| Metal oxide nanomaterials have significant applications in optics, catalysis, molecular sieve, sensing, energy conversion etc. Hydrothermal treatment is one of the most promising technologies for manufacturing oxide nanomaterials. The main advantage of hydrothermal technology is its ability to easily modulate the composition and micromorphology by changing the related synthesis parameters (such as temperature and duration). In this dissertation, MoO3, MnO2, ZnO, Fe2O3; TiO2 micro/nanomaterials were selected as the research object. Their hydrothermal processes were investigated by in situ calorimetry and XRD,TEM, SEM, IR assistive technology, thereby providing thermodynamics support to the hydrothermal technology of metal oxide nanomaterials. The main research contents and conclusions are presented below:(1) The Zn(OH)42-,Zn(Ac)2+NaOH+C2H5OH and Zn(NO3)2+C2H5OH systems were investigated by in situ calorimetry. Flower-like ZnO nanostructures, ZnO microrods, ZnO nanorods, ZnO microspheres, Zn5(OH)8(NO3)2·2H2O microspheres were prepared via in situ syntheses. A new hydrothermal synthetic way has been developed to prepare Zn5(OH)8(NO3)2·2H2O microspheres.(2) The KMnO4+ HCl and MnS04+NaClO3+PVP systems were investigated by in situ calorimetry. Flower-likeδ-MnO2 microspheres,α-MnO2 nanorod, a-MnO2 nanotube,β-MnO2 nanotube were prepared via in situ syntheses.(3) The Ti(OBu)4+ HCl, (NH4)6Mo7O24+ HNO3+CTAB and FeCl3 solutions systems were investigated by in situ calorimetry. Mesoporous rutile spheres, cauliflower-like TiO2 microspheres, mesoporous rutile nanoplates,α-MoO3 nanobelt,β-FeOOH nanorod,α-Fe2O3 pseudocubes were prepared via in situ syntheses. The formation mechanism of above-mentioned nanostructures was discussed.(4) The low-temperature heat capacities of the metal oxide nanomaterials, namely MnO2, MgO, CeO2, Fe2O3,were measured and fitted in the temperature range from 78 to 378 K.The thermodynamic functions [HT-H298.15] [ST-S298.15] were derived from the heat capacity.
|
PDF Full Text Request