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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. [ABSTRACT FROM AUTHOR]

Highly ordered TiO 2 nanotube arrays (TiO 2 NTAs) have been fabricated by the potentiostatic anodization method with Ti foils. Pt nanoparticles have been successfully deposited onto TiO 2 NTAs by UV light photoreduction method. In this work, X-ray diffraction, field emission scanning electron microscope, high resolution transmission electron microscopy, X-ray photoelectron spectroscopy, ultraviolet-visible spectroscopy and energy dispersive X-ray spectrometer methods were adopted to characterize the samples. The influence of different concentration of H 2 PtCl 6 precursor solution on the morphology and photocatalytic performances of samples was discussed. The SEM observations showed that Pt nanoparticles distributed on the wall of TiO 2 nanotubes uniformly. UV–vis spectra analysis showed that the light absorption of Pt/TiO 2 NTAs has been extended to the visible light range. When the concentration of H 2 PtCl 6 was 3 mM, the prepared sample showed the highest photodegradation rate. After irradiated under visible light for 2 h, the degradation rate of methyl orange solution reached 84.27%. Under the same condition, no obvious photodegradation of methyl orange was found for TiO 2 NTAs. Kinetic research showed that photodegradation process followed the first-order reaction, the apparent reaction rate constant of 3 Pt/TiO 2 NTAs was 1.493 × 10 −2 min −1 . [ABSTRACT FROM AUTHOR]

Abstract: Highly ordered TiO2 nanotube arrays (NTAs) were fabricated on titanium substrate via electrochemical anodization method. CdSe nanoparticles were deposited on the TiO2 NTAs through the electrodeposition process. The influence of electrolyte concentration and deposition time on the visible light photocatalytic performance of CdSe/TiO2 NTAs was studied systematically. The photocatalytic activity of as-prepared samples was evaluated by degradation of methyl orange under visible light irradiation. The results indicated that the CdSe nanoparticles distributed uniformly on the surface of TiO2 NTAs when deposited in the electrolyte containing 0.02M CdCl2, 2mM SeO2 and 0.02M Na2SO4 with time of 600s. After irradiation under visible light for 2h, the degradation rate of CdSe/TiO2 NTAs composite material reached 94.4%, while the degradation rate of unmodified TiO2 NTAs was only 6.2 % under the same condition, demonstrating that the CdSe/TiO2 NTAs exhibited higher photocatalytic activity in visible light region. In addition, a reasonable degradation rate of 80.96% was achieved even after being used for 5 times. [Copyright &y& Elsevier]