Size Effect of Gold Nanoparticles on the Photocatalytic Activity of Titanium Dioxide/Reduced Graphene Oxide (TiO2/rGO) Nanocomposite
Abstract
A comparative study of the size effect of plasmonic nanoparticles on the photocatalytic activity of the titanium dioxide/reduced graphene oxide (TiO2/rGO) nanocomposite material was performed. Gold (Au) plasmon nanoparticles with an average diameter of 20, 35, and 70 nm were embedded in the TiO2/rGO nanocomposite material. It has been shown that the introduction of Au nanoparticles into the TiO2/rGO structure leads to an increase in the absorption within the range from 475 to 600 nm. The best photocatalytic properties were recorded for the samples with 35 nm Au nanoparticles. These samples generated a photocurrent 2.3 times higher than pure TiO2/rGO. In the presence of nanocomposite films, the photodegradation rate of the Methylene blue and Congo red dyes was increased by 3 and 2.6 times that of the sample without gold nanoparticles. The synergistic effect of plasmonic nanoparticles consists of the growth of the absorptivity of nanocomposite material, the reduction of its resistance, and the effective separation and transport of charge carriers, which leads to enhanced photocatalytic activity of semiconductors. The dependence of the photocatalytic activity of the TiO2/rGO nanocomposite on the size of Au nanoparticles was explained by the hot electron injection cut off effect.