Synthesis And Properties Of Inorganic Layered Nanomaterials Liquid Control

In this dissertation, based on the comprehensive and thorough investigation of a lot of literatures, I gave a concise review on the structures, properties, applications and preparative methods, elucidated the frontier in the research of inorganic layered nanostructures' synthesis and properties.Following that, 1 developed surfactant-assisted hydrothermal route to prepare antimony nanobelts, flower-like and radial antimony hollow spheres, shale-like bismuth and NiO assembled spheres.γ-AlOOH (boehmite) andγ-Al₂O₃ nanofiber bundles have been synthesized via a convenient quencher method, waste PE film was converted into mesoporous carbon in supercritical water at 550℃. Combining the experimental analysis results and the study of the related reports, I explored their growth mechanisms, respectively. Besides, I investigated the electrochemical and magnetic properties of the NiO assembled spheres and studied the electrochemical hydrogen storage of mesoporous carbons. The research conclusions provide some original and innovative results, and the major contents are summarized as follows:1. The large-scale synthesis of antimony nanobelt bundles has been facilely realized in existence of polyethylene glycol (PEG) by a hydrothermal reduction method using aluminum powder as reducing agent. These nanobelts have width in the range of 200-600 nm and length up to several micrometres, and the width-to-thickness ratio is ca. 10. FESEM images show individual nanobelts have multi-layered structures. The size of nanobelts can be varied by adjusting the molecular weights of PEG. Based on a series of comparative experiments under different reaction conditions, the probable formation mechanism of antimony nanobelt bundles is proposed to be a solid-liquid-solid transformation and surfactant-assisted directional growth process.2. A surfactant-assisted hydrothermal reduction pathway toward various kinds of antimony and bismuth 3D superstructures, containing hollow spheres composed of nanostrips, peony-like architecture, radial sub-micrometer rod bundles and shale-like pattern. These 3D superstructures were obtained through the reduction of SbCl₃ or Bi (NO₃)₃·5H₂O by aluminum powder in different emulsion system at 120℃. The formation mechanism for Sb 3D superstructures has been properly proposed. Some influencing factors on the morphology of the final products have also been discussed. We expect this convenient method can be extended to prepare 3D superstructures of other inorganic materials, which have the similar layered structures to Sb and Bi.3. NiO solid/hollow spheres with diameters about 100 nm have been successfully synthesized through thermal decomposition of nickel acetate in ethylene glycol at 200℃. These spheres are composed of nanosheets about 3-5 nm thick. Introducing poly(vinyl pyrrolidone) (PVP) surfactant to reaction system can effectively control the products' morphology. By adjusting the quantity of PVP, we accomplish surface areas-tunable of NiO assembled spheres from～70 m²g^-1' to～200 m²g^-1. Electrochemical tests show that NiO hollow spheres deliver a large discharge capacity of 823 mAhg^-1. Furthermore, these hollow spheres also display a slow capacity-fading rate. A series of contrastive experiments demonstrate that the surface area of NiO assembled spheres has a noticeable influence on their discharge capacity. In addition, NiO assembled spheres exhibit largish coercive force (～1800 Oe) below the blocking temperature.4.γ-AlOOH (boehmite) nanofiber bundles have been synthesized via a convenient quencher method. Most nanofibers contain even smaller nanowires with an average diameter of 5 nm. A series of contrast experiments reveal that the evolvement from nanosheets to nanofibers occurs in the quencher process.γ-Al₂O₃ nanofiber bundles with mesoporous character can be obtained by calcining relevantγ-AlOOH nanostructures at 500℃.5. Mesoporous carbons were prepared by treating waste polyethylene film in supercritical water at 550℃. High-resolution transmission electron microscopy images reveal that the pore wall has a thickness of 3-4 nm and is composed of discontinuous graphitic layers, which are parallel to the tangent direction of the mesopore. Electrochemical measurements show the discharging capacity of mesoporous carbon is up to 348 mAhg^-1 (corresponding to 1.3 wt% hydrogen storage). When temperature is lower than 450 ℃, only carbon nanofibers were obtained; on the other hand, if reaction temperature is higher than 650℃, carbon nanotubes are the main products. The possible conversion mechanism from polyethylene to mesoporous carbons and other carbon materials is tentatively discussed.