Effect of the Temperature and Concentration of NaOH on the Formation of Porous TiO[sub 2]

Abstract

The influence of the temperature and concentration of NaOH on the formation of porous was investigated. The porous was obtained only after a immersion in NaOH at . The X-ray diffraction pattern indicated that the porous layer consisted of a mixture of anatase and rutile types of . During immersion in the NaOH solution, the anodic and cathodic reactions proceed at the same time on the titanium. From the cathodic polarization measurements, the cathodic reaction proceeded mainly the hydrogen evolution reaction. Therefore, a part of the adsorbed hydrogen penetrated into the titanium. The penetration of hydrogen confirmed with a glow discharge optical emission spectroscopy. The hydrogen evolution reaction continues during immersion in the NaOH solution at . However, the hydrogen evolution did not proceed in the low concentration of NaOH solution or at below . In addition, although the hydrogen evolution continues during immersion in NaOH solution at 303 or . As a result, the content of hydrogen in the titanium is insufficient to form the porous layer so that the porous layer is not produced on the titanium.