Synthesis and characterization of carbon nanotubes-treated Ag@TiO2 core–shell nanocomposites with highly enhanced photocatalytic performance

Abstract

The monodispersed, uniform Ag@TiO2 core–shell nanoparticles were successfully synthesized using Ag nanoparticles as colloid seeds and tetrabutyl titanate (TBOT) as Ti source through the simple solvothermal process. The acid vapor treated multi-walled carbon nanotubes (CNTs) were introduced into Ag@TiO2 core–shell system to obtain CNTs-loaded Ag@TiO2 nanocomposites (CNTs-Ag@TiO2) through a simple dipping method. Characterization of the composites was performed using Scanning electron microscopy (SEM), Transmission electron microscopy (TEM) and High-resolution TEM (HRTEM), Energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), UV–vis diffuse reflectance spectroscopy (DRS) and the X-ray photoelectron spectroscopy (XPS). Photocatalytic property of CNTs-Ag@TiO2 nanocomposites was investigated by photodegradation methylene blue (MB) solution under Xenon arc lamp and compared with Ag@TiO2, TiO2 and CNTs-TiO2 nanoparticles. The result showed that the photocatalysis property of CNTs-Ag@TiO2 nanocomposites was higher than other comparative particles. The presence of CNTs in the Ag@TiO2 nanocomposites could enhance the photocatalytic property owing to CNTs were good electron acceptors, can accept the excited electrons photo-initiated in the TiO2 particles and the Fermi level of the Ag is situated close to the conduction band edge of TiO2. Thus the electrons excited into the conduction band of TiO2 by UV–visible light irradiation are transferred to the surface of CNTs and Ag core easily. Therefore, recombination time of the electron–hole pair was prolonged, which was the key of enhance the photocatalytic activity.