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 BaCo _0.4Fe _0.4Zr _0.1Y _0.1O _3-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(Co _0.4Fe _0.4Zr _0.1Y _0.1) _0.90Al _0.1O _3-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 cm ² 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).