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; 7. Clean energy; 01 natural sciences; 0104 chemical sciences; EXAFS; evolucija kisika; 13. Climate action; Iridium Oxide Par-ticles; iridij; Electrochemical Dissolution of Iridium; ICP-MS; elektrokataliza; elektrolizer; 0210 nano-technology

Journal of the American Chemical Society 139(36), 12837 – 12846 (2017). doi:10.1021/jacs.7b08071<br/>Iridium based particles as the most promising proton exchange membrane electrolyser electrocatalysts were investigatedby transmission electron microscopy (TEM), and by coupling of electrochemical flow cell (EFC) with online inductivelycoupled plasma mass spectrometer (ICP-MS). Additionally, a thin-film rotating disc electrode (RDE), an identical location transmissionand scanning electron microscopy (IL-TEM and IL-SEM) as well as an X-ray absorption spectroscopy (XAS) studies havebeen performed. Extremely sensitive online time-and potential-resolved electrochemical dissolution profiles revealed that iridiumparticles dissolved already well below oxygen evolution reaction (OER) potentials, presumably induced by iridium surface oxidationand reduction processes, also referred to as transient dissolution. Overall, thermally prepared rutile type IrO2 particles (T-IrO2)are substantially more stable and less active in comparison to as prepared metallic (A-Ir) and electrochemically pretreated (E-Ir)analogues. Interestingly, under OER relevant conditions E-Ir particles exhibit superior stability and activity owing to the alteredcorrosion mechanism where the formation of unstable Ir(>IV) species is hindered. Due to the enhanced and lasting OER performance,electrochemically pre-oxidized E-Ir particles may be considered as the electrocatalyst of choice for an improved low temperatureelectrochemical hydrogen production device, namely a proton exchange membrane electrolyser.<br/>Published by American Chemical Society, Washington, DC<br/>