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.
Keywords: defect-order; electrical conductivity; iron; oxygen-evolution reaction (OER); perovskite phases.
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