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.