Formation of Graphitic Structures in Cobalt- and Nickel-Doped Carbon Aerogels
2005; American Chemical Society; Volume: 21; Issue: 7 Linguagem: Inglês
10.1021/la047344d
ISSN1520-5827
AutoresRuowen Fu, Theodore F. Baumann, Steve P. Cronin, G. Dresselhaus, M. S. Dresselhaus, Joe H. Satcher,
Tópico(s)Fiber-reinforced polymer composites
ResumoWe have prepared carbon aerogels (CAs) doped with cobalt or nickel through sol−gel polymerization of formaldehyde with the potassium salt of 2,4-dihydroxybenzoic acid, followed by ion exchange with M(NO3)2 (where M = Co2+ or Ni2+), supercritical drying with liquid CO2, and carbonization at temperatures between 400 and 1050 °C under a N2 atmosphere. The nanostructures of these metal-doped carbon aerogels were characterized by elemental analysis, nitrogen adsorption, high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD). Metallic nickel and cobalt nanoparticles are generated during the carbonization process at about 400 and 450 °C, respectively, forming nanoparticles that are ∼4 nm in diameter. The sizes and size dispersion of the metal particles increase with increasing carbonization temperatures for both materials. The carbon frameworks of the Ni- and Co-doped aerogels carbonized below 600 °C mainly consist of interconnected carbon particles with a size of 15−30 nm. When the samples are pyrolyzed at 1050 °C, the growth of graphitic nanoribbons with different curvatures is observed in the Ni- and Co-doped carbon aerogel materials. The distance of graphite layers in the nanoribbons is ∼0.38 nm. These metal-doped CAs retain the overall open cell structure of metal-free CAs, exhibiting high surface areas and pore diameters in the micro- and mesoporic region.
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