Andrei Bogdan Stoian

The electrochemical stability in NaCl solution of nanotubes and nanochannels elaborated on a new Ti-20Zr-5Ta-2Ag alloy

Nanotubular and nanochannels structures were fabricated via anodizing on a new alloy Ti-20Zr-8Ta-2Ag. A continuous coating of connected tubes/channels can be observed in the SEM micrographs forming tubular structures with diameters in hundreds of nm, as well as smaller tubes, with diameters in tens of nm. In the case of nanochannels structure, the diameters are smaller and wall thicknesses significantly thinner than in nanotubes. Wettability measurements indicate a decrease of contact angles in both cases of nanotubes and nanochannels, but the increase of hydrophilic character ismore significant in the case of nanochannels. The Tafel procedure and electrochemical impedance spectroscopy tests performed in NaCl 0.9% solution indicate a better stability for the nanostructured surfaces compared to untreated alloy, the surface with nanochannels offering higher corrosion resistance. Spectral UV-VIS determination has confirmed Ag metallic presence, opening the door for applications not only in tissue engineering but for water splitting and the photoreduction of CO2 as well.

Effects of PEG on the stability and electrochemical properties of PEDOT: PSS films obtained by spin coating

By mixing the same concentration polyethylene glycol (PEG) with molar masses of 400, 600 and 1000, a series of poly (3,4-ethylenedioxythiophene):poly (styrenesulfonate) (PEDOT: PSS) composite thin films were prepared by spin coating. The morphology of the films was inspected by Atomic Force Microscopy (AFM). Electrochemical characterizations performed over a time span of five days including Cyclic Voltammetry (CV) and Electrochemical Impedance Spectroscopy (EIS) were used to determine the stability of the films. The experimental results showed that the properties of PEDOT: PSS films were greatly influenced by the molecular weight of PEG.