Surfactant-directed synthesis of ternary nanostructures: Nanocubes, polyhedrons, octahedrons, and nanowires of PtNiFe. Their shape-dependent oxygen reduction activity
Journal
Chemistry of Materials
Journal Volume
24
Journal Issue
13
Pages
2527-2533
Date Issued
2012
Author(s)
Chou, Shang-Wei
Shyue, Jing-Jong
Chien, Chia-Hua
Chen, Chia-Chun
Chen, Yang-Yuan
Abstract
We report a rational method for preparation of ternary alloy (PtNiFe) nanocrystals with various shapes. PtNiFe nanocubes, polyhedrons, and octahedrons are prepared via fine-tuning the alloy compositions and surfactants, so that the crystal facet-surfactant bindings on the growth seed can be well controlled. Nanowires grow in the cylindrical template built via high concentrations of oleylamine. In the electrocatalysis examination, it appears that the oxygen reduction reaction (ORR) activities of all PtNiFe nanostructures outperform that of commercial Pt catalyst in the electrolyte of HClO 4 or H 2SO 4. In HClO 4, the order of ORR activity is as follows: octahedrons ≈ nanowires > polyhedrons > nanocubes. PtNiFe nanostructures enclosed by a (111) plane, such as octahedrons and nanowires, give the highest ORR activities. Conversely, in H 2SO 4, the ORR activity of PtNiFe nanocubes enclosed by {100} facets is the highest among these nanostructures. The ORR activity increases in the order of nanowires ≈ octahedrons < polyhedrons, establishing a shape dependency in the ORR activity, which is valuable upon performing nanocatalysis in fuel cells. © 2012 American Chemical Society.
Type
journal article