Improved oxygen reduction reaction activity by in-situ synthesizing Sr3Fe1.8Nb0.2O7-δ coating on SrFe0.9Nb0.1O3-δ cathode via the microwave water bath heating method

The sluggish oxygen reduction kinetics remains to be the main obstacle to the development of low temperature proton ceramic fuel cells which limits its commercial application. This phenomenon has driven the exploration of the oxide electrode materials which both possess high oxygen reduction reaction activity and heterogeneous structure. In this work, mixed ionic and electronic conductor SrFe 0.9 Nb 0.1 O 3-δ (SFN113) is partially transformed into the triple-phase conductor Sr 3 Fe 1.8 Nb 0.2 O 7-δ (SFN327) by in-situ reaction with uniformly coated SrO layer using a microwave water bath heating method. The introduction of the second phase SFN327 significantly improves the oxygen surface exchange kinetics of SFN113 investigated by the electrical conductivity relaxation method. The present work not only remarkably improves the electrocatalytic reduction activity of SFN113 by the introduction of the second phase SFN327 and the construction of the heterogeneous interface, but also provides a valuable route for the further optimization of the exiting electrode materials.