Electrochemical Dissolution of Iridium and Iridium Oxide Particles in Acidic Media: Transmission Electron Microscopy, Electrochemical Flow Cell Coupled to Inductively Coupled Plasma Mass Spectrometry, and X-ray Absorption Spectroscopy Study

• DOI: 10.1021/jacs.7b08071
• Publication Date: 2017-08-15T22:09:05Z
• Authors: Primož Jovanovič; Nejc Hodnik; Francisco Ruiz-Ze...; Iztok Arčon; Barbara Jozinović; Milena Zorko; Marjan Bele; Martin Šala; Vid Simon Šelih; Samo Hočevar; Miran Gaberšček
• Keywords: transmisijska elektronska mikroskopija; info:eu-repo/classification/ddc/540; XAS; Ir L3-edge XANES; 02 engineering and technology; 540; EXAFS; evolucija kisika; Iridium Oxide Par-ticles; iridij; Electrochemical Dissolution of Iridium; ICP-MS; elektrokataliza; elektrolizer; 0210 nano-technology

Iridium-based particles, regarded as the most promising proton exchange membrane electrolyzer electrocatalysts, were investigated by transmission electron microscopy and coupling of an electrochemical flow cell (EFC) with online inductively coupled plasma mass spectrometry. Additionally, studies using a thin-film rotating disc electrode, identical location scanning microscopy, well X-ray absorption spectroscopy have been performed. Extremely sensitive time-and potential-resolved dissolution profiles revealed that Ir particles dissolve below oxygen evolution reaction (OER) potentials, presumably induced surface oxidation reduction processes, also referred to transient dissolution. Overall, thermally prepared rutile-type IrO2 are substantially more stable less active in comparison as-prepared metallic electrochemically pretreated (E-Ir) analogues. Interestingly, under OER-relevant conditions, E-Ir exhibit superior stability activity owing altered corrosion mechanism, where formation unstable Ir(>IV) species is hindered. Due enhanced lasting OER performance, pre-oxidized may be considered electrocatalyst choice for improved low-temperature hydrogen production device, namely electrolyzer.