Pd nanoparticles deposited on poly(lactic acid) grafted carbon nanotubes: Synthesis, characterization and application in Heck C-C coupling reaction

Article abstract of DOI:10.1016/j.apcata.2011.03.050

Herein we described the synthesis of a novel f-CNTs-Pd nanocatalyst by covalent grafting of poly(lactic acid) (PLA) onto carbon nanotubes (CNTs) and subsequent deposition of Pd nanoparticles. Prior to grafting of PLA, CNTs were oxidized with a mixture of HNO₃/H₂SO₄ and successively activated with thionyl chloride. The PLA grafted CNTs (f-CNTs) were then used as platform for in situ deposition of Pd nanoparticles. The formation of f-CNTs-Pd nanocatalyst was analyzed by UV-vis, FTIR and Raman spectroscopy, powder XRD, energy dispersive spectroscopy and thermogravimetric analysis. The morphologies of the nanocatalyst were characterized using scanning and transmission electron microscopes. The f-CNTs stabilized Pd nanoparticles are found to be more effective in the promotion of Heck cross-coupling reaction between aryl halides and n-butyl acrylate. The f-CNTs-Pd nanocatalyst was regenerated for three cycles of reaction without any significant loss in its activity.

Full text of DOI:10.1016/j.apcata.2011.03.050

Applied Catalysis A: General 399 (2011) 154–160
Contents lists available at ScienceDirect
Applied Catalysis A: General
journal homepage: www.elsevier.com/locate/apcata
Pd nanoparticles deposited on poly(lactic acid) grafted carbon nanotubes:
Synthesis, characterization and application in Heck C–C coupling reaction
Gururaj M. Neelgund, Aderemi Oki∗
Department of Chemistry, Prairie View A&M University, Prairie View, TX 77446, USA
a r t i c l e i n f o
a b s t r a c t
Article history:
Herein we described the synthesis of a novel f-CNTs-Pd nanocatalyst by covalent grafting of poly(lactic
acid) (PLA) onto carbon nanotubes (CNTs) and subsequent deposition of Pd nanoparticles. Prior to graft-
ing of PLA, CNTs were oxidized with a mixture of HNO3/H2SO4 and successively activated with thionyl
chloride. The PLA grafted CNTs (f-CNTs) were then used as platform for in situ deposition of Pd nanopar-
ticles. The formation of f-CNTs-Pd nanocatalyst was analyzed by UV–vis, FTIR and Raman spectroscopy,
powder XRD, energy dispersive spectroscopy and thermogravimetric analysis. The morphologies of the
nanocatalyst were characterized using scanning and transmission electron microscopes. The f-CNTs sta-
bilized Pd nanoparticles are found to be more effective in the promotion of Heck cross-coupling reaction
between aryl halides and n-butyl acrylate. The f-CNTs-Pd nanocatalyst was regenerated for three cycles
of reaction without any significant loss in its activity.
Received 8 December 2010
Received in revised form 21 March 2011
Accepted 28 March 2011
Available online 1 April 2011
Keywords:
Carbon nanotubes
Poly(lactic acid)
Palladium
Catalytic activity
Heck reaction
Published by Elsevier B.V.
1. Introduction
ticles catalysts posses high catalytic activity, good stability, ease
separation and satisfactory reusability compared to traditional
Since their discovery in 1991, carbon nanotubes (CNTs) have
generated tremendous interest in the area of nanotechnology [1].
With the simple chemical composition and atomic bonding con-
figuration, CNTs exhibit extreme diversity and richness in their
structure dependent properties [2,3]. The considerable interest in
CNTs is strongly related to their fascinating and unique optical,
electrical, mechanical, and thermal properties. Consequently, the
exceptional properties of CNTs made them as the ideal candidates
for numerous applications in nanoelectronics [4,5], catalysis [6–8],
diagnostics [9,10] and drug delivery [11,12]. Owing to the high
aspect ratio and specific surface area, CNTs are excellent supporting
material for catalyst, especially in heterogeneous catalysis [13,14].
Since the support with a high specific surface area is ideal for depo-
sition of catalytically active metal nanoparticles, such nanoparticles
exhibit greater catalytic efficiency than their bulk counterpart due
to high surface-to-volume ratio [15]. In order to control the CNT-
nanoparticles interface and to favor a high loading of nanoparticles,
coordinating polymer grafts can act as macromolecular coupling
agents as they carry multiple binding sites.
homogeneous Pd(OAc)2, PdCl2 catalysts. Owing to these inter-
ests here we report the synthesis of a heterogeneous palladium
nanocatalyst supported on poly(lactic acid) (PLA) functionalized
carbon nanotubes (CNTs) and its efficiency in the promotion of Heck
coupling reaction.
