Large-scale Synthesis of Nitrogen-doped Carbon Nanotubes by Chemical Vapor Deposition Using a Co-based Catalyst from Lay
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Large-scale Synthesis of Nitrogen-doped Carbon Nanotubes by Chemical Vapor Deposition Using a Co-based Catalyst from Layered Double Hydroxides Ruili Xue • Zhipeng Sun • Linghao Su Xiaogang Zhang
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Received: 14 December 2009 / Accepted: 27 January 2010 / Published online: 12 February 2010 Springer Science+Business Media, LLC 2010
Abstract A catalyst with active Co particles was obtained by the calcination of Co/Al layered double hydroxides. With this catalyst, large-scale nitrogen-doped carbon nanotubes (N-doped CNTs) were synthesized by chemical vapor deposition at 850 C under a mixture of methane and acetonitrile. CNTs with different nitrogen contents were prepared by changing the flow rates of methane and acetonitrile. SEM, TEM and Raman spectroscopy were used to investigate the structure of the prepared N-doped CNTs. XPS was used to determine the nature of the chemical bonds of nitrogen in N-doped CNTs. The results show that the prepared N-doped CNTs have a uniform structure and a large amount of N doping. Keywords Co-based catalyst N-doped CNTs Chemical vapor deposition Layered double hydroxides
1 Introduction Since Iijima’s landmark papers on carbon nanotubes (CNTs) [1, 2], CNTs have drawn great attention from the scientific community for their potential use as advanced materials, such as functional composites, electrochemical electrodes, semiconductor devices, field emission devices and catalyst supports [3–6]. Up to now, several methods have been used to prepare CNTs, such as arc-discharge, laser ablation and chemical vapor deposition (CVD). Compared with other methods, CVD has been widely investigated in the
R. Xue Z. Sun L. Su X. Zhang (&) College of Material Science and Engineering, Nanjing University of Aeronautics and Astronautics, 210016 Nanjing, People’s Republic of China e-mail: [email protected]
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production of CNTs as well as CNT architectures and assemblies due to its flexibility and capability of large scale and high quality preparation in the past decade [7, 8]. CNTs produced by CVD grow through the catalytic decomposition of a carbonaceous gas on nanometric metal particles, which are typically transition metals (Fe, Co, Ni and their alloys) supported over materials with a large surface area to disperse and stabilize the metallic particles, such as metal oxides, silica and different types of zeolites. The precipitation of carbon from the saturated metal particles strongly depends on the characteristics of the catalyst. Hence, during the CVD process, the particle size and particle dispersion of the catalyst are always key factors for controlling the growth of nanotubes. Thus, not only should the type of catalyst be taken into consideration, but other experimental conditions should be considered as well for the successful controlled growth of carbon nanostructures. Recently, considerable research has explored the effect of doping CNTs with various atoms, including P, N, and B [9–11]. Research indicates that the insertion of different atoms into the nanotube lattice can alter t
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