Manipulation of rare earth on voltage-driven in-situ exsolution process of perovskite cathodes for low-temperature solid oxide fuel cells

The sluggish oxygen reduction reaction (ORR) of cathode materials below 600 degrees C is one of the greatest obstacles to realizing the operation of low-temperature solid oxide fuel cells (LT-SOFCs). In this study, the ORR activity of rare earth-doped Ln(0.2)Ba(0.8)Co(0.7)Fe(0.3)O(3) d (Ln = La, Pr, Nd) cathodes below 600 degrees C is significantly enhanced through the exsolution of highly active nanoparticles driven by applying a negative voltage of 2 V for 150 s. Pr0.2Ba0.8Co0.7Fe0.3O3-delta (PBCF) cathode exhibits an area-specific resistance of similar to 0.119 Omega cm(2) at 550 degrees C, approximately 1/3 of that for the pristine cathode (similar to 0.389 Omega cm(2)). Such improvement is ascribed to the the modification of its surface with high-density and small-size nanoparticles (CoO). Furthermore, the voltage-driven exsolution process can be manipulated by the surface oxygen vacancy concentration induced by rare earth doping. Compared with La- and Nd-doped cathodes, PBCF cathode has higher surface oxygen vacancy concentration, promoting the exsolution of Co in the bulk and resulting in the formation of higher density and smaller size nanoparticles. These enable the PBCF cathode to show the most significant improvement after treatment. This finding may provide a new strategy for the design of high-performance catalysts for LT-SOFCs.

Automated summary

The ORR activity of rare earth-doped cathodes below 600 degrees C is enhanced by exsoluting highly active nanoparticles through voltage-driven process. The PBCF cathode exhibits the most significant improvement due to the higher surface oxygen vacancy concentration induced by rare earth doping, resulting in the formation of higher density and smaller size nanoparticles. This finding may provide a new strategy for designing high-performance catalysts for LT-SOFCs.