Inorganic Hybrid Nanostructures Research Articles

Atomic Layer Deposition of ZnO on Multi-walled Carbon Nanotubes and Its Use for Synthesis of CNT–ZnO Heterostructures

In this article, direct coating of ZnO on PECVD-grown multi-walled carbon nanotubes (MWCNTs) is achieved using atomic layer deposition (ALD). Transmission electron microscopy investigation shows that the deposited ZnO shell is continuous and uniform, in contrast to the previously reported particle morphology. The ZnO layer has a good crystalline quality as indicated by Raman and photoluminescence (PL) measurements. We also show that such ZnO layer can be used as seed layer for subsequent hydrothermal growth of ZnO nanorods, resulting in branched CNT–inorganic hybrid nanostructures. Potentially, this method can also apply to the fabrication of ZnO-based hybrid nanostructures on other carbon nanomaterials.

Adding new functions to organic semiconductor nanowires by assembling metal nanoparticles onto their surfaces

We report a new class of organic–inorganic hybrid nanostructures prepared by decorating small-molecule single-crystal organic nanowires with gold, platinum, and palladium nanoparticles. We demonstrate that field-effect transistors can be fabricated from the hybrid nanostructures with a mobility and current on/off ratio of 0.01 cm2V−1 s−1 and ∼103, respectively. To further illustrate the applicability of the hybrid nanowires, we carried out simple hydrogenation reactions to demonstrate their catalytic properties. Combined, our results open the possibility of utilizing the hybrid nanomaterials for a multitude of applications in areas such as bio- and chemical sensing, catalysis, and nanoelectronics.

Ligand and solvent effects in the nonaqueous synthesis of highly ordered anisotropic tungsten oxide nanostructures

Tungsten oxide nanoparticles were synthesized by a nonaqueous sol–gel process involving the reaction of tungsten chloride either with benzyl alcohol in the presence of various catechol ligands like 4-tert-butylcatechol, pyrocatechol and nordihydroguaiaretic acid or with 4-tert-butylbenzyl alcohol only. Dependent on the reaction system, organic–inorganic hybrid nanostructures with various morphologies were found, including short-range ordered lamellar structures as well as highly organized anisotropic stacks of tungstite nanoplatelets. In the case of 4-tert-butylbenzyl alcohol, the self-organization reaches two hierarchical levels, where the inorganic nanobuilding blocks, just a few Ångstroms in thickness, form nanocolumns perfectly arranged over a length scale of up to 10 microns. Several of these stacks assemble laterally into polydisperse bundles. The structural details as well as a potential formation mechanism are provided by a combination of XRD, TEM, HRTEM, and IR spectroscopy investigations.

Growth and Assembly of Crystalline Tungsten Oxide Nanostructures Assisted by Bioligation

Here, we present a systematic study on the influence of the bioligand deferoxamine mesylate on the crystallization and assembly behavior of tungsten oxide in a soft-chemistry process. Without deferoxamine mesylate, this approach yields pseudo-single crystalline tungstite nanoplatelets consisting of a large number of crystallographically almost perfectly aligned primary crystallites. In the presence of a constant amount of deferoxamine, the particle morphology drastically changes with temperature, ranging from wormlike organic-inorganic hybrid nanostructures to single-crystalline tungsten oxide nanowires, highlighting the role of the bioligand in controlling the crystal growth and assembly behavior. The nanowires have a uniform diameter of about 1.3 nm, an aspect ratio of more than 500, and the structural flexibility of tungsten oxide. The presented process is based on the combination of biomimetic construction principles with nonaqueous sol-gel chemistry, thus combining the advantages of both tools, excellent control over particle morphology and high crystallinity at low temperature.

Organic-Inorganic Nanohybridization by Block Copolymer Thin Films

A simple route for fabricating highly ordered organic–inorganic hybrid nanostructures, using polystyrene-block-poly(ethylene oxide) diblock copolymer (PS-b-PEO) thin films coupled with sol–gel chemistry, is presented. Hexagonally packed arrays of titania nanodomains were generated by one-step spin-coating from solutions containing a titania precursor and PS-b-PEO, where the precursor was selectively incorporated into the PEO domain. The PS-b-PEO template was subsequently removed by UV treatment, leaving behind a highly dense array of hexagonally packed titania dots. The size of the dots, as well as the lattice spacing of the array, could be fine-tuned by simply controlling the relative amount of sol–gel precursor to PS-b-PEO.

ORGANIZED PLANAR NANOSTRUCTURES VIA INTERFACIAL SELF-ASSEMBLY AND DNA TEMPLATING

The methods are presented for fabrication of new nanoscale-organized planar inorganic nanostructures, ultrathin polymeric and nanocomposite films on solid substrates with incorporated nanosized functional and structural building blocks. The methods are based on interfacial synthesis and self-assembly, DNA templating and scaffolding. Ultimately thin monomolecular and multilayer ordered stable polymeric and nanocomposite films containing incorporated ligand-stabilized gold nanoclusters, interfacially in-film grown metallic ( Au , Pd ) nanoparticles and organized low-dimensional nanostructures were formed. N-alkylated derivatives of poly(4-vinilpyridine) were synthesized and used as water-insoluble amphiphilic polycations to form organized polymeric Langmuir monolayers and novel planar DNA/amphiphilic polycation complexes at the air–aqueous DNA solution interface. The extended net-like and quasi-circular toroidal condensed conformations of deposited planar DNA/amphiphilic polycation complexes were obtained in dependence on the amphiphilic polycation monolayer state during the DNA binding. Planar DNA/amphiphilic polycation complexes were used as nanotemplates for fabrication of organized planar bio-organic–inorganic hybrid nanostructures with ordered nanophase inorganic components (quasi-one-dimensional arrays of semiconductor (CdS) and iron oxide nanoparticles and nanorods) organized in planar matrix of deposited DNA/amphiphilic polycation complex film. The formed nanostructures were characterized by atomic force microscopy and transmission electron microscopy techniques.

Porphyrin-Based Bola-Amphiphiles as Structure-Directing Agents for the Synthesis of Mesostructured Silica

Amphiphilic porphyrins with a bola-type arrangement of trimethylammonium headgroups can be used to generate M41S-type silica mesostructures with a lamellar topology and alternating organic–inorganic layers. Within the organic layers, the porphyrin entities are aggregated as shown by UV-Vis spectroscopy. The use of a bola amphiphile as structure-directing agent extends the possibilities of surfactant-controlled assembly of inorganic structures. In addition, the direct functionalization of the organic part of organic–inorganic hybrid nanostructures is possible due to the combination of the amphiphilic function with that of a chromophore.