Design, Fabrication, and Modification of Cost-Effective Nanostructured TiO for Solar Energy Applications - Low-cost Nanomaterials: Toward Greener and More Efficient Energy Applications - page 24

Fig. 7 a Schematic illustration of the formation mechanism for layered TiO 2 . b SEM images of
layered TiO 2 produced via the (a) process. c Photodegradation curves of RhB (20 mgL -1 ) under
UV-light irradiation over the TiO 2 samples prepared in different concentrations of 2-propanol
(PrOH): a: 0, b: 1.5, c: 2.8, d: 4.0, and e: 8.0 M. (Reprinted with permission from Ref. [ 140 ].
Copyright Wiley-VCH)
highly toxic and corrosive in both liquid and vapor forms [ 136 ]. In response to the
safety and health concerns, a number of studies have investigated the preparation
of anatase TiO 2 single crystals with clean and exposed (001) facets via hydro-
fluoric acid-free processes [ 137 - 139 ]. Recently, Yu et al. reported the synthesis of
a layered TiO 2 structure composed of several nanosheets with exposed (001)
facets, by a simple hydrothermal method in the presence of (NH 4 ) 2 TiF 6 ,H 3 BO 3 ,
and 2-propanol, followed by calcination treatment (Fig. 7 a). The resulting layered
TiO 2 with (001) facet nanosheets (Fig. 7 b) exhibited excellent photocatalytic
activity for the degradation of rhodamine B (RhB) (Fig. 7 c) [ 140 ]. Fang et al.
synthesized submicrometer-sized yolk@shell hierarchical spheres composed of a
permeable shell self-assembled by ultrathin anatase TiO 2 NSs with nearly 90 %
exposed (001) facets and a mesoporous inner sphere with a high specific surface
area. This process used the solvothermal method in the presence of diethylene-
triamine (DETA), isopropyl alcohol (IPA) and titanium (IV) isopropoxide (TTIP),
also followed by calcination treatment. Compared to the conventional (001) fac-
eted TiO 2 NSs (4.01 %) and standard Degussa P25 (4.46 %), such anatase TiO 2