Preparation of a thin carbon coated TiO2 using humic acid for the enhanced removal of reactive red 4 dye

Abstract

Carbon (C) coated TiO2 with a thin layer of C was successfully prepared using a humic acid reagent as the C precursor followed by a thermal treatment in N2 gas flow at 650 °C. The test of the photocatalytic activity of the improved phocatalyst was carried out using an anionic reactive red 4 dye as the model pollutant with a 45 W fluorescent lamp and solar light as the light source. The C layer was found to be in the graphitic form and it was coated to the surface of TiO2 at the optimum thickness of 0.68 nm. The C content for the modified photocatalysts ranged from 0.02 to 0.16 wt% with the optimum C content at 0.05 wt%. The photocatalytic activities of the C coated TiO2 were 4.5 and 7.6 times faster than that of the unmodified TiO2 under the 45 W fluorescent lamp and solar irradiation, respectively. The higher photocatalytic activity of the C coated TiO2 was attributed to the electron scavenging ability of the incorporated C in TiO2, thus hindering the electron–hole recombination process within the irradiated semiconductor.