Search results for "ALUMINA MEMBRANE"

One-step electrochemical synthesis and physico-chemical characterization of CdSe nanotubes

2013

Abstract Stoichiometric CdSe nanotubes (NTs) with a length of ∼700 nm have been successfully grown by one-step electrochemical technique into anodic alumina membranes. Cyclovoltammetric method has been performed using porous anodic alumina as template electrode and an electrochemical bath containing Cd 2+ ions and SeO 2 . The as-prepared NTs have been identified as face-centred-cubic CdSe by XRD, while micro-Raman analysis reveals the typical peaks of nanostructured CdSe. The stoichiometric deposition of CdSe NTs formation is suggested by EDX analysis, with an average atomic percentage of Cd:Se of ∼0.93. Photoelectrochemical measurements reveal that CdSe NTs are photoactive materials with d…

Carbonization of disclike molecules in porous alumina membranes: toward carbon nanotubes with controlled graphene-layer orientation.

2005

From ZIF-8@Al2O3Composites to Self-Supported ZIF-8 One-Dimensional Superstructures

2015

International audience; Efficient preparation of composite materials consisting of ZIF-8 nanocrystals embedded inside the channels of macroporous anodic aluminum oxide membranes is reported. 1-D self-supported ZIF-8 superstructures are recovered through matrix dissolution.

Developing a procedure to optimize electroless deposition of thin palladium layer on anodic alumina membranes

2006

In recent years, the increased demand for hydrogen in many industrial applications, like petrochemical and semiconductor processing, and sustainable energy (fuel cells) has led to a renewed interest in methods for separation and purification of hydrogen from gas mixtures. In particular, palladium-based membranes have been the subject of many studies, due to their potential use as hydrogen-selective membranes for gas separation or purification [1,2]. Owing to the high cost of palladium and in order to increase the flow rate of hydrogen, composite membranes, formed by a thin layer of palladium deposited on a porous support, are largely preferred to thick self-standing metal membranes. Differe…

Nanostructured anode material for Li-ion batteries

2010

The present paper focuses on a nanostructured SnCo alloy electrochemically prepared by template method in view of its use as anode material alternative to graphite in lithium-ion batteries. The fabrication of SnCo nanowire arrays was carried out by potentiostatic co-deposition of the two metals by using nanostructured anodic alumina membranes as template. Electrochemical tests on lithiation-delithiation of these SnCo electrodes in conventional organic electrolyte (EC:DMC LiPF6) at 30°C showed that their specific capacity was stable for about the first 12 cycles at a value near to the theoretical one for Li22Sn5 and, hence, progressively decayed.

Anodization and anodic oxides

2018

Anodizing is a low-temperature, low-cost electrochemical process allowing for the growth, on the surface of valve metals and valve metal alloys, of anodic oxides of tunable composition and properties. This article is an overview on theoretical aspects concerning the general aspects of the kinetics of growth of barrier and porous anodic oxides and some of their present and possibly future technological applications of anodic oxides. The first part of the article is devoted to anodic oxide growth models, from Guntherschulze and Betz work (in 1934) to the more recent results on barrier and porous oxide films. The second part is focused on industrial processes to fabricate anodic oxides and the…

Synthesis of self-standing Pd nanowires via galvanic displacement deposition

2009

This work shows that it is possible to obtain self-standing Pd nanowires into anodic alumina membranes by a simple metal displacement deposition. By using a proper arrangement, specifically designed in order to optimize the process, polycrystalline Pd nanowires were deposited from a solution containing Pd(NH3)4(NO3)2 as precursor. Morphological analysis showed the formation of perfectly aligned nanowires with a uniform diameter throughout the entire length. This last parameter was controlled by both the deposition time and the ratio between the anodic area (active metal) and the cathodic area (pore bottom). Keywords: Displacement deposition, Template synthesis, Palladium nanowires, Alumina …

Photoconductive properties of Bi2S3nanowires

2015

The photoconductive properties of Bi2S3 nanowires synthesized inside anodized alumina (AAO) membrane have been characterized as a function of illuminating photon energy between the wavelengths of 500 to 900 nm and at constant illumination intensity of 1–4 μW·cm−2. Photoconductivity spectra, photocurrent values, photocurrent onset/decay times of individual Bi2S3 nanowires liberated from the AAO membrane were determined and compared with those of arrays of as-produced Bi2S3 nanowires templated inside pores of AAO membrane. The alumina membrane was found to significantly influence the photoconductive properties of the AAO-hosted Bi2S3 nanowires, when compared to liberated from the AAO membrane…

Growth and Characterization of Ordered PbO[sub 2] Nanowire Arrays

2008

Large arrays of PbO 2 nanowires having high aspect ratios (length-to-width ratio) were grown by potentiostatic electrodeposition into anodic alumina templates under anodic polarization. Different electrolytic solutions were used in order to obtain nanowires of pure α-PbO 2 , pure β-PbO 2 , and a a + β mixture, We have found that, in a lead nitrate bath, a crystallographic structure of nanowires depends on pH; this latter was varied adding diluted nitric acid to the electrolyte. Nanowires of pure β-PbO 2 were obtained at pH 0.6, while mixed α-PbO 2 + β-PbΟ 2 nanowires were grown at pH 2. Pure α-phase was obtained in a bath containing lead acetate at pH 6.6. In all deposition conditions, nano…

Characterization of Sn-Co nanowires grown into alumina template

2009

Nanowires of Sn-Co alloys were grown inside the channels of anodic alumina membrane by potentiostatic deposition. The scanning electron microscope images showed the formation of cylindrical nanowires whose height was increasing with deposition time. The X-ray patterns did not show significant diffraction peaks, suggesting the formation of amorphous phases. The higher content of Co in the nanowires, in comparison to the initial composition of the electrolytic bath, was attributed to a higher rate of Co electrodeposition. These nanowires seem to possess specific features suitable for innovative application in the field of Li-ion batteries due to their dimensional stability and high specific s…