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Immobilized TiO2 nanotube arrays (NTAs) co-modified with Pt and CdS nanoparticles were fabricated by using the combination of photoreduction and chemical bath deposition methods. XRD, SEM, TEM, XPS, UV-Vis and EDX methods were employed to characterize the microstructure and composition of samples, and the results showed that CdS and Pt NPs were uniformly deposited on the surface of TiO2 nanotubes. The CdS/Pt/TiO2 NTAs exhibited a much higher photocatalytic activity compared to pure TiO2 NTAs and binary CdS (or Pt)/TiO2 NTAs under visible light irradiation. A kinetic study showed that the rate constants of Pt/TiO2, CdS/TiO2 and CdS/Pt/TiO2 NTAs are 0.00736, 0.01717 and 0.02077 min−1, respectively, revealing a remarkable kinetic enhancement in the ternary heteronanostructures due to the synergistic effect of the three components. Besides, the CdS/Pt/TiO2 NTAs exhibit high stability after being used 22 times. Thus we proposed that such ternary heteronanostructures show great promise as immobilized catalysts for high efficient visible-light-driven photocatalysis. [ABSTRACT FROM AUTHOR]

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]

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]