Rapid microwave-assisted synthesis of one-dimensional silver–H2Ti3O7 nanotubes

The formation of silver hydrogen trititanate nanotubes, based on the controllable microwave-assisted hydrothermal nanocrystalline TiO2 transition, was investigated by means of XRD, UV–vis–DRS, Raman, FESEM and HRTEM. The results show that the rapid formation of H-trititanate nanotubes is achieved by self-assemblage of silver nanoparticles in which the lamellar intermediates react with NaOH in hydrothermal conditions. The presence of Ag° nanoparticles in the precursor promotes rapid and more complete formation of layered H2Ti3O7 nanotubes. After reacting for 4 h without subsequent thermal treatment, the inner diameters of the cylinder-like nanotubes are in the range of 3.6–4.0 nm, while their outer diameters are in the range of 7.6–8 nm. In addition, some straight nanotubes form bundles which are hundreds of nanometers in length. As-synthesized ultrathin nanotubes and crystalline precursors were evaluated by methyl orange dye (MOD) UV photo-oxidation. The complete degradation of MOD is achieved after 3.5 h of UV irradiation in the presence of silver–TiO2 nanocomposites, resulting in 50% of dye mineralization.

The transformation of crystalline silver–TiO2 to one-dimensional (1-D) hydrogen trititanatenanotubes occurs in only 4 h at 150 °C without subsequent thermal treatment. The presence of Ag° nanoparticles in precursors causes the rapid and more completed formation of layered H2Ti3O7 nanotubes compared to bare TiO2 precursor. It is clear that the morphology-structure is important for the photocatalytic oxidation of methyl orange dye.Figure optionsDownload high-quality image (243 K)Download as PowerPoint slideHighlights
► Silver–H2Ti3O7 nanotubes were synthesized via microwave method in only 4 h.
► The Ag° nanoparticles promote the rapid formation of H2Ti3O7 nanotubes.
► The multi-walled nanotubes have diameter of 8–10 nm and Ag° nanoparticles ∼5 nm.
► The morphology-structure is related to the photocatalytic oxidation of methyl orange.