MoS2 Doped TiO2 Nanomaterial and the Enhancement of Photocatalytic Properties for Solar Disinfection

Timothy McColgan

A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science Department of Environmental Science, Policy and Geography College of Arts and Sciences University of South Florida St. Petersburg

Abstract

This research project focused on the synthesis, characterization, and environmental application of a photocatalytic nanomaterial composed of molybdenum (IV) disulfide [MOS2] doped titanium dioxide [TiO2]. Extensive research has been conducted on the electronic uses of nanocrystalline MoS2 as a phototransistor and absorptive species (Yin et al., 2012), as well as the photocatalytic effects of TiO2 (Diebold, 2003). Research has also been performed into the generation of oxidizers from TiO2 nanocomposites (Zhang et al.,2015), but as of yet no research has been conducted on a practical application of this material. This project fills that void by evaluating its effectiveness while integrated into a solar disinfection [SODIS] platform, which has extensive humanitarian applications. Solar disinfection is the chief disinfection method recommended by the World Health Organization for developing countries (Clasen, 2008).

This project utilized the Sol-gel method to create varying concentrations of MoS2- TiO2 nanocomposite, followed by characterization using SEM (scanning electron microscopy), X-ray diffraction, FTIR spectrophotometer analysis, and solid state UVVisible analysis. It was successfully demonstrated that a synthesis of these two materials is possible at a variety of ratios, but that a blend of 5% MoS2-95% TiO2 enhanced the photocatalytic properties of TiO2, most optimally when integrated into the SOD IS platform. Doping with low concentrations of MoS2 enhanced the absorption of light by TiO2 into the visible spectrum and increased its absorbance into the UVB/UV A range, without inhibiting its inherent oxidative properties significantly. This enhancement resulted in a reduction to the time required for full elimination of deleterious Escherichia Coli [E.coli] from potable water within the SODIS platform from 150 minutes to 120 minutes, compared to pure TiO2 nanomaterial. It was also demonstrated that the other blends ofM0S2 doped TiO2 possessed equivalent photocatalytic properties compared to that of pure TiO2 (Yin et al., 2012). If properly employed, these nanocomposites could serve as an effective addition to the SODIS platform.