Synthesis of Graphdiyne Nanowalls Using Acetylenic Coupling Reaction

Article abstract of DOI:10.1021/jacs.5b04057

Synthesizing graphdiyne with a well-defined structure is a great challenge. We reported herein a rational approach to synthesize graphdiyne nanowalls using a modified Glaser-Hay coupling reaction. Hexaethynylbenzene and copper plate were selected as monom

Full text of DOI:10.1021/jacs.5b04057

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Communication
Synthesis of Graphdiyne Nanowalls using Acetylenic Coupling Reaction
Jingyuan Zhou, Xin Gao, Rong Liu, Ziqian Xie, Jin Yang, Shuqing Zhang,
Gengmin Zhang, Huibiao Liu, Yuliang Li, Jin Zhang, and Zhongfan Liu
J. Am. Chem. Soc., Just Accepted Manuscript • Publication Date (Web): 05 Jun 2015
Downloaded from http://pubs.acs.org on June 6, 2015
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Synthesis of Graphdiyne Nanowalls using Acetylenic Cou-
pling Reaction
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Jingyuan Zhou1, 2, Xin Gao1, Rong Liu1, 2, Ziqian Xie1, Jin Yang2, 3, Shuqing Zhang1,2,
Gengmin Zhang3, Huibiao Liu4, Yuliang Li4, Jin Zhang1*, Zhongfan Liu1*
1 Center for Nanochemistry, Beijing Science and Engineering Center for Nanocarbons, Beijing National Laboratory
for Molecular Sciences, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, P.R.
China
2 Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, 100871, P. R. China
3 Key Laboratory for the Physics and Chemistry of Nanodevices and Department of Electronics, Peking University,
Beijing 100871, P. R. China
4 Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. China
Supporting Information Placeholder
electrode material,10 lithium storage11, hydrogen storage,12 gas
ABSTRACT: Synthesizing graphdiyne with a well-defined
separation,13 high third-order nonlinear optical (NLO) sus-
structure is of great challenge. We reported herein a rational
ceptibility material,14 solar cell15 and so on. Meanwhile, it also
approach to synthesize graphdiyne nanowalls using a modi-
exhibits great photo-catalytic performance when hybridized
with TiO2 or Ag/AgBr.16, 17
fied Glaser-Hay coupling reaction. Hexaethynylbenzene and
copper plate were selected as monomer and substrate. By
adjusting the ratio of added organic alkali along with the
amount of monomer, proper amount of copper ions were
dissolved into the solution forming catalytic reaction sites.
To date, several attempts have been reported about estab-
lishing feasible pathways for the preparation of graphdiyne.
Pioneer work was concerned with employing convergent
synthesis to synthesize a series of building blocks of
graphdiyne based on dehydrobenzoannulenes.18,19 Attempts
to graphdiyne preparation were also conducted in UHV sys-
tem where some six-membered oligomeric cyclic units were
synthesized with the assistance of metal surface.20 However,
such routes mentioned above are not applicable to scalable
synthesis of graphdiyne. In 2010, graphdiyne film with thick-
ness of nearly 1 µm was successfully fabricated on the surface
of copper foil via an in situ Glaser coupling reaction.21 Since
then, several follow-up studies reported the obtain of various
morphologies of graphdiyne, e.g., graphdiyne nanotubes22
and graphdiyne nanowires23 through a template-assisted
method and a vapor transport process, respectively. However,
explicit component characterization and controlled mor-
phology synthesis of graphdiyne are still in the infancy.
Achieving graphdiyne with different well-defined structures
and distinct properties may make significant contribution to
both basic study and development process of such new type
of carbon allotrope.
With
a rapid reaction rate of Glaser-Hay coupling,
graphdiyne grew vertically at these sites first and then with
more copper ions dissolved, uniform graphdiyne nanowalls
formed on the surface of copper substrate. Raman spectra,
UV-Vis spectra and HRTEM results confirmed the features of
graphdiyne. These graphdiyne nanowalls also exhibited ex-
cellent and stable field emission properties.
