The growth mechanism of ordered nanoporous alumina

The paper scrutinizes the peculiarities of porous alumina growth during electrochemical anodic oxidation in the orthophosphoric acid solution at constant potential of 100 Volt. On the basis of atomic-force microscopy data the paper presents consecutive stages of ordering pores in the oxide with the formation of hexagonal dense package after two-stage anodic treatment.

OBTAINING PARTIALLY UNZIPPED CARBON NANOTUBES FOR OXYGEN ELECTRODES

Various methods for unzipping carbon nanotubes are described, which differ only in the method of acting on multi-walled carbon nanotubes which leads to obtain a partial unzipped carbon nanotubes or the creation of a defective hybrid structure in carbon nanotubes. By electrochemical anodic oxidation in 80 % sulfuric acid of multi-walled carbon nanotubes synthesized partially unzipped nanotubes and shows the results of the study. Using the methods of X-ray phase analysis, electron microscopy, and Raman spectra, it has been established that, as a result of electrochemical anodic oxidation, partially unzipped multi-walled carbon nanotubes are obtained. Two-layer oxygen electrodes were made, where synthesized materials were used as an active layer. Studies of the electrocatalytic characteristics of oxygen electrodes from partially unzipped multi-walled carbon nanotubes were carried out in a mock up of fuel cell with alkaline electrolyte. It is established that the degree of unzipping of multi-walled carbon nanotubes depends on the time of electrochemical oxidation. It has been suggested that it is possible to control the process of synthesis of partially unzipped nanotubes. It has been established that one of the methods for estimating the degree of unzipping of multi-walled carbon nanotubes can be studies the electrochemical characteristics of oxygen electrodes based on these materials. Electrochemical investigation has established that the obtained samples of partially unzipped multi-walled carbon nanotubes are promising materials as catalysts carrier for oxygen electrodes of fuel cells. The developed method synthesis of partially unzipped multi-walled carbon nanotubes allows obtaining electrode materials for chemical current sources. Oxygen electrodes, based on such electrochemically produced materials, were stable for six months at a discharge current density of 200 mA/cm2. Partially unzipped multi-walled carbon nanotubes are promising catalyst carrier for electrodes of chemical current sources, as well as a material for hybrid nanocomposites with predetermined characteristics.