Photocatalytic potential of ZnO/TiO2: a bionanocomposite from Ocimum basilicum

Abstract

Decolorization of textile dyes by photocatalysis is an area that has gained considerable interest due to the need to minimize pollution. Nanocomposites possess prominence owing to their small size, good catalytic activity, high surface area and selectivity. Although nanocomposites have been synthesized by conventional techniques, green synthesis remains an unexplored area. Thus, the present study is the first one on ‘green’ synthesis of a zinc oxide (ZnO)/titanium dioxide (TiO2) nanocomposite using leaf extract of Ocimum basilicum L. var. purpurascens Benth. Lamiaceae as a novel source, along with an insight into its photocatalytic potential for decolorization of the textile dye Blue RGB under sunlight and ultraviolet (UV) irradiation. Hexagonal-shaped zinc oxide/titanium dioxide nanocomposites with a size of 50 nm have been synthesized and characterized using X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy and energy-dispersive X-ray spectroscopy. Maximum photodecolorization was observed for sunlight-mediated photocatalytic decolorization (99·8%) compared to UV (95·8%) within 8 h. The study adds value to the applications of nanoparticles in various fields such as photocatalysis for degradation of pollutants and in wastewater treatment.