Achieving excellent and durable CO2 electrolysis performance on a dual-phase fuel electrode in solid oxide electrolysis cells

Abstract

Abstract Conversion of CO2 into valuable chemicals through solid oxide electrolysis cells (SOECs) is a promising technology towards efficient utilization of CO2 and reducing its emission. However, the well-established Ni-cermet fuel electrode is not applicable for high-concentration or pure CO2 electrolysis due to the Ni oxidation and coking issues. Here, we report that a novel nominal Pr0.2Ca0.8Fe0.8Ni0.2O3-δ perovskite fuel electrode, which is self-assembled into Pr(Ca)Fe(Ni)O3-δ perovskite and Ca2Fe2O5 brownmillerite dual-phase composite during the calcination process, possesses efficient CO2 electrolysis activity. The presence of Ca2Fe2O5 with abundant oxygen vacancies significantly improves CO2 chemical adsorption and activation and Pr(Ca)Fe(Ni)O3-δ serves charge carrier matrix, and consequently leads to a high CO2 reduction reaction rate constant of 1.104\xa0×\xa010−4\xa0cm−1\xa0at 800\xa0°C as determined by the electrical conductivity relaxation method. The electrochemical performance of pure CO2 electrolysis is investigated in model SOECs, exhibiting an excellent current density of 0.648 Acm−2 at 1.5\xa0V and 800\xa0°C. Moreover, the cell shows no noticeable degradation under two constant current densities of 0.421 Acm−2 at 800\xa0°C and 0.3 Acm−2 at 700\xa0°C for nearly a total of 300\xa0h. The present study reveals a novel strategy to develop dual-phase Pr(Ca)Fe(Ni)O3-δ-Ca2Fe2O5 materials as a reliable electrode for pure CO2 electrolysis.