CO2 concentration effects on CO2/H2O co-electrolysis in a solid oxide electrolysis button cell

Abstract

Abstract: The influence of CO<inf>2</inf> gas concentration on the co-electrolysis performance of an electrolyte-supported button cell (NiO-YSZ/NiO-SDC/ScSZ/LSCF-GDC/LSCF) was investigated. At 800 oC/1.5V, the interfacial polarization resistance (R<inf>p</inf>) values for 10%CO<inf>2</inf>/15%H<inf>2</inf>O and 30%CO<inf>2</inf>/15%H<inf>2</inf>O are 7.19 and 26.91 ?.cm2, respectively. CO<inf>2</inf> gas concentration significantly affects the R<inf>p</inf> value. Gas diffusion resistance is dominant in the overall polarization resistance. As the CO<inf>2</inf> concentration increases (10%?30%), H<inf>2</inf> consumption increases, indicating RWGS dominance. For 30% CO<inf>2</inf>/15% H<inf>2</inf>O, CO<inf>2</inf> out is slightly more than the input value due to the WGS and Boudouard reactions. As the applied voltage value increases from OCV, the H<inf>2</inf> residue increases. H<inf>2</inf>O and CO<inf>2</inf> co-electrolysis occurs at 1.5 V. The post-test XRD and Raman spectra results show NiO reduction and metallic Ni appearance. The post-test FE-SEM micrographs show no delamination at the air electrode/electrolyte interface, and carbon deposition is observed in the composite fuel electrode layer. © The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature 2025.