Designing highly active core/shell cathode materials for low-temperature PCFCs

Designing a cathode with exceptional oxygen reduction reaction (ORR) activity and durability at intermediate-to-low temperatures is vital to increase the improvement of solid oxide fuel cells (SOFCs), a captivating energy conversion technology with reduced environmental impact and high performance. Cathodes made of perovskite oxides have been developed extensively. Doping is a crucial method for modifying perovskites' lattice diffusion and surface exchange properties to achieve desired catalytic performances in a wide range of redox reactions, including oxygen reduction reactions (ORRs) for ceramic fuel cells (CFCs). The reported BaCo0.4Fe0.4Zr0.1Y0.1O3-δ (BCFZY) is a potential cathode in CFCs. Here, we systematically explore the partial doping of B-sites with Al of varied content (from 5% to 30%) to further enhance the performance of BCFZY at lower temperatures. The polarization impedance of proton ion conducting fuel cells is lowest in Ba(Co0.4Fe0.4Zr0.1Y0.1)0.90Al0.1O3-δ (BCFZYA). The oxygen mobility, surface exchange kinetics, and bulk oxygen ion conductivity are all enhanced by 10%Al doping, as determined by EIS and performance tests. Moreover, Al doping led to the formation of the core-shell structure during the rearrangement of atoms. This results in an oxygen reduction reaction (ORR) of up to 0.157 cm2 at 520 oC on proton ion conducting electrolytes. As a result, BCFZYA appears to be a strong candidate for use in the cathode of advanced PCFCs (proton ceramic fuel cells). [Display omitted] •The BCFZYA cathode was prepared via the sol-gel method.•The BCFZYA has demonstrated higher fuel cell performance of 695 mW/cm2 at 520 oC.•The Al doping into BCFZY reveals better ORR activity of up to 0.157 cm2 at 520 oC on proton ion conducting electrolytes.•Core-shell structure and energy band alignment phenomena have been proposed.•The designed cathode has revealed a lower ASR value at 520 °C.