RSC Advances
Paper
under the atmosphere of nitrogen. The magnetic properties of
samples were examined by vibrating sample magnetometer
(VSM) on a LakeShore 7307. Optical microscope was used to
investigate the magnetic response on DMM-330C microscope.
UV-vis diffuse reectance absorption spectra was measured on
a Lab-Tech spectrophotometer.
The preparation of 1D magnetic nanochains
The 1D magnetic nanochains were formed by modied distil-
lation precipitation polymerization under external magnetic
eld.40 In a typical synthesis, 0.03 g of hollow Fe3O4 nano-
particles were dispersed in 40 mL acetonitrile in a 150 mL three-
necked ask and then a mixture solution of MAA (0.5 g), DVB
(0.5 g) and AIBN (0.02 g) was added into the three-necked ask.
Aer even mixing, the solution was heated up to 80 ꢁC. Aer
reacting for 2 h, the product was collected with a magnetic and
washed with ethanol for several times. Finally, the product was
dried in a in a freezer dryer.
Results and discussion
Superparamagnetic hollow nanoparticles were prepared by
hydrothermal method with sodium citrate as reductant, urea as
ꢁ
alkaline environment, and PAM as stabilizer at 200 C. Nano-
particles subsequently self-assembled into 1D nanochains by
the external magnetic eld and were coated with polymer
P(MAA-DVB) under the initiation of AIBN by distillation
precipitation polymerization. Finally, the palladium loaded 1D
peapod-like magnetic nanochains (Fe3O4@P(MAA-DVB)–Pd(0))
were obtained through complexation and late reduction by
NaBH4. The preparation process is illustrated in Scheme 1. The
morphology and size of the nanoparticles and nanochains were
characterized by SEM and TEM images. It can be easily seen
from the SEM images (Fig. 1A and B) that, nanoparticles with
the average diameter of approximate 260 nm have a uniform
gibbous spherical shape and a narrow size distribution. Like-
wise, the TEM image (Fig. 2A) shows that nanoparticles with
a rough surface have good mono-dispersion in water and are
composed of irregular shaped primary particles. And Fig. 2A
further demonstrates that the nanoparticle has offwhite center
while the edge is relatively dark, which rmly conrms the
hollow structure of the obtained nanoparticles. Besides, Fig. 1C
clearly displays that one-dimensional nanochains, just like
‘Tanghulu’, have a uniform diameter of about 380 nm and an
average length of 20 mm. Furthermore, the TEM image shows
that the 1D nanochains have a core–shell structure with an
average shell thickness of about 56 nm aer coated with poly-
mer and the visible interparticle spacing between adjacent
particles lled with polymer P(MAA-DVB) is about 25 nm
(Fig. 2C). The thickness of polymer P(MAA-DVB) shell can be
further altered by changing the amount of monomer, nano-
particles or the reaction time. And Fig. 2D represents that Pd
nanoparticles are distributed on the surface of the peapod-like
nanochains, manifesting that Pd particles have been success-
fully loaded on the surface of the nanochains through
complexation between carboxyl on the surface of nanochains
and palladium ion, and NaBH4 reduction. Additionally, the
high-resolution TEM image (Fig. 2E) amplifying the red zone in
The preparation of 1D Fe3O4@P(MAA-DVB)–Pd(0) magnetic
nanochains
1D Fe3O4@P(MAA-DVB)–Pd(0) magnetic nanochains were
formed by complexation effect between carboxyl and palladium
ion.43 In a typical synthesis, the above product of 1D magnetic
nanochains was dispersed in 60 mL ethanol in a 250 mL three-
necked ask with mechanical stir. Then, Palladium acetate
(Pd(C2H3O2)2, 4.45 ꢂ 10ꢀ3 mol Lꢀ1, 10 mL) was added dropwise.
Aer the above solution being stirred at room temperature for
10 h, 30 mL NaBH4 solution (2.7 ꢂ 10ꢀ2 mol Lꢀ1) was added in
it and the reaction was maintained for 2 h. Finally, the product
was collected using magnet and washed with water and ethanol
for several times and then dried in a freezer dryer.
Catalytic reduction
The catalytic ability of the palladium loaded 1D magnetic
nanochains was evaluated through catalytic reduction of dye
like RhB. Typically, RhB solution (20 mg Lꢀ1, 200 mL) was added
into microcontainer, and then fresh NaBH4 solution (3.78 g Lꢀ1
,
50 mL) was added. Subsequently, 50 mL aqueous dispersion of
Fe3O4@P(MAA-DVB)–Pd(0) (0.9 mg Lꢀ1, 50 mL) was added, the
magnetic stirrer was turned on and the track of time was kept.
Aer reduction, 200 mL solution was mixed with 3 mL distilled
water and then was recorded by UV-vis absorption spectra in
different reaction time. For catalytic performance of different
catalytic concentration and the catalytic reduction of other dyes,
the procedures were similar to the above reduction progress. In
addition, the magnication experiment of RhB solution (20 mg
Lꢀ1, 3 mL) was catalyzed in catalysis (0.9 mg Lꢀ1, 0.5 mL) with
NaBH4 solution (3.78 g Lꢀ1, 0.5 mL), the procedures are similar
to the above reduction progress.
Characterization
Fig. 2D is collected and clear crystal fringe can be clearly seen
˚
1D Fe3O4@P(MAA-DVB)–Pd(0) magnetic nanochains was char- and the d-spacing between neighbouring planes of 2.26 A and
˚
acterized by a transmission electron microscope (TEM, JEOL- 1.94 A could determine the (111) plane and (220) plane of Pd in
3010). A scanning electron microscope (SEM, JSM-6700F) was accordance with the JCPDS le.
used to record the scanning electron microscope (SEM) and
In order to further illustrate the structure and composition
(EDS), respectively. Powder X-ray diffraction (XRD, XRD-7000) of Fe3O4@P(MAA-DVB)–Pd(0), we collected the XRD and EDS
was used to characterize the phase structure of the samples. spectrum, respectively. As can be observed in Fig. 1F, the strong
Fourier transform infrared spectroscopy (FT-IR) was measured peaks of Fe, O, C and Pd conrm that the Pd has been anchored
on a TENSOR27 spectrometer. The shell thickness structure was on the surface and the Pd content is about 5.19 wt%. Fig. 3
investigated by thermal gravimetric analysis (TGA, Q50) froꢀm1 shows the XRD spectra of the Fe3O4, Fe3O4@P(MAA-DVB) and
room temperature to 800 ꢁC with a heating rate of 10 ꢁC min
Fe3O4@P(MAA-DVB)–Pd(0). The peaks could be clearly seen
97884 | RSC Adv., 2016, 6, 97882–97889
This journal is © The Royal Society of Chemistry 2016
Wang, Hai
