Abstract
Strontium iron oxyhalide perovskitic oxides were investigated by electrochemical characterization as bi-functional electrocatalysts for oxygen evolution (OE) and oxygen reduction (OR) reactions in alkaline media. The electrochemical investigations showed that the presence of lower levels of oxygen and higher levels of chloride, as in Sr4Fe3O8Cl2 and Sr2FeO2Cl2 significantly enhanced the oxygen evolution and reduction over the other perovskitic oxides. Additionally, Sr4Fe3O8Cl2 and Sr2FeO2Cl2 was proven to have high bi-functional activity due to an overpotential gap (Delta E = 0.70 V) between the OER and ORR much lower than that of other similar perovskite bi-functional catalysts. In comparison with other strontium iron oxyhalide based electrocatalysts, Sr2FeO2Cl2 was shown to have higher OER activities among all investigated catalysts. This work demonstrates that the oxygen-deficient layered perovskites of the type A(2)BO(2)X(2) are a new class of high-performance electrocatalysts for oxygen evolution (OE) and oxygen reduction (OR) reactions in alkaline media. (C) 2016 The Electrochemical Society. All rights reserved.