Nanostructured Mg-doped Mn–Cr spinel oxide cathodes for solid oxide fuel cells with optimized performance.

The cathode properties are critical for solid oxide fuel cells (SOFCs) performance and a major challenge for commercialization. This study employs the impregnation method to produce uniformly distributed Mg-doped manganese-chromium spinel oxide nanoparticles infiltrated into a network on the Gd 0.1 Ce 0.9 O 1.95 (GDC) skeleton as SOFC cathodes. The effects of Mg doping on the performance of these nanostructured spinel oxides are investigated. Both experimental results and density functional theory (DFT) calculations demonstrate that Mg doping can optimize the electronic structure of the manganese-chromium spinel oxide, increase the oxygen vacancy concentration, and significantly enhance the electrical conductivity and oxygen reduction reaction (ORR) catalytic activity. The Mg-doped manganese-chromium spinel oxide cathode exhibits superior performance, with an area-specific polarization resistance of 0.33 Ω cm2 and a maximum power density of 976 mW cm−2 at 800 °C. Moreover, the nanostructures of the cathode barely change after 100 h of cell operation. These findings provide a new strategy for optimizing the performance of SOFC spinel oxide cathodes. • Mg doping lowers bandgap and facilitates oxygen vacancy formation of Mn–Cr spinel. • Mg-doped Mn–Cr spinel cathode exhibits superior performance. • Nanostructures of Mg-doped Mn–Cr spinel remain stable after 100 h cell operation. [ABSTRACT FROM AUTHOR]