Controllable One-demensional Ti/TiO₂Nanostructure: Fabrication And Property Research

One-dimensional metallic nanostructures such as nanorods, nanowires and nanotubes areparticular interests since they possess both the advantages of one-dimensional materials andof nanostructures, indicative of their unique optical, magnetic, electronic and catalyticproperties. Various metallic systems including Pd, Pt, Ag, Au, Ru and Cu etc. have beensuccessfully fabricated via many ways, such as electrodeposition method, template method,physical evaporation deposition method, hydrothermal and plasma atomic layer deposition.However, the Ti nanostructure materials have rarely been studied so far. In this paper, wefirstly prepared self-organized homogeneous Ti nanorod array via selective corrosion of Tisubstrate by using electrochemical anodization at galvanostatic regime.Vast previous researches have shown that potentiostatic and/or galvanostatic anodizationof Ti in a fluoride-containing electrolyte leads to the formation of TiO₂nanotubes. Whereaswe have fabricated the homogeneous and closed packed Ti nanorods by utilizing galvanostaticanodization in1.45wt%NH₄F and1.93wt%H₂C₂O₄mixed solution as electrolyte at theroom temperature. Besides, the nanorod length can be tuned periodically via tailoring theelectrochemical conditions during titanium anodization. Therefore length-controlled of Tinanorods could be obtained by altering the anodizing time. To the best of our knowledge,these results have never been reported previously. We also comprehensively analysed theeffects of current value, H⁺and F-concentration on preparing Ti nanorods and proposed apossible mechanism to explain the formation of Ti nanorods with periodic length.Based on the result as above-mentioned, the effect of reaction temperature has beendiscussed. We found that the temperature point t₁and t₂were existed under potentiostatic andgalvanostatic regime respectively. When the electrochemical anodization was proceededunder the designed temperature lower than t₁at200mA galvanostatic regime, TiO₂nanotubeswere obtained without Ti nanorods. While the temperature higher than t₁, Ti nanorods weregained. The same phenomenon that nanotubes transform to nanorods was explored at20Vpotentiostatic regime as the reaction temperature increasing to t₂and above it. Theexperimental results also showed that Ti nanorods were achieved at200mA galvanostaticregime in special electrolyte with14:20（mass ratio） NH₄F and H₂C₂O₄regardless of thereaction temperature. Nevertheless, TiO₂nanotubes were obtained by electrochemicalanodization in electrolyte with1:8NH₄F and H₂C₂O₄at the same condition. Besides, we alsofound that the same regularities were turned up at20V potentiostatic regime in definiteelectrolyte with14:20NH₄F and H₂C₂O₄and with4:6. In this paper, the property of Ti nanorod array and TiO₂nanotube were studiedrespectively, such as protein absorbability and hydrophily. Experimental results demonstratethat the protein absorbability of Ti nanorod falls in between Ti foil and TiO₂nanotube, and isrelated to its length. They are all hydrophobic materials.