Ultrafine TiO2 nanofibers for photocatalysis†
We report a simple synthesis route for producing ultrafine porous TiO2 nanofibers (∼10 nm diameters) from electrospun rice-shaped TiO2 nanostructures. The rice-shaped TiO2 obtained by annealing the as-spun TiO2–PVAc composite nanofibers was treated with concentrated alkali (with KOH under hydrothermal conditions) followed by acid treatment and low temperature sintering. The alkali treatment produces the titanate (K2Ti3O7) which undergoes exchange of ions (protons) during the acid treatment resulting in H2Ti3O7. The heat treatment of the protonated titanate (H2Ti3O7) results in their conversion to ultrafine TiO2 (titanate-derived TiO2) nanofibers. The rice-shaped TiO2 and the titanate-derived TiO2 nanofibers were characterized by SEM, TEM, XRD, XPS, Raman and BET measurements and the latter has ∼2.5 times higher surface area than the former. The TiO2 nanofibers showed superior photocatalytic applications than the commercial P-25 TiO2 .