Enhanced Visible Light Activity of Ag-Loaded TiO<sub>2</sub> Nanotube Arrays by AC Electrodeposition

In this work, highly-ordered TiO 2 nanotube arrays were prepared by constant-voltage anodization, followed by electrodeposition of Ag to obtain Ag-loaded TiO 2 (Ag-TiO 2 ) nanotube arrays via alternating current (AC) process. The results of SEM and XRD show that the morphology and crystal structure of Ag-TiO 2 layer depend greatly on the electrodeposition parameters. Ag-TiO 2 nanotube arrays prepared in 2.5 mmol/L AgNO 3 solution by electrodeposition with applied voltage of 12 V for 1 minute performed the best photoelectrochemical current response and photocatalystic activity. The photocurrent density of Ag-TiO 2 is 43.32 μA/cm 2 under sunlight irradiation (70 mW/cm 2 ), which is 4.2 times as that of unloaded TiO 2 nanotube arrays. Methyl orange (MO) degradation rate with the Ag-TiO 2 nanotube arrays achieves 52.13% after 90 min sunlight irradiation which is obvious higher than that of TiO 2 nanotube arrays. The mechanism of enhancing photoelectrochemical activity of decorating titania with Ag has also been discussed in the view of energy band theory.