A research on the visible light photocatalytic activity and kinetics of CdS/CdSe co-modified TiO2 nanotube arrays

Abstract CdS and CdSe nanoparticles (NPs) were deposited on highly ordered TiO 2 nanotube arrays (NTAs) by chemical bath deposition (CBD) and electrodeposition methods. FESEM, XRD, HRTEM, XPS, UV–Vis and EDX methods were employed to characterize the microstructure and composition of samples. CdSe and CdS nanoparticles were found to be uniformly deposited on the wall of TiO 2 nanotubes after 10 controlled deposition cycles of CdS and a period of 600 s deposition of CdSe. The photocatalytic performances of TiO 2 , CdS/TiO 2 , CdSe/TiO 2 and CdSe/CdS/TiO 2 NTAs were systematically investigated. Both single modification and co-modification extended the light absorption of TiO 2 NTAs to the visible light range. The degradation rate of CdSe/CdS/TiO 2 NTAs to Methyl Orange solution reached 96.0% after being irradiated in the visible light (250 W metal halide lamp) for 2 h, and remained at 84.3% after being reused for 15 times. Comparatively, the degradation rates of CdSe/TiO 2 and CdS/TiO 2 NTAs to Methyl Orange solution for the first use were just 92.8% and 89.8% respectively. Kinetic research shows that the apparent reaction rate constants for CdS/TiO 2 , CdSe/TiO 2 and CdSe/CdS/TiO 2 NTAs are 0.01889, 0.02176 and 0.02701 min − 1 respectively.