Composition- and Aspect-Ratio-Dependent Electrocatalytic Performances of One-Dimensional Aligned Pt–Ni Nanostructures

Abstract

This work presents the synthesis of 1D aligned Pt–Ni nanostructures with ultrahigh aspect ratio (>1000) based on the anodic aluminum oxide (AAO) template and their composition- and aspect-ratio-dependent catalytic performances to methanol oxidation reaction (MOR). The 1D aligned Pt–Ni nanostructures were electrochemically deposited in the pores of the AAO template, and the diameter and length of the synthesized nanostructures are comparable with the diameter of pores and thickness of the used AAO. The aspect ratio of the 1D aligned nanostructures can be tuned merely by altering AAO templates with the appropriate aspect ratios. Voltammetric results show that the catalytic activities (both mass activities and specific activities) of the 1D aligned Pt–Ni nanostructures for MOR are composition dependent, and the highest electrocatalytic activity exhibits at a Pt/Ni molar ratio of 1:1 (PtNi). The mechanism of the promoting effect of Ni on Pt is explained based on modification of the electronic characteristics of the surface Pt atoms (Pt 4f) by Ni atoms due to the shift in electron transfer from Ni to Pt. Moreover, the catalytic activities of the 1D aligned PtNi nanostructures are in an aspect-ratio-dependent manner and increase in the order 0D PtNi nanoparticles, 1D aligned PtNi nanostructures at aspect ratios of ∼200, 500, and 1300 due to the preferential exposure of certain crystal facets and less surface defects of the 1D aligned nanostructures. This work is believed to open new and exciting possibilities for enhancing the performance of fuel cell catalysts. Our synthesized high-aspect-ratio 1D aligned nanostructures may also be useful as sensors and in other electrochemical applications.

Composition- and Aspect-Ratio-Dependent Electrocatalytic Performances of One-Dimensional Aligned Pt–Ni Nanostructures

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Abstract

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