Cobalt-free perovskite Ba1-xNdxFeO3-δ air electrode materials for reversible solid oxide cells

We report on Ba1-xNdxFeO3-delta, a cobalt-free perovskite material, with a view to its use as a next-generation air electrode material in reversible solid oxide cells (RSOCs). BaFeO3-delta (BFO) has long been considered a potential candidate cathode material due to its high oxygen vacancy concentration and electrical conductivity; however, it is difficult to synthesize in a single phase. To overcome this problem, Nd3+ is doped into Ba-sites to reduce impurity phases and create a single perovskite phase. In-situ high temperature and room temperature X-ray diffraction analyses are carried out to investigate Nd3+-doped BFO. We find that Ba0.97Nd0.03FeO3-delta shows the highest electronic conductivity and lowest TEC value among the various doping concentrations tested, making this material most suitable for application in RSOCs. In addition, the polarization resistance of Ba0.97Nd0.03FeO3-delta has the lowest value in yttria-stabilized zirconia symmetric cells. To determine the reasons for the high catalytic activity of Ba0.97Nd0.03FeO3-delta, X-ray photoelectron spectroscopy and iodometric titration are carried out, the results demonstrate that the lower doping concentration of Nd3+ results in an advantage in terms of the number of additional oxygen vacancies created. Moreover, electrical conductivity relaxation measurements show that the Ba0.97Nd0.03FeO3-delta has a fast bulk diffusion coefficient and fast surface exchange coefficient. Hence, the solid oxide fuel cell and electrolysis mode performances when using Ba0.97Nd0.03FeO3-delta are excellent and a high power output of 1.2 W cm(-2) at 800 degrees C can be achieved.

Automated summary

The study focuses on Ba1-xNdxFeO3-delta as a potential air electrode material for reversible solid oxide cells. Doping Nd3+ into Ba-sites enhances electronic conductivity and reduces impurity phases, resulting in a material suitable for application in RSOCs. The lower doping concentration of Nd3+ leads to higher catalytic activity due to the creation of additional oxygen vacancies.