Rutile TiO2 nanowires on anatase TiO2 nanofibers: A branched heterostructured photocatalysts via interface-assisted fabrication approach

A water–dichloromethane interface-assisted hydrothermal method was employed to grow rutile TiO2 nanowires (NWs) on electrospun anatase TiO2 nanofibers (NFs), using highly reactive TiCl4 as precursor. The water–dichloromethane interface inhibited the formation of rutile NWs in water phase, but promoted the selective radial growth of densely packed rutile NWs on anatase NFs to form a branched heterojunction. The density and length of rutile NWs could be readily controlled by varying reaction parameters. A formation mechanism for the branched heterojunction was proposed which involved (1) the entrapment of rutile precursor nanoparticles at water–dichloromethane interface, (2) the growth of rutile NWs on anatase NFs via Ostwald ripening through the scavengering of interface-entrapped rutile nanoparticles. The heterojunction formed at anatase NF and rutile NW enhanced the charge separation of both under ultraviolet excitation, as evidenced by photoluminescence and surface photovoltage spectra. The branched TiO2 heterostructures showed higher photocatalytic activity in degradation of rodamine B dye solution than anatase NFs, and the mixture of anatase NFs, and P25 powders, which was discussed in terms of the synergistic effect of enhanced charge separation by anatase–rutile heterojunction, high activity of rutile NWs, and increased specific area of branched heterostructures.

A water–oil interface assisted fabrication approach was employed to fabricate rutile TiO2 nanowires-anatase TiO2 nanofibers heterostructures. The as-fabricated branched heterostructures display higher photocatalytic activities than pure TiO2 nanofibers as well as P25 powders.Figure optionsDownload high-quality image (83 K)Download as PowerPoint slideHighlights
► We employ water–oil interface assisted hydrothermal technique to TiO2 based heterostructure fabrication.
► The as-fabricated heterostructure displayed interesting branched morphology.
► The branched heterostructure showed higher photocatalytic activity than pristine TiO2 nanofibers and P25 powders.