Carbon-Deposited TiO₂: Synthesis, Characterization, and Visible Photocatalytic Performance

Abstract

Carbon-deposited TiO2 (TiO2@C) was prepared with a one-pot hydrothermal process by using glucose as a carbon source. The physical properties of TiO2@C were studied by XRD, TG-DTA, HRTEM, and UV−vis diffuse reflectance spectra (DRS), while the chemical states of carbon were discussed via X-ray photoelectron spectroscopy (XPS). A graphite carbon layer was formed out of the TiO2 grain during the hydrothermal process via the dehydration of glucose, which consisted of not only Cn but also C—OH (and C—O—C) and C═O (and COO). TiO2@C has remarkable light absorption in the visible region. It was found that the photocatalytic activity of TiO2@C was greatly enhanced compared to noncarbon-TiO2 under visible irradiation. The photocatalyst with the highest photocatalytic activity for the degradation of Acid Orange 7 (AO7) was G15 TiO2@C, while that for the degradation of 2,4-dichlorophenol (2,4-DCP) was G5 TiO2@C. Two kinds of sensitization processes, carbon sensitization and dye sensitization, are responsible for the visible light-induced photocatalysis of TiO2@C. Carbon sensitization reached its optimal condition in G5, while dye sensitization occurred in its maximum efficiency in G15.