Magnetic recyclable TiO2/multi-walled carbon nanotube nanocomposite: Synthesis, characterization and enhanced photocatalytic activity

Abstract

In this study, a type of magnetic recyclable photocatalyst TiO2/Fe3O4/multiwalled carbon nanotubes (MWNTs) ternary nanocomposite was synthesized by hydrolysis in situ. In this method, tetra-n-butyl titanate was used for titanium source, which coated on the surfaces of MWNTs and wrapped Fe3O4 nanoparticles (Nps). Through hydrolysis and calcinations, tetra-n-butyl titanate around MWNTs transformed to teeny abundant TiO2 Nps in situ. A range of analytical techniques including XRD, TEM, SEM, VSM and EDX were employed to reveal the crystal structure, morphology and property of the nanocomposite. The photocatalytic performance was evaluated by degradation of methylene blue (MB) in UV light. Morphology characterization showed that TiO2 Nps with size of about 10nm and Fe3O4 Nps with size of about 30nm coated on the surfaces of MWNTs. XRD results revealed that anatase TiO2 and cubic spinel Fe3O4 exist in the nanocomposite. The as-synthesized nanocomposite could be rapidly separated from aqueous solutions for repeated use under the external magnetic field. Furthermore, it exhibited excellent photocatalytic activity compared with pure TiO2. The removal rate of MB for TiO2/Fe3O4/MWNTs nanocomposite with 30wt% TiO2 content reached 92.4% after 100min UV irradiation, which was about 2 times of pure TiO2. The removal rate of MB was still 90.6% after repeated six times, which indicates that the TiO2/Fe3O4/MWNTs nanocomposite has stable photocatalytic activity as well as magnetic responsiveness. These enhanced and unique properties of TiO2/Fe3O4/MWNTs nanocomposite can be ascribed to the synergistic effect among three components.