Engineering anisotropic silver nanoparticles/TiO2 nanocomposites and its photodegradation process optimization under polychromatic light irradiation

Abstract

AbstractIn this work, we engineered the functionalization of titanium dioxide (TiO2) with silver nanoparticles (AgNP) of different morphologies aiming the application of TiO2/AgNP nanocomposites as a smart photocatalytic material for environmental purposes. The characterizations confirmed TiO2‐Ag Schottky barrier formation, which allows the electron transfer process at the materials interface, increasing charge carriers lifetime. The photocatalysis process using methyl orange as a pollutant model in water and polychromatic Hg lamp was first maximized using factorial design statistics. Photodegradation kinetic evaluations showed that the nanocomposites were up to nine times more efficient than bare TiO2. The results show that dependence on AgNP size does not follow simple rules, while anisotropic AgNPs promoted higher efficiencies. Mechanism evaluation shows that photocatalysis occurred by three main routes: i) photoreduction of pollutant adsorbed on TiO2 surface; ii) reduction by radical superoxide; and iii) by hot electrons back injection on TiO2 conduction band. The effects ii and iii occurred preferentially at anisotropic nanostructures corners. In this scenario, photodegradation rates followed the order rod≥prisms>spheres. Therefore, this work systematic evaluated the influence of nanoparticle's morphology in the photocatalytic power of a TiO2/AgNP and points anisotropic AgNP‐functionalized nanocomposite as a promising nanomaterial for further environmental applications.