Mechanistic Studies on Room Temperature Photoexcitation Effects on Passivity Breakdown of Ultrathin Surface Oxide Films Formed on Ternary Al−5%Cu−5%Ni Alloys

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• 作者：Chia-Lin Chang ; Mark H. Engelhard ; Shriram Ramanathan
• 刊名：Journal of Physical Chemistry C
• 出版年：2010
• 出版时间：October 21, 2010
• 年：2010
• 卷：114
• 期：41
• 页码：17788-17795
• 全文大小：364K
• 年卷期：v.114,no.41(October 21, 2010)
• ISSN：1932-7455

文摘

How the composition of nanoscale surface oxides formed on complex metal alloys affects their passive state is a problem of great interest in physical chemistry as well as in technological applications. In this work, we report on experimental studies regarding the problem concerning the role of room-temperature photoexcitation on altering composition of ultrathin oxides formed on ternary Al−Cu−Ni thin film alloy surface and its influence in passivity breakdown in aqueous media. Extensive studies have been carried out on pure copper, Al−5%Cu, and Al−5%Cu−5%Ni alloy thin films to investigate the mechanistic role of alloying elements as well as their oxide formation characteristics on the passive state. The differences in nanoscale oxide composition formed have a remarkable influence on the passivity breakdown of the oxide films as verified from electrochemical measurements, and possible mechanisms leading to the observations are discussed in detail.