Study of dye-modified Ag/TiO2 nanocomposites for application in photocatalysis

Among the current environmental problems, we can highlight the considerable increase in the levels of wastewater discharges polluted. A great effort has been made to develop technologies, mainly involving the photocatalysis process to treat contaminated water. This process is based on the electronic excitation of semiconducting oxides, such as titanium dioxide (TiO2). The photoactivity of TiO2 depends on its crystalline phase and its textural, structural and morphological properties play an important role in the photodegradation efficiency of dyes. A strategy to improve the photoactivity of the TiO2 is the combination with silver nanoparticles and dye molecules enabling the increase in the recombination time of the electron/hole pairs and the range of light absorption. In this work, the synthesis of TiO2 nanoparticles was carried out from titanium tetrachloride and microwave radiation. Surface modification of the oxide was performed using natural dye from jabuticaba and silver nanoparticles. To prove the surface modification with dyes, UV-vis and fluorescence spectroscopy were used. The X-ray diffraction showed the presence of the anatase phase in syntheses performed in basic conditions and in acidic conditions, rutile phase was observed. XRD also provided crystallite size, and these were confirmed by transmission electron microscopy (TEM) (Figure 1). Through gas adsorption, the oxides showed specific surface areas varying from 40 m2g-1 to 200 m2g-1. The photocatalytic test using structurally modified TiO2 showed a greater potential for methylene blue degradation.