Titanate nanosheets and nanotubes: alkalinity manipulated synthesis and catalyst support application

Abstract

Titanate nanosheets (TiO-NS) and nanotubes (TiO-NT) were prepared under hydrothermal or solvothermal conditions in varied alkali solutions following similar procedures. Relatively low alkalinity (5M NaOH) was associated with TiO-NS, but high alkalinity (10M) resulted in TiO-NT. Addition of low-boiling point organic solvents could increase the reproducibility of TiO-NT, and sometimes lower the alkalinity needed for nanotubes formation. The two nanomaterials were used to load Pd nanoparticles to study their morphology-dependence as catalyst supports. The Pd-loaded titanate nanosheets (Pd/TiO-NS) showed higher activity than the Pd-loaded nanotubes (Pd/TiO-NT) in CO catalytic oxidation reactions. High resolution transmission electronic micrography (HRTEM) revealed much better dispersion of the supported Pd nanoparticles on nanosheets than nanotubes. The better catalytic performance of Pd/TiO-NS was believed to be related to less aggregation of the Pd nanoparticles on TiO-NS.