Evolution of Iridium-Based Molecular Catalysts during Water Oxidation with Ceric Ammonium Nitrate

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• 作者：Douglas B. Grotjahn ; Derek B. Brown ; Jessica K. Martin ; David C. Marelius ; Marie-Caline Abadjian ; Hai N. Tran ; Gregory Kalyuzhny ; Kenneth S. Vecchio ; Zephen G. Specht ; Sara A. Cortes-Llamas ; Valentin Miranda-Soto ; Christoffel van Niekerk ; Curtis E. Moore ; Arnold L. Rheingold
• 刊名：Journal of the American Chemical Society
• 出版年：2011
• 出版时间：November 30, 2011
• 年：2011
• 卷：133
• 期：47
• 页码：19024-19027
• 全文大小：870K
• 年卷期：v.133,no.47(November 30, 2011)
• ISSN：1520-5126

文摘

Organometallic iridium complexes have been reported as water oxidation catalysts (WOCs) in the presence of ceric ammonium nitrate (CAN). One challenge for all WOCs regardless of the metal used is stability. Here we provide evidence for extensive modification of many Ir-based WOCs even after exposure to only 5 or 15 equiv of Ce(IV) (whereas typically 100鈥?0000 equiv are employed during WOC testing). We also show formation of Ir-rich nanoparticles (likely IrOb>xb>) even in the first 20 min of reaction, associated with a Ce matrix. A combination of UV鈥搗is and NMR spectroscopy, scanning transmission electron microscopy, and powder X-ray diffraction is used. Even simple IrClb>3b> is an excellent catalyst. Our results point to the pitfalls of studying Ir WOCs using CAN.