Porous Titanium Dioxide Coatings Obtained by Anodic Oxidation for Photocatalytic Applications

Abstract

The aim of this work is to obtain porous titanium dioxide with good efficiency for photocatalytic environmental applications. TiO 2 coatings were obtained by anodic spark deposition, at constant applied potential (150 V), using a platinum cathode and 0.5 M sulfuric acid as electrolyte. Samples of titanium Grade 2 were used as substrate, metallographically prepared until 1 μm diamond surface finishing. The variables of the process were temperature (25 and 40 °C) and anodization time (5 and 10 min). Samples obtained at 40 °C showed a higher current density than those obtained at 25 °C and the potential reached by these samples was lower than those obtained at 25 °C. These results are attributed to an increased electrolyte conductivity. Optical microscopy images of the oxides obtained at 40 ºC showed heterogeneity in color, indicating a non-uniform oxide thickness. This coincides with the images obtained by scanning electron microscopy that revealed "valleys" where the material did not present porosity. On the other hand, the oxides obtained at 25 °C showed a complete homogeneous porous structure. The average pore diameter was reduced with the increased oxidation time and temperature of the electrolyte. An increase of the crystalline anatase phase was observed with an increase of the anodization time; besides, rutile formation was observed, probably due to the final potential achieved by the samples.

Evolution of anodised titanium for implant applications

“…Thereby, porous oxide layer will not be formed on the titanium anodised at higher bath temperature. Yetim [ 194 ] and Traid et al [ 195 ] also found that higher bath temperature leads to the reduction of porosity and thickness of TiO 2 anodic layer. Similarly, lower bath temperature also induces the formation of TiO 2 nanotubes with ideal packed hexagonal prisms.…”

Immobilized particle coating for optimum photon and TiO 2 utilization in scaled air treatment photo reactors

“…literature [20]. This includes physical and chemical vapor deposition, anodic oxidation, atomic layer coating, magnetron sputtering, pulsed laser coating, electro deposition, dip coating [21][22][23][24][25][26][27][28][29]. Dip coating is in fact, one of the most popular methods.…”

Archives of Metallurgy and Materials

“…The electrochemical anodizing is a common surface modification method for Ti and its alloys where the work piece is used as anode in an electrolytic cell to form stable oxide coating [1][2][3][4][5][6][7][8]. The process can be performed under potentiostatic or galvanostatic mode in numerous electrolytes.…”