  The oxygen evolution reaction (OER) is considered a key reaction for
electrochemical energy conversion but slow kinetics hamper application in
electrolyzers, metal-air batteries and other applications that rely on
sustainable protons from water oxidation. In this review, the prospect of
epitaxial perovskite oxides for the OER at room temperature in alkaline media
is reviewed with respect to fundamental insight into systematic trends of the
activity. First, we thoroughly define the perovskite structure and its
parameter space. Then, the synthesis methods used to make electrocatalytic
epitaxial perovskite oxide are surveyed, and we classify the different kinds of
electrodes that can be assembled for electrocatalytic investigations. We
discuss the semiconductor physics of epitaxial perovskite electrodes and their
consequences for the interpretation of catalytic results. Prototypical
mechanisms of the OER are introduced and comparatively discussed. OER
investigations on epitaxial perovskite oxides are comprehensively surveyed and
selected trends are graphically highlighted. The review concludes with a short
perspective on opportunities for future electrocatalytic research on epitaxial
perovskite oxide systems.
