A simple method to ordered mesoporous carbons containing nickel nanoparticles
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A simple method to ordered mesoporous carbons containing nickel nanoparticles Xiqing Wang · Sheng Dai
Published online: 20 March 2009 © Springer Science+Business Media, LLC 2009
Abstract A series of ordered mesoporous carbons containing magnetic Ni nanoparticles (Ni-OMCs) with a variety of Ni loadings was made by a simple one-pot synthetic procedure through carbonization of phenolic resin-Pluronic block copolymer composites containing various amount of nickel nitrate. Such composite materials were characterized by N2 sorption, XRD, and STEM. Ni-OMCs exhibited high BET surface area, uniform pore size, and large pore volume without obvious pore blockage with a Ni loading as high as 15 wt%. Ni nanoparticles were crystalline with a facecenter-cubic phase and observed mainly in the carbon matrix and on the outer surface as well. The average particle size of Ni nanoparticles was dependent on the preparation (carbonization) temperature and Ni loading; the higher the temperature was used and the more the Ni was incorporated, the larger the Ni nanoparticles were observed. One of the applications of Ni-OMCs was demonstrated as magnetically separable adsorbents. Keywords Ordered mesoporous carbon · Magnetic · Adsorbent · Nickel · Synthesis
1 Introduction Ordered mesoporous carbons (OMCs) have recently attracted much attention because of their structural regularity,
Dedicated to Professor Mietek Jaroniec on the occasion of his 60th birthday. X. Wang · S. Dai () Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6201, USA e-mail: [email protected]
chemical and thermal stabilities, and electrical conductivity (Liang et al. 2008). Incorporation of magnetic metal or metal oxide nanoparticles into OMCs without the blockage of mesoporosity is of great interest since it enables an alternative and simple separation of OMCs by means of an external magnetic field. Therefore, such composite materials are potentially useful as magnetically separable catalysts (Lee et al. 2005b), catalyst supports (Lu et al. 2004; Tian et al. 2007), and adsorbents (Cao et al. 2007b). OMCs containing magnetic nanoparticles have so far been prepared by two general methods. The first method is to deposit or load magnetic nanoparticles on the presynthesized OMCs, which are prepared using ordered mesoporous silicas as the hard templates (Cao et al. 2007b; Lee et al. 2005b; Lu et al. 2004; Tian et al. 2007). For example, Lu et al. fabricated magnetic CMK-3 by depositing Co nanoparticles on the outer surface of a carbon/SBA15 composite with coating of a thin carbon layer on Co nanoparticles to anchor them on the surface of CMK-3 and to prevent dissolution by HF. This method could be simplified by impregnation of a solution of iron salt or nickel salt into the pores of C/silica composites or OMCs, followed by the reduction of iron or nickel salt into magnetic Fe3 O4 (Lee et al. 2005b; Tian et al. 2007) or Ni nanoparticles (Cao et al. 2007b), respectively. In the second method, ordered mesoporous silicas were pre-loaded with magne
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