Hydrothermal/solvothermal Synthesis, Characterization And Performance Research Of Transitional Metal-based Micro-/nano- Materials

Nanostructured materials have aroused a worldwide interest because of their unique properties that are notably different from bulk materials and single molecules. Many studies found that the shape, dimension, structure, size and phase of nanomaterials play an important role in their properties. Therefore, how to effectively control these factors has been frontier fields and hot research topics in material science. Synthesizing nano-materials by hydrothermal/Solvothermal method is a noticeable field in material science. By this friendly method, well discreted and crystalline nanoparticles can be prepared, as well as toxic reaction can also be taken in this system. In this thesis, novel hydrothermal/solvothermal methods were carried out to prepare transitional metal-based micro-/nano- materials. The preparation parameters were fully optimized, the properties and the growthmechanisms were also investigated and proposed. The control of size, shape and phase of transitional metal-based micro-/nano- materials during the synthesis process has been successfully realized, and some novel synthetic routes to transitional metal-based micro-/nano- materials have been established. The main contents of this work are summarized as follows.1. Honeycomb-like Ni@C composite nanostructures have been successfully prepared via a simple two-step solution route. Homogeneous Ni nanospheres with the average diameter of ¹00 nm were firstly obtained via a DMF-water mixed solvothermal route; then honeycomb-like Ni@C composite nanostructures were prepared through the hydrothermal carbonization of glucose solutions with suitable amounts of Ni nanospheres. It was found that the as-obtained honeycomb-like Ni@C composite nanostructures showed good electrochemical properties and could be used as an electrochemical sensor for the detection of glucose molecules. Furthermore, the honeycomb-like Ni@C composite nanostructures presented good capacities for selective adsorption of Pb²⁺, Cd²⁺ and Cu²⁺ ions in water, and could be easily separated from water and reused.2. In this paper, we employed a facile hydrothermal route to successfully synthesize nanosized nickel phosphide particles with controlled phases, using nontoxic red phosphorus and nickel dichloride as the starting materials, via selecting different surfactants at different temperatures and times. Furthermore, the experiments indicated that the pure Ni₂P phase possessed stronger photocatalytic degradation ability than the pure Ni1₂P₅ phase.3. In this paper, we reported the successful synthesis of hollow hemispherical Mn11(HPO3)8(OH)6 superstructures on a large scale via a facile mixed-solvothermal route without assistance of any surfactant, employing MnAc₂·4H₂O and NaH₂PO₂·H₂O as the reactants, the mixture of N,N-dimethylformamide (DMF) and water as the solvent. The reaction was carried out at 160°C for 1₂ h. Some factors influencing the morphology of the hollow hemispherical Mn11(HPO3)8(OH)6 superstructures, such as the reaction temperature, time, the amount of NaH₂PO₂, and the volume ratio of DMF/water, were systematically investigated. A possible growth mechanism was proposed based on experimental results.