Over the past two decades, tremendous efforts have been
devoted to searching new carbon allotropes where novel
forms such as fullerene,1 carbon nanotubes,2 and graphene3
have been added to the family. All-carbon materials pos-
sessing certain advantages of light-weight, flexibility and
diverse fabrication approaches have been studied experimen-
tally and theoretically.4 Different types of carbon allotropes
have been constituted by altering the periodic binding motif
in networks consisted of sp, sp2 and sp3 hybridized carbon
atoms.5 Specifically, graphyne, which was firstly proposed by
Baughman in 1987,6 refers to a family of carbon allotropes
merely composed of sp and sp2 hybridized carbon atoms ex-
tending in two-dimensional plane. Among various predicted
structures, graphdiyne is a certain framework containing
hexagonal benzene rings connected by diacetylenic linkages.
It is predicted to be the most stable carbon network contain-
ing diacetylenic linkages with a heat of formation of 18.3 kcal
per g-atom C.7 With highly conjugated structure, remarkable
electronic properties,8 uniformly distributed pores and dis-
tinct optical properties, graphdiyne is forecasted to be prom-
ising for various applications in semiconductor devices,9
Herein, we report a feasible synthetic route of graphdiyne
nanowalls by employing a modified Glaser-Hay coupling.
Glaser coupling is a classic reaction to prepare 1, 3-diynes24
and it has also been proven beneficial to the synthesis of
graphdiyne film.21 For the structural control of nanomaterials,
catalyst distribution and monomer concentration are critical
factors.26 It would appear that Glaser-Hay coupling is a good
candidate for synthesizing graphdiyne with well-defined
structure. It is a crucial modification reported by Hay indi-
cating that addition of catalytic amount of a nitrogen ligand
N, N, N’, N’ –tetramethylethylenediamine (TMEDA) allowed
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the coupling reaction to be carried out with a rapid rate in
Figure 1b and Figure 1c are typical SEM images from top view
other non-alkaline solution such as acetone.25 There are sev-
eral merits of this reaction. Firstly, the coupling yield can be
promoted because of the enhanced solubility of the reactive
species. Secondly, the generation of copper ions can be
properly tuned by addition amount of alkali so that the reac-
tion sites could be regulated. Finally, with a faintly acid
property of terminal alkyne, the monomer HEB is supposed
to be more stable in acetone solution rather than in pyridine
with weak acidity. By adjusting the ratio of pyridine and
TMEDA and concentration of monomer, graphdiyne nan-
owalls were observed and after that, the morphology, com-
position and structure of graphdiyne nanowalls were studied
systematically. Notably, the unique structures with the con-
jugated plane and abundant vertical sharp sheets enable
graphdiyne nanowalls exhibit excellent and stable field emis-
sion performance.
and cross-sectional view respectively. Surprisingly, it was
found that continuous matrix of vertically erected nanowalls
possessing large voids of submicron in diameter. The cross
section view suggests these vertical walls are around hun-
dreds of nanometers high. Actually, the distribution of the
nanowalls is remarkably uniform over the whole substrate
surface (typically 1×2 cm2). Further SEM and atomic force
microscope (AFM) characterization (Figure 1d and Figure 1e)
of mechanically exfoliated sample transferred on Si/SiO2
substrate indicate that such “walls” are of layered structures
with thickness ranging from several to dozens of nanometers.
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The schematic illustration of the synthetic process is de-
picted in Figure 1a. Graphdiyne nanowalls were prepared
through a modified Glaser-Hay coupling reaction with hexa-
ethynylbenzene (HEB) as precursor. The commonly-
employed copper salt catalyst was replaced by Cu plates.
Briefly, copper plates were placed in the mixed solution of
acetone, pyridine and TMEDA with proper ratio and then
acetone solution of procedure was added in a drop-wise
manner (See Supporting Information for details). Copper is
easy to convert to Cu ion with the presence of catalytic
amount of base,21 where a Glaser-Hay reaction took place
efficiently with the aid of TMEDA. By adjusting the dosage of
N-ligands, graphdiyne nanowalls could be uniformly grown
on Cu plates.
Figure 2. (a) TEM image and (b, c) HRTEM images of
graphdiyne nanowalls, related SAED patterns are in corre-
sponding insets. (d) XPS spectra of graphdiyne nanowalls for
C 1s. (e) Raman spectra and (f) UV-Vis spectra of graphdiyne
nanowalls.
