In situ construction of a double perovskite heterostructure with exsolved FeNi3 alloy nanoparticles for CO2 electrolysis in solid oxide electrolysis cells

Abstract

Solid oxide electrolysis cells (SOECs) have attracted widespread attention because of their high Faraday efficiency and controllability. However, the development and commercial viability of CO₂ electrolysis using SOECs are hindered by the inferior electrochemical activity and durability of cathode materials. In this study, we successfully achieved the in situ construction of a double perovskite with exsolved FeNi₃ alloy nanoparticles by reducing (PrBa)_0.95Fe_1.6Ni_0.4O_6−δ (PB95FN) at 800 °C for 2 h. The electrolysis cell with a reduced PB95FN (R-PB95FN) cathode demonstrated a high current density of 1.093 A cm⁻² for CO₂ electrolysis at an applied voltage of 1.5 V at 800 °C. The excellent electrochemical performance of the R-PB95FN cathode can be attributed to the in situ exsolved FeNi₃ alloy nanoparticles and oxygen vacancies generated within the perovskite substrate, which can provide plentiful active sites for CO₂ adsorption and electrolysis. Meanwhile, the SOEC with the R-PB95FN cathode demonstrated excellent long-term stability during 100 hours of continuous operation at an applied voltage of 1.5 V at 800 °C owing to the structural anchoring of the alloy nanoparticles in the perovskite substrate. Therefore, FeNi₃ alloying regulates the electronic structure of Ni and prevents the formation of carbon deposits on the cathode surface. This work provides a strategy to develop an efficient and durable cathode for CO₂ electrolysis and other heterogeneous catalytic reactions.