Characterization And Application Of Functional Nanomaterials Prepared By Using Carbon Spheres As Templates

In this dissertation, we prepared a variety of functional nanomaterials with controlled structures and morphologies by using carbon spheres as the hard template. The mophpology and structure of the nanomaterials can be tuned by varying the synthetic method, reaction medium, template pretreatment, adding surfactant, etc. The contents of the dissertation mainly incude four parts.?1? Carbon spheres with hydrophilic surfaces were successfully synthesized by using a hydrothermal route. The diameter of the spheres could be readily tuned over a broad range by controlling the preparation conditions such as the reaction time or reaction temperatures. With the increase of reaction time, the diameter of the carbon spheres increases from 300 nm to 900 nm. The growth of carbon spheres was demonstrated to follow the LaMer model. Besides, the hydrophilic property of the sphere surface can be tune by alkali or acidic pretreatment, the number of hydrophilic groups can be increased by the alkali pretreatment and decreased by theacidic pretreatment.?2? Two types of nanostructures for MgAl2O4 spinel, the hollow spheres and 3D hierarchical structures assembled from 2D thin nanosheets were successfully prepared with carbon sphere as template. Particularly, the achieved materials are highly uniformed in morphologies and the 3D hierarchical Mg Al2O4 owns a relatively large specific surface area of 180 m2.g-1. Interestingly, the syntheses of the two types nanostructures for materials are based on different solvents, in which the growth can be controlled to be either a diffusion controlled one for spheres or a kinetically controlled one for the hierarchical structure. The application of the Mg Al2O4 spinel as metallic Ni supports was examined in CO2 reforming of methane, and the Ni/hierarchical Mg Al2O4 shows remarkably excellent performance in both activity and stability, which should be ascribed to its large surface areas and unique structures.?3? The 3D hierarchical urchin-like and coral-like Co3O4 hollow structure were synthesized via facile hydrothermal method with Co²⁺-functionalized carbon spheres as templates. The hierarchical urchin-like Co3O4 are assembled from radially oriented 1D structures with diameters of 3?m- 5?m. The core of the urchin-like assembly is hollow with typically 600 nm in diameter, and the building blocks?1D structures? are nanowires with typically lengths of 2?m- 4?m. The nanowires are needle-like with widths of 10 nm. While, the coral-like Co3O4 consisted of 1D nanorods with a diameter of 50 nm and the length of 200 nm-300 nm. The observations indicate that the PVP can control the morphology of the precursors to a certain extent due to the PVP coordinate to the Co²⁺ to form complexes in the reaction solution, which hinders the combination of cobalt ions and anions?CO32- and OH-?. The pore-size distribution plots of urchin-like Co3O4 as well as coral-like Co3O4 reveal a bimodal characteristic with a narrow distribution centered at-3 nm and a wide distribution centered at- 40 nm. The two materials both showed very good performance in the photo-catalytic degradation of organic pollution under UV-light irradiation in the presence of H2O2. After four cycles, the urchin-like Co3O4 as well as coral-like Co3O4 both showed good reusability and long-term stability.?4? Dual-porosity Mn₂O₃ cube materials were prepared by using carbon spheres as the hard templates for macropores, while the mesopores are produced by adopting a template-free method. The attained dual-porosity Mn₂O₃ materials have 24 nm of large-pore mesopores and 700 nm of macropores. Besides, the achieved materials own cubic morphologies with particle sizes as large as 6 ?m, making them separable in the solution by a facile natural sedimentation. Dye adsorption measurements reveal that the materials exhibit excellent adsorption performance and recycling usability due to their unique dual porosity distribution.