Synthesis And Spectral Analysis Of One-dimension Nanomaterials And Their Assemblies

Nanostructures have received increasing interests as a result of their peculiar and fascinating properties, which are superior to their bulk counterparts. The most successful example is provided by microelectronics, where "smaller" has meant greater performance ever since the invention of integrated circuits: more components per chip, faster operation, lower cost, and less power consumption. It is also clear that a lot of interesting phenomena are associated with nanostructures, with the best-established examples including size-dependent excitation or emission, quantized conductance, metal-insulator transition. Recently, one-dimensional (ID) nanostructures have attracted more and more attention for their potential applications, such as nanoelectronics, functional nanostructural materials, and probe microscopy tips. In this paper, we synthesized some ID nanostructures and their assemblies by different methods, including polyoxometalate nanostructures, In(OH)3 nanorods, tetrapod ZnO nanostructures, and ZnO nanotubes.Polyoxometalates (POMs) constitute a significant class of inorganic compounds with potential applications in catalysis, conductivity, photoelectronic device, and so on. In this paper, POM nanostructures and their assemblies are synthesized in an inverse microemulsion system, surfactant (C12-18EO9) / cyclohexane / water. The results of morphology analyses revealed that controlled growth of POM nanostructures could be achieved. To evaluate influence of the volume ratio of surfactant (Vs) to water (Vw) on morphology of products, different values of VS/VW are examined. As Vs/Vw changed, morphology transition of K3[PMo12O40]-nH2O nanostructures from nanoparticles (VS/VW=2.5) to nanorods (Vs/Vw=5.0), and to slices (Vs/Vw=7.5) are realized. This transition may result from the shape transition of micelle for changing the value of V/VW. Under the same reaction conditions as K3[PMo12O40] -nH2O nanorods, POM nanostructures with different heteropolyanions, including K4[SiW12O40]-nH2O nanowires and rodlike K3[PW12O4o]-nH2O, are also synthesized.The aspect ratios of these products decrease in the series: K4[SiW12O40]>K.3[PW12O40]> K3[PMo12O40], and the change of aspect ratio is attributed to the differenct reactivity of heteropolyanions in water pool of the micelle. In addition, the K3[PMo12O40]-nH2O nanorods synthesized in the inverse microemulsions tend to self-assemble a starlike 3-dimensional (3D) assembly, which K.3[PMo12O40] -nH2O nanorods with diameters ranging from 50 to 100 nm linked to each other at one end to form symmetric 3D stars. Besides 3D organizations of K3[PMo12O40]-nH2O, plait [(C4H9)4N]3[PMo12O40]-nH2O nanostructures and a few starlike Cs3[PMO12O40] -nH2O are also obtained. The trend of self-assembly deals with complicated process, which may correlate with the interaction among cation, heteropolyanion and surfactant. The experimental results reveal that too big aspect ratio and non-uniform dimension are not suitable for the formation of symmetric assembly.Nanosize indium hydroxide and indium oxide have drawn much interest due to their special semiconducting and optical properties. Here we reported an effective soft-template method for controllable synthesis of In(OH)3 nanostructures, in which indium nitrate was hydrolyzed in the .presence of hexamethylene tetraamine (HMT) and surfactant cetyltrimethylammonium bromide (CTAB). Under optimum conditions, uniform In(OH)3 nanorods (diameter ranging from 25 to 55nm and length up to 120-200 nm) are obtained in high yield (>95%). Morphology analyses revealed that the In(OH)3 nanorods were composed of many subunit nanorods (diameter, 8-10 nm) grown along the [110] direction. Moreover, the In(OH)3 nanorods were employed as hard-template to be heated at 450癈 in static air to form In2O3 nanorods with similar dimensions. PL spectrum of the In2O3 nanorods showed a broad peak at about 462 nm, which may be attributed to the existence of oxygen vacancies.Nanoscale ZnO is intensively studied for its outstanding electronic and optical properties. A...