Photocatalytic Activity of Anodized Titanium Sheets under Ultra-Violet and Visible Light Irradiation

Abstract

A commercially pure titanium sheet precipitated TiC in the surface layer was fabricated by anodic oxidation in NH 4 NO 3 solution and heat treatment in air. The fabricated sheet showed relatively high photocatalytic activity in 0.1 M KI solution, which was close to the activity level of the P-25 particle made by Degussa Corporation. It exhibited photocatalytic activity in antifungal and antivirus tests under black light irradiation. The better photocatalytic activity under black light irradiation is considered to be related to the formation of anatase and rutile type titanium dioxides and rough surface. It also showed photocatalytic activity under visible light irradiation, which is considered to be attributable to carbon and nitrogen doping in titanium dioxide.

Photocatalytic Activity of Titanium Dioxide Powder Fabricated from an Anodized Titanium Sheet under Ultra-Violet and Visible Light Irradiation

“…The surface of the titanium substrate was coated with a titanium oxide layer with a thickness of approximately 0.1 μm and a relatively large size of titanium oxide powders exfoliating from the substrate was observed. As already described [10], anodization of the CP substrate occurred very radically owing to a high applied voltage, (80 V), thus, the thickness of titanium oxide increased to a large extent, and particles were formed by exfoliation from the titanium substrate. Figure 7 shows magnified cross-sectional TEM image and EDS analysis of the anodized and heat-treated titanium substrate.…”

“…After irradiation with black light or the fluorescent light, a peak intensity of 0.1 mol/l KI solution at 287 nm was measured by an absorption spectrophotometer (U2910, HITACHI) for measuring 3 I − formed by the photocatalytic reaction. 3 I − is slightly formed by dissolved oxygen without a phtocatalyst, thus, 0.1 mol/l KI solution without test specimen were also measured as control [10] [11] [13]. The photocatalytic activity of the P-25 powder was also measured by the same method described above under the ultra violet and visible light irradiation.…”

“…The photocatalytic activity was measured using KI solution [10] [11] [13]. Tapes an ultra-violet ray-shielding sheet was applied to irradiate only visible light to the sample.…”

“…The sample also showed photocatalytic activity under visible light irradiation. It is considered that visible light response is caused by doping of carbon and nitrogen in titanium dioxide [10] [11].…”

Characterization of Surface Oxide Layers on Black-Colored Titanium

“…The authors [7] also conducted studies to develop an anodized titanium sheet with enhanced photocatalytic activity. An anodized titanium sheet that showed high photocatalytic activity under UV irradiation was fabricated by the anodic oxidation of a commercially pure (CP) titanium sheet in a 0.06 M NH 4 NO 3 aqueous solution, followed by heat treatment at 803 K for 1 h in air.…”