Construction And Photocatalytic Properties Of Cu@ZnO/Ag Heterostructures

In this thesis,Cu@ZnO core-shell nanostructured photocatalysts were developed and prepared by constructing metal@semiconductor structures.The 2-component composite showed enlarged light response range as compaired with ZnO,by combining the semiconductor properties of ZnO with the surface plasmon resonance(SPR)effect of Cu.The photocatalytic properties and photocatalytic reaction mechanism of the composite were explored.On the basis of this,the Ag nanoparticles are supported on the surface of the composite material,and the ability of the nano-Ag to capture electrons is further utilized to further improve the transmission performance of the photogenerated carriers between the interfaces,thereby achieving the purpose of suppressing re-combination of the photo-generated charges.Thus,a highly efficient Cu@ZnO/Ag heterostructure nanostructured composite photocatalyst was prepared.The details are as follows:1.Monodisperse Cu nanowire with a diameter of about 100 nm was prepared by hydrothermal reaction.Meanwhile,ZnO seed solution was prepared by solvothermal method.The two solutions are then mixed to allow the ZnO seeds to be absorbed to the surface of the Cu nanowires.Under suitable condition,ZnO seeds on the Cu nanowires were grown into ZnO nanorods and the 2-components composite Cu@ZnO with flower cluster morphology was obtained with Cu nanowires as the core and ZnO nanorods as the shell.Photocatalytic performance test was carried out by degrading Rhodamine B(Rh B)under simulated sunlight conditions.The effects of experimental conditions include reactant concentration,the amont of catalyst used,the p H of the reaction solution,and the additives on the photocatalytic performance of Cu@ZnO core-shell structure and the photocatalytic degradation reaction were also investigated.The results show that the synergistic effect of ZnO semiconductor on photoexcitation and the surface plasmon resonance effect of Cu nanowires are important to the excellent photocatalytic performance of Cu@ZnO core-shell nanostructures.It is also shown that the composite structure greatly expands the absorption range of light while effectively promote the separation of photogenerated electron-hole pairs.2.Cu@ZnO/Ag ternary heterostructures were constructed by introducing Ag to the surface of the above prepared Cu@ZnO with photodeposition reaction.It was found by SEM,HRTEM and some other characterization methods that the morphology of Cu@ZnO/Ag ternary heterostructures was not influenced by the introduction of Ag,and the original flower cluster morphology remained.The internal composition of Cu@ZnO/Ag ternary heterostructures was determined by XRD and XPS and the photocatalytic performance of the 3-component composite was investigated with catalytic degradation of methylene blue(MB)under simulated sunlight condition.It was found that the Cu@ZnO/Ag ternary heterostructures with a Ag loading of 5 wt.% showed the best photocatalytic performance.According to the photoluminescence spectroscopy,in the Cu@ZnO/Ag ternary heterostructure nanostructure composite,the Ag nanoparticles act as an electron trapping agent,so that the photogenerated electronhole pairs in the ternary structure are further separated.Therefore,the ternary composite material has more excellent charge transport performance and separation efficiency,and exhibits more excellent catalytic performance.