Efficient carbon dioxide electrolysis in a symmetric solid oxide electrolyzer based on nanocatalyst-loaded chromate electrodes

•LSCM cathode with loaded iron catalyst shows promising electrode polarization.•LSCM anode with loaded iron oxide also shows promising electrode polarization.•Mixed conductivities of LSCM electrode in pulsed redox atmospheres are reported.•Efficient CO2 electrolysis using LSCM-Fe cathode and LSCM-Fe2O3 anode is verified.

Composite cathode based on redox-stable La0.75Sr0.25Cr0.5Mn0.5O3−δ (LSCM) can be handled to perform for direct CO2 electrolysis without a flow of reducing gas over the electrode; however, the insufficient electrocatalytic activity of the ceramic composite cathode still limits the electrode performances and current efficiencies. In this case, catalytic-active iron nanocatalyst and iron oxide catalyst were loaded into the LSCM-based composite cathode and anode, respectively, to improve the electrode performances. Then efficient direct CO2 electrolysis was demonstrated by using the symmetric solid oxide electrolyzer based on LSCM loaded with 2 wt% Fe2O3 at 800 °C. The dependences of conductivity of LSCM were studied on temperature and oxygen partial pressure and further correlated to the electrode performance. The loading of nanocatalyst considerably improves the electrode performance and the current efficiency of CO2 electrolysis was accordingly enhanced by approximately 75% for the impregnated LSCM-based electrode at 800 °C. The synergistic effect of catalyst-active iron nanoparticles and redox-stable LSCM perovskite ceramic leads to the excellent stability and better cathode performance for the direct CO2 electrolysis at high temperatures.