A Dissolution/Precipitation Equilibrium on the Surface of Iridium-Based Perovskites Controls Their Activity as Oxygen Evolution Reaction Catalysts in Acidic Media

Ronghuan Zhang (1, 2) , Nicolas Dubouis (1, 2) , Manel Ben osman (3, 2) , Wei Yin (1, 2) , Moulay Tahar Sougrati (4, 2) , Daniel A. D. Corte (1, 2) , Domitille Giaume (5, 2) , Alexis Grimaud (1, 2)

1 CSE - Chimie du solide et de l'énergie
2 RS2E - Réseau sur le stockage électrochimique de l'énergie
3 LCMCP - Laboratoire de Chimie de la Matière Condensée de Paris
4 ICGM - Institut Charles Gerhardt Montpellier - Institut de Chimie Moléculaire et des Matériaux de Montpellier
5 IRCP - Institut de Recherche de Chimie Paris

Recently, Ir (V)-based perovskite-like materials were proposed as oxygen evolution reaction (OER) catalysts in acidic media with promising performance. However, iridium dissolution and surface reconstruction were observed, questioning the real active sites on the surface of these catalysts. In this work, Sr2MIr (V) O6 (M = Fe, Co) and Sr2Fe0.5Ir0.5 (V) O4 were explored as OER catalysts in acidic media. Their activities were observed to be roughly equal to that previously reported for La2LiIrO6 or Ba2PrIrO6. Coupling electrochemical measurements with iridium dissolution studies under chemical or electrochemical conditions, we show that the deposition of an IrOx layer on the surface of these perovskites is responsible for their OER activity. Furthermore, we experimentally reconstruct the iridium Pourbaix diagram which will help guide future research in controlling the dissolution/precipitation equilibrium of iridium species for the design of better Ir-based OER catalysts.

Mots clés: perovskites; iridium dissolution; Pourbaix diagrams; oxygene volution reaction

Domaines: Catalyse

Ronghuan Zhang, Nicolas Dubouis, Manel Ben osman, Wei Yin, Moulay Tahar Sougrati, et al.. A Dissolution/Precipitation Equilibrium on the Surface of Iridium-Based Perovskites Controls Their Activity as Oxygen Evolution Reaction Catalysts in Acidic Media. Angewandte Chemie International Edition, 2019, 58 (14), pp.4571-4575. ⟨10.1002/anie.201814075⟩. ⟨hal-02388351⟩