Hybrid TiO2 nanostructures with engineered morphologies (flakes, spheres and buds) supporting Ag
nanocrystals were produced by a simple synthetic approach based on cooperative solegel chemistry of
either titanium iso-propoxide or n-butoxide and self-assembly of polyvinyl alcohol with polyethylene
glycol. The as-synthesized catalysts were characterized using XRD, TEM, DRUVeVis, N2 sorptiometry and
FTIR spectroscopy and their performances toward 4-nitrophenol (4-NP) reduction were also investigated.
Among the structures investigated, the catalyst derived from n-butoxide (Ttev) exhibited the best
catalytic performance in the reduction of 4-NP to 4-aminophenol (4-AP) in 2 min with 100% conversion
when loaded with 2% Ag ions (TtevAg2). In concordance, the TevAg6 catalyst; derived from isopropoxide,
of bud shape and particle sizes of 20 nm showed a comparable activity to that of TtevAg2 and exhibited
a rate constant of 6.9 103 s1 resembling that of 7.2 103 s1 for TtevAg2 exceeding that of TevAg2.
Enhancing the activity of TevAg6 and TtevAg2 compared to TevAg2 was rationalized in terms of the
surface content of Ago nanoparticles of medium sizes (15e20 nm) inside mesoporous network of TiO2 of
tailored morphology (proportional amounts of buds and spheres structures) as well as pore volume
values. No deactivation for the former catalysts was observed after repeated recycling. |
