Synthesis and optical properties of ZnO–ZnS core-shell nanotube arrays

Abstract

Heterostructured ZnO-ZnS core-shell nanotube arrays with the diameters of 50-80 nm and lengths up to 1 m were synthesized by a two-step chemical reaction. First, the ZnO layer was grown by atomic-layer deposition. It was found that the preferred growth orientation was strongly dependent on the substrate temperature. After sulfuration conversion from arrayed ZnO nanorods, the ZnS-ZnO composite arrays can be successfully prepared, as evidenced from transmission electron microscopy. This confirms that the ZnO-ZnS core-shell nanotube-arrayed structure has been fabricated. X-ray photoelectron spectroscopy analysis indicates that the binding energy of S 2p is the same as that of bulk single-crystal ZnS and that the Zn 2p 3/2 peak is shifted about 0.5 eV due to the formation of Zn-S bonds. Photoluminescence shows the relative-intensity ratio of ultraviolet emission ͑I UV ͒ to deep-level emission ͑I DLE ͒ for ZnO / ZnS core-shell nanotubes can be enhanced to be nine times that of original ZnO nanotubes.

Synthesis and photovoltaic effect of vertically aligned ZnO/ZnS core/shell nanowire arrays

“…Qualitatively, the effect of a ZnS coating is similar to that of a ZnSe coating reported previously. 15 It was recently reported that a ZnS coating over ZnO nanotubes or nanorods enhanced UV emission, 19,20 which appears to agree with conventional wisdom that ͑1͒ the coating of a large-band gap material diminishes the loss through surface recombination and ͑2͒ the UV emission is from the bulk part of the ZnO. However, this understanding is not expected to hold true for type II combinations such as ZnO/ZnS, even though ZnS has a larger band gap.…”

Facile Synthesis of Heterostructured ZnO–ZnS Nanocables and Enhanced Photocatalytic Activity

“…5(b)). 18 Moreover, it can be Gaussian fitted to two peaks locating at 161.9 and 162.9 eV, which may arise from differential charging of the surface layer or some surface contamination (like residual Na 2 S) 12 …”

Synthesis of Inorganic Nanotubes

“…Typical examples of such nanostructures are the following: Integration of ZnO nanotubes with ordered nanorods, [227] conversion of ZnO nanorod arrays into ZnOÀZnS nanocable and ZnS nanotube arrays, [228] core-sheath heterostructure CdSÀTiO 2 nanotube arrays, [229] ZnS nanotube-In nanowire core-shell heterostructures, [230] ZnOÀZnS core-shall nanotube arrays, [231] Cu nanotube-Bi nanowire heterojunctions, [232] carbon nanotubes in TiO 2 nanotubes, [233] TiO 2 ÀPt coaxial nanotube arrays, [234] Sn nanowires on TiO 2 nanotubes, [235] Fe 2 O 3 ÀTiO 2 nanorod-nanotube arrays, [236] SiO 2 ÀTa 2 O 5 core-shell nanowires and nanotubes, [237] multi-walled BCN-carbon nanotube junctions, [238] and BN nanotubes with periodic iron nanoparticles. [239] …”