Peptide-Templated Synthesis of TiO₂ Nanofibers with Tunable Photocatalytic Activity

Nanofabrication based on biological templates has attracted considerable interest because of its applications in materials science and biomedicine. Herein, a facile method is reported for the synthesis of well-defined TiO₂ nanofibers by using a simple N-(9-fluorenylmethoxycarbonyl)-protected phenylalanine-phenylalanine-aspartic acid tripeptide (Fmoc-Phe-Phe-Asp-OH, Fmoc-FFD) as the template. Compared with other synthetic methods of inorganic nanomaterials, these self-assembling peptides could control the structure and the catalytic activity of the synthesized nanomaterials produced under mild synthetic conditions. The as-synthesized peptide-TiO₂ hybrid nanofibers and the calcined TiO₂ nanofibers were characterized by using transmission electron microscopy (TEM), scanning electron microscopy (SEM), circular dichroism (CD) spectroscopy, and X-ray diffraction (XRD). The results show that well-defined TiO₂ nanofibers could form when the pH of the peptide solution was 5-7, whereas nanoparticles formed when the pH was 8. Moreover, the peptide-templated TiO₂ nanofibers showed improved photocatalytic activity for the degradation of methyl orange (MO). Finally, the photocatalytic activity of the TiO₂ could be controlled by adjusting the pH of the peptide solution during the synthetic process.