Please cite this article in press as: A.W. Morawski, et al., Photocatalytic degradation of acetic acid in the presence of visible light-active TiO 2 -reduced graphene oxide photocatalysts, Catal. Today (2016), http://dx.doi.org/10.1016/j.cattod.2016.05.055 ARTICLE IN PRESS G Model CATTOD-10286; No. of Pages 6 Catalysis Today xxx (2016) xxx–xxx Contents lists available at ScienceDirect Catalysis Today journal homepage: www.elsevier.com/locate/cattod Photocatalytic degradation of acetic acid in the presence of visible light-active TiO 2 -reduced graphene oxide photocatalysts A.W. Morawski a,∗ , E. Kusiak-Nejman a , A. Wanag a , J. Kapica-Kozar a , R.J. Wróbel a , B. Ohtani b , M. Aksienionek c , L. Lipi ´ nska c a West Pomeranian University of Technology, Institute of Inorganic Technology and Environment Engineering, Pulaskiego 10, 70-322 Szczecin, Poland b Hokkaido University, Research Institute for Catalysis, Sapporo 001-0021, Japan c Institute of Electronic Materials Technology, Wólczy´ nska 133, 01-919 Warsaw, Poland a r t i c l e i n f o Article history: Received 30 January 2016 Received in revised form 15 May 2016 Accepted 23 May 2016 Available online xxx Keywords: Photocatalysis Titanium dioxide Graphene Reduced graphene oxide Acetic acid photooxidation Visible light a b s t r a c t Visible light-active TiO 2 –reduced graphene oxide photocatalysts were prepared using simple mechanical mixing of titanium dioxide with different amounts of rGO (0.1, 0.5, 1.0 and 2.0 wt.%) in the presence of 1-butyl alcohol. Structures and morphologies of the samples were examined by means of FTIR/DRS, UV–vis/DR, XRD, SEM, TEM and Raman spectroscopy. The photocatalytic properties were checked on the basis of acetic acid photooxidation (the steady rate of linear increase of the CO 2 yield was used for the estimation of photocatalytic activity). The maximum photodegradation rate was observed for TiO 2 decorated with 0.5 wt.% of rGO. The enhancement of photodegradation efficiency should be related to -conjugation system, two-dimensional planar structure and efficient charge separation of reduced graphene oxide nanosheets. © 2016 Elsevier B.V. All rights reserved. 1. Introduction In recent years, graphene, a two-dimensional novel carbon nanomaterial with zero band gap, large specific surface area, excel- lent mechanical, electrical, optical and thermal properties and its applications in sensors and biosensors, electronic devices, liquid crystalline displays, capacitors solar cells, H 2 production, energy storage and nanocomposites including TiO 2 /graphene materials, has been intensively studied [1–10]. Graphene is composed of sin- gle or less than 10 planar sheets of sp 2 –bonded carbon atoms forming six–membered rings [11]. Singh et al. [5] described in detail the most common methods of graphene preparation: exfoliation and cleavage, chemical vapour deposition CVD, graphene oxide reduction, total organic synthesis or un-zipping carbon nanotubes. Recently, the combination of graphene and semiconductors, especially titanium dioxide, as a promising route to obtain new graphene–TiO 2 nanocomposites with enhanced charge separation in electron–transfer, has been intensively studied. Incorporation of graphene or graphene oxide into TiO 2 provides large specific sur- face area and high charge carrier mobility due to the moving of TiO 2 ∗ Corresponding author. E-mail address: amor@zut.edu.pl (A.W. Morawski). generated electrons across the graphene 2D–sheets, which mini- mizes the electron- hole recombination and enhances the oxidative reactivity [11–13]. Huang et al. [13] explained the enhancement of TiO 2 –graphene nanocomposites photocatalytic activity by inter- facial charge transfer through a C Ti bond, which increased the number of holes participating in the photocatalytic process due to markedly decreasing recombination of electron- hole pairs. The formation of Ti O C bonds results expanding the light absorption to longer wavelengths and the possibility of TiO 2 excitation with visible or solar light. Wang et al. [11] proposed the graphitization of melamine used as carbon source dispersed in methanol and mixed with P25 TiO 2 and then homogenized in ultrasonic bath. The sig- nificant enhancement of photocatalytic activity of new hybrid TiO 2 –graphene materials, calculated on the basis of Methylene Blue (MB) decomposition under UV light source, was caused by a rapid photoinduced charge separation and the inhibition of recombina- tion for electron–hole pairs. This results in the increase of number of holes participating in the photooxidation process of used thi- azine dye. Thus the synergetic effect between graphene–like carbon and titanium dioxide was also proved. Ni et al. [14] discussed new photocatalytic mechanisms of MB degradation under visible light in the presence of graphene supported TiO 2 and graphene strongly wrapped–TiO 2 nanocomposites. Firstly, the higher photoactivity of http://dx.doi.org/10.1016/j.cattod.2016.05.055 0920-5861/© 2016 Elsevier B.V. All rights reserved.