Preparation and Photoelectrochemical Properties of Multilayered WS2 Coated Titanium Dioxide Nanocomposites
In this paper, graphene-liked WS2 was chosen due to its activity as HER (hydrogen evolution reaction) catalyst and relatively abundant storage . The expected composite was formed through high energy ball milling technique which makes WS2 disperse on the surface of TiO2nanoparticles .
The composites consist of 99.5% TiO2 and 0.5% WS2and were prepared by high energy ball milling for five different periods of time-2hours, 4hours, 8hours, 16hours and 32hours. To identify phase evolution of the as-prepared nanocomposites during high energy ball milling procedure, X-ray diffraction (XRD) was performed to examine phase transition, which is shown in Fig.1. It can be seen that, with increasing milling time, the crystallization decrease at first and increase after further milling.
To further study the photoelectrochemical (PEC) characterization of composites after ball milling, a three-electrode setup was used, which is shown in inset of Fig. 2. This three-electrode device consists of a reference electrode (Ag/AgCl), a Pt wire counter electrode, a quartz container filled of 0.5M Na2SO4 aqueous solution and a working electrode. Sintered composites on indium-tin-oxide (ITO) glass substrate acts as the working electrode. Fig.2 shows the PEC measurement results of pure TiO2 and milled composites with milling time for 2hours, 8hours and 32hours. As can be seen, composite reaches the best photocurrent response with 8 hours milling. It is obvious that compared to pure TiO2 sample, adding of WS2and high energy ball milling make positive effect to composites.
In summary, the structure of TiO2 and WS2 nanocomposites through high energy ball milling has been studied by X-ray diffraction. Photoelectrochemical properties of the TiO2 coated with few layered WS2 shows the optimization photochemical response for 8 hours milled nanocomposites. This work provides a facile and low cost process for large amount production of few layer doped TiO2nanocomposites.
 A. Fujishima, K. Honda, Nature, 238 (1972) 37.
 Q. Liu, Z. Pu, A. M. Asiri, A. H. Qusti, A. Q. Al-Youbi, X. Sun,. J Nanopart Res 15 (2013) 1.
 W. Zhou, Z. Yin, Y. Du, X. Huang, Z. Zeng, Z. Fan, & H. Zhang, Small, 9(2013) 140.
 D. Merki, X. Hu, Energ Environ Sci, 4 (2011) 3878.