2 research outputs found
Mesoporous Hollow Sphere Titanium Dioxide Photocatalysts through Hydrothermal Silica Etching
Robust, monodisperse, mesoporous titanium dioxide (TiO<sub>2</sub>) submicrometer hollow spheres were synthesized through a
single
step hydrothermal silica etching reaction under mild conditions. Efficient
silica (SiO<sub>2</sub>) removal was achieved without the use of toxic
reagents, and a unique controllable silica redeposition mechanism
was identified, imparting the hollow spheres with excellent structural
integrity. The parameters of the hydrothermal reaction affecting the
etching process, including pH, temperature, and silica concentration,
were systematically investigated and optimized for the production
of silica-templated hollow structures. The resulting processing conditions
yielded TiO<sub>2</sub> hollow spheres with a surface area of ∼300
m<sup>2</sup> g<sup>–1</sup> and anatase phase crystallization,
which exhibited high adsorption capacity for methylene blue dye and
good photocatalytic activity without requiring high-temperature calcination
Recyclable Graphene Oxide-Supported Titanium Dioxide Photocatalysts with Tunable Properties
A modular synthesis technique was
developed for producing graphene-supported titanium dioxide photocatalysts.
The modular synthesis allowed for simple tuning of the ratio of particle
loading on the graphene oxide (GO) surface as well as good photocatalytic
activity of the composite and quick, efficient magnetic separability.
GO flakes were used as a support for titanium dioxide nanoparticles
and SiO<sub>2</sub> insulated nano-sized magnetite aggregates. Different
composition ratios were tested, resulting in a catalyst formulation
with photocatalytic activity exceeding that of a commercial photocatalyst
by a factor of 1.2 as well as excellent recyclability, with the capability
to degrade 3 mg/L methylene blue in aqueous solution over 10 consecutive
trials with minimal loss in photocatalytic efficiency. Recovery of
the catalyst was achieved by simply exposing the nanocomposite to
a magnetic field for ∼1 minute. Furthermore, it was found that
the catalyst could be regenerated to its initial efficiency through
simple UV treatment to provide additional re-use. To highlight the
importance of the nanocomposite to the current water treatment industry,
we showed rapid degradation of pharmaceutical compounds caffeine and
carbamazepine within 60 min. The nanocomposite shows activity exceeding
that of commercial photocatalyst P25 with the added benefit of being
fully recoverable, reusable, and easy to produce. Overall, a simple
technique for producing and tuning an effective magnetically recyclable
nanocomposite was developed which should allow easy scalability and
industrial production, a factor critical for the implementation of
nano-based water treatment techniques