Enhancing the Catalytic Activity and Coking Tolerance of the Perovskite Anode for Solid Oxide Fuel Cells through In Situ Exsolution of Co-Fe Nanoparticles

Abstract

The in situ exsolved nanoparticles from the perovskite matrix have achieved increasing attention and wide applications in solid oxide fuel cells (SOFCs) due to their excellent stability and high catalytic activity. Herein, an A-site-deficient (Ba0.9La0.1)0.95Co0.7Fe0.2Nb0.1O3 – δ (BL95CFN) perovskite oxide with in situ exsolved Co-Fe nanoparticles is developed and investigated as an anode for SOFCs. Compared with stoichiometric BLCFN, a tiny A-site deficiency (5%) promoted the exsolution of cobalt and iron from the perovskite matrix of BL95CFN. This hybrid anode catalyst showed excellent electrochemical performance. The polarization resistance is 0.11 Ω cm2 for the BL95CFN anode at 750 °C, about 42% lower than that of the BLCFN anode. The maximum peak density (MPD) reaches 513.2 mW cm–2 at 750 °C for an electrolyte-supported single cell with the BL95CFN anode. The high electrochemical performance could be attributed to the accelerated hydrogen surface exchange process provided by exsolved Co-Fe nanoparticles and oxygen ion transport in the A-site-deficient perovskite matrix. High-resolution transmission electron microscope (HRTEM) reveals that exsolved Co-Fe nanoparticles are embedded in the oxide matrix, forming a firm anchoring structure, which ensures excellent anode coking tolerance. At the current density of 200 mA cm–2, the output voltage of the single cell remained stable within 200 h in methane fuel. Overall, the high catalytic activity and coking tolerance of the hybrid electrocatalyst manifest a bright prospect of application in SOFCs and electrolytic cells.