2. Experimental
2.1. Materials
All the reagents were purchased from Aldrich and used without
any purification. All aqueous solutions were prepared with ultra-
pure water obtained from the Milli-Q Plus system (Millipore). The
tetrahydrofuran (THF) was dried over sodium benzophenone under
nitrogen and freshly distilled prior to use.
2.2. Synthesis of PLA
PLA was synthesized according to previously reported method
[18,19] and the molecular weight measured from gel permeation
chromatography (GPC) was found to be 50,000 g/mol.
Palladium nanoparticles are of current interest due to their
superior catalytic performance and these nanoparticles are find-
ing enormous industrial applications in both heterogeneous and
homogeneous catalytic reactions [16,17]. Supported Pd nanopar-
2.3. Covalent grafting of PLA to CNTs
Pristine CNTs (p-CNTs) were refluxed under stirring in the mix-
ture of 1:3 (v/v) HNO3 and H2SO4 at 70 ◦C for 24 h, which was
followed by centrifugation and repeated washings with DI water
∗
Corresponding author. Fax: +1 936 261 3117.
E-mail address: aroki@pvamu.edu (A. Oki).
0926-860X/$ – see front matter. Published by Elsevier B.V.
doi:10.1016/j.apcata.2011.03.050

G.M. Neelgund, A. Oki / Applied Catalysis A: General 399 (2011) 154–160
155
Scheme 1. Covalent grafting of PLA onto CNTs and successive deposition of Pd nanoparticles.
[20]. The carboxylated CNTs (CNTs-COOH) thus obtained were
dried under vacuum at 40 ◦C and reacted with excess of SOCl2 at
room temperature for 24 h. The acylated CNTs (CNTs-COCl) were
separated by centrifugation, subsequently washed with anhydrous
THF and dried in vacuum at 40 ◦C for 12 h. The CNTs-COCl were
then dispersed in CH2Cl2 by sonication for 10 min, mixed with a
solution of PLA in CH2Cl2 and allowed to react with flowing nitro-
gen at 35 ◦C for 12 h. The resulting PLA functionalized CNTs (f-CNTs)
were centrifuged, washed with CH2Cl2 and dried in vacuum.
2.4.2. Preparation of CNTs-COOH–Pd nanocatalyst
The CNTs-COOH–Pd nanocatalyst was prepared similar to the
procedure mentioned above for f-CNTs-Pd nanocatalyst using
CNTs-COOH instead of f-CNTs.
2.4.3. Preparation of PLA-Pd nanocatalyst
PLA (40 mg) was dissolved in CH2Cl2 and a solution of PdCl2 in
methanol (10 mL, 0.01 mol L−1) was added. This mixture was stirred
at room temperature for 2 h followed by addition of NaBH4 solution
(10 mL, 0.05 mol L−1). Then the reaction was allowed to proceed at
room temperature for 4 h. The resulting PLA-Pd nanocatalyst was
separated by centrifugation, successively washed with CH2Cl2 and
water and dried under vacuum for 8 h.
2.4. Preparation of nanocatalysts
2.4.1. Preparation of f-CNTs-Pd nanocatalyst
In all the nanocatalysts, a total Pd loading of 40% was obtained
by controlling the concentration of PdCl2.
The f-CNTs (40 mg) were dispersed in 15 mL DI water by
sonication for 10 min and a aqueous solution of PdCl2 (10 mL,
0.01 mol L−1) was added to dispersion of f-CNTs. The mixture was
stirred for 2 h in room temperature to complete attainment of coor-
dination, which follows slow addition of a freshly prepared solution
of NaBH4 (10 mL, 0.05 mol L−1) in DI water. The reaction mixture
was then stirred under ambient conditions for 4 h. Thus yielded
f-CNTs-Pd nanocatalyst was subjected to centrifugation, washed
with DI water and dried in vacuum at 40 ◦C for 12 h. The overall
synthesis of f-CNTs-Pd nanocatalyst is schematically demonstrated
in Scheme 1.
