The Electrochemical Formation and Shielding Mechanism of TiO₂Nanotubes in Organic Electrolytes with Different Viscosity

Abstract

The present paper reports on the formation and respectively shielding of TiO2 nanotubes elaborated in two water-containing organic electrolytes with the addition of NH4F, via potential step anodizing method. The organic compounds used ethylene glycol (EG) and polyethylene glycol (PEG), have significantly different molecular weights and viscosities. As a consequence, the resulting nanotubes layers are unshielded in first electrolyte and shielded in the second and have different diameters and lengths. FT-IR spectra reveal the incorporation of electrolyte anions to the surface of the TiO2 nanotubes when employing the most viscous electrolyte. This could be an explanation for different contact angle values, roughness and corrosion resistance in bioloquids.

Antibacterial efficiencies of TiO2 nanostructured layers prepared in organic viscous electrolytes

“…3. In the case of samples Ti/EG 3%w, and Ti/PEG 600 3%w we obtain nanotubes, as we have previously reported for those electrolytes with 2% of water [24,25]. Nanotubes have different diameters; in EG around 50 nm and between 117 nm and 208 nm in case of PEG 600 electrolyte.…”

“…Nanotubes have different diameters; in EG around 50 nm and between 117 nm and 208 nm in case of PEG 600 electrolyte. In PEG 400, with 2% water, we have obtained nanotubes [24] compared to the present study, in which, for Ti/PEG 400 3%w sample, we have obtained nanotubular layer, but with nanotubes not very well defined and arranged. So, it seems that in this electrolyte the water content is very important for obtaining nanotube structures, and small differences between the amounts of water can radically change the morphology of the sample.…”

“…In previous works we successfully obtained TiO 2 nanotubes in organic electrolytes (EG and PEG with average molecular weights 400 and 600) with addition of NH 4 F and small water content [24,25]. Thus, in this work, TiO 2 nanostructured surfaces were obtained in very viscous PEG 1000.…”

“…In the previous works, we showed that some remaining viscous electrolyte is still present on the surface of the anodized samples, despite the fact that those were carefully rinsed with purified water before recording FT-IR spectra [24,25]. The surface of anodized Ti was analyzed using the FT-IR transmission spectra, in order to probe if this observation is also valid for the samples anodised in those electrolytes with more water content.…”

Enhancing antimicrobial activity of TiO2/Ti by torularhodin bioinspired surface modification

“…In a previous work [11], we showed that this shielding layer also contains traces of anodizing electrolyte, PEG 400, with antibacterial activity [12]. TiO 2 nanotubes found applications in different domains, such as: dye-sensitized solar cells, photo-catalysis, gas sensing, water splitting, ion-intercalation (insertion) devices, supercapacitors [10,13].…”