Composition dependent synergistic effects on oxygen evolution reaction catalysis for CaFe11xMnxO3

We investigate oxygen evolution reaction (OER) catalytic activity for CaFe11xMnxO3. The OER activity o CaFe11xMnxO3 decreases almost monotonically with increasing Mn content x. No any compositions do no exceeded CaFeO3 in OER activity, but we observe that the OER activity is gently decreased except for Fe-ric side (x = 0.1) in comparison with the weighted average OER activity between the endmembers of highly activ CaFeO3 (x = 0) and less active CaMnO3 (x = 1). We discuss probable electronic effects of the Fe4+–Mn4+ coupl on OER activity based on the density functional theory calculation using the special quasirandom structur models. The local electronic states of Mn ions were deactivated by Fe substitution on the Fe-rich side (x = 0.25) whereas the Fe ions are constantly activated by Mn substitution in the entire composition range. This findin proposes that local electronic states are variously changed by the kind of couples of multiple elements, whic may contribute to the design of mixed transition metal oxides for OER catalysts. ©2024 The Ceramic Society of Japan.