Organic-Inorganic Layered Metal Hydroxides And Their Derived Carbon-Based Nanocomposites:Controllable Synthesis, Characterization And Application

Over the past decades, organic-inorganic layered metal hydroxides have been received much attention due to their fascinating features. Meanwhile, the layered metal hydroxides are also important precursors to achieve novel metal oxide, sulfide, nitride, and carbide nanostructures via secondary treatments, indicating new opportunities to design various functional materials In this dissertation, we report the facile synthesis and characterization of high-quality, organic-inorganic layered hydroxide. By choosing appropriate organic-inorganic nanomaterials precursors and under suitable experimental conditions, desired nanomaterials (CoxNi1-x@C, ZnO@C, Ag@C) with special morphologies and excellent properties are synthesized. The detained contents are listed as follows:1. New pink organic- inorganic layered cobalt hydroxide nano-fibers intercalated with benzoate ions [Co(OH)(C6H5COO)·H2O] have been synthesized by using cobalt nitrate and sodium benzoate as reactants in water with no addition of organic solvent or surfactant. The high-purity nanofibers are single-crystalline in nature and very uniform in size with a diameter of about 100 nm and variable lengths over a wide range from 200 ?m down to 2 ?.m by simply adjusting reactant concentrations. Our results demonstrate that the structure consists of octahedral cobalt layers and the benzoate anions, which are arranged in a bilayer due to the ?-? stacking of small aromatics. The carboxylate groups of benzoate anions are coordinated to Co" ions in a strong bridging mode, which is the driving force for the anisotropic growth of nano fibers. When NaOH is added during the synthesis, green irregular shaped platelets are obtained, in which the carboxylate groups of benzoate anions are coordinated to the Co? ions in a unidentate fashion. Interestingly, the nano fibers exhibit a reversible transformation of the coordination geometry of the Co? ions between octahedral and pseudotetrahedral with a concomitant color change between pink and blue, which involves the loss and reuptake of unusual weakly coordinated water molecules without destroying the structure. This work offers a facile, cost-effective, and green strategy to rationally design and synthesize functional nanomaterials for future applications in catalysis, magnetism, gas storage or separation, and sensing technology.2. The highly stable Co nanoparticles embedded in graphitic carbon nanorods have been in situ synthesized by one-step solid-state pyrolysis of simple metal-organic cobalt hydroxide nanorods precursor. With the low cost of Co(OH)(C6H5CO3)·H2O nanorods, this method avoids the requirements for hard templates, complicated activations, aggressive chemicals and specific precursors, and could be industrially feasible. The as-prepared Co@C nanorods show enhanced magnetic behavior, and excellent catalytic activity toward the reduction of 4-nitrophenol (4-NP) by NaBH4, which can be easily recycled by an external magnet after the catalytic reduction. The catalysts can be successfully recycled and reused for at least nine successive cycles of reaction with stable conversion efficiency of around 100%, which make the products be attractive materials for various potential applications. After acid treatment, the metal cobalt was removed, and the porous carbon with the rod-like morphology was obtained. This work offers a facile, cost-effective, green, and scalable strategy to rationally design and synthesize multifunctional nanomaterial for future applications in catalysis, magnetism, separation, and electrochemistry.One-dimensional CoxNi1-x@C nanocomposites have been prepared by one-step solid-state pyrolysis of simple metal-organic hydroxide nanorods precursor; the metal composition can be freely manipulated by tailoring the molecular composition of the CoxNi1-x(OH)(C6H5CO3)H2O precursors.3. We present a facile and scalable in situ synthesis strategy to fabricate two different of ZnO/carbon nanocomposites derived from the layered zinc hydroxides with interlayer salicylate anions precursor. The precursors were prepared by the coprecipitation method. After calcinating, the ZnO nanoparticles are homogeneously dispersed in the carbon matrix. The ZnO/carbon nanocomposites exhibit higher photocatralytic activity and adsorptivity than commercial ZnO and P25 under visible light irradiation. By investigating the effect of different form of carbon on the photocatalytic activity and adsorption, we found that the fluorescent carbon nanoparticles show better performance than the graphitic carbon. It is hoped that our work could sever a valuable source of reference on fabricating ZnO/carbon nanocomposites for their application as a photocatalyst in the bioscience and energy energy technology.Several kinds of porous carbon nanoplates are easily prepared by using layered zinc hydroxides with interlayer salicylate anions precursor. The Brunauer-Emmett-Teller (BET) surface areas for five NPC samples obtained by carbonizing at the temperatures from 600 to 900? fall into the range from 678 to 3403 m2 g-1. Novel type of Ag@C nanocomposite have been fabricated through in situ reduction of AgNO3 by hydroxylic groups on carbon nanoplates and show excellent catalytic activity toward the reduction of 4-nitrophenol (4-NP) by NaBH4.