Enhanced photocatalytic activity of ternary multilayered Ag/TiO 2 /CNT composites for methylene blue degradation

The TiO 2 modified carbon nanotube composites (TiO 2 /CNT) and Ag deposited ternary multilayered composites (Ag/TiO 2 /CNT) were prepared by chemical deposition and sonochemical reaction, respectively. The composites were characterised by transmission electron microscopy, scanning electron microscopy, X-ray diffraction, Fourier-transform infrared spectroscopy, and ultraviolet-visible (UV-vis). The results showed that anatase TiO 2 layers were wrapped on the surfaces of the CNTs. The face-centred-cubic structure of Ag nanoparticles (NPs) was dispersedly formed on the surfaces of the Ag/TiO 2 /CNT composites. The expected formation and good dispersion of Ag was obtained by high-intensity ultrasound irradiation assistance. All the resulted TiO 2 /CNT and Ag/TiO 2 /CNT composites exhibited a higher photocatalytic performance than that of TiO 2 for the degradation of methylene blue. The novel nanocomposite photocatalysts were developed through structural changes and double effects of carbon materials and noble metals as electron acceptors. Inhibited recombination of electron-hole pairs allows effective electron transfer and active redox reaction on the surfaces of the composites. The novel composite combines the CNTs with excellent electronic nature and nobel metallic NPs with the special semiconductor-metal junction. It can provide new guidance for the application of carbon nanotube-based photocatalytic materials in photocatalysis field from UV-vis spectrum.