One-step fabrication of Ag/RGO doped TiO2 nanotubes during anodization process with high photocatalytic performance

Abstract

Reduced graphene oxide (RGO) and Ag nanoparticles were incorporated simultaneously with two-step anodic TiO2 nanotube through anodization process, and their photocatalytic activity was investigated in the degradation of 2,4-dichlorophenol (2,4-DCP). Furthermore, the optical properties and photocatalytic degradation efficiency were examined as a function of Ag NPs concentration in Ag/RGO–TiO2 nanotube. Morphological characterization showed that Ag NPs and RGO sheets were well-doped inside and outside the TiO2 nanotubes’ walls. Meanwhile, X-ray diffraction and EDX analysis confirmed the existence of both Ag NPs and RGO. The optical investigation revealed that the incorporation of Ag NPs and RGO with TiO2 nanotubes improved the light absorbance and the narrowing of TNT bandgap energy (from 2.85 to 2.35 eV). Therefore, among the various samples, Ag50/RGO–TNTs photocatalyst had the most optimal performance, degrading 96% and 66% of 2,4-DCP under UV and visible light irradiation, respectively. The kinetic study confirmed that degradation reactions over all photocatalysts followed zero-order kinetics. Finally, the recovery test of the optimum sample (Ag50/RGO–TNT) showed 6% reduction following 5-cycle photocatalytic degradation of 2,4-DCP under UV irradiation.