Preparation of carbon-coated magnetic iron nanoparticles from composite rods made from coal and iron powders Jieshan Qiu a,b, * , Yongfeng Li a , Yunpeng Wang a , Yuliang An a , Zongbin Zhao a , Ying Zhou a,b , Wen Li c a Carbon Research Laboratory, School of Chemical Engineering, Center for Nano Materials and Science, State Key Lab of Fine Chemicals, Dalian University of Technology, 158 Zhongshan Road, P.O. Box 49, Dalian 116012, China b State Key Laboratory for Materials Modification by Laser, Ion and Electron Beams, Dalian University of Technology, Dalian 116024, China c State Key Laboratory of Coal Conversion, CAS, P.O. Box 165, Taiyuan, Shanxi 030001, China Accepted 30 March 2004 Abstract We report the preparation of carbon-coated magnetic iron nanoparticles with diameters mainly around 40–55 nm from iron-filled coal-derived hollow carbon rods by arc discharge. These monodispersed carbon-coated iron nanoparticles were found in the soot-like deposits formed around the cathode. The transmission electron microscopy and X-ray diffraction studies show that these nanoparticles are perfectly coated with graphitic carbon shells with a thickness of 20–30 nm. A simple model is proposed to explain the growth of the carbon-coated metal nanoparticles in terms of the properties of coal-derived carbon and the arcing conditions. D 2004 Elsevier B.V. All rights reserved. Keywords: Carbon onions; Coal; Arc discharge; Encapsulated nanomaterials 0378-3820/$ - see front matter D 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.fuproc.2004.03.006 * Corresponding author. Carbon Research Laboratory, School of Chemical Engineering, Center for Nano Materials and Science, State Key Lab of Fine Chemicals, Dalian University of Technology, 158 Zhongshan Road, P.O. Box 49, Dalian 116012, China. Fax: +86 411 8363 3080. E-mail address: jqiu@dlut.edu.cn (J. Qiu). Fuel Processing Technology 86 (2004) 267– 274 www.elsevier.com/locate/fuproc