Facile Synthesis Of Semiconductor And Semiconductor Nanocomposites And Their Photocatalytic Activity

In today’s life, environmental pollution not only has caused ecological problem but also has far reaching negative consequences in the lives of humans.Degradation of organic pollutants, which have a deleterious effect on the well being of mankind, has become the center point of research efforts in today’s scientific world. Photocatalytic technology has developed in recent decades as a new type environmental protection technology due to its high efficiency, low energy consumption, economic and so on. For semiconductor nanomaterial, some active species such as·O2-and·OH emerge on the surface of semiconductor materials which can be activated under the irradiation of visible-light or UV irradiation, so they can decompose of toxic compounds to nonhazardous product, which have very important research and applied value in the degradation of organic pollutants and wastewater treatment. So it has important theoretical and practical significance to develop appropriate photocatalysts. This article pays attention to the preparation of semiconductor and semiconductor Nanocomposites photocatalysts and the visible light photocatalytic activities of these nanomaterials. This paper mainly includes the following three parts:1. Facile growth of ZnO nanocrystals on nitrogen-doped carbon nanotubes for visible-light photodegradation of dyesIn this chapter, we have synthesized of nitrogen-doped carbon nanotubes by a modified chemical vapor deposition (CVD) method. Subsequently, we demonstrate a facile chemical precipitation strategy for the accurate coating of ZnO nanocrystals on the surface of nitrogen-doped carbon nanotubes (N-CNTs) to form ZnO/N-CNTs nanohybrids. Additionally, ZnO/CNTs were successfully prepared in aqueous solution according to the same method. The studies of the photocatalytic properties of the both demonstrated that as-prepared ZnO/N-CNTs nanohybrids possessed a higher photocatalytic activity in the degradation of rhodamine B (RhB) and benzoic acid when exposed to visible light irradiation than ZnO/CNTs nanohybrids and commercial ZnO nanoparticles under the same conditions.2. One-pot solvothermal synthesis of multi-shelled α-Fe2O3hollow spheres with enhanced visible-light photocatalytic activityIn this work, α-Fe2O3hollow spheres with novel multiple porous shells were successfully prepared by a facile solvothermal treatment carbon spheres and FeCl3·6H2O in ethylene glycol at200℃for10h, followed by calcination in air at500℃for3h. The photocatalytic activities of the as-obtained multi-shelled and α-Fe2O3hollow spheres showed enhanced photocatalytic activity for the degradation of organic dye RhB compared to single-shelled α-Fe203hollow spheres in the presence of H2O2under visible-light illumination. This facile method can be extended for the fabrication of multi-shelled structures of other metal oxides.3. Facile formation of Ag2WO4/AgX (X=Cl, Br, I) hybrid nanorods via a room-temperature anion exchange reaction and their enhanced photocurrent and photocatalytic activitiesThis chapter demonstrated a facile strategy for preparation of a series of uniform Ag2WO4/AgX hybrid nanorods via in-situ anion exchange reaction between pregrown Ag2WO4nanorods and different X-ions in water at room temperature. the as-prepared1D hybrid nanorods exhibit enhanced photocurrent and excellent photocatalytic activities under visible-light irradiation. Especially, the as-prepared Ag2WO4/AgBr hybrid nanorods exhibit the highest photocatalytic activity among the three samples. The active species tests indicates that the superoxide radical and photogenerated holes were responsible for the enhanced photocatalytic performance of Ag2WO4/AgBr,the enhanced photocatalytic mechanism of Ag2WO4/AgBr/Ag hybrid materials was also discussed. We believe that the1D Ag2WO4nanorods obtained in this case could act as nanoscale building blocks for the preparation of other more complex1D nanostructures, and could thus provide new promising applications.