The effect of growth rate enhancement on the magnetic properties and microstructures of ac electrodeposited Co nanowires using non-symmetric reductive/oxidative voltage

Non-symmetric reductive/oxidative voltage was employed to electrodeposit the Co nanowires through the alumina barrier layer into porous aluminum oxide templates grown in oxalic acid. The minimum and maximum oxidative voltages were 12 and 18 V while the maximum difference between the oxidative and reductive voltage was 6 V. The effect of barrier layer modification on the growth rate of the Co nanowires during the electrodeposition procedure was studied. In order to investigate the effects of the non-symmetric electrodeposition voltage on the growth rate the wire's length, the saturation magnetization, the instantaneous and the rms current were measured. Different reductive/oxidative voltages enable us to fabricate electrodeposited nanowires with a wide variety of growth rates. Using same reductive voltage, reducing the oxidative voltage increased the growth rate. At the same reductive voltage (18 V), average growth rate was seen to increase 2.5 times, when the oxidative voltage reduces to 12 V from initially 18 V. The barrier layer thickness of the samples made with different non-symmetric reductive/oxidative deposition voltage was investigated through impedance measurement during the deposition procedure. Reducing the growth rate of deposition reduces the intensity of the (1 0 0) preferential direction of hcp phase thereby improving the magnetic properties. Manipulating the growth rate through non-symmetric electrodeposition enables us to fabricate the Co nanowires with coercivity ranging from 460 to 1850 Oe.     

Controlled Cu content of electrodeposited CoCu nanowires through pulse features and investigations of microstructures and magnetic properties

CoCu alloy nanowire arrays embedded in anodic alumina template were fabricated by ac pulse electrodeposition. Different off-times between pulses in an electrolyte with constant concentration of Co⁺² and Cu⁺² and acidity of 4 were employed. The effect of deposition parameters on the alloy contents, microstructures and magnetic properties of Co_xCu_1−x nanowires were studied. It is shown that Co content decreased by increasing the off-time between pulses in a wide range (x = 0.53-0.07). These results are in consistence with saturation magnetization, which was reduced with increase in the off-time between pulses. It was also found that by optimizing the off-times, it is possible to fabricate CoCu nanowires with mixed phase of hcp Co, fcc Cu and fcc CoCu crystal phase.     

Selective Terminal Functionalization of Linear Alkanes**

A two-step sequential strategy involving a biocatalytic dehydrogenation/remote hydrofunctionalization, as a unified and versatile approach to selectively convert linear alkanes into a large array of valuable functionalized aliphatic derivatives is reported. The dehydrogenation is carried out by a mutant strain of a bacteria Rhodococcus and the produced alkenes are subsequently engaged in a remote functionalization through a metal-catalyzed hydrometalation/migration sequence that subsequently react with a large variety of electrophiles. The judicious implementation of this combined biocatalytic and organometallic approach enabled us to develop a high-yielding protocol to site-selectively functionalize unreactive primary C−H bonds.