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2. Electrochemical Active Surface Area Determination of Iridium‐Based Mixed Oxides by Mercury Underpotential Deposition

Author

Duran, Silvia, Elmaalouf, Marine, Odziomek, Mateusz, Piquemal, Jean‐Yves, Faustini, Marco, Giraud, Marion, Peron, Jennifer, Tard, Cédric, Piquemal, Jean-Yves, Piquemal, J.-Y, Laboratoire de chimie moléculaire (LCM), Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-École polytechnique (X), Interfaces, Traitements, Organisation et Dynamique des Systèmes (ITODYS (UMR_7086)), Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Laboratoire de Chimie de la Matière Condensée de Paris (LCMCP), and Institut de Chimie du CNRS (INC)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Materials science, Oxygen evolution, chemistry.chemical_element, 02 engineering and technology, 010402 general chemistry, 021001 nanoscience & nanotechnology, Underpotential deposition, Electrochemistry, 01 natural sciences, Catalysis, 0104 chemical sciences, Mercury (element), Chemical engineering, Physisorption, chemistry, Degradation (geology), Iridium, [CHIM.OTHE]Chemical Sciences/Other, 0210 nano-technology
Abstract

International audience; The electrochemical surface area (ECSA) is a critical property to describe, analyze and compare electrocatalysts. The determination of the mass activity of a given catalyst is associated with this parameter which can thus lead to materials benchmarking. Reliable and robust methods to measure ECSA are needed, and those have to accommodate different structures, morphologies and compositions. In this study, we investigate mercury underpotential deposition (HgUPD) as a way to estimate ECSA for ultraporous electrocatalysts based on iridium and iridium-molybdenum electrocatalysts for the oxygen evolution reaction. Results reveal a clear agreement between physisorption measurements and HgUPD with excellent reproducibility. The method shows also that pre- and post-catalysis surface area measurements are not affected by the catalytic process on short timescale, opening the possibility of electrocalyst stability and degradation monitoring.

Published
2021

5. Green synthesis of water splitting electrocatalysts: IrO 2 nanocages via Pearson's chemistry.

Author

Elmaalouf M, Da Silva A, Duran S, Tard C, Comesaña-Hermo M, Gam-Derouich S, Briois V, Alloyeau D, Giraud M, Piquemal JY, and Peron J

Abstract

Highly porous iridium oxide structures are particularly well-suited for the preparation of porous catalyst layers needed in proton exchange membrane water electrolyzers. Herein, we report the formation of iridium oxide nanostructured cages, via a water-based process performed at room temperature, using cheap Cu 2 O cubes as the template. In this synthetic approach, based on Pearson's hard and soft acid-base theory, the replacement of the Cu 2 O core by an iridium shell is permitted by the difference in hardness/softness of cations and anions of the two reactants Cu 2 O and IrCl 3 . Calcination followed by acid leaching allow the removal of residual copper oxide cores and leave IrO 2 hierarchical porous structures with outstanding activity toward the oxygen evolution reaction. Fundamental understanding of the reaction steps and identification of the intermediates are permitted by coupling a set of ex situ and in situ techniques including operando time-resolved X-ray absorption spectroscopy during the synthesis., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Published
2022
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