Impacts of A-site gadolinium doping on electrocatalytic performance of La0.33Ba0.62Gd0.05Co0.7Fe0.3O3-δ to realize promising cathode for intermediate-temperature solid oxide fuel cells

Abstract

With respect to intermediate-temperature solid oxide fuel cells (IT-SOFCs), electrocatalytic activity of the cathodes dominates their output power. Herein A-site gadolinium-doped La0.33Ba0.62Gd0.05Co0.7Fe0.3O3-δ (LBG0.05CF) perovskite is synthesized and systematically evaluated as the cathode for IT-SOFCs. We demonstrate outstanding catalytic activity of LBG0.05CF toward oxygen reduction reaction (ORR). Benefiting from enhanced electrical conductivity, oxygen surface exchange and diffusion rates, the ORR activity of LBG0.05CF outperforms that of La0.33Ba0.67Co0.7Fe0.3O3-δ (LBCF), as evidenced by the lower polarization resistance (0.035 Ω cm2) at 700 °C. The Ce0.9Gd0.1O1.95 (CGO) electrolyte-supported fuel cell with the LBG0.05CF cathode delivers a peak power density (PPD) of 371 mW cm−2 at 700 °C, which surpasses the PPD (278 mW cm−2) for LBCF-based cell. Furthermore, LBG0.05CF exhibits an improved CO2 tolerance compared with pristine LBCF. These results highlight a promising strategy of A-site replacement of Ba by lanthanide for optimizing catalytic ORR activity of the perovskite materials.