A novel CeO 2 /Bi 2 WO 6 composite with highly enhanced photocatalytic activity Sudarat Issarapanacheewin a , Khatcharin Wetchakun b , Sukon Phanichphant c , Wiyong Kangwansupamonkon d , Natda Wetchakun a,n a Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200, Thailand b Program of Physics, Faculty of Science, Ubon Ratchathani Rajabhat University, Ubon Ratchathani 34000, Thailand c Materials Science Research Centre, Faculty of Science, Chiang Mai University, Chiang Mai 50200, Thailand d National Nanotechnology Center, Thailand Science Park, Phahonyothin Road, Klong 1, Klong Luang 12120, Phathumthani, Thailand article info Article history: Received 2 March 2015 Accepted 25 April 2015 Available online 5 May 2015 Keywords: Composite Metal oxide Semiconductor Hydrothermal Photocatalytic activity abstract A straight forward strategy was designed for the preparation of novel CeO 2 /Bi 2 WO 6 composite photocatalysts with differing CeO 2 /Bi 2 WO 6 mole ratios by hydrothermal method. The X-ray diffraction (XRD), scanning electron microscopy (SEM), and UV–vis diffuse reflectance spectrophotometry (UV–vis DRS) techniques were found to be most suitable for describing the physicochemical properties of CeO 2 / Bi 2 WO 6 onto the photocatalytic activity. Photocatalytic activities of all samples were evaluated by the degradation of rhodamine B under simulated solar light irradiation. The 0.4CeO 2 /0.6Bi 2 WO 6 composite exhibits highest photocatalytic activity due to the introduction of CeO 2 and Bi 2 WO 6 , which can improve the separation of the electron–hole pairs. & 2015 Elsevier B.V. All rights reserved. 1. Introduction Throughout last decades, heterogeneous photocatalysis has been positioned as a promissory efficient technology to resolve environ- mental and energy problems [1–4]. In recent years, there are many papers focused on the preparation of bismuth compounds which can degrade organic pollutants. Among different bismuth compounds, bismuth tungstate (Bi 2 WO 6 ) has also been demonstrated to exhibit visible light driven photocatalytic activity [5–7]. Moreover, cerium dioxide (CeO 2 ) has also been shown to be a particularly effective catalyst [8]. Therefore, it can be serve as an ideal support material with improved the separation of photogenerated electron–hole pairs and increase the charge carrier lifetime. There are several works investi- gated on the preparation and properties of the Bi 2 WO 6 -, CeO 2 -, coupled with other materials, and they found the composite photo- catalyst shows enhanced photocatalytic activity for water splitting and organic degradation [9–12]. However, there is no report focused on the preparation and photocatalytic properties of CeO 2 /Bi 2 WO 6 com- posite. Therefore, in the present work, the novel CeO 2 /Bi 2 WO 6 composite photocatalyst was synthesized by coupling with homoge- nous precipitation and hydrothermal methods in different mole ratios. The samples were characterized for their physical and chemical properties based upon XRD, SEM, and UV–vis DRS techniques. The photodegradation activity of rhodamine B (RhB) was used as a measurement for photocatalytic performance of pure CeO 2 , pure Bi 2 WO 6 and CeO 2 /Bi 2 WO 6 samples. To further understand the effect of physical and chemical properties of CeO 2 and Bi 2 WO 6 on the photocatalytic activity and the photocatalytic mechanism of CeO 2 / Bi 2 WO 6 composite photocatalyst were discussed. 2. Materials and methods Preparation: The pure CeO 2 and pure Bi 2 WO 6 photocatalysts were synthesized by homogenous precipitation method and hydrothermal method, respectively. First, 10.9078 g of cerium(III) nitrate hexahydrate (Ce(NO 3 ) 3  6H 2 O, Sigma-Aldrich, US, 99%) was dissolved in 100 mL of 80% v/v ethylene glycol solution (EG, Fisher Scientific, UK, 99%) and heated at 50 1C until a homogeneous solution was obtained. After that, 25 mL of 3.0 M ammonium hydroxide solution (NH 4 OH, Sigma-Aldrich, US, 30%) was added. The obtained suspension was then centrifuged at 7000 rpm for 10 min, washed with deionized water 3 times and then dried in an oven at 70 1C for 24 h. The powder was subsequently calcined in a furnace at a temperature of 400 1C for 1 h and finally pure CeO 2 was obtained. The pure Bi 2 WO 6 was synthesized by hydrothermal method. In a typical synthesis used bismuth nitrate pentahydrate (Bi(NO 3 ) 3  5H 2 O, Sigma-Aldrich, US, 98.5%) and sodiumtungstate dihydrate (Na 2 WO 4  2H 2 O, Sigma-Aldrich, US, 99%) in molar ratio Contents lists available at ScienceDirect journal homepage: www.elsevier.com/locate/matlet Materials Letters http://dx.doi.org/10.1016/j.matlet.2015.04.139 0167-577X/& 2015 Elsevier B.V. All rights reserved. n Corresponding author. Tel.: þ66 84 0459424; fax: þ66 5394 3445. E-mail address: natda_we@yahoo.com (N. Wetchakun). Materials Letters 156 (2015) 28–31