Inter‐relationships between Oxygen Evolution and Iridium Dissolution Mechanisms

Abstract

Figure 1. a) Electrochemical oxide pathway. [13] Copyright 2016, John Wiley and Sons. b) Cationic redox mechanism proposed by Kçtz et al. [21] Copyright 1984, IOP Publishing. c) Scheme of the OER, including the formation of an OOH intermediate, as detected by Sivasankar et al. [24] Copyright 2011, AmericanC hemical Society.d )Schematic representation of O2pbands penetrating into Ir dorbitals and triggering an anionic redox process. [27] Copyright 2016, Springer Nature. e) OER scheme showing the formation of oxyl species, as aresult of hybridization of Ir and O orbitals, which are prone to nucleophilic attack by water and the formation of an OÀObond. [33] Copyright2 019, Elsevier.

Recent developments of iridium-based catalysts for the oxygen evolution reaction in acidic water electrolysis

“…56 Balakrishnan et al 57 investigated the third dissolution route which is the inevitable dissolution of metallic iridium accompanying the formation of an oxide layer on the metal surface, not directly related to the OER. Except for these dissolution pathways, Lončar et al 58 pointed out that a dissolution mechanism related to the anionic redox process should also be in progress. In the future, the dissolution process should be better understood such as whether the reaction is chemical or electrochemical, and appropriate strategies should be proposed to suppress these dissolution ways.…”

Simultaneous optimization of CoIr alloy nanoparticles and 2D graphitic-N doped carbon support in CoIr@CN by Ir doping for enhanced oxygen and hydrogen evolution reactions

“…[10][11][12][13] A CoIr alloy with trace of precious Ir based on the abundance of Co, which possesses favorable electronic properties for the OER and Pt-like electron states for the HER, is capable of promoting both OER and HER processes. [14][15][16][17] Because of distinct electronegativity and atomic radii for different metal atoms, the d-band center of Co would be modied to locate in the vicinity of the Fermi level owing to the Ir incorporation, which can moderate the intermediate adsorption free energy to reduce the OER/HER barrier. 15 Regrettably, such a single electronic structure modulation is insufficient for metal catalysts, and it still suffers from the poor stability in acid/alkaline solution.…”

Protonated Iridate Nanosheets with a Highly Active and Stable Layered Perovskite Framework for Acidic Oxygen Evolution

“…While it has become a common understanding that the initial 3D perovskite framework does not make main contribution to the superior activity, the key structural motif of the perovskite-derived amorphous IrO x phase is still a controversial topic. Anatase IrO 2 , IrO 3 , or honeycomb-like IrO x H y motifs are proposed to be crucial structural fragments responsible for the superior activity based on the theoretical and/or spectroscopic results, − and the participation of activated lattice oxygen in OER has also been observed by some researchers. , Moreover, another undesirable aspect is that the high activity of Ir-based perovskite catalysts gains generally at the expense of structural stability. The iridium dissolution of most of the recently developed Ir-based perovskite catalysts is more serious than that of IrO 2 during OER. − To simultaneously achieve great activity and stability for OER, two questions of Ir-based perovskite catalysts need to be addressed: (i) how to minimize dissolution and reconstruction and (ii) how to expose more active sites on the surface.…”