Figure 2a displays a transmission electron microscopy
(TEM) observation of as-obtained graphdiyne nanowalls,
verifying that the “walls” are flat and continuous. High-
resolution TEM (HRTEM) characterization and correspond-
ing selected area electron diffraction (SAED) patterns reveal
the high crystallinity of graphdiyne nanowalls in certain are-
as (Figure 2b). The lattice fringe is 0.466 nm in good agree-
ment with the theoretical result.8 What’s more, another form
of crystal lattice is shown in Figure 2c. It clearly reveals
curved streaks with a lattice parameter of 0.365 nm, which
can be assigned to the spacing between carbon layers9,27 sug-
gesting the presence of curved graphdiyne sheets. This value
is a slightly higher than that of graphene28 owing to a more
delocalized system of graphdiyne. Moreover, the interlayer
spacing value was also studied theoretically. With different
stacking configurations, the value varies within 0.340 nm to
0.365 nm.29
Figure 1. (a) Schematic illustration of the experimental
setup. (b, c) SEM images of graphdiyne nanowalls on Cu sub-
strate. (b) Top-view. (c) Cross-sectional view. (d) SEM image
and OM image (in inset) of an exfoliated sample. (e) AFM
image of an exfoliated sample on Si/SiO2 substrate. The
height profile is taken along the white line, representing a
15.5 nm thick film.
In addition, the elementary composition and bonding
structure were studied systemically with spectra of X-ray
photoelectron spectra (XPS), Raman spectroscopy and UV-
The morphology of the as-prepared graphdiyne nanowalls
were characterized by scanning electron microscopy (SEM).
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Vis absorption spectra, separately. The spectra of XPS indi-
cate that the graphdiyne nanowalls are composed of mainly
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elemental carbon (Figure S4), which is identical to the result
of energy-dispersive spectrometer (EDS) in Figure S5. The
peak at 284.8 eV shows essentially identical binding energy
for C1s orbital. In detail, the peak of C1s can be deconvoluted
into four sub-peaks, corresponding to sp2 (benzene rings) at
binding energy of 284.5 eV, sp (C≡C) at 285.2 eV, C-O at
286.4 eV and C=O at 287.5 eV, respectively.30 The presence of
O element derives from the adsorption of air in the pores of
nanowalls and few amounts of oxygen-containing of groups.
They come from oxidation of some terminal alkyne, resulting
in some defects. Beyond that, Raman spectroscopy is a pow-
erful tool to monitor Raman-active carbon-carbon triple
bonds. As shown in Figure 2e, Raman spectrum displays four
prominent peaks around 1383.7 cm-1, 1568.7 cm-1, 1939.8 cm-1
and 2181.1 cm-1 which are consistent with previously reported
values.21 The peak at 1383.7 cm-1 corresponds to the breathing
vibration of sp2 carbon domains in aromatic rings (D band).
1568.7 cm-1 is due to the first-order scattering of the E2g mode
for in-phase stretching vibration of sp2 carbon lattice in aro-
matic rings (G band).30 The peak at 2181.1 cm-1 can be at-
tributed to the vibration of conjugated diyne links.21 As for
terminal alkyne monomers, a sharp peak around 2106 cm-1
can be detected for carbon-carbon triple bond stretching
(Figure S6). When it reacts to diyne linkage, there will be an
obvious hypochromatic shift to 2181.1 cm-1. However, we ha-
ven’t found explicite theoretical assignment to 1939.8cm-1.
Careful analysis of our experimental system indicates that it
can only be assigned to some vibration related to carbon-
carbon triple bonds and previous work expressed the same
view with us.21 Relevant theoretical research has also been
reported by our group and revealed similar results.31 To in-
vestigate the optical properties of as-prepared graphdiyne
nanowalls, UV-Vis absorption test was also employed. Some
previous studies have demonstrated the correlation between
the number of chromophores and the absorbance frequency.
Compared with the monomer, there is an obvious batho-
chromic shift in UV-Vis spectra (Figure 2f), indicating en-
hanced electron delocalization through the extendedly con-
jugated π-system32.
