The Common Intermediates of Oxygen Evolution and Dissolution Reactions during Water Electrolysis on Iridium. Issue 9 (5th February 2018)

• Record Type: Journal Article
• Authors: Kasian, Olga; Grote, Jan‐Philipp; Geiger, Simon; Cherevko, Serhiy; Mayrhofer, Karl J. J.
• Is Part Of: Angewandte Chemie international edition. Volume 57:Issue 9(2018)
• Page Start: 2488
• Page End: 2491
• Publication Date: 2018-02-05
• Subjects: electrochemical mass spectrometry -- iridium dissolution -- oxygen evolution reaction -- reaction mechanisms -- water electrolysis; Chemistry -- Periodicals; 540
• DOI: 10.1002/anie.201709652
• Languages: English
• ISSNs: 1433-7851

Abstract

Abstract: Understanding the pathways of catalyst degradation during the oxygen evolution reaction is a cornerstone in the development of efficient and stable electrolyzers, since even for the most promising Ir based anodes the harsh reaction conditions are detrimental. The dissolution mechanism is complex and the correlation to the oxygen evolution reaction itself is still poorly understood. Here, by coupling a scanning flow cell with inductively coupled plasma and online electrochemical mass spectrometers, we monitor the oxygen evolution and degradation products of Ir and Ir oxides in situ. It is shown that at high anodic potentials several dissolution routes become possible, including formation of gaseous IrO3 . On the basis of experimental data, possible pathways are proposed for the oxygen‐evolution‐triggered dissolution of Ir and the role of common intermediates for these reactions is discussed. Abstract : Possible routes of Ir dissolution are proposed based on the detection of a common intermediate in the oxygen evolution reaction. At least three dissolution pathways are possible depending on the nature of the electrode and potential. At high current densities two reactions proceed via formation of volatile IrO3 . Hindering IrO3 hydrolysis can be a strategy to improve electrode stability in the oxygen evolution reaction.