2.5. Catalytic activity
In order to evaluate the catalytic activity of immobilized Pd
nanoparticles, the heterostructured f-CNTs-Pd nanocatalyst was
used in the important carbon–carbon bond forming Heck cou-
pling reaction. The cross-coupling of arylhalide with n-butyl
acrylate in the presence of f-CNTs-Pd nanocatalyst (Scheme 2)
was accomplished as follows. The mixture containing arylhalide
(5 mmol), n-butyl acrylate (5.5 mmol), triethylamine (5.5 mmol)

156
G.M. Neelgund, A. Oki / Applied Catalysis A: General 399 (2011) 154–160
alizing CNTs-COOH with PLA. The substantial red shift of 24 nm
O
Et3N
Pd catalyst
X
O
in the spectrum of f-CNTs and the differences observed in the
spectra of f-CNTs and mixture of PLA and CNTs-COOH (see the
Supporting Information, Fig. S1) exhibits existence of strong inter-
actions between PLA chains and CNTs, which favors the efficient
dispersibility of f-CNTs in both organic and aqueous media. No dis-
tinctive surface plasmon resonance for Pd nanoparticles could be
observed in the spectrum of f-CNTs-Pd nanocatalyst (Fig. 1c), which
is inline with the previous reports that Pd nanoparticles are known
to absorb in the UV region with virtually no structure [21,22]. While
the characteristic band of CNTs further red shifted to 279 nm by
deposition of Pd nanoparticles onto f-CNTs. There is no new absorp-
tion features emerged after deposition of Pd nanoparticles, which
implies that there is no charge diffusion or electronic interaction
between f-CNTs and Pd nanoparticles.
R
O
R
+
O
DMF
X=I, Br, Cl; R=CH3, C2H5
Scheme 2. Heck reaction between arylhalide and n-butylacrylate catalyzed by f-
CNTs-Pd nanocatalyst.
in 10 mL N,N-dimethyl formamide (DMF) was stirred at 100 ◦C in
the presence of f-CNTs-Pd nanocatalyst (10 mg). Then a solution of
Na2CO3 (0.25 g) in 10 mL DI water was added to reaction mixture,
stirred at room temperature for 15 min and subjected to centrifu-
gation. The resulting reaction mixture was treated with 10 mL 2%
HCl solution, which yields to precipitation of the reaction product.
The crude product was then purified by recrystallization.
The composition of f-CNTs-Pd nanocatalyst was analyzed by
FTIR spectroscopy. Fig. 2a–c represent the IR spectra obtained for
PLA, f-CNTs and f-CNTs-Pd nanocatalyst, respectively. The spec-
trum of f-CNTs displayed all the important characteristic bands
associated with PLA, the most obvious changes are diminished
intensity in bands and displacement of position. The ester C–O
stretching band for PLA was appeared at 1760 cm−1 and for f-
CNTs it was at 1750 cm−1, this blue shifting of band in f-CNTs is
owing to grafting of PLA chains onto CNTs. The broad feature at
3500 and 3430 cm−1 for PLA and f-CNTs, respectively corresponds
to the absorption of –OH stretching of hydroxyl groups. The res-
onances due to C–CH3 stretching and –CH3 asymmetric bending
mode were appeared at 1090 and 1460 cm−1, respectively [23].
The absorption around 1180 cm−1 corresponds to C–C–O stretching
[24]. Another important observation is the appearance of doublet
at 3000 and 2950 cm−1 due to –CH twisting vibrations. In addition,
2.6. Characterization
The molecular weight of PLA was measured by Waters GPC
system using polystyrene as the standard and THF as eluent. The
UV–vis absorption spectra were recorded on Varian Carry 50 Bio
UV–vis spectrophotometer and Fourier transform infrared (FTIR)
spectra were recorded using Thermo-Nicolet IR 2000 spectrometer
(KBr pellet). Thermogravimetric analyses (TGA) were performed
with a Perkin Elmer Diamond TG/DTA instrument at a heating rate
of 10 ◦C/min under flow of nitrogen. Raman spectra were recorded
using Renishaw R-3000QE system in the backscattering configu-
ration using an Argon ion laser with wavelength of 785 nm. XRD
patterns were recorded on Scintag X-ray diffractometer (PAD X),
equipped with Cu K␣ photon source (45 kV, 40 mA) at a scanning
rate of 3◦/min. Scanning electron microscopy (SEM) measurements
were performed on a JEOL JXA-8900 microscope and the X-ray
energy dispersive spectroscopy (EDS) measurements were made
with a ThermoNoran EDS System 6 attached to SEM. Transmission
electron microscopy (TEM) images were obtained with a Hitachi
H-8100 microscope at 200 kV.
the spectrum of f-CNTs exhibited C–C absorption at 1576 cm−1
,
which indicates that the graphene structures of CNTs were not
disturbed by functionalizing with PLA [25]. The spectrum of f-
CNTs-Pd nanocatalyst appeared with few characteristic bands with
low intensity. The conformational changes occurred by the deposi-
tion of Pd nanoparticles demonstrates the strong interaction exists
between f-CNTs and Pd nanoparticles, which causes for higher sta-
bilization of f-CNTs-Pd nanocatalyst. Therefore, it is valid to contend
the successful grafting of PLA chains onto CNTs and subsequent
deposition of Pd nanoparticles.
