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2020
ACL
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R.Zhang, P.E.Pearce, V.Pimenta, M.Courty, J.Cabana, H.Li, D.Alves Dalla Corte, A.M.Abakumov, G.Rousse, D.Giaume, M.Deschamps, A.Grimaud, 'First example of protonation of Ruddlesden-Popper Sr2IrO4: a route to better water oxidation catalysts', Chem. Mat. 32(8) 3499–3509 (2020) doi:10.1021/acs.chemmater.0c00432
Water electrolysis is considered a promising way to store and convert excess renewable energies into hydrogen, which is of high value for many chemical transformation processes such as the Haber-Bosch process. However, to take advantage of the polymer electrolyte membrane (PEM) technology, the main challenge lies in the design of robust catalysts for oxygen evolution reaction (OER) under acidic conditions since most of transition metal based complex oxides used undergo structural degradation under these harsh acidic conditions. To broaden the variety of candidate materials as OER catalysts, a cation-exchange synthetic route was recently explored to reach crystalline pronated iridates with unique structure and properties. In this work, a new protonated phase H3.6IrO4∙3.7H2O, prepared via Sr2+/H+ cation exchange at room temperature starting from the parent Ruddlesden-Popper Sr2IrO4 phase, is described. This is the first discovery of crystalline protonated iridate forming from a perovskite-like phase, and adopting a layered structure with apex-linked IrO6. Furthermore, H3.6IrO4∙3.7H2O is found to possess not only an enhanced specific catalytic activity, superior to that of other perovskite-based iridates, but also a mass activity even comparable to that of nanometric IrOx particles, while showing an improved catalytic stability owing to its ability to reversibly exchange protons in acid.
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