Studies On The Synthesis And Application Of Multifunctional Carbon Nanocomposites Derived From Layered Double Hydroxides

Carbon nanocomposites have used in energy storage and conversion, drug delivery, contaminants removal, catalysis and other fields, due to they combine with the excellent performance of carbon and inorganic nanoparticles. However, carbon nanocomposites are synthesized by carbon materials, such as graphene and carbon nanotubes. They are worse uniformity, inorganic nanoparticles are easy to gather together, and systhesis methods are complicated. Therefore, finding a simple and efficient method to prepare carbon nanocomposites with uniformity size and high dispersion is an important topic. In this paper, we synthesis high quality and multifunctional carbon/metal/metal oxide nanocomposites through an in situ solid synthesis process using layered double hydroxide intercalated with organic anions as precursors. This paper focused on their application in pollution removal and catalyst support. The main results of this paper are as follow:1. We successfully synthesized hexagonal C/Co/Mg(Al)O and C/Co/Al2O3 nanocomposites through an in situ solid synthesis process using layered double hydroxides intercalated with salicylate anions (CoMgAl-sal LDH and CoAl-sal LDH) as precursor. The influences of the proportion of metal elements and pyrolysis temperature on the composition and structure of the nanocomposites have been studied. The results indicated that hexagonal precursors with diameter of of 0.5-4μm and thickness of 50-200nm. Co nanoparticles about 8nm and metal oxide in the range of 3-5nm are uniformly embedded in carbon matrix. The surface of C/Co/Mg(Al)O nanocomposites are functionalized with-OH and-COO-groups. The nanocomposites exhibit high specific surface areas and typical ferromagnetic behaviors.2. The obtained C/Co/Mg(Al)O nanocomposites were used as adsorbents in water treatment. The influence of calcinations temperature, metal elements proportion, pH and temperature of solution have been studied. The results revealed that C/Co/Mg(Al)O nanocomposites exhibit excellent adsorption properties on anionic dyes Congo Red, Orange Ⅱ, Methyl Orange and Evans Blue, especially for Congo Red (Qmax=2787mg/g). The nanocomposites can be easily recycled and reused. Further mechanism study indicates the nanocomposites recover the layered structures in aqueous solution, which provide more active sites contacting with dyes. The presence of functional groups on the surface of carbon and a lot of pore makes C/Co/Mg(Al)0 nanocomposites owned excellent adsorption properties.3. We synthesized hexagonal C/Mg(Al)O nanocomposites through an in situ solid synthesis process using layered double hydroxides intercalated with salicylate anions (MgAl-sal LDH) as precursor. Without templates and catalysts, hexagonal porous carbon nanosheets were prepared through acid dissolution of C/Mg(Al)O nanocomposites. The porous carbon nanosheets are ideal catalyst supports due to exhibiting high specific surface areas, high stability, and the surface of them are functionalized with-OH and-COO-groups. We successfully synthesized C/Ag catalysts without reducing agent by impregnation technology. The Ag nanoparticles (8nm) homodispersed on the porous carbon support. The catalysts exhibit high catalytic activity and stability for the reduction of p-nitrophenol by NaBH4.