A novel strategy to enhance ultraviolet light driven photocatalysis from graphene quantum dots infilled TiO2 nanotube arrays

Abstract

Herein, a novel strategy has been proposed to fabricate graphene quantum dots (GQDs) infilled titanium dioxide (TiO₂) nanotube arrays (NTAs) hybrid structure for dye degradation of methylene blue (MB) under UV light (365 nm) irradiation. GQDs are infilled inside the TiO₂ NTAs (via anodic oxidation of a Ti sheet) through an impregnation method. Moreover, the morphology of the TiO₂ NTAs is well maintained after filling the GQDs inside, which is favorable for mass transfer. The peak intensity of photoluminescence (PL) spectra of the GQDs infilled TiO₂ NTAs catalyst is lower than that of annealed TiO₂ NTAs and a strong violet UV emission is obtained at 387 nm upon 252 nm deep UV excitation. The photocatalytic activities of the TiO₂ NTAs are evaluated in terms of the efficiencies of photo-decomposition and adsorption of MB in aqueous solution under UV light irradiation, after the impregnation of GQDs inside the TiO₂ NTAs. The highly-efficient photocatalytic activity is attributed to the broad absorption in the visible wavelength region, large photo-induced charge separation through the transfer of photo-generated electrons from the TiO₂ NTAs to GQDs, as well as the strong adsorption capacity of the GQDs to MB molecules. Thus, the GQDs infilled TiO₂ NTAs could be widely used as a photocatalyst for treating organic contaminants in the field of environmental protection.