A symmetrical solid oxide electrolysis cell supported by nanostructured electrodes for highly efficient CO2 electrolysis

High-temperature carbon dioxide (CO2) electrolysis in solid oxide electrolysis cells (SOECs) is a promising strategy for the electrochemical conversion of CO2 into valuable chemical fuels powered by renewable energy. However, nowadays SOECs are still dominated by the state-of-the-art nickel-yttria stabilized zirconia (Ni-YSZ) cathode which suffers from oxidation at high CO2 concentration and coking at high carbon monoxide (CO) concentration. Herein, a novel symmetrical cell supported by La0.75Sr0.25Cr0.5Fe0.5O3-δ (LSCrF)-YSZ ceramic electrodes is developed for pure CO2 electrolysis. The electrode has a hierarchical pore structure modified with Gd0.2Ce0.8O1.9 (GDC) nano-catalysts on the inner surface of the scaffold. The cell delivers an ultra-high electrochemical performance for pure CO2 electrolysis, e.g., the current density is 1.44 A cm−2 at 1.5 V and 800 °C. The distribution of relaxation time (DRT) analysis reveals that the vertically-aligned pores facilitate the infiltration of GDC nano-catalysts and the fast gas transport, while the skin layer adjacent to the electrolyte modified with highly continuous GDC nano-catalysts provides abundant active sites. Particularly, the cell also demonstrates excellent electrolysis performance in CO2-lean atmosphere and impressive durability in CO-rich atmosphere. This work presents a highly promising unique architecture of SOECs for CO2 electrolysis.