Short Communication Electrospun nanofibers of ZnO/BaTiO 3 heterostructures with enhanced photocatalytic activity Pengrong Ren, Huiqing Fan ⁎, Xin Wang State Key Laboratory of Solidification Processing, School of Materials Science and Engineering, Northwestern Polytechnical University, Xi'an 710072, China abstract article info Article history: Received 3 February 2012 Received in revised form 25 March 2012 Accepted 4 April 2012 Available online 9 April 2012 Keywords: BaTiO 3 ZnO Heterostructures Photocatalytic ZnO/BaTiO 3 nanofiber heterostructures with highly uniformly dispersed ZnO nanoparticles grown on primary BaTiO 3 nanofibers have been obtained by the combination of an electrospinning and a hydrothermal process. Powder X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to characterize the ZnO/BaTiO 3 nanofiber heterostructures. Furthermore, their UV-induced catalytic activities were studied by a degradation reaction of methyl orange (MO) dye. Compared with pure ZnO powders, ZnO/BaTiO 3 nanofiber heterostructures showed better performance of the photocatalytic property, which was ascribed to the synergistic effects of photogenerated electron and hole pair separation and high specific surface area. © 2012 Elsevier B.V. All rights reserved. 1. Introduction In the last decades, photocatalysis, as a “green” technique, has aroused great attention for its efficiency and broad applicability to elim- inate toxic chemicals in the environment [1]. It has been reported that many nanostructural semiconductor metal oxides can degrade various organic pollutants under UV or visible light irradiation [2–6]. Currently the key focus to improve efficiency of photocatalysis is to inhibit the quick recombination of photoinduced charge carriers. Thus, semicon- ductor materials with heterostructures are applied because of the effec- tive electron hole pair separation [7–9]. Among various heterostructures, nanofiber heterostructures are thought to be one of the most promising solutions. On the one hand, nanofibers, mainly prepared by electrospinning technology, have been proven to be effective supports owing to their high porosity and large surface area. The high porosity of a nonwoven mat of nanofibers usually enables direct growth of secondary nanostructures via heterogeneous nucleation [10]. The successful employment of electrospun nanofibers as substrates for other metal oxide nanostructures has been demon- strated for a number of reactions [11–13]. On the other hand, the separation of the nanostructural photocata- lysts from the solution after a reaction is another challenge in a practical photocatalytic process. In order to solve this problem, using nanofibers as catalysts is a good choice since they can be easily separated from the solution due to the large length-to-diameter ratio. Additionally, the as- electrospun nanofibers could be reclaimed by sedimentation without a decrease in photocatalytic activity [14]. Zinc oxide (ZnO) nanomaterials, naturally n-type semiconductors with a wide band gap (Eg = 3.37 eV), have been recognized as an excel- lent material for photocatalytic processes [15]. Besides, barium titanate (BaTiO 3 ), a well-known perovskite-type multi metallic oxide with a band gap of 3.14 eV, has a great potential for optoelectronics [16]. More interestingly, BaTiO 3 offers favorable energy for photocatalysis since its conduction band edge is lower than ZnO [17]. In this regard, under UV light irradiation, a proper combination of BaTiO 3 and ZnO can lead to not only the transfer of electron from the conduction band of ZnO to that of BaTiO 3 , but also the transfer of hole from the valence band of BaTiO 3 to that of ZnO. As such, the improved separation between photogenerated electrons and holes is expected to improve the photocatalytic activity of ZnO. A similar effect was also found in the SrTiO 3 /TiO 2 nanofiber heterostructures [18]. On the basis of the above discussion, ZnO nanoparticles and BaTiO 3 nanofibers were chosen as the candidates for the heterojunction sys- tem. ZnO/BaTiO 3 heterostructures were obtained by the combination of an electrospinning and a hydrothermal process. 2. Experimental 2.1. Preparation of ZnO/BaTiO 3 nanofiber heterostructures The experimental process included two steps. In the first step, 1 mL of tetrabutyl titanate and 0.747 g of barium acetate were dissolved in 1.5 mL of acetic acid and 5 mL of ethanol. After stirring at room temper- ature for 2 h, the above homogeneous sol was added to 10 mL of polyvi- nylpyrrolidone (PVP) ethanolic solution (8 wt.%) with vigorous stirring Catalysis Communications 25 (2012) 32–35 ⁎ Corresponding author. Tel.: + 86 29 88494463; fax: + 86 29 88492642. E-mail address: hqfan3@163.com (H. Fan). 1566-7367/$ – see front matter © 2012 Elsevier B.V. All rights reserved. doi:10.1016/j.catcom.2012.04.003 Contents lists available at SciVerse ScienceDirect Catalysis Communications journal homepage: www.elsevier.com/locate/catcom