Shape-controlled synthesis of Pt nanoframes

Abstract

Plate-like Pt nanoframes were synthesized using Au nanoplates as a template, followed by formation of a Ag layer coating on the Au template, and selective chemical etching of Au and Ag leaving the Pt structure intact. Circular, triangular, and hexagonal Au nanoplates successfully served as templates for fabrication of various Pt nanoframe shapes, which resembled the original Au nanoplate shape. A thin Ag layer was found to play a critical role as an electron-transfer mediator in the galvanic replacement reaction between the thin Ag layer on Au nanoplates and Pt precursors. During the replacement reaction, the Pt layer grew faster at the {112} edges than at the {111} terraces of Au nanoplates. The thicker periphery of the nanoplates survived the chemical etching step, while the thinner center was etched, leading to formation of Pt nanoframes in high yield and good homogeneity.