Min-Tao Wu

Fabrication and Characterization of Cu2O Nanorod Arrays and Their Electrochemical Performance in Li-Ion Batteries

This study is an investigation of the electrochemical performance of Cu 2 O nanorods in Li ion battery application. The templatemediated electroplating was applied to fabricate Cu 2 O nanorod arrays. The morphological observation shows that the nanorods with 60 nm diam and 450 nm length were grown perpendicularly to the substrate. The cyclic voltammetry sweeping indicates a reversible electrochemical reactivity between Cu 2 O nanorods and Li, and cycling tests show that the nanorod arrays exhibit a capacity of 330 mAh/g after 100 cycles. The high capacity and good cycle retention imply that Cu 2 O nanorods are a candidate anode material for rechargeable power source.

Effect of polishing pretreatment on the fabrication of ordered nanopore arrays on aluminum foils by anodization

It is reported that a pretreatment step is required for the fabrication of ordered nanopore arrays on Al by anodization. In this study, one step anodization was carried out on the Al foils with different surface features that resulted from different polishing conditions. The effect of surface morphologies on their anodization characteristics was determined. When the nonelectropolished Al substrate was anodized, only limited-sized ordered domains could be obtained. Nearly perfect hexagonal close packed ordered pore arrays with domain size of about 2–4 μm could be obtained on the electropolished Al substrate even with different surface features due to different electropolishing conditions. In addition, the differences of current density for the electropolished and nonelectropolished substrates were affected by the distinct characteristics of the oxide. The increase of the oxidation current in the later stage of anodization was caused mainly by the breakdown of the oxide on the nonelectropolished substrates ...

Preparation of Ni Nanodot and Nanowire Arrays Using Porous Alumina on Silicon as a Template Without a Conductive Interlayer

Recently, various technologies have been developed to create nanoscale structures over a large area at low cost. 1-3 One way to this goal is the template-mediated process. Many nanostructures have been fabricated using porous materials as a mask or a template. 4-6 Porous anodic alumina ~PAA! is now a most popular material for the fabrication of nanometer-sized structures due to its controllable pore characteristics and simplicity of production. One-dimensional nanostructures may be obtained by depositing materials into the PAA through many methods, such as chemical vapor deposition, 7 electrodeposition, 8 electroless deposition, 9 and sol-gel deposition. 10 Among these methods, electrodeposition is a powerful tool for the fabrication of nanostructures with a high aspect ratio due to fieldassisted migration of ions into channels of the template membranes. Conventionally, a conductive layer, such as Ag and Au, must be deposited on one side of the PAA as the cathode for electrodeposition. 11,12 In this study, a simple process was presented for the preparation of Ni nanodots and nanowires. A conductive layer was not necessary for the fabrication of Ni nanostructures into the PAA on the Si substrate. The dots and wires may be obtained over a large area with high efficiency and good reproducibility. Moreover, some findings regarding the electrodeposition process and the formation mechanism for these nanostructures are reported. The Ni nanostructures can be used as the magnetic storage media in the recording devices and as the mold for the nanoimprinting process. 13,14 Moreover, Ni nanostructures may also be used as nanoelectrode ensembles for investigating an electrochemistry and redox process that is difficult to measure using conventional macroscopic electrodes. 15,16

Density Control for Carbon Nanotube Arrays Synthesized by ICP-CVD Using AAO/Si as a Nanotemplate

Carbon nanotubes (CNTs) with tunable density have been grown directly by inductively coupled plasma chemical vapor deposition (ICP-CVD) using anodic aluminum oxide (AAO) on silicon as a substrate. The density of CNTs (10 6 to 10 9 CNTs/cm 2 ) can be controlled by changing the length of catalytic Ni nanowires embedded in AAO. The one-dimensional CNTs-Ni nanowire heterojunction without observable defects by transmission electron microscopy characterization ensures good contact between the CNT and the Ni nanowire. The realization of combining AAO on silicon and controlling the density of carbon nanotubes by a plasma process is significant for application of CNTs as field emitters and nanoelectronic devices.

Growth characteristics of oxide during prolonged anodization of aluminum in preparing ordered nanopore arrays

In this study, one-step anodization was conducted on both mechanically polished and electropolished Al foils at different temperatures to examine their growth characteristics during prolonged anodization. Several unusual phenomena different from those reported previously were observed, especially for the preparation of ordered pore arrays on electropolished Al foils. First, under a constant voltage condition, a continuous increase of the oxidation current with fluctuation was observed in a prolonged period of anodization at high temperatures. Second, the ordered pore arrangement of the oxide initially obtained on the electropolished Al foil anodized at 25 °C was found to become disordered after being anodized for 72 h. Third, the total film thickness increased in the beginning and decreased in the prolonged period when the anodization was conducted at a high temperature. Thus, it is concluded that a highly ordered pore configuration with a large aspect ratio could only be obtained on the electropolished s...