K-doping induced high-entropy engineering in perovskite cathode for high-performance CO2 electrolysis in solid oxide electrolysis cells

Solid oxide electrolysis cell (SOEC) has emerged as a highly efficient technology for electrochemical CO 2 reduction, offering promising pathways for sustainable carbon capture and utilization. The development of advanced electrocatalysts with enhanced CO 2 adsorption and reduction activity is essential for improving the performance of SOECs. This study explores a series of K-doped and A-site entropy regulated perovskite oxides with a nominal composition of La 0.2 Pr 0.2 K x Sr 0.2 Ca 0.2 Fe 0.8 Ni 0.2 O 3−δ ( x = 0.2, 0.4 and 1.0) as cathode catalyst in SOEC for CO 2 reduction. The results confirm that the cell with La 0.2 Pr 0.2 K 0.2 Sr 0.2 Ca 0.2 Fe 0.8 Ni 0.2 O 3−δ (K2) cathode achieves a current density of 1.1 ‍A·cm −2 at 1.5 V and 850 °C for pure CO 2 electrolysis, exhibiting excellent durability for nearly 200 h under 1 ‍A·cm −2 at 1.5 V. The appropriate introduction of K, characterized by its high basicity and low valence, facilitates the formation of oxygen vacancies and adjusts the electronic properties of the active sites, thereby improving CO 2 adsorption, splitting, and CO evolution of the cathode. This work highlights an effective K-doping strategy to optimize the electrocatalytic properties of high-entropy perovskite oxides, providing valuable insights to design advanced cathode materials for CO 2 electrolysis. • K-doped La 0.2 Pr 0.2 K x Sr 0.2 Ca 0.2 Fe 0.8 Ni 0.2 O 3-δ is synthesized for CO 2 reduction. • K2 achieves remarkable current density of 1.1 A cm −2 at 1.5 V and 850 °C in CO 2 . • Long-term stability tests confirm >200 h of operation at 1 A cm −2 . • K-doping enhances oxygen vacancy formation, CO 2 adsorption and CO desorption.