Figure 3. (a) Proposed reaction process of graphdiyne
nanowalls. (b) SEM images of the formation process of
graphdiyne nanowalls in time-series. Bare Cu plate before
reaction, 8 hours and 10 hours after reaction.
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For further explanation, the Cu plate was exposed to air af-
ter pretreatment so that small amount of metallic oxide
formed on the surface. As shown in Figure S7, oxidation state
of copper can be observed from the XPS spectra. So we con-
sider that the valence ascending of copper ascribe the oxida-
tion and copper ions in reaction solution was also detected
by inductively coupled plasma (ICP) test (Table S1). It has
been confirmed that the Cu (II) could be reduced by phe-
nylacetylene to Cu (I) and the homocoupling procedure
completes via a Cu (I)-Cu (II) synergistic reaction and Cu (I)
plays a role as catalyst.33 From this point of view, both species
of Cu ion can form catalytically active centers.
Figure 4. (a) Typical plots of the electron-emission current
density (J) as a function of applied electric field (E). (b) Cor-
responding F-N plots and fitting linear.
With a highly conjugated structure and uniformly distrib-
uted sharp walls, graphdiyne nanowalls is believed to exhibit
superior field emission performance. The field-emission
properties of as-prepared graphdiyne nanowalls are in Figure
4. Figure 4a shows the schematic diagram of set-up while
Figure 4a shows the typical plot of emission current density J
versus the applied electric field (J-E curve). The Eto (turn-on
field) is about 6.6 V/µm and Ethr (threshold field) is 10.7
V/µm. Figure 4b shows the corresponding Fowler-Nordheim
(F-N) plots and corresponding fitted curve. The curve is well
consistent with the F-N mechanism, indicating that the elec-
tron emission from the samples is a result of electron tunnel-
ing.34 The value of Eto is higher than that of vertical graphene
nanosheets35 because the carrier mobility of graphdiyne is
much lower than that of graphene.8 However, the value of Eto
is still considerably low among common-used field emission
devices. In all, graphdiyne nanowalls exhibit good field emis-
sion properties consistent with F-N theory. From the SEM
images of comparison between the nano-walls morphology
before and after field emission test (Figure S8), It can be seen
that some “walls” were destroyed under a high current while
some others were intact. Furthermore, in contrast, the field
emission properties of graphdiyne with random mentioned
above showed substantially higher Eto (12.6 V/µm) and Ethr
Concerning the growing mechanism of graphdiyne nan-
owalls, we tried to trace the process of the reaction and a
feasible mechanism of the process can be proposed and di-
vided into three steps (as shown in Figure 3a). Firstly, with
the presence of pyridine molecule, a small amount copper
ions generated on the surface of copper plates and dissolved
into the solution acting as catalyst in the initial stage of reac-
tion. Secondly, at these catalytically active sites, Glaser-Hay
coupling reaction occurred immediately with the presence of
TMEDA. As the concentration of monomer solution was very
low and it was introduced by dripping slowly, only few
amount of monomers reacted at these sites, forming some
single vertical graphdiyne nano-sheets. Finally, as the reac-
tion progressing more Cu ion dissolved into the solution and
graphdiyne nanowalls became more compact. Figure 4b
shows the process as described above corresponding to se-
quential time-series. If more pyridine was added, more ran-
dom structures could be observed (shown in Figure S7) be-
cause too much copper ions came into the solution in a short
time. So the formation of graphdiyne nanowalls originated
from two factors: the slow-release of catalyst concentration
and the rapid reaction rate of this reaction.
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(16.3 V/µm) because of lack of emission tips. The results
(7) Wan, W. B.; Brand, S. C.; Pak, J. J.; Haley, M. M. Chem.
Eur, J. 2000, 6, 2044.
(8) Long, M. Q.; Tang, L.; Wang, D.; Li, Y. L.; Shuai, Z. G. ACS
Nano 2011, 5, 2593.
(9) Qian, X. M.; Liu, H. B.; Huang, C. S.; Chen, S. H.; Zhang,
L.; Li, Y. J.; Wang, J. Z.; Li, Y. L. Sci. Rep. 2015, 5, 7756.
