Energy resource availability and environment remediation are
crucial challenges which have attracted attention of researchers at
regular intervals. Materials, like ceria, have attracted interest due
to their unique properties and resultant promise of addressing
both the issues. In spite of having unfavorable band edge location
with respect to the redox potential for dissociation of water
molecules, many of its complementary attributes make ceria an
interesting photo/catalyst material. An important property of
ceria-based catalysts is its high oxygen storage capacity and its
ability to release or uptake oxygen depending on switching
between Ce4þ/Ce3þ redox cycles [1]. As a result it finds diverse
applications in photocatalysis, fuel reforming (in solid oxide fuel
cell), thermal catalysis, UV blocking/shielding, solar cell, material
polishing, and as luminescent material [2–6]. The band gap of bulk
ceria is 3.2 eV which makes it a photocatalyst sensitive to
ultraviolet radiation only. Also the photogenerated charge carriers
in ceria do not migrate easily to the surface, and this is another
possible reason of photocatalytic inefficiency of this material [7].
By tailoring or lowering the band gap, the absorbance of ceria in
the visible range can be achieved. The method to realize it are one
or a combination of techniques such as – (i) introduction of
intrinsic defects into the system, (ii) doping by complementary
atoms, (iii) deposition of plasmonic resonant materials over the
system, and (iv) developing intrinsic homocomposite of heterophasic
(mixed phase/biphasic) ceria system.