A novel “gel–sol” strategy to synthesize TiO 2 nanorod combining reduced graphene oxide composites Lu Shao a,n , Shuai Quan a , Yang Liu a , Zhanhu Guo b , Zhenxing Wang a a State Key Laboratory of Urban Water Resource and Environment (SKLUWRE), School of Chemical Engineering and Technology, Harbin Institute of Technology, Harbin 150001, China b Integrated Composites Laboratory (ICL), Dan F. Smith Department of Chemical Engineering, Lamar University, Beaumont, TX 77710, USA article info Article history: Received 27 March 2013 Accepted 16 June 2013 Available online 21 June 2013 Keywords: Composites Graphene oxide Titanium dioxide Nanostructure Semiconductors Nanorods abstract In this study, a novel so-called “gel–sol” process is firstly reported for synthesis of TiO 2 nanorod (TN) combining reduced graphene oxide (RGO) composites. By utilizing the triethanolamine (TEOA) as shape controller and under specific conditions (such as pH¼12), the hybrid composites can be readily obtained. The higher pH value benefits the deprotonation of TEOA for adsorption to the stationary nuclei. Therefore, the synthesized hybrid composites have the morphology of crystalline anatase TiO 2 nanorods anchored into the surface of reduced graphene oxide. The hybrid composites fabricated by the novel process have distinct advantages over the traditional methods for obtaining TiO 2 and graphene-based composites in terms of the well-confined TiO 2 morphology and the formation of Ti–C bonds between TN and RGO simultaneously. & 2013 Elsevier B.V. All rights reserved. 1. Introduction Carbonaceous materials have been widely utilized for modify- ing semiconductors for effectively transporting electrons [1,2]. As the emerging carbon-based derivatives, graphene has superior mechanical flexibility, large surface area and excellent electrical conductivity [3,4]. Theoretically, graphene with tunable redox properties has great potentials for enhancing the performance of semiconductors. On the other hand, TiO 2 suffering from the low efficiency and narrow light response range is the typical semi- conductor which has be widely studied. The architectural combi- nation of graphene and TiO 2 has been considered as the most exciting idea to produce the next-generation hybrid materials with the high performance. Up to now, various strategies have been explored for fabricating high performance TiO 2 /graphene hybrids, which include the simple mixture/sonication [5–7], self- assembling [8,9], hydrothermal [10–12], solvothermal [13–15] and sol–gel processes [16]. These approaches have generally produced TiO 2 /graphene hybrid materials which have weak interactions (chemical bonds) among graphene and TiO 2 and no well-defined nanostructure of TiO 2 . In fact, the formation of chemical bonds between graphene-based materials and TiO 2 and the nanostruc- ture of TiO 2 particles are crucial for practical applications [17]. Therefore, the new strategy is urgently required for developing advanced TiO 2 /graphene hybrid materials. For the first time, TiO 2 nanorod/reduced graphene oxide (TNGRO) hybrid materials are synthesized by a novel “gel–sol” process which is contrast with the traditional sol–gel approach [18]. With the aid of shape controllers of triethanolamine (TEOA) during the gel–sol process [19], the well-defined TiO 2 nanorod (TN) with the large aspect ratio can be obtained and TNRGO can be formed by incorporation of graphene oxide. The basic process is investigated and the synthesized TNGRO is characterized. 2. Experimental Graphene oxide (GO) was prepared by the modified Hummers method [20]. In a typical gel–sol process for synthesizing TNRGO, a variable amount of GO was dispersed in 40 mL distilled water under sonication. Then, 40 mL aqueous stock solution by mixing triethanolamine (TEOA) with titanium (IV) isopropoxide (TIPO) at a molar ratio of [TEOA]:[TIPO] ¼ 2:1, was added. After adjusting pH value to 12 by adding NaOH solution under vigorous stirring, the mixed solution was transferred into a 100 mL Teflon lined stainless steel autoclave, and aged at 110 1C for 24 h, 150 1C for 72 h and 190 1C for 24 h, respectively. The products were collected by centrifugation, washed with water and ethanol, and then treated in nitrogen at 400 1C for 2 h. The obtained TNRGO is ready for characterizations. Pure TiO 2 nanorods were prepared with the similar procedure. Wide-angle X-ray diffraction (WAXD) spectra Contents lists available at SciVerse ScienceDirect journal homepage: www.elsevier.com/locate/matlet Materials Letters 0167-577X/$- see front matter & 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.matlet.2013.06.050 n Corresponding author: Tel.: +86 451 86413711; fax: +86 451 86418270. E-mail addresses: odysseynus@hotmail.com, shaolu1976@gmail.com (L. Shao). Materials Letters 107 (2013) 307–310