(10) (a) Sun, C.; Searles, D. J. J. Phys. Chem. C 2012, 116, 26222.
(b) Zhang, H.; Xia, Y.; Bu, H.; Wang, X.; Zhang, M.; Luo, Y.;
Zhao, M. J. Appl. Phys. 2013, 113, 044309.
1
2
3
4
5
6
7
8
show the following conclusions. First, the graphdiyne nan-
owalls are consist of high density of effective emission tips,
that is, the edges of vertically oriented thin “walls” as shown
in Figure 1. Second, some regions of the sample were merely
with amorphization or lower polymerization degree which
couldn’t endure a strong current and were burned. Finally,
the sheets of graphdiyne nanowalls with regular structure are
tolerant to a high current attributed to the conjugated struc-
ture, indicating graphdiyne as a candidate for all-carbon
electric devices.
(11) Huang, C. S.; Zhang, S. L.; Liu, H. B.; Li, Y. J.; Cui, G. L.; Li,
Y. L. Nano Energy 2015, 11, 481.
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10
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47
48
49
50
51
52
53
54
55
56
57
58
59
60
(12) Hwang, H. J.; Lee, H. J. Phys. Chem. C 2012, 116, 20220.
(13) Cranford, S. W.; Buehler, M. J. Nanoscale 2012, 4, 4587.
(14) Bhaskar, A.; Guda, R.; Haley, M. M.; Goodson J. Am.
Chem. Soc. 2006, 128, 13972.
(15) Xiao, J.; Shi, J.; Liu, H.; Xu, Y.; Lv, S.; Luo, Y.; Li, D.; Meng,
Q.; Li, Y. Adv. Energy Mater. 2015, 1401943.
(16) Yang, N. L.; Liu, Y. Y.; Wen, H.; Tang, Z. Y.; Zhao, H. J.; Li,
Y. L.; Wang, D. ACS Nano 2013, 7, 1504.
(17) Zhang, X.; Zhu, M. S.; Chen, P. L.; Li, Y. J.; Liu, H. B.; Li, Y.
L.; Liu, M. H. Phys. Chem. Chem. Phys. 2015, 17, 1217.
(18) Haley, M. M.; Brand, S. C.; Pak, J. J. Angew. Chem., Int.
Ed. Engl. 1997, 36, 836.
(19) Johnson, C. A.; Lu, Y.; Haley, M. M. Org. Lett. 2007, 9,
3725.
(20) Zhang, Y. Q.; Kepčija, N.; Kleinschrodt, M.; Diller, K.;
Fischer, S.; Papageorgiou, A. C.; Allegretti, F.; Björk, J.;
Klyatskaya, S.; Klappenberger, F.; Ruben, M.; Barth, J. V. Nat.
Commun. 2012, 3, 1286.
In conclusion, for the first time, graphdiyne nanowalls
were synthesized successfully via a modified Glaser-Hay cou-
pling reaction by regulating the catalytic active sites. It bears
typical Raman peaks of diyne and benzene rings along with
lattice spacing of 0.466 nm. What’s more, such novel mor-
phology of graphdiyne has shown extraordinary and stable
field emission properties. The strategy used here has thrown
a glimmer of light on exploration of graphdiyne construction
with well-defined nanostructure. With a better understand-
ing of the reaction process, it’s promising to synthesize large
domain of graphdiyne with high crystallization and study
some basic properties of graphdiyne.
ASSOCIATED CONTENT
Supporting Information
Experimental details, characterization methods, supplemen-
tary figures. This material is available free of charge via the
Internet at http://pubs.acs.org.
(21) Li, G. X.; Li, Y. L.; Liu, H. B.; Guo, Y. B.; Li, Y. J.; Zhu, D. B.
Chem. Commun. 2010, 46, 3256.
(22) Li, G. X.; Li, Y.L.; Qian, X. M.; Liu, H. B.; Lin, H. W.;
Chen, N.; Li, Y. J. J. Phys. Chem. C 2011, 115, 2611.
(23) Qian, X. M.; Ning, Z. Y.; Li, Y. L.; Liu, H. B.; Ouyang, C.
B.; Chen, Q.; Li, Y. J. Dalton Trans. 2012, 41, 730.
