Shape-Controlled Synthesis And Performance Study Of Lanthanum Oxide With Hierarchical Structure

As one of the most important rare earth oxides, La2O3 has plenty of property, such as resistance to high temperature, large specific surface area and high catalytic activity. La2O3 had been used to make optical glasses and fibers. It is also an ingredient for the manufacture of piezoelectric and thermoelectric materials as well as dielectric and conductive ceramics. Various La2O3 nanostrucstures such as nanoparticals, nanorods, nanowires and nanotubes had been prepared and reported. Recently, the synthesis of lanthanum oxide (La2O3) micro/nano-materials with hierarchical structures has attracted increasingly great attention and possessed more advantages, such as rich mesopores and large specific surface area, which were composed of smaller nanoparticles, nanofibers or nanoflakes.In this thesis, three different morphologies of La2O3 micro/nano-structrues have been synthesized by a simple urea precipitation. X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), thermo gravimetric thermal analysis (TG-DTA), scanning electron Microscope (SEM), high resolution transmission electron microscopy (HRTEM) were used to analysis the composition, structure and morphology of the products. Meanwhile, the as-prepared La2O3 nanomaterials were used to investigate the performance such as phosphate adsorption, growth inhibition of bacteria, and degradation of rhodamine B solution under visible light. Some results were obtained as follows.(1) Preparation of three different La2O3 nanomaterials:three different morphologies such as spindles, polyhedrons and spheres were prepared via urea precipitation. Results showed that the resultant morphologies of La2O3 might be influenced by concentration of the reactants, reaction temperature and cooling treatment. When the ratio of the concentration of La (NO3)3 to CO (NH2)2 is 1/2, spindles of La2O3 nanostructures were synthesized at 90℃; When the ratio is 1/6, polyhedrons of La2O3 nanostructures were prepared at 125℃; When the ratio is 1/400, spheres of La2O3 nanostructures were obtained at 85℃.(2) Three different morphologies of La2O3 nanostructures were used to investigate their performance such as phosphate adsorption, growth inhibition of bacteria and photocatalytic degradation. Results show that three La2O3 nanostructures exhibit phosphate adsorption ability and can inhibit the growth of bacteria to varying degrees. The smaller the assembled particles of hierarchical structures are, the stronger their phosphate adsorption ability is.