Investigation of Pt Catalysts Supported on Multi-Walled Carbon Nanotubes with Various Diameters and Lengths
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Investigation of Pt Catalysts Supported on Multi-Walled Carbon Nanotubes with Various Diameters and Lengths Ying Liang Æ Jun Li Æ Shi-Zhong Wang Æ Xian-Zhu Fu Æ \Qing-Chi Xu Æ Jing-Dong Lin Æ Dai-Wei Liao
Received: 16 July 2007 / Accepted: 10 September 2007 / Published online: 29 September 2007 Ó Springer Science+Business Media, LLC 2007
Abstract Platinum electrocatalysts supported on multiwalled carbon nanotubes (MWCNTs) with various diameters and lengths were studied by using transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and cyclic voltammetry (CV) and Chronoamperometry. The results indicated that the MWCNTs with smaller diameter generated more amorphous carbon after a sonochemical oxidation treatment. Compared with the long MWCNTs, the short MWCNTs had more open ends, resulting in high-Pt dispersion and electrocatalytic activity towards methanol oxidation. Pt nanoparticles supported on short MWCNTs with a diameter of 30–50 nm exhibited the best Pt dispersion and highest methanol oxidation activity among the catalysts studied. The high activities of the catalysts based on short MWCNTs were due to both the intrinsic high activity of the ends of MWCNTs and a good Pt distribution. Keywords Multi-walled carbon nanotubes Platinum Methanol oxidation Diameter and length
Y. Liang S.-Z. Wang X.-Z. Fu Q.-C. Xu J.-D. Lin D.-W. Liao (&) The State Key Laboratory of Physical Chemistry on Solid Surfaces, Department of Chemistry, College of Chemistry and Chemical Engineering, Institute of Physical Chemistry, Xiamen University, Xiamen 361005, China e-mail: [email protected] Y. Liang e-mail: [email protected] J. Li College of Power Engineering, Chongqing University, Chongqing 400030, China
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1 Introduction Carbon nanotubes (CNTs) have attracted more and more interest in the applications of the new carbon materials in a variety of fields, including chemical and biological sensors [1, 2], separation membranes [3, 4], field emission devices [5, 6], energy storage [7, 8]. CNTs are widely studied as supports of depositing metal nanoparticles as heterogeneous catalysts due to their extraordinary structure, good electronic conductivity and improved accessibility of reactants to the active sites [9, 10]. For instance, Ru, Pd, Au and Pb were deposited on carbon nanobutes and resulted in good catalytic activity [11–14]. The CNTs have also attracted great attention as supports for Pt and Pt alloy catalysts in low-temperature fuel cell [15–22]. Studies have shown that the Pt base catalysts supported on CNTs may provide improved electrocatalytic activity compared to the catalysts on the traditional Vulcan XC-72 carbon support in fuel cell. The improvement catalytic activity can be usually attributed to various causes [15–18], including (a) higher electronic conductivity of CNTs, (b) higher electrochemical surface area (ECSA), (c) decreased impurities in the CNTs when compared with the Vulcan carbon, (d) higher durability during the electrochemical conditions. Huang et al. [22] showed that P
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