Papers by Keyword: AAO Template

Abstract: Anti-reflective polystyrene nanopillar arrays were fabricated by the process of hot embossing where it utilizes the nickel coated anodised aluminium oxide template. Electroless plating being a catalytic method of plating uniformly coats the membrane which increases its strength. The supporting layer of nickel makes AAO template suitable to be used as a mould multiple times. Highly conformal nanopillars of average diameter 400nm and length 30 μm to 50μm were fabricated on the area of ⁓5cm². Hot embossing process ensures repeatability with precision and high throughput. The enhanced light entrapping is attributed to the multiple internal reflection in the nanopillars of high aspect ratio.

Abstract: Polycrystal ZnO nanotube arrays with outer diameter about 46 – 70 nm have been fabricated by annealing zinc oxalate in the pores of anodic aluminum oxide (AAO) template. Each nanotube is made up of small nanoparticles with the average size of 4 –7 nm. The nanotubes embedded in the pores of AAO template constitute to a kind of quantum wells arranged alternatively by ZnO, Al₂O₃ and thin air layer. Rough surfaced structure increases the interactions between these layers, and enhances the quantum confinement effect. Similar to the ZnO/Al₂O₃ multiply layer structure, a strong near-band edge emission at about 336 nm is observed under the excitation of 220 nm. The blue shift of the near band transition originates from the raises of the Fermi level of ZnO nanotubes generated by the addition of donor Al³⁺. With the decrease of wall thickness, this ultraviolet peak becomes broad and stronger. Under the excitation of 380 nm, a main emission platform from 430 nm to 530 nm appears originated from the transition from conduction band tails to valence band tails contain a complex mechanical strains effected by many crystal defect. The higher energy emission properties may have potential applications for the ultraviolet light-emitting diodes and laser diodes.

Abstract: The Fe nanowire arrays are prepared by the method of alternating current, constant voltage and constant current respectively. the morphology and composition of the Fe nanowires have been characterized By scanning electron microscope (SEM), Energy-dispersive X-ray spectroscopy (EDS). The Fe nanowires growth rate with different current density was studied in anodic aluminum oxide (AAO) template for pore diameter of 85 nm, pore depth of 55 μm under the same total charge. Research shows that the deposition rate of nanowires first slightly decreased, dramatically increased again and then reduced greatly with the increase of current density from 1 mA/cm² ~ 5 mA/cm².

Abstract: One-dimensional Fe, Co, Ni nanotube arrays ware fabricated successfully by the electrochemical deposit in porous anodic alumina oxide (AAO) templates. The microstructure of nanotubes were observed by scanning (SEM) and transmission electron microscopes (TEM) respectively. The obtained Fe, Co, Ni nanotubes are arranged orderly. The magnetic property of nanotubes was measured and analyzed. The results show that the residual magnetization of Ni nanotubes is the biggest, and that of Fe nanotubes is the smallest. It is easy to be magnetized along the axial direction.

Abstract: Abstract: Thin anodic alumina (AAO) templates with uniform nanoscale pore diameters and interpore distances were fabricated by a two-step anodization technique on a Si-based (AAO/Ti/Si structure) under controllable anodizing conditions. The obtained thin AAO templates were approximately 60 nm in pore diameter and 1.2 µm in length with 110 nm interpore distances in area of 1 cm². A bottom barrier layer of the anodic alumina (AAO) templates was removed by a wet etching using phosphoric acid (5 wt%) under control of etching time. As an application, Cu nanorods arrays embedded in anodic alumina (AAO) template were fabricated by electrodeposition. The morphologies and structure of the templates and the Cu nanorods produced were analyzed using Field-emission scanning electron microscope (FESEM), Energy dispersive x-ray spectroscopy (EDX) and X-ray diffraction (XRD).

Abstract: Three-dimensional (3D)-hybrid surface-enhanced Raman scattering (SERS) substrates have been achieved via simultaneous assembled silver nanoparticles (AgNPs) onto the anodic aluminum oxide (AAO) templates. The AAO templates were prepared from the UHV aluminum foil in 0.3 M oxalic acid using the two-step anodization process at 0°C. The effect of applied voltage ranging from 30 to 50 V on the porous diameter and the inter-porous distance of the AAO templates was investigated and observed with filed-emission scanning electron microscope (FE-SEM). The results showed that the porous distance and the inter-porous distance were linearly increased with the increase in the voltage potentials. To investigate the pore-size effect on the SERS activities, the AgNPs were deposited on the AAO nanoporous templates. The SERS activities of these nanostructures were demonstrated with the methylene blue (MB) as the probing molecules.

Abstract: In this study, anodic aluminum oxide (AAO) fabricated from phosphoric acid electrolyte at ambient temperature was used as the porous template, while a sol gel procedure was used for the preparation of the TiO₂ sol with the addition of 0.1, 0.3, and 0.5 g of polyethylene glycol (PEG). The addition of PEG to the TiO₂ sol prevents surface cracks and improves the adhesion of the sol to the template to produce different surface morphologies which were visible under the scanning electron microscope (SEM). Although, complete degradation of the methyl orange (MO) dye was not achieved initially with the TiO₂ coated template, until an oxidizer in the form of H₂O₂ with different concentrations of 0.029M, 0.088M, and 0.147M were added during the photocatalysis process to shorten the degradation time and to ensure complete mineralization of the MO dye.

Abstract: Plasma sputtering deposition of platinum on porous substrates is a relevant way for building high performance catalytic thin films. The knowledge and control of platinum density adsorbed in the porous medium, during deposition, are of primary importance. We show that the experimental concentration depth profiles originate from a superdiffusion phenomenon. Moreover experimental results are well described by a classical porous-fractal diffusion model, for which diffusion coefficient is also time-dependent, even if such a model does not include the proper physical mechanisms.

Abstract: Highly ordered Cu, Ag and Au nanowire arrays with high aspect ratio and highly dense self-supporting nanowire patterns of copper group were successfully prepared using cyclic voltammetry with the assistance of anodic aluminum oxide (AAO) template. The X-ray diffraction (XRD) patterns of the metal nanowries were indexed to the face-centered cubic structure. The field emission scanning electron microscope (FE-SEM) results demonstrated that the length of nanowire could be controlled by changing the electrodepositon conditions. The aspect ratio of nanowire arrays can be tuned.

Abstract: Anodic aluminium oxide (AAO) templates were fabricated via a two-step anodization method. On the basis of getting the optimum preparation parameters of AAO templates, effects of two different pore-extending methods on morphology of AAO templates were studied. Field emission scanning electron microscope (SEM) was used to research surface morphology of AAO templates. The SEM images indicated that different pore-extending methods had a significant influence on morphology of AAO templates. The shape of nanopores of AAO templates was cylindrical after floating pore-extending method, but it was truncated cone-shaped with one dimensional gradient using immersed pore-extending method. Meanwhile, mechanism of different pore-extending methods on morphology of AAO templates was elucidated.