Synthesis And Photocatalytic Properties Of ZnO-based Core-shell Nano Material

With the progress of technology and the development of human society,the energy are running out,the environmental pollution is more and more increasingly to seriously threat to the survival of human beings.Therefore,the developments of clean energy and efficient catalysts would be inevitable to solve energy and environmental problems by photocatalytic technology.It is well-known that,zine oxide is one of the most widely used semiconductor catalyst,its catalytic efficiency depends on its composition,specific surface area,photornetrics and morphology.Therefore,the control of morphology for the zine oxide is an important issue for optimize the performance.However,during the photocatalytic reaction,the photocatalytic activity of zine oxide will lose efficiency easily caused by the corrosion of acidity substance and alkaline substance.Therefore,improving the performence and sorving the problem of the corrosion caused by the acidity substance and alkaline substance should be taken into consideration at the same time.This paper introduced the preparation of hollow ZnO/TiO₂ core-shell nanocomposites?CSNCs?after the preparationed of polystyrene/ZnO CSNCs and hollow ZnO nanomaterial.First of all,the monodisperse polystyrene microspheres?PS?were synthesised by using a emulsion polymerization method.Then the PS/ZnO nano-composites were synthesized by chemical bath precipitation method with well-dispersed polystrene microspheres as the templat.In order to interfacial behavior of the core-shell type microscopic particle,reaction parameters such as PVP,NaOH concentration and reaction temperature were carefully investigated.The results showed that the as-prepared nano-composites which in PVP,NaOH solution concentration is 0.2 mol/L,the reaction temperature is 55°C have core-shell structure with an average diameter of ca.200 nm and the shell thickness of the nanoparticles is ca.20nm.Under uv irradiation,PS/ZnO CSNCs exhibited good photocatalytic activity and stability.The successful preparation of PS/ZnO CSNCs for the synthesis of hollow ZnO and double shell or multi-layer core-shell materials provides maneuverability.Secondly,the hollow ZnO nanomaterials were prepared by removing the central template PS in toluene solution and high-temperature calcination respectively.The influence of the two different template removal methods on the surface micromorphology,crystal structure and photocatalytic activity of hollow ZnO nanospheres were carefully performed by a comparative study.Results show that the method of high-temperature calcination was confirmed to be better by comparing the morphology,photornetrics and photocatalytic activity of the two samples that prepared by the two different methods.In addition,the formation mechanism of the product was also discussed.At last,the PS/ZnO/TiO₂ CSNCs were obtained by using immersion and hydrothermal methods with TBOT as precursors.The morphology and elemental analysis were needed to confirm the best method to synthesis PS/ZnO/TiO₂ CSNCs.After a calcination,hollow ZnO/TiO₂ CSNCs were perpared.Under uv irradiation,hollow ZnO/TiO2 CSNCs showed the best catalytic activity.At the same time,since the existence of the protective layer of TiO₂,the pollutions with wider pH range were well degradated by the hollow ZnO/TiO₂ CSNCs,and the practical application value of ZnO in the scale of photocatalytic was broden.In addition,probes into the two components of the catalyst on the photocatalytic degradation of MB solution mechanism.