TiO_2 Nanotube Prepared via Anodizing and Its Photocatalytic Performance

High density,well ordered,vertically aligned and uniform titanium oxide nanotube arrays were fabricated on the surface of pure titanium sheet by direct electrochemical anodic oxidation with 0.5%HF and 0.5%HF+1 mol/L(NH4)H2PO4 as the supporting electrolyte at 20 V.XRD and SEM techniques were used to characterize titanium oxide nanotube arrays.The XRD result shows that TiO_2 showed the anatase phase after having been annealed for 1 hour under 400 ℃.SEM shows the length of nanotubes did not increase after reaction for 20 mins in an electrolyte solution of 0.5%HF.But in an electrolyte solution of 0.5%HF+1 mol/L(NH4)H2PO4,at 20 V after reaction for 15 h,the average diameter of nanotubes is about 70~90 nm,and the length of nanotubes is about 2.2 μm.Photo-electrochemical character curves were tested in an electrolyte solution of 1 mol/L KOH under the irradiation of a high-voltage mercury lamp,photocurrent is about 3.5 mA/cm2 for nanotubes with a length of 2.2 μm.With TiO_2 nanotubes of 2.2 μm in length as anode,under illuminating of a high-voltage mercury lamp at 0.45 V bias potential,after 4 h,the COD degradation degree of Methylene Blue electrolyte(10 mg/L) is about 93%.