Synthesis Of Zn@Cu Layered Dounble Hydroxides Nanocomposite And The Photocatalytic Application

Nano-ZnO and ZnS as wide band gap semiconductors are good photocatalysts, the electron and hole pairs of ZnO and ZnS nanomaterials generate very fast under UV irradiation, the photo-generated electrons and holes also have a strong oxidation-reduction capacity. Carbon nanomaterials such as grapheme, carbon fiber and so on become excellent catalyst carriers because of their good conductivity and stability. In recent years, ZnO and ZnS nano-carbon composite materials in the environment and energy sectors showed good prospects, but there are still some problems in practical application:1. ZnO and ZnS nanomaterials easily aggregate, poor stability because of the nanometer size effect between particles.2. The catalytic effect of ZnO and ZnS in the visible range is weak, of the natural energy sunlight can not be making good use of. Based on the preparation and application problems of ZnO and ZnS nanomaterials, this thesis has prepared two Ternary nanocomposites with uniform and stable, good visible catalytic performance property, by solid-situ pyrolysis reaction, and using Organic-inorganic layered metal hydroxide as the precursor:one-dimensional Cu/ZnO/C and 1D Zn1-xCu2xS/C. And their visible degradation of MB and photocurrent response have been studied. Details are as follows:1.We have prepared the one-dimensional ZnCu(OH)BA-LDH nanomaterials for the first time,using the zinc nitrate, copper nitrate, sodium benzoate as the raw material, by controlling the reaction temperature, pH and other conditions, and without the need for templating agents and other surfactants conditions. And by SEM, XRD, EDS, FTIR characterizations, we have researched the influence between ZnCu(OH)BA-LDH morphology and crystal structure at different temperatures and pH, and the ZnCu(OH)BA-LDH chemical composition and anion layer arranged manner.The high dispersion of one-dimensional Cu/ZnO/C nanocomposites have been prepared by using the one-dimensional ZnCu(OH)BA-LDH as precursors with the conditions of no additional templating agent and reducing agent, using the row bout of uniformity of the metal ions between LDH layer, and by the method of in-situ solid pyrolysis with the one-dimensional ZnCu(OH)BA-LDH being calcined in an inert atmosphere. The characterizition of XRD, XPS, HRTEM, FTIR has showed that ZnO and Cu nanoparticles have been uniformly dispersed in the carbon matrix, there are tight interaction between the metal Cu, ZnO and C, there is a Zn-O-C bond action between ZnO and C, and could improve the electronic and hole separation. The carbon matrix formed by benzoic acid as a carbon source could improve the ZnO visible light activity by a sensitizing effect, carbon matrix contains a lot of hydrophilic groups (-OH,-COO-), effectively improve the energy of one-dimensional Cu/ZnO/C dispersing in water. Benzoic acid released the reducing gas during the pyrolysis and reduced Cu2+to metallic Cu, the resonance effect of Cu metal surface area also enhanced visible light activity of ZnO. We apply the calcined one-dimensional Cu/ZnO/C catalyst at different temperatures for visible degradation of MB, experiments show that: the sample of calcining under 400 ? has the best catalytic activity and the catalytic activity is higher than the commercial ZnO.2. Using the one-dimensional ZnCu (OH) BA-LDH as precursors, we have obtain a highly dispersed one-dimensional Zn1-xCu2xS/C nanocomposites with no additional modifications and reducing agents under an inert atmosphere, by a gas-solid reaction the metal ions have been sulfided between laminates. XRD, XPS, HRTEM, FTIR characterize that our prepared Zn1-xCu2xS solid solution uniformly dispersed in the carbon matrix, and between Zn1-xCu2XS and C there has been M-O-C key interaction, favoring the electron conduction between Zn1-xCu2xS and C, and closely integration with the C and Zn1-xCu2xS increased greatly the stability of Zn1-xCu2xS in the air. Further Cu2S as a narrow band gap semiconductor has a strong absorption in the visible region, the forming solid solution of Cu2S with ZnS effectively enhanced the catalytic activity of ZnS in the visible region. We studied visible light catalytic activity of the obtained one-dimensional Zn1-xCu2xS/C nanocomposite with different Zn, Cu ratio by using MB degradation as a probe reaction. Results show that:one-dimensional Zn1-xCu2xS/C nanocomposite has the highest visible catalytic activity when the ratio of Zn and Cu is 4:1. One-dimensional Zn1-xCu2xS/C nanocomposites are tested in optical current experiment with different element ratio of Zn and Cu, the results show that:, light response current of the one-dimensional Zn1-xCu2xS/C nanocomposite is larger when the atom ratio of Zn and Cu is 4:1.