3. Results and discussion
The UV–vis spectrum of CNTs-COOH (Fig. 1a), dispersed in
water displayed the characteristic absorption band with decreas-
ing absorptivity at 249 nm [20]. This characteristic band in the
spectrum of f-CNTs (Fig. 1b) displaced to 273 nm after function-
The phase structure of the nanocatalyst was revealed through
powder XRD. The XRD patterns acquired for pristine CNTs (p-CNTs),
f-CNTs and f-CNTs-Pd nanocatalyst is shown in Fig. 3. The diffraction
peaks at 26.3◦ and 42.6◦ for p-CNTs (Fig. 3a) are attributed to (0 0 2)
and (1 0 0) planes of hexagonal graphite and appearance of these
(c)
(b)
(c)
(b)
(a)
(a)
200
400
600
800
1000
500
1000 1500 2000 2500 3000 3500 4000
Wavelength (nm)
Wavenumber (cm-1)
Fig. 1. UV–vis absorption spectra of (a) CNTs-COOH, (b) f-CNTs and (c) f-CNTs-Pd
nanocatalyst.
Fig. 2. FTIR spectra of (a) PLA, (b) f-CNTs and (c) f-CNTs-Pd nanocatalyst.

G.M. Neelgund, A. Oki / Applied Catalysis A: General 399 (2011) 154–160
157
and (2 2 0) crystallographic planes of face-centered cubic (fcc) pal-
ladium at 39.8◦, 46◦ and 67.2◦, respectively (JCPDS No. 89-4897).
The additional two peaks in Fig. 3c at 26.3◦ and 46◦ were from
CNTs. Thus the XRD results indicate efficient immobilization of fcc
structured Pd nanoparticles on f-CNTs.
(c)
(b)
The Raman spectra of p-CNTs (Fig. 4a), f-CNTs (Fig. 4b) and
f-CNTs-Pd nanocatalyst (Fig. 4c) revealed the existence of charac-
(c)
(a)
10
20
30
40
50
60
70
80
2θ (degree)
(b)
(a)
Fig. 3. Powder XRD patterns of (a) p-CNTs, (b) f-CNTs and (c) f-CNTs-Pd nanocatalyst.
peaks withhigh intensitysuggeststhatp-CNTs haveahighgraphitic
structure [20]. After functionalization, the diffraction peaks corre-
sponding to (0 0 2) and (1 0 0) planes of CNTs were appeared at 26◦
and 42.5◦ for f-CNTs (Fig. 3b). A minute blue shift in the bands was
observed for f-CNTs, which signifies that functionalization of CNTs
with PLA did not destroy or alter the original structure of p-CNTs.
The f-CNTs-Pd nanocatalyst (Fig. 3c) clearly exhibited (1 1 1), (2 0 0)
500
1000
1500
2000
2500
3000
Raman frequency (cm-1)
Fig. 4. Raman spectra of (a) p-CNTs, (b) f-CNTs and (c) f-CNTs-Pd nanocatalyst.
Fig. 5. SEM images of (a) and (b) f-CNTs and (c) and (d) f-CNTs-Pd nanocatalyst.

158
G.M. Neelgund, A. Oki / Applied Catalysis A: General 399 (2011) 154–160
Table 1
to G-band (ID/IG) provides information about defects caused by
functionalization. The value of ID/IG for p-CNTs, f-CNTs, f-CNTs-Pd
nanocatalyst was 0.4, 1.23 and 1.14 respectively. The significant
increase in the value of ID/IG for f-CNTs was primarily attributed to
conversion of carbon atoms from sp2 to sp3 hybridization, which
indicates existence of more number of surface defects in f-CNTs
generated by the treatment of p-CNTs with acids and SOCl2 (see the
Supporting Information, Fig. S2). The value of ID/IG for f-CNTs-Pd
nanocatalyst was lower than that of the f-CNTs, which reflects that
the disorder in nanotubes was not directly affected by the deposi-
tion of Pd nanoparticles. Considering these conformational changes
in the Raman spectra, we can reasonably conclude that CNTs are
effectively functionalized through grafting of PLA and further depo-
sition of Pd nanoparticles.
