Exfoliation of layered titanate Cs_xTi _(2-x/4)□_x/4O₄ into colloidal nanosheets by a more competitive chemical process

Chemical exfoliation process for lepidocrocite-related Cs _xTi_(2-x/4)□_x/4O4 (where □ expresses vacancy) utilizing an amino acid intermediate has been described. Ammoundecanoic acid (AUA, H₂N(CH₃)₁₀COOH) molecules were chosen to intercalate into the layered titanate in boiling aqueous solution and the basal spacing of layered titanates expanded from 0.84 to 2.31 nm. The exfoliation of the titanate slabs into elementary nanosheets was accomplished by a host-guest repulsive interaction induced by deprotonation of the interlayered amino acid molecules with NaOH solution. This results are supported by an entire disappear in the X-ray intensities of (001) reflections. The largest bandgap energy shift can be up to 1.6 eV. Microscopic observations also confirm the complete exfoliation of the pristine lamellar material into the metal oxide nanosheets. HRTEM image showed that the apparent size of the particles fall into the range of about 10 nm in lateral dimension and 2∼10 nm elementary oxide sheets in height.