Cabon Nanofibrous Materials Prepared from Electrospun Polyacrylonitrile Nanofibers for Hydrogen Storage
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Cabon Nanofibrous Materials Prepared from Electrospun Polyacrylonitrile Nanofibers for Hydrogen Storage S. H. Park1, B. C. Kim1, S. M. Jo, D. Y. Kim, and W. S. Lee Polymer Hybrid Research Center, Korea Institute of Science and Technology, 39-1, Hawolgok dong, Seongbuk-gu, Seoul 136-791, Republic of Korea 1 Division of Applied Chemical Engineering, Hanyang University, 17, Haengdang-dong, Seongdong-Ku, Seoul 133-791, Republic of Korea ABSTRACT Electrospun PAN nanofibers were carbonized with or without iron(III) acetylacetonate to induce catalytic graphitization within the range of 900-1500oC, resulting in ultrafine carbon fibers with the diameter of about 90-300 nm. The structural properties and morphologies of the resulting carbon nanofibers were investigated using XRD, Raman IR, SEM, TEM, and surface area/pore analysis. The PAN-based carbon nanofibers carbonized without a catalyst had amorphous structures, with d002 = 0.37 nm, and smooth surfaces with very low surface areas of 22-31 m2/g. The carbonization of PAN-based nanofibers in the presence of the catalyst produced the graphite nanofibers (GNF) with d002 = 0.341 nm, indicating turbostrate structures. The graphite structures were grown by increasing the catalyst contents and the carbonization temperature. The hydrogen storage capacities of the aforementioned carbon nanofiber materials were evaluated through the gravimetric method using Magnetic Suspension Balance (MSB) at room temperature and at 100 bars. The storage data were obtained after the buoyancy correction. The CNFs showed hydrogen storage capacities of 0.16-0.50 wt.%, increasing with the increase of carbonization temperature, but that of the CNF at 1500oC was lowest. The hydrogen storage capacities of the GNFs with low surface areas of 100-250m2/g were 0.14-1.01 wt%. INTRODUCTION Hydrogen storage in carbon materials is very attractive because high gravimetric storage capacities may be possible due to the low specific weight of carbon. Since hydrogen storage using carbon nanomaterials was first reported by Dillon et al. [1], several studies on hydrogen storage using single wall nanotube(SWNT), multi wall nanotube(MWNT), graphite nanofiber(GNF), etc., have been conducted [2-4]. The recent hydrogen storage capacity of SWNTs measured using volumetric method, however, showed scattered capacities within the range of 0.03-4 wt% at room temperature because of introduction of some error during the measurement [5,6]. The SWNTs in more accurate volumetric measurement showed low capacity within the range of 0.14-0.43 wt%. Those of MWNT and graphite powder were less than 0.04 wt% [7]. Typical carbon materials, such as active carbon, active carbon fiber, and graphite powder, were also investigated as potent materials for hydrogen storage [8-9]. They have very low capacities at room temperature because their pores that are effective for hydrogen storage are too few, although they generally have very high surface areas.
N3.14.2
There is a growing interest in the electrospinning process of polymer solution
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