Raman bands displayed for p-CNTs, f-CNTs and f-CNTs-Pd nanocatalyst.
Position of band (cm−1
)
ID/IG
D-band
G-band
D2-band
D*-band
p-CNTs
f-CNTs
f-CNTs-Pd nanocatalyst
1306
1312
1313
1587
1579
1591
–
1607
1616
2583
2624
2631
0.40
1.23
1.14
(–) denotes that D2-band was not displayed for p-CNTs.
teristic D- and G-bands around 1310 and 1585 cm−1, respectively.
In addition, the D*-band was displayed for all the samples around
2610 cm−1 and the D2-band, which is a shoulder of the G-band
was observed only for f-CNTs and f-CNTs-Pd nanocatalyst around
1610 cm−1. The location of all bands is summarized in Table 1. The
D- and D2-bands were attributed to defects in the hexagonal frame-
work of graphite and G-band to in-plan vibrations of the graphite
(sp2-hybridized carbons) [26]. Thus the intensity ratio of D-band
The surface morphology of f-CNTs and f-CNTs-Pd nanocatalyst
were characterized through SEM and TEM. The SEM images of f-
CNTs (Fig. 5a and b) exhibit effective grafting of PLA onto CNTs
and the efficient entanglement of CNTs by functionalization. This
Fig. 6. TEM images of (a) and (b) f-CNTs and (c) and (d) f-CNTs-Pd nanocatalyst.

G.M. Neelgund, A. Oki / Applied Catalysis A: General 399 (2011) 154–160
159
100
80
60
40
20
0
demonstrates that strong interaction exists between CNTs and PLA
chains, which facilitates the high dispersing ability of f-CNTs in
both organic and aqueous media. The existence of Pd nanopar-
ticles, deposited on f-CNTs was clearly distinguishable as bright
spots in Fig. 5c and d. The density of Pd nanoparticles in f-CNTs-Pd
nanocatalyst is abundant and these nanoparticles together formed
some clusters. The formation of clusters might have originated by
twinned or multiple twinned seeding of Pd nanoparticles, which
is in accordance with previous reports [27,28]. The interpretations
made on the basis of SEM images were further supported by the
TEM images shown in Fig. 6. In the images of f-CNTs (Fig. 6a and
b) the graphitic frame of CNT is easily distinguishable below PLA
layer. That is, a core shell structure of CNTs at the center can be
seen clearly, which indicates that the CNTs were covalently grafted
by PLA chains. The thickness of PLA layer grafted onto the surface of
the CNTs was around 4 nm and the PLA chains provided an effective
steric barrier against bundling of CNTs. The thickness of grafted PLA
on some places of CNTs was found to be non-uniform. The images of
f-CNTs-Pd nanocatalyst (Fig. 6c and d) exhibits that Pd nanoparti-
cles are randomly dispersed on f-CNTs and some of them appeared
twinned together. The random distribution of Pd nanoparticles may
be attributed to the large number of defect sites produced by the
harsh treatment of acids. The mean diameter of Pd nanoparticles
immobilized on f-CNTs was found to be around 12 nm. The exis-
tence of metallic Pd in f-CNTs-Pd nanocatalyst was further revealed
by EDS shown in Fig. 7. The peak corresponding to C was originated
by CNTs with a small contribution from PLA chains. The signal cor-
responding to O was also generated by PLA and the signal Pd was
originated by Pd nanoparticles. The peaks derived from Cu were
from the copper grid used in TEM measurements.
To obtain more quantitative information about extent of func-
tionalization and contents of PLA, TGA analysis was performed and
the profiles obtained are exhibited in Fig. 8. The profile of CNTs-
COOH showed a minute weight loss of about 3% at 500 ◦C owing to
decomposition of carboxyl groups (Fig. 8a). In addition, there is a
major weight loss of 16.4% displayed for CNTs-COOH in the temper-
ature range of 500–615 ◦C due to combustion of CNTs [29] and the
residual weight remained from CNTs-COOH at 800 ◦C was 81.5%.
