Facile Fabrication of TiO 2 -Graphene Composite with Enhanced Photovoltaic and Photocatalytic Properties by Electrospinning Zhu Peining, †,‡ A. Sreekumaran Nair,* ,‡ Peng Shengjie, ‡ Yang Shengyuan, ‡ and Seeram Ramakrishna †,‡ † Department of Mechanical Engineering, National University of Singapore, Singapore, 117574, Singapore ‡ Healthcare and Energy Materials Laboratory, Nanoscience and Nanotechnology Initiative, National University of Singapore, 117581, Singapore * S Supporting Information ABSTRACT: We report the fabrication of one-dimensional TiO 2 -graphene nano- composite by a facile and one-step method of electrospinning. The unique nanostructured composite showed a significant enhancement in the photovoltaic and photocatalytic properties in comparison to TiO 2 as demonstrated in dye-sensitized solar cells and photodegradation of methyl orange. KEYWORDS: electrospinning, TiO 2 -graphene composite, dye-sensitized solar cells, photocatalysis, one-dimensional mesostructures G raphene, a two-dimensional nanomaterial, is attracting widespread attention because of its remarkable properties such as superior mechanical strength, 1 excellent mobility of charge carriers, 2 high thermal conductivity, 3 and large specific surface area. 4 Graphene and its composites 5 found applications in fields such as photocatalysis, 6 liquid crystal displays, 7 lithium- ion batteries, 8-10 and solar cells. 11-13 Integration of graphene into materials such as metal oxides and polymers render them unique functionalities. 14 For example, solar cells with layered graphene/quantum dots and graphene/TiO x /quantum dots have been demonstrated to have good performances due to the ability of graphene in enhancing charge collection and transport. 15,16 The extended light absorption range as well as the improved charge separation caused by the incorporation of graphene into TiO 2 have been attributed to the enhanced photocatalysis performance. 6,17 Among the graphene-based composites, TiO 2 -graphene composites (TGCs) have been widely studied for various applications. TGCs with enhanced performance in lithium-ion batteries, 8-10 solar cells, 12,18 and photocatalysis 19-25 have been reported. So far, TiO 2 -graphene composites (TGCs) have been fabricated by the methods of hydrothermal method, 12,26 molecular grafting, 11 solvothermal method, 10 and heteroge- neous coagulation. 13 However, most of the TiO 2 -graphene composites reported have been fabricated with complicated processes involving hydrothermal treatments, assembly of graphene with TiO 2 by multistep methods, or the reduction of the TiO 2 -graphene oxide composite into TiO 2 -graphene composite. 12,20,27 For photovoltaic and photocatalysis applica- tions, TiO 2 in one-dimensional (1D) morphology is desired compared to the spherical TiO 2 nanoparticles owing to excellent mobility of charge carriers, 28 high surface areas, 29 scattering more light at the red part of the solar spectrum, 30 and the existence of straight pores which enhance the accessibility of electrodes to the hole transporting materials 31 and hence enhanced charge collection and transport. 32,33 There were only a few reports on TGCs with 1D TiO 2 ; however, these employed graphitic oxide (GO). 19 Thus it is desirable to develop a simple method to integrate graphene into 1D nanostructured TiO 2 for enhanced photovoltaics and photo- catalytic applications. In this letter, we report for the first time a simple method to fabricate TGCs by electrospinning. Electrospinning is a simple and cost-effective technique to fabricate 1D nanostructures in random and aligned, core/shell and hollow configurations. 34,35 Besides the traditional 1D nanostructures of nanofibers/ nanowires, we have recently shown that a novel 1-D rice- shaped TiO 2 mesostructures with single crystallinity and high surface area could also be fabricated by electrospinning. 36,37 The unique mesostructures showed better photocatalytic and photovoltaic properties than the commercial P-25 TiO 2 and electrospun TiO 2 nanofibers. In the present case, by the introduction of cetyltrimethylammonium bromide (CTAB)- functionalized DMF soluble graphene 38,39 (see the Supporting Received: October 20, 2011 Accepted: January 31, 2012 Published: January 31, 2012 Letter www.acsami.org © 2012 American Chemical Society 581 dx.doi.org/10.1021/am201448p | ACS Appl. Mater. Interfaces 2012, 4, 581-585