of automobiles to meet the stringent emission standards for both
NOx and particulate matter [1–3]. SiO2/TiO2 exhibits super
hydrophilic properties which makes it an ideal material for
antifogging and self cleaning surfaces such as for window
glasses, automobile mirror wind shields, etc. [4]. Numerous
papers have appeared on the fundamentals of pure titania
systems; the mechanisms of oxidation and the ways to improve
its photocatalytic activity (PCA) have been investigated in detail
[5–9]. The improvement of the PCA of TiO2 has been achieved
by coating with noble metals such asAg [10],Au[11], Pt [12], Pd
[13] which can trap the electrons facilitating an effective charge
separation. Complementary to metal/TiO2 photocatalysts, TiO2
has been coupled with other semiconductors such as SnO2 [14–
17] which can induce effective charge separation by trapping
photogenerated electrons. The PCA of metal/metal oxide
modified TiO2 photocatalysts can be further improved if the
metal/metal oxide adsorbs more pollutant along with the function