A novel route to ZnO/TiO 2 heterojunction composite fibers
- PDF / 374,193 Bytes
- 6 Pages / 584.957 x 782.986 pts Page_size
- 20 Downloads / 240 Views
unxu Pana) School of Physics and Technology and MOE Key Laboratory of Artificial Micro- and Nano-structures, Wuhan University, Wuhan 430072, China; and Center for Electron Microscopy, Wuhan University, Wuhan 430072, China (Received 15 May 2012; accepted 2 August 2012)
ZnO/TiO2 heterojunction composite fibers were prepared via a physical route, i.e., first electrospinning titanium dioxide (TiO2) fibers, then pulse plating zinc (Zn) on the fibers, and at last thermal treating the fibers. The morphologies, phase structures, and photocatalytic property of the composite fibers were characterized by using field-emission gun scanning electron microscope, x-ray diffractometer, high-resolution transmission electron microscope, and ultraviolet–visible spectrophotometer. It was found that a full or partial lattice coherent heterojunction was formed between the TiO2 fibers and zinc oxide (ZnO) particles, due to thermal treatment at 400 °C, which simultaneously resulted in the phase transformations including Zn to ZnO and amorphous TiO2 to anatase TiO2. The experimental results demonstrated that the photocatalytic activity of the composite fibers was improved and exhibited a value more than two times higher than that of TiO2 fibers.
I. INTRODUCTION
Oxide semiconductors have attracted wide attention in the past decades, due to the potential applications in the areas such as photocatalyst, solar cell, and optoelectronic, etc. Compared to other oxide semiconductors, titanium dioxide (TiO2) has been extensively studied for its excellent optical and electronic properties, stabilization, and security. However, its applications are still limited because of its inherent defects involving large band gap (anatase 3.2 eV), which restricts the absorbing wave length no longer than 387 nm within the ultraviolet (UV) light, and the other inherent defect of TiO2 is the high recombining ratio of photoinduced electron–holes, which lowers the photocatalytic property.1,2 Up to now, many methods have been exploited for overcoming these disadvantages, e.g., doping with metal/nonmetal ion3–5 and coupling with other oxide semiconductors.6–21 Generally, coupling with oxide semiconductor is a simple and efficient method to improve photocatalytic efficiency. That is to say, a heterojunction is introduced between different oxide conductors for both enhancing utilization of solar energy and also reducing the recombination ratio of photoinduced electron and holes pairs simultaneously. Recently, the composite systems includingV2O5/TiO2,6 SnO2/TiO2,7,8 CdO/TiO2,9 ZnO/TiO210–21 have been reported. a)
Address all correspondence to this author. e-mail: [email protected] DOI: 10.1557/jmr.2012.282 J. Mater. Res., Vol. 28, No. 3, Feb 14, 2013
http://journals.cambridge.org
Downloaded: 13 Mar 2015
Around the possible available oxide semiconductor, ZnO/TiO2 composite system obviously has attracted more attentions. The band gap of ZnO is 3.2 eV, which is similar to that of TiO2 (anatase).10 Nano ZnO is a typical wide band gap oxide semiconductor with strong size effect and rema
Data Loading...
