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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]

TiO nanotube arrays (NTAs) with different intertube spaces were fabricated via electrochemical anodization process in the electrolyte with different water contents. Uniform distributed cadmium selenide (CdSe) nanoparticles were deposited onto the TiO NTAs through electrodeposition method. The influence of water contents in electrolyte on the microstructure and photocatalytic property of CdSe/TiO NTAs were studied. The results show that increasing the water content in electrolyte from 2 to 12 vol% can enlarge the intertube space from 0 to 22 nm, which is beneficial for the deposition of CdSe nanoparticles. The photocatalytic activity of CdSe/TiO NTAs was evaluated by measuring the degradation of methyl orange solutions under visible light. When water content was 10 vol%, CdSe nanoparticles distributed uniformly on the inner and outer surface of TiO NTAs. The photocatalytic tests indicated that CdSe/TiO NTAs composites exhibits excellent photocatalytic properties after visible light irradiation for 2 h, the degradation rate reached from 55.7 to 94.5 % when water content increased from 2 to 10 vol%, whereas the degradation rate of the TiO NTAs without CdSe modification is just 4.8 %. Graphical Abstract: [Figure not available: see fulltext.] [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]