Open Access Nano Express

Hollow nitrogen-containing core/shell fibrous carbon nanomaterials as support to platinum nanocatalysts and their TEM tomography study

Cuifeng Zhou1, Zongwen Liu1*, Xusheng Du2*, David Richard Graham Mitchell1, Yiu-Wing Mai2, Yushan Yan3 and Simon Ringer1

Author Affiliations

1 Australian Centre for Microscopy and Microanalysis, The University of Sydney, New South Wales, 2006, Australia

2 Centre for Advanced Materials Technology, School of Aerospace Mechanical and Mechatronic Engineering J07, The University of Sydney, New South Wales, 2006, Australia

3 Chemical and Biomolecular Engineering, University of Delaware, Newark, DE, 19716, USA

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Nanoscale Research Letters 2012, 7:165  doi:10.1186/1556-276X-7-165

Published: 2 March 2012

Abstract

Core/shell nanostructured carbon materials with carbon nanofiber (CNF) as the core and a nitrogen (N)-doped graphitic layer as the shell were synthesized by pyrolysis of CNF/polyaniline (CNF/PANI) composites prepared by in situ polymerization of aniline on CNFs. High-resolution transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared and Raman analyses indicated that the PANI shell was carbonized at 900°C. Platinum (Pt) nanoparticles were reduced by formic acid with catalyst supports. Compared to the untreated CNF/PANI composites, the carbonized composites were proven to be better supporting materials for the Pt nanocatalysts and showed superior performance as catalyst supports for methanol electrochemical oxidation. The current density of methanol oxidation on the catalyst with the core/shell nanostructured carbon materials is approximately seven times of that on the catalyst with CNF/PANI support. TEM tomography revealed that some Pt nanoparticles were embedded in the PANI shells of the CNF/PANI composites, which might decrease the electrocatalyst activity. TEM-energy dispersive spectroscopy mapping confirmed that the Pt nanoparticles in the inner tube of N-doped hollow CNFs could be accessed by the Nafion ionomer electrolyte, contributing to the catalytic oxidation of methanol.

Keywords:
carbon nanofiber; N-doping; core/shell; polyaniline; catalyst support; methanol oxidation; TEM tomography