Novel nanostructures of rutile fabricated by templating against yarns of polystyrene nanofibrils and their catalytic applications

This Article describes a facile approach to the synthesis of rutile nanostructures in the form of porous fibers or bundles of nanotubes by maneuvering the surface wettability of yarns made of polystyrene nanofibrils. Specifically, hierarchically porous fibers were obtained by hydrolyzing titanium tetraisopropoxide to form TiO₂ nanoparticles in the void spaces among hydrophobic nanofibrils in each yarn. After calcination in air at 800 C, the resultant fibers were comprised of many interconnected rutile nanoparticles whose diameters were in the range 20-80 nm. After converting the nanofibrils and yarns into hydrophilic surfaces through plasma treatment, however, the TiO ₂ formed conformal coatings on the surfaces of nanofibrils in each yarn during hydrolysis instead of just filling the void spaces among the nanofibrils. As a result, bundles of rutile nanotubes were obtained after the sample had been calcined in air at 800 C. The thermodynamically stable rutile nanostructures were then explored as supports for Pt nanoparticles whose catalytic activity was evaluated using the reduction of p-nitrophenol by NaBH₄. The Pt supported on porous rutile fibers exhibited a better performance than the Pt on rutile nanotubes in terms of both induction time (t_ind) and apparent rate constant (k_app).