First Example of Protonation of Ruddlesden–Popper Sr 2 IrO 4 : A Route to Enhanced Water Oxidation Catalysts

Ronghuang Zhang , Paul E Pearce , Vanessa Pimenta , Jordy Cabana , Heifang Li , Daniel Alves , Dalla Corte , Artem M Abakumov , Gwenaëlle Rousse , Domitille Giaume , Michaël Deschamps (1, 2) , Jordi Cabana , Daniel Alves Dalla Corte , Alexis Grimaud (3)

1 CEMHTI - Conditions Extrêmes et Matériaux : Haute Température et Irradiation
2 UO - Université d'Orléans
3 CSE - Chimie du solide et de l'énergie

Water electrolysis is considered as 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 allow for the widespread of the polymer electrolyte membrane water electrolysis (PEMWE) 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 oxides 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 structural properties and stability. In this work, a new protonated phase H 3.6 IrO 4 •3.7H 2 O, prepared via Sr 2+ /H + cation exchange at room temperature starting from the parent Ruddlesden-Popper Sr 2 IrO 4 phase, is described. This is the first discovery of crystalline protonated iridate forming from a perovskite-like phase, adopting a layered structure with apex-linked IrO 6 octahedra. Furthermore, H 3.6 IrO 4 •3.7H 2 O is found to possess not only an enhanced specific catalytic activity, superior to that of other perovskite-based iridates, but also a mass activity comparable to that of nanosized IrO x particles, while showing an improved catalytic stability owing to its ability to reversibly exchange protons in acid.

Domaines: Matériaux

Ronghuang Zhang, Paul E Pearce, Vanessa Pimenta, Jordy Cabana, Heifang Li, et al.. First Example of Protonation of Ruddlesden–Popper Sr 2 IrO 4 : A Route to Enhanced Water Oxidation Catalysts. Chemistry of Materials, 2020, 32 (8), pp.3499-3509. ⟨10.1021/acs.chemmater.0c00432⟩. ⟨hal-03000055⟩