Ultrasound aided photochemical synthesis of Ag loaded TiO2 nanotube arrays to enhance photocatalytic activity

National Natural Science Foundation of China [20773100]; National Basic Research Program of China [2007CB935603]; Natural Science Foundation of Fujian Province, China [U0750015]; Technical Program of Fujian Province and Xiamen City, China [2007H0031, 3502Z20073004]