title: CdS-encapsulated TiO2 nanotube arrays lidded with ZnO nanorod layers and their photoelectrocatalytic applications.
abstract: A novel TiO(2) nanotube array/CdS nanoparticle/ZnO nanorod (TiO(2) NT/CdS/ZnO NR) photocatalyst was constructed which exhibited a wide-absorption (200-535 nm) response in the UV/Vis region and was applied for the photoelectrocatalytic (PEC) degradation of dye wastewater. This was achieved by chemically assembling CdS into the TiO(2) NTs and then constructing a ZnO NR layer on the TiO(2) NT/CdS surface. Scanning electron microscopy (SEM) results showed that a new structure had been obtained. The TiO(2) NTs looked like many "empty bottles" and the ZnO NR layer served as a big lid. Meanwhile the CdS NPs were encapsulated between them with good protection. After being sensitized by the CdS NPs, the absorption-band edge of the obtained photocatalyst was obviously red-shifted to the visible region, and the band gap was reduced from its original 3.20 eV to 2.32 eV. Photoelectric-property tests indicated that the TiO(2) NT/CdS/ZnO NR material maintained a very high PEC activity in both the ultraviolet (UV) and the visible region. The maximum photoelectric conversion efficiencies of TiO(2) NT/CdS/ZnO NR were 31.8 and 5.98% under UV light (365 nm) and visible light (420-800 nm), respectively. In the PEC oxidation, TiO(2) NT/CdS/ZnO NR exhibited a higher removal ability for methyl orange (MO) and a high stability. The kinetic constants were 1.77×10(-4) s(-1) under UV light, which was almost 5.9 and 2.6 times of those on pure TiO(2) NTs and TiO(2) NT/ZnO NR, and 2.5×10(-4) s(-1) under visible light, 2.4 times those on TiO(2) NT/CdS.
authors.affiliation: Department of Chemistry, Tongji University, Singping Road 1239, 20092 Shanghai, P. R. China.
authors.forename: Ya-nan
authors.initials: YN
authors.lastname: Zhang
authors.forename: Guohua
authors.initials: G
authors.lastname: Zhao
authors.forename: Yanzhu
authors.initials: Y
authors.lastname: Lei
authors.forename: Peiqiang
authors.initials: P
authors.lastname: Li
authors.forename: Mingfang
authors.initials: M
authors.lastname: Li
authors.forename: Yuning
authors.initials: Y
authors.lastname: Jin
authors.forename: Baoying
authors.initials: B
authors.lastname: Lv