On the Microstructure, Chemical Composition, and Porosity Evolution of Nanoporous Alloy through Successive Dealloying of Ternary Al鈥揚d鈥揂u Precursor

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• 作者：Xiaoguang Wang ; Junzhe Sun ; Chi Zhang ; Tianyi Kou ; Zhonghua Zhang
• 刊名：The Journal of Physical Chemistry C
• 出版年：2012
• 出版时间：June 21, 2012
• 年：2012
• 卷：116
• 期：24
• 页码：13271-13280
• 全文大小：845K
• 年卷期：v.116,no.24(June 21, 2012)
• ISSN：1932-7455

文摘

In the present Article, we have investigated the microstructure, composition, and porosity evolution of nanoporous alloy during successive dealloying of ternary Al₇₅Pd_17.5Au_7.5 precursor in NaOH/HCl and HNO₃ aqueous solutions. The results show that the selective dissolution of Al through the first-step dealloying contributes to the formation of Pd鈥揂u nanoporous composites, which are composed of two distinct structures: the finer nanoporous AuPd dendrites derived from the dealloying of Al₂(Au,Pd) and the coarser nanoporous Pd(Au) derived from the dealloying of Al₃(Pd,Au). Moreover, compared with those dealloyed in the 20 wt % NaOH solution, the Pd鈥揂u nanocomposites exhibit a coarser length scale of ligaments/channels in the 5 wt % HCl solution. After the second-step dealloying in the 65 wt % HNO₃ solution, the nanoporous Pd(Au) dissolves away, and the Pd dissolution results in the formation of Au-rich nanoporous alloy with bimodal channel size distributions. Nanoporous alloys with unique structures and compositions can be fabricated by dealloying based on alloy design and control over selective dissolution of elements in suitable electrolytes.