Electron Transfer Facilitated by Dendrimer-Encapsulated Pt Nanoparticles Across Ultrathin, Insulating Oxide Films

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• 作者：Nevena Ostojic ; James H. Thorpe ; Richard M. Crooks
• 刊名：Journal of the American Chemical Society
• 出版年：2016
• 出版时间：June 1, 2016
• 年：2016
• 卷：138
• 期：21
• 页码：6829-6837
• 全文大小：515K
• 年卷期：0
• ISSN：1520-5126

文摘

Electrocatalytic oxygen reduction at carbon electrodes fully passivated by Al₂O₃ is reported. Specifically, pyrolyzed polymer film (PPF) electrodes were prepared and then coated with pinhole-free Al₂O₃ layers ranging in thickness from 2.5 to 5.7 nm. All of these ultrathin oxide film thicknesses completely passivated the PPF electrodes, resulting in no faradaic current for either inner-sphere or outer-sphere electrochemical reactions. The electrodes could, however, be reactivated by immobilizing Pt dendrimer-encapsulated nanoparticles (DENs), containing an average of 55 atoms each, on the oxide surface. These PPF/Al₂O₃/Pt DEN electrodes were completely stable under a variety of electrochemical and solution conditions, and they are active for simple electron-transfer reactions and for more complex electrocatalytic processes. This approach for preparing well-defined oxide electrodes opens the door to a better understanding of the effect of oxide supports on reactions electrocatalyzed by metal nanoparticles.