3-Dimensional Graphene Carbon Nanotube Carpet-Based Microsupercapacitors with High Electrochemical Performance

James M. Tour, Jian Lin.

The development of nanostructured-capacitive structures has been an active area of research because they would allow us to have smaller and flexible electronics, breaking the limit of actual technics.

In this paper it’s shown how 3D grapheme/CNT carpets can work has supercapacitors at good frequencies and altern current, mainly used for line filtering applications. With a frecuency response comparable to the aluminum electrolytic capacitors but with higher current density.

The microcapacitor was fabricated first with photolithography over silicon, then nickel was added to the marked substrate, it acts as both the current collector and the catalyst to grow the graphene.

The graphene was synthesized over the Ni electrodes by CVD at 800º C.After, the CNT carpets were synthesized from the patterned Fe/Al₂O₃/at was first deposited by CVD over the graphene layer. 

The capacitor propierties were teasted with a potensiostat in a two-electrode cell configuration. They used 1M Na₂SO₄ aqueous electrolyte to measure.

They tested the frecuency response specific areal capacitances and found an excellent response in frequencies over 120Hz.

The potential application of this capacitors can go from smaller chargers, noise filters of different electronic circuits and  even signal filtering in sensors mounted over mobile electronics. 

Coupling of Nanoparticle Plasmons with Colloidal Photonic Crystals as a New Strategy to Efficiently Enhance Fluorescence

En este artículo presentan una estrategia para mejorar la eficiencia de fluorescencia, basado en el acoplamiento de plasmones de superficie de las partículas de metal con las propiedades ópticas de cristales fotónicos. 

Encontraron que de esta forma se puede mejorar efectivamente el efecto de campo cercano y el efecto inducido por plasmón de las partículas de metal, pero también puede ser favorable para la extracción de la emisión, lo que lleva colectivamente a una mejora adicional significativa de metal mejorada de fluorescencia. 

Este sistema híbrido podría servir como una plataforma para la mejora de la fluorescencia de diversos fluoróforos y tienen un gran potencial en biosensores químicos basados ​​en fluorescencia.

Cheng-an Tao, Wei Zhu,  Qi An,  Haowei Yang, Weina Li,  Changxu Lin,  Fuzi Yang,  and Guangtao Li. Coupling of Nanoparticle Plasmons with Colloidal Photonic Crystals as a New Strategy to Efficiently Enhance Fluorescence.  J. Phys. Chem. C 2011, 115, 20053–20060

Encuentra el artículo completo aqui.

Conformational Molecular Rectifiers

Alessandro Troisi, Mark A. Ratner

One of the goals of the emerging field of molecular electronics (ME) is the realization of molecular scale rectifiers, switches, or transistors coupled one another via metallic wiring.1,2 The extension of conventional electronics approaches requires that the molecular device is rigid, with functions entirely determined by electronic structure. With several remarkable exceptions,3 most current experiments in ME are focused on rigid molecules, with molecular motions generally regarded as unwanted complications.

Conformational motions driven by the electric field might lead a molecular junction to exhibit switching behavior.

Controllable dynamical stereochemistry breaks the analogy that sees the molecule only as the ultimately miniaturized “material” for electronics, and thereby opens many interesting mechanistic and device possibilities.

In this papper, the researchers presented two examples of conformational molecular rectifiers.

One of them was a benzenethiol meta-substituted with the cyanomethyl group that can be easily chemisorbed on a gold surface. The next figure shows how the conformation can change with the change of the potential applied.

Another simple example is shown in the next figure, here we can see that again, by changing the polarization. This effect is due to a change in the relative erngies of the orbital conformation, that allow the molecule to change according to the most stable conformation formed by the symmetry on the molecular orbitals, specially over the delocalized π electrons.

 It is clear, from these two examples, that one essential condition for viable CMRs is the possibility to control the molecule orientation at the interface.