(24) Glaser, C.; Ber. dtsch. chem. Ges. 1869, 2, 422.
(25) Hay, A. S.; The J. Org. Chem. 1962, 27, 3320.
(26) Kumar, B.; Lee, K. Y.; Park, H.-K.; Chae, S. J.; Lee, Y. H.;
Kim, S.-W. ACS Nano 2011, 5, 4197.
(27) Alexandrou, I. Phys. Rev. B 1999, 60, 10903.
(28) Reina, A.; Jia, X.; Ho, J.; Nezich, D.; Son, H.; Bulovic, V.;
Dresselhaus, M. S.; Kong, J. Nano Letts 2009, 9, 30.
(29) Zheng, Q.; Luo, G.; Liu, Q.; Quhe, R.; Zheng, J.; Tang, K.;
Gao, Z.; Nagase, S.; Lu, J. Nanoscale 2012, 4, 3990.
(30) Ferrari, A. C.; Meyer, J. C.; Scardaci, V.; Casiraghi, C.;
Lazzeri, M.; Mauri, F.; Piscanec, S.; Jiang, D.; Novoselov, K. S.;
Roth, S.; Geim, A. K. Phys. Rev. Lett. 2006, 97, 187401.
(31) Wang, J. Y.; Zhang, S. Q.; Zhou, J. Y.; Liu, R.; Du, R.; Xu,
H.; Liu, Z. R.; Zhang, J.; Liu, Z. F. Phys. Chem. Chem. Phys.
2014, 16, 11303.
(32) Luo, G.; Qian, X.; Liu, H., Qin, R.; Zhou, J.; Li, L.; Gao, Z.;
Wang, En.; Mei, W.; Li, Y.; Shigeru Nagase, Phys. Rev. B, 2011,
84, 075439.
(33) (a) Zhang, G. H.; Yi, H.; Zhang, G.; Deng, Y.; Bai, R. P.;
Zhang, H.; Miller, J. T.; Kropf, A. J.; Bunel, E. E.; Lei, An W. J.
Am. Chem. Soc. 2014, 136, 924. (b) Bai, R. P.; Zhang, G. H.; Yi,
H.; Huang, Z. L.; Qi, X. T.; Liu, C.; Miller, J. T.; Kropf, A. J.;
Bunel, E. E.; Lan, Y.; Lei, An W. J. Am. Chem. Soc. 2014, 136,
16760.
AUTHOR INFORMATION
Corresponding Author
jinzhang@pku.edu.cn
zfliu@pku.edu.cn
Notes
The authors declare no competing financial interests.
ACKNOWLEDGMENT
We thank Jinying Wang and Zhenzhu Li for valuable discus-
sion from the perspective of theoretical calculation.
This work was financially supported by the Ministry of Sci-
ence and Technology of China (Grants 2013CB932603,
2012CB933404), the National Natural Science Foundation of
China (Grants 51432002) and the Ministry of Education
(20120001130010).
REFERENCES
(1) Kroto, H. W.; Allaf, A. W.; Balm, S. P. Chem. Rev. 1991, 91,
1213.
(2) Iijima, S. Nature 1991, 354, 56.
(3) Novoselov, K. S.; Geim, A. K.; Morozov, S. V.; Jiang, D.;
Zhang, Y.; Dubonos, S. V.; Grigorieva, I. V.; Firsov, A. A. Sci-
ence 2004, 306, 666.
(4) Diederich, F. Nature 1994, 369, 199.
(5) Heimann, R. B.; Koga, Y. Carbon 1997, 35, 1654.
(6) Baughman, R. H.; Eckhardt, H.; Kertesz, M. The J. Chem.
Phys. 1987, 87, 6687.
(34) Yu, T.; Zhu, Y.; Xu, X.; Shen, Z.; Chen, P.; Lim, C.; Thong,
J.; Sow, C. H. Adv. Mater. 2005, 17, 1595.
(35) Wu, Z. S.; Pei, S. F.; Ren, W. C.; Tang, D. M.; Gao, L. B.;
Liu, B. L.; Li, F.; Liu, C.; Cheng, H. M.; Adv. Mater. 2009, 21, 17.
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