ABSTRACT We present a simple method for the texturing of commercial silicon solar cells in a two-step process by etching in an HF solution containing H2O2. This etching process is facilitated by silver nanoparticles which act as catalytic sites. The etching times for the fabrication of nano-pores on the surface are established. The optical properties of the nano-structures on the surface of silicon solar cell were investigated by spectrometer measurements. The samples presented a total reflection coefficient lower than that of silicon solar cells without the treatment. The global efficiency of the silicon solar cell depends on the chosen preparation conditions for the silver ion concentration, and time of wet etching. The textured surface of solar cells showed an increase in efficiency, with a circuit photocurrent higher than that of a reference silicon solar cell without texturing. The J-V curves of various silicon cells are presented and discussed in correlation with the surface morphology.

In this study, the effects of the parameters such as applied potential difference, time and annealing temperature in the titania nanotubes formation were evaluated. The morphology of the nanotubes was evaluted by using Field Emission Gun - Scanning Electron Microscope (FEG-SEM), Atomic Force Microscope (AFM), contact angle and X-rays diffraction (XRD). Self-organized nano-structures were formed on the Ti-7.5Mo alloy surface from the same electrolyte (glycerol/NH4F) for all conditions. It was observed that the potential influenced the diameter while the length was changed according to the anodization time lenght. The presence of the phases anatase and rutile was altered by annealing temperature. Results showed that 20V-48h-450 ºC was the better than other conditions for application as biomaterial.

This paper addresses the performance study on, low viscosity, nano-modified adhesives by graphene. For achieving this goal, single-lap joints following ASTM D 5868-01 were manufactured and tested. X-ray diffraction, scanning electron microscopy and nanoindentation were employed for graphene based nanostructures characterization. The increase on joint strength was around 57% when compared against the control group. Furthermore, all failures for the nano-modified adhesive were cohesive failure for the carbon fibre/epoxy composites indicating that the adhesive was tested. X-ray diffractions signatures indicate formation of nano-structures with 17-19 nm diameters. Moreover, nanoindentation tests revealed a homogeneous dispersion of graphene.

Sais derivados do cátion 1,3-dialquilimidazólio são uma das mais populares e investigadas classes de líquidos iônicos a temperatura ambiente. Embora, em vários casos, suas propriedades físico-químicas e/ou o resultado dos processos que ocorrem nesses líquidos diferem significantemente daqueles obtidos em solventes orgânicos dipolares, estes ainda podem ser descritos como simples solventes orgânicos. Nesta revisão, será introduzido o conceito que líquidos iônicos derivados do cátion 1,3-dialquilimidazólio são mais convenientemente descritos como estruturas poliméricas supramoleculares do tipo {[(DAI)x(X)x-n)] n+ [(DAI)x-n(X)x)] n-}n onde DAI representa o cátion 1,3-dialquilimidazólio e X o ânion. Este padrão estrutural é observado geralmente em sólidos e mantido em grande extensão no estado líquido e mesmo em fase gasosa. A introdução de outras moléculas ou macromoléculas no líquido iônico provoca a perturbação da rede de ligações de hidrogênios podendo gerar, em alguns casos, nano-estruturas com regiões polares e apolares onde compostos de inclusão podem ser formados.

1,3-dialkyl imidazolium salts are one of the most popular and investigated classes of room temperature ionic liquids. Although in various cases the physical-chemical properties and/or the outcome of the processes in these liquids significantly differ from those performed in "classical" dipolar organic solvents, they are still regarded as merely homogeneous solvents. In this brief overview it is developed the concept that pure 1,3-dialkylimidazolium ionic liquids are better described as hydrogen-bonded polymeric supramolecules of the type {[(DAI)x(X)x-n)] n+ [(DAI)x-n(X)x)] n-}n where DAI is the 1,3-dialkylimidazolium cation and X the anion. This structural pattern is a general trend for the solid phase and is maintained to a great extent in the liquid phase and even in the gas phase. The introduction of other molecules and macromolecules occurs with a disruption of the hydrogen bond network and in some cases can generate nano-structures with polar and non-polar regions where inclusion-type compounds can be formed.