Synthesis And Characterization Of Transition-Metal Oxides Nanomaterials

The structure,shape-control and properties of inorganic nanomaterials have been the key issues in modern synthesis of materials. This paper aimed to explore new solution chemical routes for the synthesis of inorganic transition-metal oxides nanomaterials. By systematical adjusting the crucial factors in the solution systems, CuO and MnO₂ nanomaterials with different morphologies and phases have been successfully synthesized and the possible formation mechanisms for these materials have also been discussed. The results can be summarized as follows:1. CuO shuttle-like nanocrystals have been successfully synthesized by a surfactant-assisted hydrothermal reaction of Cu(CH₃COO)₂·H₂O and NaOH. The shuttle-like aggregates are made of nanorods by oriented attachment. Experimental factors such as reaction temperature, reaction time, copper source, and surfactant (CTAB) existing in the reaction system will remarkably affect the morphologies of the target. A possible mechanism for these shuttle-like aggregates is discussed.2. With the assistance of HMTA (CH₂)₆N₄, CuO hollow spheres assembled by nanoparticles were fabricated by hydrothermal route. In this system, HMTA acted as not only coordination compound, but also the substance releasing ammonia and carbon dioxide, which can offer soft template for the synthesis of hollow spheres. Experimental factors such as reaction temperature and the molar ratio of reactants have crucial effects on the resulting samples. The possible formation mechanism for the CuO hollow spheres has been proposed.3. For the release of ammonia and dioxide by urea at high temperature, the gases could act as the soft template for the hollow spheres. The CuO hollow spheres have been prepared using urea and copper acetate as reactants through hydrothermal treatment. The hollow spheres are assembled by nanoparticles, its formation mechanism is similar to that of CuO hollow spheres prepared with HMTA. The paramagnetism of the CuO hollow spheres has also been investigated. The results showed the hollow spheres represent hyper-fine signals, which is caused mainly by the absorbance oxygen or the imperfections.4.α-,β-,δ-,-MnO₂ have been successfully synthesized through a novel redox in diluted HC1 or distilled water by adjusting the reaction process. The MnO₂ samples with different phase have different morphologies. They represent 1D rod (wire, needle)-like, hollow octahedron, sheet-assembled flower-like,nanostructures. Experimental results indicated that reaction temperature, reaction time, pH value, and the molar ratio of reactants are of great importance to the phase and morphologies of the samples. In the sunshine, these three kinds of MnO₂ all have catalytic properties on the degradability of MB, and it will be helpful to manage pollution.