Applied
Catalysis
B:
Environmental
132–
133 (2013) 452–
459
Contents
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at
SciVerse
ScienceDirect
Applied
Catalysis
B:
Environmental
jo
u
r
n
al
hom
ep
age:
www.elsevier.com/locate/apcatb
One-step
synthesis
of
easy-recycling
TiO
2
-rGO
nanocomposite
photocatalysts
with
enhanced
photocatalytic
activity
Ping
Wang
a
,
Jin
Wang
a
,
Xuefei
Wang
a
,
Huogen
Yu
a,∗
,
Jiaguo
Yu
b
,
Ming
Lei
c,∗
,
Yonggang
Wang
c
a
Department
of
Chemistry,
School
of
Science,
Wuhan
University
of
Technology,
Wuhan
430070,
PR
China
b
State
Key
Laboratory
of
Advanced
Technology
for
Material
Synthesis
and
Processing,
Wuhan
University
of
Technology,
Wuhan
430070,
PR
China
c
School
of
Science,
Beijing
University
of
Posts
and
Telecommunications,
Beijing
100876,
PR
China
a
r
t
i
c
l
e
i
n
f
o
Article
history:
Received
25
October
2012
Received
in
revised
form
8
December
2012
Accepted
9
December
2012
Available online xxx
Keywords:
Reduced
graphene
oxide
TiO
2
Photocatalytic
activity
Easy
recycling
Green
method
a
b
s
t
r
a
c
t
The
addition
of
reduced
graphene
oxide
(rGO)
in
the
TiO
2
has
been
demonstrated
to
be
one
of
the
effective
methods
to
improve
the
photocatalytic
performance
of
TiO
2
photocatalyst.
Despite
tremendous
efforts,
developing
facile
and
green
synthetic
method
of
TiO
2
-rGO
nanocomposites
still
remains
a
great
challenge.
In
this
study,
a
one-step
green
hydrothermal
method
for
the
fabrication
of
easily
recycled
TiO
2
-rGO
com-
posites,
based
on
the
initial
formation
of
strong-coupling
TiO
2
-GO
nanocomposite
and
the
subsequent
in
situ
reduction
of
GO
to
rGO
during
hydrothermal
treatment,
was
developed
in
the
pure
water
without
using
any
reductant
and
surfactant.
It
is
found
that
the
TiO
2
nanoparticles
with
a
clean
surface
and
a
good
dispersion
are
highly
required
for
the
formation
of
the
easy-recycling
TiO
2
-rGO
composite
photo-
catalyst.
Photocatalytic
experimental
results
indicated
that
compared
with
the
high-efficiency
P25
TiO
2
precursor,
the
photocatalytic
performance
could
be
obviously
improved
(about
23%)
for
the
decompo-
sition
of
phenol
after
coupling
1-wt%
rGO.
The
enhanced
photocatalytic
performance
can
be
attributed
the
cooperation
effect
of
the
effective
separation
of
charge
carriers
via
rGO
cocatalyst,
the
enrichment
of
phenol
molecular
on
the
rGO,
and
the
strong
coupling
interaction
between
TiO
2
nanoparticles
and
rGO
nanosheets.
Considering
its
completely
green
and
facile
preparation
and
recyclable
feature
from
an
aqueous
solution,
the
present
TiO
2
-rGO
nanocomposite
photocatalyst
can
be
regards
as
one
of
the
ideal
photocatalysts
for
various
potential
applications.
© 2012 Elsevier B.V. All rights reserved.
1.
Introduction
TiO
2
is
one
of
the
most
widely
investigated
photocatalysts
that
exhibits
effective
photocatalytic
degradation
for
various
organic
pollutants
[1–3].
However,
the
TiO
2
photocatalyst
still
cannot
be
widely
used
in
practical
applications
due
to
its
low
pho-
tocatalytic
activity.
Therefore,
it
is
highly
required
to
develop
new
methods
to
improve
the
photocatalytic
performance
of
TiO
2
photocatalyst.
Compared
with
a
single-component
photocatalyst,
composite
photocatalysts
usually
exhibit
a
higher
photocatalytic
performance.
The
general
principle
for
the
enhanced
photocatalytic
performance
of
these
composite
photocatalysts
is
that
they
have
different
electronic
energy
levels
so
that
the
charge
separation
can
be
enhanced
by
the
internal
electric
field
driving
force
[4,5].
Vari-
ous
strategies
have
been
developed
to
synthesize
TiO
2
composite
materials
for
the
inhibition
of
high
electron-hole
recombination
rate,
such
as
coupling
with
noble
metal
[6,7],
transition
metal
ions
(or
their
oxides)
[8,9]
and
other
semiconductors
[10,11].
Recently,
∗
Corresponding
authors.
Tel.:
+86
27
87871029;
fax:
+86
27
87879468.
E-mail
addresses:
yuhuogen@yahoo.cn (H.
Yu),
mlei@bupt.edu.cn
(M.
Lei).
the
addition
of
graphene
has
been
demonstrated
to
be
one
of
the
effective
methods
to
improve
the
photocatalytic
performance
of
TiO
2
owing
to
its
large
specific
surface
area
and
excellent
mobility
of
charge
carriers
[12–15].
Graphene
oxide
(GO)
is
one
of
the
main
precursors
for
the
prepa-
ration
of
various
graphene-based
photocatalytic
materials
due
to
its
large-scale
production
and
facile
synthetic
method
[16].
However,
the
microstructures
of
the
GO
are
completely
different
from
that
of
the
pristine
graphene
owing
to
the
presence
of
large
amount
of
oxygen-containing
functional
groups
such
as
hydroxyl
and
epox-
ide,
resulting
in
a
great
decrease
of
the
electronic
properties
[17,18].
Therefore,
for
the
preparation
of
highly
efficient
graphene-based
TiO
2
photocatalysts,
the
deoxygenation/reduction
process
of
GO
is
highly
required
in
order
to
recover
its
excellent
mobility
of
charge
carriers.
It
was
reported
that
hydrazine
and
sodium
borohy-
dride
have
been
demonstrated
to
be
excellent
reducing
agents
for
the
effective
reduction
of
GO
[19,20].
However,
considering
their
toxic
affect
on
both
human
and
environmental
health,
the
explo-
ration
of
greener
and
more
sustainable
reduced
strategy
of
GO
would
be
greatly
beneficial
for
the
preparation
of
TiO
2
-rGO
photo-
catalysts.
Several
researcher
groups
have
reported
that
UV-light
photocatalytic
reduction
of
the
GO
is
an
effective
and
green
method
0926-3373/$
–
see
front
matter ©
2012 Elsevier B.V. All rights reserved.
http://dx.doi.org/10.1016/j.apcatb.2012.12.009