Remarkable Oxygen-Evolution Activity of a Perovskite Oxide from the Ca2-x Srx Fe2 O6-δ Series.

Herein in we report the unprecedented catalytic activity of an iron-based oxygen-deficient perovskite for the oxygen-evolution reaction (OER). The systematic trends in OER activity as a function of composition, defect-order, and electrical conductivity have been demonstrated, leading to a methodical increase in OER catalytic activity: Ca2 Fe2 O6-δ <CaSrFe2 O6-δ <Sr2 Fe2 O6-δ . Sr2 Fe2 O6-δ also has the highest electrical conductivity and a unique type of defect-order. In conventional experiments using glassy carbon electrode, Sr2 Fe2 O6-δ shows better OER activity than the current state of the art catalysts, Ba0.5 Sr0.5 Co0.8 Fe0.2 O3-δ and RuO2 . It also offers a high intrinsic electrical conductivity, which allows it to act as a catalyst without the need for glassy carbon electrode or carbon powder. Pure disks of this material exhibit an outstanding activity for OER, without any additives or need for electrode preparation.