Colloidal Hollandite Holey Rods Produced by Presynthetic Nanohybridization

Electrostatically stabilized binary hybrids comprising TiO₂ nanotubes and Fe₂O₃ nanoparticles were self-assembled and investigated as precursors for a KFTO material. Presynthetic nanohybridization is a way to organize the components, with the caveat that the mere nanomaterial combination cannot grant a high degree of control due to their general susceptibility to aggregation, resulting in masses with poor spatial order. Various hybridization conditions were explored, and the effects of the experimental parameters were investigated in detail, considering KCl concentration, Fe/Ti ratio, and hydrothermal treatment temperature. The optimized synthetic product was obtained at a remarkably low temperature (800 °C), and it was characterized by small size, partially hollow morphology (cavity diameter ca. 100 nm), and water colloidal stability, likely inherited from the parent nanotubes. These hollow rods can be envisioned as nanoreactors for confined space synthesis and as tools for environmental remediation.