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peak between 600 and 900 nm caused by the complex of Cu
2
+
on the surface of the
hybrid network, giving rise to a better use of visible light. Independently, the con-
centrations of the metal ions decreased gradually with the reaction time, and nearly,
98 % of ions could be removed after 8-h experiment, which signified that the pres-
ence of RhB did not prohibit the adsorption process of the heavy metal ions. Herein,
both organic and inorganic pollutants could be eliminated under simulated solar
light radiation, while the homogeneously coordinated metal ions on the hybrid mate-
rials could improve the photocatalytic activity simultaneously [
17
]. This inspired us
with an alternative method for the preparation of new photocatalysts.
Improving the separation efficiency of photoinduced charge carriers is the basic
rule for designing new photocatalytic systems. In general, there are two strategies
[
33
]. Doping with metallic and nonmetallic elements was considered to reduce the
band gap for wide band gap metal oxides [
34
]. The other efficient approach is cou-
pling with other materials so as to build a heterojunction structure at the interface
to enhance the separation efficiency of photogenerated electron-hole pairs dur-
ing the photocatalytic process. Mesoporous phosphonated titania hybrid materials
were prepared with the use of amino trimethylene phosphonic acid (ATMP) as the
coupling molecule and triblock copolymer F127 as the template [
35
], in which the
phosphonate groups homogeneously anchored on the mesoporous titania, allowing
monolayer adsorption of Zn
2
+
by extensive coordination with the organic bridg-
ing groups (Fig.
5.6
). The highly dispersed photoactive ZnO nanoparticles were
then formed through low-temperature annealing (180 °C) of the Zn
2
+
adsorbed
mesoporous phosphonated titania, and the resultant ZnO-coupled mesoporous
phosphonated titanium oxide photocatalysts exhibited excellent photocatalytic
activity and stability in the photodegradation of RhB under both UV and visible
light irradiation [
36
]. In comparison with the pristine mesoporous phosphonate tita-
nia, the commercial titania P25, and the ZnO/mesoporous titania prepared by con-
ventional impregnation, the superior photocatalytic performance and stability of the
coupled catalyst of ZnO nanoparticles highly dispersed on the mesoporous phos-
phonated titania might be due to the coupling effect, the well-defined mesoporos-
ity and the incorporation of phosphonic moieties into the TiO
2
network, presenting
potential applications in the fields of environmental remediation and solar cells.
Fig. 5.6
Typical synthesis procedure of the ZnO-phosphonated-TiO
2
mesoporous-coupled pho-
tocatalysts. Reprinted with permission from Ref. [
36
]. Copyright 2014, Elsevier
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