Photocatalytic performances of mesoporous TiO2 films doped with gold clusters

We report on the single-pot fabrication of ordered mesoporous crystallized titania films doped with
gold. Au is incorporated in TiO2 films by adding to the coating solution precursors such as AuCl3 or
monodisperse Au11
3+ nanoclusters, and Au nanoparticles are formed by calcination. A systematic study
is performed to correlate structure, Au doping and photocatalytic activity of such films.
Two-dimensional small angle X-ray scattering (2D-SAXS), transmission electronic microscopy (TEM),
scanning electronic microscopy (SEM) and porosimetry-ellipsometry show that the films retain their
mesoporous order even for doping levels as high as 1% Au : Ti atomic ratio. Wide angle X-ray
scattering (WAXS), and cyclovoltammetry (CV) show that Au11
3+ nanoclusters promote the formation
of the TiO2 (B) phase in competition with the anatase phase. AuCl3 stabilizes instead only the
anatase phase. The highest photocatalytic activity is exhibited by films where Au11
3+ is employed as
a precursor, which we attribute to the combination of the mixed anatase/TiO2 (B) phase, of
Au nanoparticle doping and of a well-ordered mesoporous TiO2 matrix.