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.

Quantification of Iridium Dissolution at Water Electrolysis Relevant Conditions Using a Gas Diffusion Electrode Half-Cell Setup

“…14 The higher stability was hypothesized to stem from kinetically hindered dissolution 11 and lower participation of lattice oxygen during the OER. 15 A study focusing on the transferability of IrO x dissolution stability from AMSs to single-cell electrolyzers indicated a substantial underestimation of Ir stability in the AMS, mainly attributed to differences in the systems' pH and measurement duration. 16 To quantify IrO x dissolution from catalyst layers in singlecell electrolyzers, so far post-mortem transmission electron microscopy (TEM) analysis of catalyst coated membrane (CCM) cross sections 17,18 and additionally dissolution of the cathode CL and quantification by ICP-MS 19 were utilized, sacrificing the investigated CCM.…”

“…Rutile IrO 2 was shown to be up to 2 orders of magnitude more stable during the OER, compared to hydrous IrO x in an aqueous model system (AMS) . The higher stability was hypothesized to stem from kinetically hindered dissolution and lower participation of lattice oxygen during the OER . A study focusing on the transferability of IrO x dissolution stability from AMSs to single-cell electrolyzers indicated a substantial underestimation of Ir stability in the AMS, mainly attributed to differences in the systems’ pH and measurement duration …”

Hydroxyl-rich KIr4O8 Nanowires Promote Acidic Water Oxidation Electrocatalysis with Industrial Current Density

“…The stability is another challenge possibly caused by the dissolution and amorphization of Ir and non-Ir metals in the catalysts during the OER. [9][10][11][12] Recently, it is reported that A x Ir y O z usually forms bulk with large size and irregular morphology due to the conventional use of solid phase synthesis method with high temperature and pressure. 13 Unlike the above catalysts, A x Ir y O z with regular morphology can expose more catalytic active sites.…”