Preparation And Characterization Of Functional Hybrid Materials Based On Layered Double Hydroxides

Layered double hydroxides (LDHs) are a series of anionic layered nanomaterials with attractive and unique properties such as controllable morphology and tunable composition. In recent years, hybrid materials have been continuously developed and utilized. By applying hybridization technique, on one hand, optimization of physical and chemical properties of different nanomaterials can be achieved; on the other hand, synergistic effect between different nanoparticles can bring novel functions to the hybrids. Therefore, hybridization of LDHs nanoplatelets and other nanoparticles can simultaneously maximize the advantages of both LDHs and other nanoparticles, thus broadening the application of LDHs.In this thesis, two kinds of LDH-based hybrid materials were prepared via electrodeposition and hydrothermal in-situ growth approaches, and the applications in the fields of electrochemical sensors and dye adsorption of the hybrid materials were studied and discussed. The research content of this thesis mainly consists of two parts:In the first part, LDHs which can form stable suspension in aqueous systems were synthesized successfully. Certain amount of the as-prepared LDH suspension was dropped onto the surface of glassy carbon electrodes. By electrodepositing Ag+on glassy carbon electrodes modified with LDHs, Ag nanodendrites/LDH hybrid hierarchical structure modified glassy carbon electrodes were obtained. Electrochemical and morphology characterizations were carried out to investigate the growth mechanism of Ag nanodendrites. Results indicate that the introduction of LDH substrate can reduce the reduction rate of Ag+, leading to the formation of smaller and denser Ag nanodendrites. After optimization of experimental conditions, a H2O2sensor with a wide linear range (10μM～19.33mM), a low detection limit (2.2μM) and fast response time (less than3s) was obtained. This sensor also exhibited good selectivity and reproducibility. In the second part, graphene oxide (GO)/LDH hybrid was synthesized by in-situ growth of NiAl-LDHs on the surface of GO nanoplatelets under hydrothermal condition. Morphological characterizations indicated that LDHs were evenly distributed on the surface of GO, and thus the aggregation of... was successfully avoided. Magnetic reduced graphene oxide (rGO)/Ni/mixed metal oxide (MMO) hybrid nanomaterials were synthesized by calcining GO/LDH hybrid in nitrogen atmosphere. The ability of dye removal of rGO/Ni/MMO hybrid was tested. The rGO/Ni/MMO hybrid was found to possess excellent adsorption ability toward methyl orange (maximum adsorption capacity:210.8mg g-1). The dye removal process was found to obey the Redlich-Peterson isotherm model and its adsorption kinetic follows pseudo-second-order rate equation. This magnetic hybrid nanomaterial also exhibits good recycle ability for dye removal, demonstrating great potential in the applications of environment protection and water treatment.In this thesis, hybrid nanostructures were successfully synthesized by loading other nanoparticles on LDHs substrate and loading LDHs on other nanoparticles. The relationship between structure and performance of these hybrid nanostructures has been investigated. The results obtained in this thesis will provide supplement for the design of LDH-based hybrid nanomaterials experimentally and theoretically, and will be also beneficial for the preparation of high-performance functional nanocomposites.