Compositional effect on oxygen reduction reaction in Pr excess double perovskite Pr1+xBa1-xCo2O6-δ cathode materials

Abstract The kinetics of oxygen reduction reaction (ORR), being a prime requisite for electrode materials after the higher conductivity. Further, electrodes are observed to dissolute on reaction at triple phase boundary. However, the compositional effect on ORR is least understood. In order to inspect the ORR mechanism with substitution, a series of (1 + x) PrCoO3 − (1 − x) BaCoO3 (x = 0.2 to 1.0 with step of 0.2) compositions are prepared using conventional solid-state route method. The Rietveld refinement of X-ray diffractograms and specific heat curves confirms the formation of double phase comprising orthorhombic Pmmm phase corresponding to PrBaCo2O6-δ and Pnma phase corresponding to PrCoO3 for x = 0.2 to 0.8 with well connected and porous microstructure. The triple phase boundary reactions suggest the formation of Co(OH)3 along with H2 gas on reaction of these composite electrodes with H2O during electrochemical dissolution. However, chronoamperometric studies prove the suitability of x = 0.6 sample with higher ORR and liberation of H2 gas at room temperature.