Studies On The Preparation,characterization And Property Of Ag/Cu-containing Nanomaterials

In recent years, with the development of nanotechnology, nanomaterials have been received extensive attention due to their unique properties. Silver-,copper-containing inorganic nanocomposites have been widely applied in many fields because of their highly efficient catalytic properties and/or adsorption performances.For example, catalytic(photocatalytic) degradation of dyes and organic pollutants,adsorption removal of dyes and heavy metal ions in wastewater treatment,biochemical analysis of H2O2, glucose, ascorbic acid and so on. Developing a simple method for preparing novel silver-, copper-containing nanomaterials and finding their application in various fields are one of the current research hotspot.In this thesis, AgCl@Ag, Cu2 O, Fe3O4@Cu@Cu2O and Fe3O4@Ag@Cu nanomaterials were prepared via a simple one-pot method. These nanomaterials were characterized by SEM, TEM, XRD, EDS, and XPS and so on. Then the catalytic properties and adsorption behavior of the nanomaterials were investigated. The main work includes the following four aspects:1. A highly efficient and stable AgCl@Ag hybrid photocatalyst was successfully prepared via a simple one-pot method at low temperature. The photocatalytic activity of the as-prepared AgCl@Ag hybrid photocatalyst was evaluated by the photodecoloration/photodegradation of various mode organic pollutants, methyl orange(MO), methylene blue(MB), rhodamine B(RhB) and 4-nitrophenol(4-NP). It was found that the as-prepared AgCl@Ag exhibited high photocatalytic activity and excellent photostability not only under visible light, but also sunlight irradiation.Kinetic studies by using active species scavenger technology suggested that hydroxyl radicals(·OH) was not the dominant photooxidant, while holes(h+) and superoxide anion radicals(·O2-) generated in the photocatalytic process played key roles in MO degradation. A possible mechanism for the charge separation and MO photodecoloration is proposed.2. Polyhedral cuprous oxide nanoparticles(Cu2O NPs) with rough surfaces were prepared by a one-pot sonochemical precipitation method. The adsorption behavior of Congo red(CR) from aqueous solution onto the as-prepared Cu2 O NPs was systematically investigated. The equilibrium and kinetic studies suggested that the adsorption process followed Freundlich isotherm and pseudo-second order model,respectively. The as-prepared Cu2 O NPs exhibited remarkable adsorption propertiestoward CR. The maximum adsorption capacity at 20 °C was 3904 mg g-1, which was the highest reported value so far in adsorption removal of CR. Together with the evaluation of the thermodynamic parameters such as Gibbs free energy, enthalpy and entropy change, our results show that the adsorption of CR onto Cu2 O is a spontaneous, endothermic and chemisorption process. A putative interaction model between CR and Cu2 O NPs was proposed. Moreover, the Cu2 O adsorbent could be regenerated photocatalytically and reused without significant loss of its adsorption capability.3. Fe3O4@Cu@Cu2O nanocomposites were prepared by a facile one-pot solvothermal method. It was found that the Fe3O4@Cu@Cu2O nanocomposites posses dual catalytic functions, it can catalyze not only the oxidation of peroxidase substrates such o-phenylenediamine(OPDA), 3,3’,5,5’-tetramethylbenzidine dihydrochloride(TMB) in the presence of hydrogen peroxide but also the reduction of 4-nitrophenol(4-NP) and RhB in the presence of sodium borohydrate(NaBH4). In comparison with natural peroxidase such as horseradish peroxidase(HRP), the as-prepared Fe3O4@Cu@Cu2O nanocomposites have advantages of low cost, easy preparation,high stability, facile recyclability and reusability, which make the Fe3O4@Cu@Cu2O nanocomposites a promising peroxidase mimetic candidate and may find potential applications in biocatalysis, bioassays, nano-biomedicine and environmental protection.4. Fe3O4@Ag@Cu nanocomposites were firstly prepared through a simple one-pot solvothermal method. It was found that the Fe3O4@Ag@Cu nanocomposites posses peroxidase-like activity, it can catalyze the oxidation of typical peroxidase substrate, TMB, in the presence of hydrogen peroxide(H2O2) to produce a blue product. Based on these findings, a sensitive and selective colorimetric method for the detection of H2O2, glucose, ascorbic acid and sulfite was developed.