The profile of PLA exhibited a single and complete weight loss in
the temperature range of 280–390 ◦C because of degradation of PLA
(Fig. 8b). While f-CNTs exhibited a weight loss of 23% in the temper-
ature range from 300–600 ◦C due to degradation of PLA grafted onto
CNTs, which indicates that the amount of PLA grafted to CNTs was
23 wt% (Fig. 8c) [30]. An increment of about 20 ◦C in the degradation
of PLA was observed in f-CNTs, which exhibits existence of strong
(a)
(d)
(c)
700
(b)
100
200
300
400
500
600
800
Temperature (oC)
Fig. 8. TGA profiles of (a) CNTs-COOH, (b) PLA, (c) f-CNTs and (d) f-CNTs-Pd nanocat-
alyst.
interaction between PLA chains and CNTs. The second weight loss
observed at higher temperature range of 600–720 ◦C for f-CNTs was
due to combustion of CNTs. The degradation behavior of f-CNTs-Pd
nanocatalyst (Fig. 8d) is entirely different from that of f-CNTs and
the residual weight measured at 800 ◦C was 23.4%, these observa-
tions demonstrates that Pd nanoparticles are well anchored onto
f-CNTs.
To evaluate the catalytic activity of f-CNTs-Pd nanocatalyst, we
studied the Heck reaction between bromobenzene and methyl
acrylate in the absence of any catalyst and observed that there
was no formation of product after 15 h. Similarly, use of f-CNTs
as a catalyst also did not exhibit any catalytic activity. However,
the reaction was carried out in the presence of f-CNTs-Pd nanocat-
alyst demonstrated efficient conversion of reactants to product.
To further confirm the generality in the activity of f-CNTs-Pd
nanocatalyst, the Heck reaction was studied with different aryl-
halides and n-butyl acrylates, the results are shown in Table 2.
The reactants, arylhalides and n-butyl acrylates efficiently con-
verted to their respective coupling product with good yield in the
presence of f-CNTs-Pd nanocatalyst. The high catalytic activity of f-
CNTs-Pd nanocatalyst is attributed to the large active surface area
of Pd nanoparticles. To find the stability, f-CNTs-Pd nanocatalyst
separated by centrifugation from the reaction mixture between
bromobenzene and methyl acrylate was washed with DI water,
subsequently with acetone and dried at 110 ◦C for 2 h. The recy-
cled f-CNTs-Pd nanocatalyst was then used in other three cycles
of reaction, which resulted in the formation of methyl cinnamate
with ≈2% lower yield than previous cycle, which indicates that the
f-CNTs-Pd nanocatalyst is an excellent catalyst to use in multiple
cycles of reactions.
Further the performance of f-CNTs-Pd nanocatalyst was com-
pared with CNTs-COOH–Pd (without PLA) and PLA-Pd (without
CNTs) nanocatalysts by Heck reaction between bromobenzene
and methyl acrylate. Both, the control experiments using CNTs-
COOH–Pd and PLA-Pd nanocatalysts and the typical experiment
with f-CNTs-Pd nanocatalyst were conducted under identical
conditions. The duration for completion of reaction between bro-
mobenzene and methyl acrylate in the presence of f-CNTs-Pd
nanocatalyst was found to be 8 h, while the duration for completion
of same reaction using CNTs-COOH–Pd and PLA-Pd nanocatalysts
was found to be 11 h and 15 h, respectively. Hence the combination
of PLA and CNTs provides favorable environment for enhancement
in catalytic activity of Pd nanoparticles. Overall, the PLA function-
alized CNTs are ideal platforms for better immobilization of Pd
nanoparticles and to gain their enhanced performance.
Fig. 7. EDS of f-CNTs-Pd nanocatalyst.

160
G.M. Neelgund, A. Oki / Applied Catalysis A: General 399 (2011) 154–160
Table 2
Acknowledgements
Heck reaction between aryl halide and n-butyl acrylate catalyzed by f-CNTs-Pd
nanocatalyst.
The authors acknowledge the support from NIH-NIGMS grant
#1SC3GM086245, NIH-NIGMS RISE grant #1R25GM078361 and
the Welch foundation.
Aryl halide n-Butyl acrylate
Product
Time (h) Yield (%)
O
O
O
O
O
O
I
CH3
O
O
O
O
O
O
O
Appendix A. Supplementary data
CH3
O
O
O
O
O
O
7.5
8
64.2
61.5
52.7
65.8
63.7
54.6
Supplementary data associated with this article can be found, in
the online version, at doi:10.1016/j.apcata.2011.03.050.
Br
Cl
I
CH3
O
O
O
O
O
CH3
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