SiO2 nanotubes with nanodispersed Pt in the walls

SiO2 nanotubes (NTS) of different wall thickness were prepared using fibres of [Pt(NH3)(4)](HCO3)(2) salt crystals. During growth of the SiO2 nanotube walls by sol-gel condensation from tetraethyl orthosilicate (TEOS) on the surface of the templating Pt-salt fibres parts of the salt nanocrystals are incorporated into the walls due to strong SiO2-salt interaction. This leads to a significant softening in the vibration density of states (VDS) Of SiO2- With increasing thickness of the SiO2 NT walls the degree of Pt-salt incorporation decreases and consequently the observed shifting of IR Si-O vibration bands is more pronounced for NTs with thinner walls. In all cases the VDS relaxes during calcinations to those of pure SiO2- Calcination leads to the formation of Pt nanoparticles and micropores within the nanotube walls. (c) 2006 Elsevier Inc. All rights reserved.