Distinguishing the contribution of electrochemistry and thermochemistry in the CO2/H2O co-electrolysis process of solid oxide cells

In this study, a high-sealing-performance electrolysis stack was designed to conduct comparative experiments with different gas compositions and quantitative analysis of tail gas. The aim was to investigate the quantitative contributions of electrochemical and thermochemical reactions during CO 2 /H 2 O co-electrolysis in a solid oxide electrolysis cell (SOEC) stack. The results show that, in the presence of hydrogen as a protective gas, the electrochemical contribution to CO 2 reduction becomes increasingly dominant with higher electrolysis current density, while the thermochemical contribution gradually decreases. Under these conditions, the electrochemical contribution exceeds 90%, while the thermochemical contribution dropping to below 10%. Under the condition of no reducing gas, H 2 O electrolysis dominates the co-electrolysis process, and the electron distribution ratio is approximately 55%–69% for H 2 O electrolysis and 31%–45% for CO 2 electrolysis.