Nanoporous gold film (NPGF) electrode was fabricated by applying multicyclic potential scans on a polished gold electrode in an electrolyte composed of ZnCl 2 and benzyl alcohol. In the cathodic potential scan, Zn was first electrodeposited on the gold electrode surface, and Au-Zn alloy was then directly formed on the surface under an elevated temperature. In the subsequent anodic potential scan, dealloying of Zn took place, resulting in a nanostructured gold film. Furthermore, Zn was then electrodeposited onto the porous gold surface and a Au-Zn alloy was formed at the same time. Through controlling the parameters of cyclic voltammetry and cyclic times, we finally obtained a three-dimensional NPGF with nanopores. The resulting NPGF possessed ultrahigh roughness factor and surface area. Results showed that the electrochemical activity of the NPGF electrode was much higher than that of the polished gold electrode. We believe that the resulting NPGF electrode is promising in the fields of catalysis, sensors, and so on. Meanwhile, this multicyclic electrochemical alloying/dealloying method may be applied to fabricate other nanoporous metal films.
Nanoporous films (NPFs) of copper, silver, and gold were directly fabricated on the corresponding metal
substrates by a general alloying/dealloying process. This process involved the electrodeposition of Zn on
metal surfaces, thermal alloying, and chemical dealloying of Zn. Electrodeposition of Zn on metal substrates
was realized in commercial Zn plating electrolyte at room temperature. Then surface zinc−metal alloys were
formed by thermal treatment at relatively low temperatures (below 150 °C) in nitrogen gas. By immersing
the alloys in etching solutions, we obtained metal NPFs through chemical dissolution of Zn from the alloys.
Characterization results showed that the morphologies and porous structures of the products were greatly
affected by the thickness of the deposited Zn layer and thermal alloying temperature. Moreover, preliminary
testing showed that the as-prepared gold NPF possessed a higher surface area than the polish one. Furthermore,
the Au NPF could serve as a nanoporous skeleton for fabricating Pt-coated a Au NPF electrode. The oxidation
current of glucose was improved about 180 times when using the resulting Pt-coated Au NPF composite
electrode instead of the polished Pt electrode. This study provides a general method to directly fabricate
nanoporous metal films on the corresponding metal substrates.
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