Recent Advances in Directed Assembly of Nanowires or Nanotubes

Nanowires and nanotubes of diverse material compositions,properties and/or functions have been produced or fabricated through various bottom-up or top-down approaches.These nanowires or nanotubes have also been utilized as potential building blocks for functional nanodevices.The key for the integration of those nanowire or nanotube based devices is to assemble these one dimensional nanomaterials to specific locations using techniques that are highly controllable and scalable.Ideally such techniques should enable assembly of highly uniform nanowire/nanotube arrays with precise control of density,location,dimension or even material types of nanowires/nanotubes.Numerous assembly techniques are being developed that can quickly align and assemble large quantities of one type or multiple types of nanowires through parallel processes,including flow-assisted alignment,Langmuir-Blodgett assembly,bubble-blown technique,electric/magnetic-field directed assembly,contact/roll printing,knocking-down,etc..With these assembling techniques,applications of nanowire/nanotube based devices such as flexible electronics and sensors have been demonstrated.This paper delivers an overall review of directed nanowire/nanotube assembling approaches and analyzes advantages and limitations of each method.The future research directions have also been discussed.

Substitute of Expensive Pt with Improved Electrocatalytic Performance and Higher Resistance to CO Poisoning for Methanol Oxidation: the Case of Synergistic Pt-Co_3O_4 Nanocomposite

In this paper, Pt-Co_3O_4 nanocomposite was synthesized by a sol gel process combined with electrodeposition method. Its electrocatalytic activity towards methanol oxidation was investigated at room temperature using cyclic voltammetry(CV), electrochemical impedance spectroscopy(EIS) and current density time curve. It is found that the resultant Pt-Co_3O_4 catalysts with minute amount of Pt exhibite attractive electrocatalytic activity for methanol oxidation reaction(MOR) but with a high resistance CO poisoning due to the synergistic effects from Pt and Co_3O_4. Together with the low manufacturing cost of Co_3O_4, the reported nanostructured Pt-Co_3O_4 catalyst is expected to be a promising electrode material for direct methanol fuel cells(DMFC).