![]() ![]() PEM water electrolysis offers many advantages, such as high current densities, ultrahigh gas purities, low ohmic losses and good compactness 24. ![]() For instance, proton exchange membrane (PEM) water electrolysis is an attractive and advanced route for sustainable hydrogen production 24, especially when coupled with some renewable energy systems. Despite the difficulties, there are strong demands for the OER in acidic pH regime. Whereas a large number of oxygen evolution electrocatalysts based on a wide range of transition metals work well under alkaline conditions 6, 7, 8, 9, 10, 11, 12, 13, only the few of the recently developed electrocatalysts are found to be effective for OER in acidic media 14, 15, 16, 17, 18, 19, 20, 21, 22, 23. Therefore, over the past several years, considerable effort has been devoted to the search and synthesis of efficient electrocatalysts that can significantly lower the kinetic barriers for OER. Due to its multi-proton/electron-coupled kinetics, the OER is a quite sluggish half-reaction, and often has a crucial role in the overall efficiency of these electrochemical processes 1, 4, 5. The oxygen evolution reaction (OER) is the primary reaction that occurs at the anode in many electrochemical energy conversion processes, such as water splitting, CO 2 reduction, N 2 fixation, etc 1, 2, 3. Theoretical calculations indicate that the existence of face-sharing octahedral dimers is mainly responsible for the superior activity of 6H-SrIrO 3 thanks to the weakened surface Ir-O binding that facilitates the potential-determining step involved in the OER (i.e., O* + H 2O → HOO* + H + + e ¯). 6H-SrIrO 3 is the most active catalytic material for OER among the iridium-based oxides reported recently, based on its highest iridium mass activity. 6H-SrIrO 3 contains 27.1 wt% less iridium than IrO 2, but its iridium mass activity is about 7 times higher than IrO 2, a benchmark electrocatalyst for the acidic OER. Here we present the identification of 6H-phase SrIrO 3 perovskite (6H-SrIrO 3) as a highly active electrocatalyst with good structural and catalytic stability for OER in acid. The widespread use of proton exchange membrane water electrolysis requires the development of more efficient electrocatalysts containing reduced amounts of expensive iridium for the oxygen evolution reaction (OER). ![]()
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