Designing highly active and CO2 tolerant heterostructure electrode materials by a facile A-site deficiency strategy in Pr1-xBaCo2O5+δ double perovskite

Abstract

Solid oxide fuel cells (SOFCs) have received continuous attention as an energy conversion device, and the development of highly electrochemically active materials is important. In this work, highly active and CO2 tolerant BaBixCo1-xO3@PrBaCo2O5+δ heterostructure electrode materials were fabricated by a facile A-site deficiency in Pr1-xBaCo2O5+δ double perovskite. A-site excess-deficient Pr0.8BaCo2O5+δ (PBC80) double-perovskite oxide were prepared and designed to induce the self-assembly dissolution to form BaCoO3-δ (BCO) heterostructure through cationic high-concentration deficiency. However, the surface-dissolved alkaline earth metal (Ba2+) readily forms carbonates with CO2, which severely limits the cathode catalytic activity and long-term stability. Thus, bismuth ion-modified PBC80 (BBCO@PBCO) was prepared to further tailor the material properties, which provides more active sites for oxygen reduction reaction (ORR) by strengthening the synergistic interaction between the heterogeneous interfaces. More importantly, BBCO@PBCO exhibits the most stable Area specific resistance (ASR) under CO2 atmosphere, indicating the incorporation of acidic Bi ions effectively mitigated the adsorption and reaction between the material and the acidic gas CO2. These results indicate that the heterostructure induced by A-site deficiency promotes the ORR activity of PrBaCo2O5+δ cathode, while further modification of Bi ions enhances both the electrochemical activity and the stability of the materials, delivering superior resistance to CO2 poisoning.