Applied Surface Science 357 (2015) 2217–2222 Contents lists available at ScienceDirect Applied Surface Science jou rn al h om ep age: www.elsevier.com/locate/apsusc Synthesis of green TiO 2 /ZnO/CdS hybrid nano-catalyst for efficient light harvesting using an elegant pulsed laser ablation in liquids method M.A. Gondal a,∗ , A.M. Ilyas a , T.A. Fasasi a , M.A. Dastageer a , Z.S. Seddigi b , T.F. Qahtan a , M. Faiz a , G.D. Khattak a a Laser Research Group, Physics Department & Center of Excellence in Nanotechnology, King Fahd University of Petroleum and Minerals, Dhahran 31261, Saudi Arabia b Department of Environmental Health, Faculty of Public Health and Health Informatics, Umm Al-Qura University, 21955 Makkah, Saudi Arabia a r t i c l e i n f o Article history: Received 18 July 2015 Received in revised form 8 September 2015 Accepted 25 September 2015 Available online 30 September 2015 Keywords: Nanocomposite (TiO2/ZnO/CdS) Efficient light harvesting photocatalyst Pulsed laser ablation in liquids Quantum dots a b s t r a c t The main limitation on the applications of TiO 2 as a photocatalyst is its large band gap (3.2 eV) which limits its absorption only to the ultraviolet region of the solar spectrum. To overcome this problem, a facile strategy for clean synthesis of a nanocomposite green catalyst of zinc oxide (ZnO), titanium dioxide (TiO 2 ) and cadmium sulphide (CdS) was developed using pulsed laser ablation in liquids (PLAL) technique for the first time to the best of our knowledge. The main aim of addition of ZnO is to reduce the electron–hole recombination in the TiO 2 while CdS is used to increase the light harvesting efficiency of TiO 2 in the visible spectral region. The absorption spectrum of the TiO 2 /ZnO/CdS composite obtained from the UV–vis spectrophotometer exhibits strong absorption in the visible region as compared to the pure TiO 2 whose absorption band lies around 380 nm which is in the UV-region. The morphology of the composite quantum dots was also investigated using high resolution TEM technique which shows that the synthesized composite size ranges between 10 and 40 nm. These nanocomposites have demosntarted noticible improvement in the carriers transport in the visible region which could enhance its efficiency for many applications in the visible region especially for energy harvesting using solar radiations. © 2015 Elsevier B.V. All rights reserved. 1. Introduction The removal of organic pollutants has been of great interest due to its long-term toxic effects on the environment and severe hazards to the public health [1]. TiO 2 has been tested since long time as a potential photo-catalyst for the degradation of organic dyes. This is due to the fact that the synthesis of TiO 2 is cost effec- tive, it is non-toxic and has a high photo-stability. However its drawback is its large band gap (3.2 eV), which limits its absorp- tion only to the ultraviolet region of the solar spectrum [2]. Various types of techniques have been applied to modify its band gap in order to achieve efficient utilization of photons in the visible region. Such methods include doping with transition metals and non-metallic elements, in combination with other semi-conducting materials, and sensitization by organometallic dye molecules, etc. [3–10]. Another promising photo-catalyst and suitable alternative ∗ Corresponding author. E-mail address: magondal@kfupm.edu.sa (M.A. Gondal). to TiO 2 is ZnO [11]. ZnO is one of the wide band gap semiconductor reported useful in reducing fast recombination of photo-generated charge carriers limiting the photo-catalytic efficiency in TiO 2 when coupled to TiO 2 [12]. This can also improve the interfacial charge transfer process in TiO 2 thereby improving its photo-catalytic effi- ciency along with band gap shift. This coupling method has been achieved using several techniques such as solvo-thermal method [13], facile hydrothermal [14], and electro-spinning [15]. In solar energy conversion using dye sensitized solar cells, TiO 2 use is limited by its absorbtion wavelength which lies in the ultravi- olet region and several ways have been employed to shift its absorbance to the visible light region. Its combination with narrow band gap semiconductors has been an effective approach to modify its band gap [16]. This approach was achieved in the past using ther- mal evaporation [17], bi-functional linker [18], compartmentalized hydrolysis [19] and surface functionalized method [20]. Therefore, in hetero-structure of this nature, electrons generated from the conduction band of the narrow band gap semiconductors after photo-excitation are transferred into the conduction band of TiO 2 [21]. In order to increase the photo-catalytic performance, ternary http://dx.doi.org/10.1016/j.apsusc.2015.09.213 0169-4332/© 2015 Elsevier B.V. All rights reserved.