Performance and Stability of Solid Oxide Electrolysis Cell for CO₂ Reduction under Various Operating Conditions

抄録

In this study, effects of operating conditions on the electrochemical reduction of CO₂ on solid oxide electrolysis cell (SOEC) were systematically investigated. Experimental results revealed that the reducing gas can influence the behavior of Ni–YSZ cermet cathode. Supply of hydrogen as a reducing gas was found to be the most promising approach to obtain better cell performance for CO₂ reduction. Even a small amount of H₂ can facilitate the CO₂ reduction due to the kinetically fast reverse water gas shift reaction. High temperature operation is favorable from thermodynamic viewpoint because the Gibbs free energy significantly decreases at elevated temperature. The partial pressure of oxygen at the cathode side is another critical factor that found to be beneficial. A considerable increase in cell voltage was observed when Ni–YSZ | YSZ | LSM–YSZ cell operated under constant current densities of −0.75 and −0.90 A cm⁻² at 900°C, whereas the stable cell performance could be possible at −0.15 A cm⁻² for 7 h. The increase in cell voltage was attributed to the degradation of anode.