TiO2/g-C3N4 Visible-Light-Driven Photocatalyst for Methylene Blue Decomposition

Abstract

In this work, graphitic carbon nitride (g-C3N4)/titanium dioxide (TiO2) nanoparticles with heterostructures were synthesized in situ from a mixture of melamine and peroxo-titanium complexes in a calcination process. The TiO2 nanoparticles are well-dispersed on the g-C3N4 nanosheets. The prepared TiO2/g-C3N4 composites have a heterostructure and excellent photocatalytic activity for decomposing methylene blue (MB) under visible light irradiation. The as-obtained g-C3N4 embroiled with TiO2 has a much larger surface area than its components (66.7 and 6.6 m2·g−1 for TiO2 and g-C3N4 against 95.5–143.8 m2·g−1 for the composite, respectively). It enhances the separation of photo-generated charge carriers. The TiO2/g-C3N4 photocatalytic degradation of MB was investigated in aqueous heterogeneous suspensions. The experimental kinetic data for the photocatalytic process follow the pseudo-first-order kinetic model. Furthermore, TiO2/g-C3N4 retains high photocatalytic activity after four reaction cycles. In addition to prompt removal of the color, the TiO2/g-C3N4 photocatalyst can oxidize MB almost completely to final oxidation products. The pathway of MB decomposition was also addressed. Additionally, the TiO2/g-C3N4 photocatalytic system was employed to eliminate other typical organic pigments, such as malachite green, methyl blue, and methyl red. The TiO2/g-C3N4 material, with remarkable dye degradability, is a promising catalyst in industrial textile treatment and can find applications in light-harvesting systems.