Tailoring the Ratio of A-Site Cations in Pr_1–<i>x</i>Nd<i>_x</i>BaCo_1.6Fe_0.4O_5+δ to Promote the Higher Oxygen Reduction Reaction Activity for Low-Temperature Solid Oxide Fuel Cells

Abstract

Solid oxide fuel cells (SOFCs) are promising sustainable energy systems due to their high energy conversion efficiency and low pollutant emission rate. However, the high operating temperature induces poor durability of the systems. Therefore, it is crucial to improve the oxygen reduction reaction (ORR) activity of the cathode material to lower the operating temperature. Recently, a double-layered perovskite material (AA′B2O5+δ), especially PrBaCo1.6Fe0.4O5+δ (PBCF), has received significant attention due to its high ORR activity. Herein, we report an A-site-tailored PBCF cathode material to enhance the ORR activity by employing a dopant that can increase oxygen vacancies in the structure. Since the oxygen vacancy is known as the charge carrier for the oxygen ion in oxide materials, increasing the oxygen vacancy concentration can improve the electrochemical performances of the cathode material at a lower operating temperature range (under 600 °C). Nd was employed as a dopant at the A-site due to its similarity in size to Pr and the lower valance state, which can increase the oxygen vacancy concentration in the structure. The cathode material with 20% Nd in the A-site of PBCF showed the highest I–V–P performance and lowest activation energy for the oxygen reduction reaction. As a result, our designed material showed a high peak power density of 1.34 W/cm2 at 600 °C, which is 109% higher than that of PBCF.