Synthesis And Characterization Of Molybdenum Based Non-Metal Materials

The goal of this dissertation is to explore the synthesis and characterization of some molybdenum based inorganic materials and their related nanostructures. Based on a wide and in-depth literature investigation, the author successfully synthesized MoO₃, MoO₂ and MoN via hydrothermal or ethanothermal route and investigated the catalytic property of MoO₃. The details are summarized as follows:1. Single crystalline nanobelts or nanoribbons and spherical or flowerlike hierarchical structures of α-MoO₃ were obtained through homogeneous precipitation and subsequent hydrothermal treatment. It has been found that temperature, concentration of cationic surfactant cetyltrimethylammonium bromide (CTAB), and the addition order of reactants are the three critical factors for the assembly of nanobelts in the current process.2. Synthesis of porous molybdenum dioxide MoO₂ with one-dimensional (1D) and spherical morphology in aqueous solutions has been investigated systematically by varying the precursors and the reducing agents as well as the reaction temperature and durations. The average diameter of the MoO₂ nanofibers is about 80-225 nm, and the length is up to 2 μm. The average diameter of the MoO₂ nanospheres is about 260-500 nm. The reduction of precursor yields metastable amorphous oxide of lower-valence molybdenum, which will crystallize around 400°C after calcinations. It has been found that the 1D morphology of the trioxide precursor and the hydrogen bonds associated with organic acid play a decisive role in determining the size and shape of the final product. The current method provides an approach to fabricate porous structure from a shaped template through redox etching process at ambient temperatures.3. The Pechini process was modified to provide an ethanothermal reduction route to molybdenum dioxide microspheres at ambient temperature. The effects of citric acid (CA), ethylene glycol (EG), and H₂SO₄ environment on the formation of molybdenum oxide (MoO₂) were studied. Nanoparticles with the average diameter...