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Preparation of magnetic CoFe
2
O
4
-functionalized graphene sheets
via a facile hydrothermal method and their adsorption properties
Nianwu Li
a
, Mingbo Zheng
b
, Xiaofeng Chang
a
, Guangbin Ji
a
, Hongling Lu
a
, Luping Xue
a
,
Lijia Pan
b
, Jieming Cao
a,
n
a
Nanomaterials Research Institute, College of Materials Science and Technology, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China
b
National Laboratory of Microstructures, School of Electronic Science and Engineering, Nanjing University, Nanjing 210093, China
article info
Article history:
Received 9 October 2010
Received in revised form
28 December 2010
Accepted 16 January 2011
Available online 25 January 2011
Keywords:
CoFe
2
O
4
Magnetic
Graphene
Nanocomposites
Adsorption
abstract
Magnetic CoFe
2
O
4
-functionalized graphene sheets (CoFe
2
O
4
–FGS) nanocomposites have been synthe-
sized by hydrothermal treatment of inorganic salts and thermal exfoliated graphene sheets. Scanning
electron microscopy (SEM) and transmission electron microscopy (TEM) observations show that cobalt
ferrite nanoparticles with sizes of 10–40 nm are we ll dispersed on graphene sheets. OH
was
recognized as a tie to integrate the inorganic salts with the graphene sheets, which made reaction
started and developed on the surface of graphene sheets and formed cobalt ferrite nanoparticles on
graphene sheets. The adsorption kinetics investigation revealed that the adsorption of methyl orange
from aqueous solution over the as-prepared CoFe
2
O
4
–FGS nanocomposites followed pseudo-second-
order kinetic model and the adsorption capacity was examined as high as 71.54 mg g
1
. The
combination of the superior adsorption of FGS and the magnetic properties of CoFe
2
O
4
nanoparticles
can be used as a powerful separation tool to deal with water pollution.
& 2011 Published by Elsevier Inc.
1. Introduction
Magnetic nanoparticles and carbon nanotubes nanocompo-
sites have applications in waste water treatment and drug
delivery [1–3]. Graphene, a two-dimensional honeycomb lattice
formed by a flat monolayer of hexagonally arrayed sp
2
-bonded
carbon atoms, is the basal building block in all graphitic materi-
als [4,5]. It has excellent mechanical [6], electrical [7], thermal [8],
optical properties [9], high surface area (calculated value,
2630 m
2
g
1
) [10], and fascinating transport phenomena (such
as the quantum hall effect) [11]. It is believed that magnetic
nanoparticles and graphene nanocomposites would have better
performances in these applications.
Recently only a few researchers have managed to fabricate
magnetic graphene nanocomposites [12–15]. Yang’s group pre-
pared GO (graphene oxide) and Fe
3
O
4
nanoparticles nanocompo-
sites via the chemical precipitation method under N
2
atmosphere,
and showed their application in drug carriers [12]. Yu’s group
prepared magnetite (Fe
3
O
4
) nanoparticles functionalized RGO
(reduced graphene oxide) using Fe(acac)
3
as precursor and
refluxing at 278 1C under an argon protection, and showed its
potential application in magnetic resonance image [13]. Fan and
co-workers attached Fe
3
O
4
nanoparticles to graphene oxide by
covalent bonding [14]. Magnetite and RGO nanocomposites also
have been reported for an arsenic removal [15]. Up to now, all the
magnetic graphene nanocomposites are carried out on GO
and RGO.
As another main graphene derivate to prepare graphene
nanocomposites, FGS (functionalized graphene sheets) have the
highest BET surface area (300–900 m
2
g
1
), and a broad pore size
distribution in the range 2–200 nm stacked by graphene
sheets [16,17], thus it is a potential excellent adsorption material.
Consequently, it is considered as a novel adsorbent, which has
great potential in the treatment of contaminant from an aqueous
solution. To the best of our knowledge, the preparation and
adsorption properties of CoFe
2
O
4
–FGS nanocomposites have not
been reported.
Herein, we report a facile hydrothermal method to prepare
CoFe
2
O
4
–FGS nanocomposites. On the basis of results obtained
from microstructure characterization, the cobalt ferrite nanoparti-
cles with diameters of 10–40 nm were uniformly distributed on
FGS and the formation mechanism of CoFe
2
O
4
nanoparticles on
graphene sheets was initially discussed. To investigate the adsorp-
tion of CoFe
2
O
4
–FGS, the usual contaminant methyl orange (MO)
was selected as the model compound. Furthermore, we demon-
strated that CoFe
2
O
4
–FGS nanocomposites have great potential as
an effective absorbent for removing MO in water, due to its high
adsorption capacity and convenient magnetic separation.
Contents lists available at ScienceDirect
journal homepage: www.elsevier.com/locate/jssc
Journal of Solid State Chemistry
0022-4596/$ - see front matter & 2011 Published by Elsevier Inc.
doi:10.1016/j.jssc.2011.01.014
n
Corresponding author. Fax: +86 25 84895289.
E-mail address: jmcao@nuaa.edu.cn (J. Cao).
Journal of Solid State Chemistry 184 (2011) 953–958