradation. Microstructural analysis shows that GDC promotes the formation of a protective ceria overlayer, while excessive GDC causes Ni agglomeration and structural degradation. Density functional theory calculations of the reverse Boudouard reaction further reveal that partially reduced ceria provides the most favorable energetic landscape for carbon removal and stabilizes CO intermediates via charge transfer mechanisms. These results demonstrate that the carbon tolerance of the Ni–cerium oxide interface is strongly influenced by the ceria redox state, providing clear guidance for the rational design of coke-resistant SOFC anodes for carbon-containing fuels.