Probing oxygen vacancy effect on oxygen reduction reaction of the NdBaCo2O5+δ cathode for solid oxide fuel cells

In this work, abundant oxygen vacancies are introduced into NdBaCo2O5+delta (NBCO) by partial substitution of cobalt to facilitate the electrochemical activity of ORR. The oxygen vacancy concentration of NdBaCo1.8Sc0.2O5+delta (NBCSc-2) is more than twice as that of NdBaCo2O5+delta. The increased oxygen surface exchange, bulk diffusion coefficients and adequate conductivity for NBCSc-2 can be responsible for the decrease of oxygen ion transfer activation energy. Consequently, the NBCSc-2 cathode shows a significantly reduced polarization impedance of 0.035 Omega cm(2) at 700 degrees C, which is only about 35% of NBCO. We also investigate the influence of the doping strategy on the stability of cathode. Thus, the enhanced ORR kinetics and high durability make NBCSc-2 as potential cathode material for solid oxide fuel cells.