A strategy to enhance the catalytic activity at the surface of an oxide thin film is unveiled through epitaxial orientation control of the surface oxygen vacancy concentration. By tuning the direction of the oxygen vacancy channels (OVCs) in the brownmillerite SrCoO2.5 , a 100-fold improvement in the oxygen reduction kinetics is realized in an epitaxial thin film that has the OVCs open to the surface.
Keywords: brownmillerite; oxygen reduction reaction; pulsed laser epitaxy; solid oxide fuel cells; strontium cobaltite.
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