Molecular Insight in Structure and Activity of Highly Efficient, Low-Ir Ir鈥揘i Oxide Catalysts for Electrochemical Water Splitting (OER)

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• 作者：Tobias Reier ; Zarina Pawolek ; Serhiy Cherevko ; Michael Bruns ; Travis Jones ; Detre Teschner ; S枚ren Selve ; Arno Bergmann ; Hong Nhan Nong ; Robert Schl枚gl ; Karl J. J. Mayrhofer ; Peter Strasser
• 刊名：Journal of the American Chemical Society
• 出版年：2015
• 出版时间：October 14, 2015
• 年：2015
• 卷：137
• 期：40
• 页码：13031-13040
• 全文大小：723K
• ISSN：1520-5126

文摘

Mixed bimetallic oxides offer great opportunities for a systematic tuning of electrocatalytic activity and stability. Here, we demonstrate the power of this strategy using well-defined thermally prepared Ir鈥揘i mixed oxide thin film catalysts for the electrochemical oxygen evolution reaction (OER) under highly corrosive conditions such as in acidic proton exchange membrane (PEM) electrolyzers and photoelectrochemical cells (PEC). Variation of the Ir to Ni ratio resulted in a volcano type OER activity curve with an unprecedented 20-fold improvement in Ir mass-based activity over pure Ir oxide. In situ spectroscopic probing of metal dissolution indicated that, against common views, activity and stability are not directly anticorrelated. To uncover activity and stability controlling parameters, the Ir鈥揘i mixed thin oxide film catalysts were characterized by a wide array of spectroscopic, microscopic, scattering, and electrochemical techniques in conjunction with DFT theoretical computations. By means of an intuitive model for the formation of the catalytically active state of the bimetallic Ir鈥揘i oxide surface, we identify the coverage of reactive surface hydroxyl groups as a suitable descriptor for the OER activity and relate it to controllable synthetic parameters. Overall, our study highlights a novel, highly active oxygen evolution catalyst; moreover, it provides novel important insights into the structure and performance of bimetallic oxide OER electrocatalysts in corrosive acidic environments.