Eduardo Saito

Fast preparation of nano-hydroxyapatite/superhydrophilic reduced graphene oxide composites for bioactive applications

A method for the direct electrodeposition of globular nano-hydroxyapatite (nHAp) onto reduced graphene oxide (RGO) is presented and a model for the specific growth preference is discussed. Results show that the carboxyl (carboxylic acid)/carboxylate functional groups attached directly to the RGO after oxygen plasma treatment were essential to accelerate the OH- formation and the deposition of globular nHAp crystals. High resolution scanning electron microscopy, energy dispersive X-ray and X-ray diffraction showed that homogeneous, highly crystalline, stoichiometric nHAp crystals, with preferential growth in the (002) plane direction, were formed without any thermal treatment. The nHAp/RGO composites were shown to be an appropriate surface for mesenchymal stem cell adhesion with active formation of membrane projections.

Vertically Aligned Carbon Nanotubes/Carbon Fiber Composites for Electrochemical Applications

Carbon fibers have been studied for electrochemical applications. Recently, carbon nanotubes present a wide potential uses in electric, mechanic, electrochemical and materials science field. At present study, vertically aligned carbon nanotubes were produced over carbon fibers. The process occurs catalytically by chemical vapor deposition (CVD) using mixture with camphor and ferrocene. After that, the VACNT/CF composite are treated by oxygen plasma for oxygen functionalization. Prior the electrochemical analysis, CNT/Carbon fibers are treated by hydrochloric acid to remove residual catalyst. The electrodes were tested in a usual electrolyte (with H2SO4 0.5M) in a conventional electrochemical cell. The specific capacitance was tested in a separate device. The configuration of carbon fibers and VACNT presents a high potential application for electro analytical application and energy storage.

Electric Double Layer Capacitor of Multiwall Carbon Nanotubes under Different Degree of Acid Oxidations

Carbon nanotubes (CNT) are a material with unique properties (mechanical, electrical, electrochemical, etc) allied with low density and high specific area. The present paper studied the electrochemical properties of carbon nanotubes growth by Chemical Vapor Depostion (CVD) technique. The samples were characterized by SEM, Raman Spectroscopy and the double layer capacitance of the powders was evaluated in a Teflon capacitor system with a Ag/AgCl (3M) as reference electrode. The catalyst remotion is provided in Hydrochloric acid washing and the wet oxidative treatments promotes the CNT oxidation and increase the pseudocapacitive response.