Synthesis of Vertically Aligned Hollow Platinum Nanotubes with Single Crystalline Nanoflakes

This paper reports on a methodology for synthesizing vertical arrays of hollow platinum nanotubes with [111] single-crystalline nanoflakes. Initially, single-component nickel nanorods were fabricated with the aid of AAO templates and electrochemical deposition. When the resulting nickel nanorods were immersed in a Pt-ion-containing aqueous solution, the nickel metal dissolved into Ni 2+ ions through spontaneous galvanic replacement with Pt ions. However, the direct replacement between nickel nanorods and Pt ions led to an irregular architecture in the resulting deposition of platinum. Instead, a pitting corrosion pretreatment of the nickel nanorods produced nucleation sites for replacement with the Pt ions. This step was critical for accelerating the interfacial replacement reaction rate and the formation of the regular platinum nanotubes with ultrathin superficial nanoflakes. We found that the Kirkendall effect was operative in the formation of platinum nanotubes.