Synthesis, Characterization, and Applications of Nano-functional Transition Metal Oxides Materials and Graphite Anode Modified by CVD Carbon Coating
ProQuest, 2008 - 145 pages
This research consists of two major sections. The first section of this research is focused on developing novel synthesis methods, characterization, and catalytic applications of multi-functional transition metal oxides including manganese oxide nano-materials (2x2 tunel structured manganese oxide octahedral molecular sieve), 3D hierarchical nano-architecture epsilon-MnO2 and cobalt oxides, and cobalt based materials. Manganese oxide octahedral molecula sieves (OMS) have ID open framework structures with various theoretical nano-scale tunnel size materials have been investigated extensively as low cost and environmentally benign ionic and molecular sieves and efficient redox catalysts. A novel and efficient solvent-free method has been developed to synthesize manganese oxides with 2 x 2 tunnel structures. The properties of the synthesized OMS-2 materilas have been compared with that synthesized by conventional reflux and hydrothermal methods. Epsilon manganese dioxides with controlled novel 3D architectures have been fabricated via a hydrothermal chemical reaction. The effects of reaction time and reaction temperature on the morphology of the final epsilon-MnO2 are investigated, and the formation mechanisms of the hierarchical nano-architectures are proposed. The magnetic properties of epsilon-MnO2 are also studied. Resides manganese oxides, a microwave-heating reflux route has been used to synthesize 3D flower like cobalt hydrotalcite-like compounds with layered structure and these compounds can be transferred into spinel structure of Co3O 4. Both materials show the electrocatalytic activity and stability for the electrochemical reduction of oxygen. Therefore these materials have the potential to be electrocatyltic catalysts.
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SYNTHESIS AND CATALYTIC ACTIVITY
HYTHERMAL GROWTH OF MANGANESE
SYNTHESES OF NANOSTRUCTURES OF COBALT
CARBON FILM GROWTH ON IRON SUBSTRATES BY A
adsorption anode branches C03O4 samples calcination catalytic activities central axis Chemical Vapor Deposition chemisorption cobalt hydrotalcite-like compounds compounds and C03O4 cryptomelane crystal growth Crystallite crystallographic CVD carbon coating CVD treatment cycle cyclohexanol deposition temperatures different deposition different temperatures dioxide disordered carbon e-MnCh electrode electrolyte Fe substrates ferromagnetic FESEM images Figure formed graphite electrode graphite particles graphite powder graphite surface hexagonal hierarchical architectures HRTEM HRTEM image hydrotalcite hydrothermal ions irreversible capacity K-OMS-2 materials prepared K-OMS-2s nano-rods lattice fringes lithium lithium ion batteries magnetic properties mAh/g manganese oxide mesopores microstructure microwave molecular sieves morphology nano nano-materials nano-structures nanoflakes nucleation OMS materials phase Physisorption precipitator precursor produced on Fe pyramids Raman spectra reaction temperature redox reflux method samples prepared scan shown in Fig shows Sol-gel solution solvent solvent-free method spectra of carbon studied synthesized templates total pore volume tunnel structure uncoated graphite X-ray diffraction X-ray diffraction patterns XRD patterns