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Preperation And Characterization Of Nano-Carbon And Nano-ZnO Particles In Micropous Crystals

Posted on:2005-06-27Degree:DoctorType:Dissertation
Country:ChinaCandidate:C Y XiFull Text:PDF
GTID:1101360152956679Subject:Inorganic Chemistry
Abstract/Summary:PDF Full Text Request
Zeolites, which possess regular channel and cage structures, have been utilized as the hosts for the templated synthesis of novel materials. There has been a recent avalanche of literature focused on the templated synthesis of new carbon materials such as porous carbon, fullerenes and carbon nanotubes, due to the interesting physical, magnetic and electronic properties these new materials possess. Under general conditions, carbon sources are introduced externally into the channels and cages of zeolites. In this word, however, we use the organic structure-directing agent for the formation of zeolites as carbon sources. Under the pyrolysis condition, the interaction of the organic structure-directing agent and zeolites framework causes uniform collapsed space in the zeolite single crystals. Utilizing these uniform hole and regular cages of zeolites, we prepared PAHs (polyclycyclic acromatic hydrocarbons) and nanographite particles. We studied magnetic and electrochemical properties of the nanographite particles.Perfect gallophosphate GaPO4-LTA single crystals, with the LTA framework structure, have been synthesized using (-methly pyridine as the structure-directing template. We studied the pyrolysis of mPy in the α-supercage of GaPO4-LTA under vacuum or in a nitrogen flow. Under these conditions, PAHs are produced in the α-cages. The species of PAHs are closely related to the rate of temperature increase and the terminated temperature. The PAHs formed in the cages of GaPO4-LTA may act as a precursor for the formation of small fullerene molecules by further rearrangement in the inorganic host.Utilizing reasonable heating programme, we prepared nanographite with uniform sized by pyrolysis of (-methly pyridine in the GaPO4-LTA framework at 760 oC. The as-prepared nanographite has been examined by Raman spectroscopy, transmission electron microscopy (TEM), electron spin resonance (ESR) and magnetization characterizations. The TEM image shows that the size of individual nanographite particles is about 7 nm, and it is proved that there are spins of sp2-type (π-type) radical electrons localized on the zigzag edge sites of the nanographite. The magnetic susceptibility of the nanographite shows crossover from a high-temperature diamagnetic to a low-temperature paramagnetic behavior, in good agreement with the theoretical expectation.Using SAPO-44 with the organic structure-directing as precursor materials, nanographite particles were synthesized at 850 oC. We studied electrochemical properties of lithium into-out these nanographites particles. The charge-discharge cycling tests revealed that the cycling efficiency of the nanographite particles prepared at 850 oC is higher than MCMB, which is one of the commercial carbon materials in lithium cells.Nano-sized ZnO particles were prepared via heating the Zn(Ac)2-loaded SAPO-34. We studied the luminescence properties of ZnO/SAPO-34 composites calcined at different temperatures.
Keywords/Search Tags:Characterization
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