International Journal of Application or Innovation in Engineering & Management (IJAIEM)
Web Site: www.ijaiem.org Email: editor@ijaiem.org
Volume 3, Issue 7, July 2014
ISSN 2319 - 4847
Optical Absorption for Composite SiO2 @Au-Cu
Nanoparticles
Ali Rudainahab, Qingsong Jianga, Lin Yia
a
School ofPhysics, Huazhong University of Science and Technology, Wuhan 430074,PR China
b
Physics Department of college science,Diyala University, Iraq
ABSTRACT
The present research describes the synthesis of Cu nanoparticles composite with SiO2@Au particles and absorption properties by
chemical methods for different cases.The synthesis was made in two steps, in the first, SiO2 nanoparticles were coated with Au by
using Stober method.The second step involved the production of silica-coated Au-Cu particles by changing the amount of NaoH
and reaction time.The result shows that variationof the amount of NaoH led to absorption transform in the same reaction time,
and when fixing the amount of NaoH and alteringreaction time, the absorbance properties changed. On the other hand, when
absorbance increased and had a peak with the increase inreaction time in one case and another case. we had the opposite .
Keywords : Nanoparticles, Absorption, Composite SiO2@ Au-Cu
1. INTRODUCTION
There is a large amount of interest in metallic nanoparticles[1].Nanoparticles of materials such as gold, copper have been
shown to act as catalysts for certain reactions[2] . The impact of the nanoparticles is greater if there is more than one
element, as in the case of new nanostructured systems like Au/Ag [3] and particularly Au/Cu compound materials, which
are mostly used in catalysis [4], sensors [5], energy sources [6] and in many other applications. Bimetallic nanoparticles
may be supported on matrices, for instance γ -alumina [4, 7] and Pt.–C [8] Nanoparticles often possess unexpected optical
properties as they are small enough to confine their electrons and produce quantum effects. For example gold
nanoparticles appear deep red to black in solution. Nanoparticles of usually yellow gold and grey silicon are red in color.
Gold nanoparticles melt at much lower temperatures (~300 °C for 2.5 nm size) than the gold slabs (1064 °C)[9].And
absorption of solar radiation in photovoltaic cells is much higher in materials composed of nanoparticles than it is in thin
films.Copper is a highly conductive, much cheaper, and industrially widely used material, possessing a valence shell
electron structure similar to the other two coinage metals. Furthermore, it is unique with the chemical reactivity capable
of serving as precursors for the fabrication of conductive structures[10].Fabrication of Cu nanoparticles has received less
attention as compared to that of Au and Ag ones [9,11], and is still open for more intensive investigation. Several
methods have been developed for the preparation of copper nanoparticles, including thermal reduction[12], son chemical
reduction[13], metal vapor synthesis[14], chemical reduction[15, 16, 17], vacuum vapor deposition [18], radiation
methods [19], and microemulsion techniques[11]. In addition to nanoparticle geometry, the optical properties of
plasmonic nanoparticles can also be strongly influenced by the electronic structure of the constituent metal, which
determines the metal’s dielectric function. Here we study absorption properties for of SiO2@Au@Cuin many cases,where
we fabrication of SiO2@Au-Cu and change the geometric of SiO2@Au@Cu by changingreaction time and the amount
of NaoH. This has led to the change of the plasmon resonate energies in nanoparticles geometry. It has been observed that
the surface plasmon resonance phenomenon can be controlled during synthesis by varying the reaction time,pH, and
relative ratio of copper sulfate to the surfactant.
2. EXPERIMENTAL METHOD
We preparedSiO2@Au-Cu in the following way :- (1)PreparationSiO2 @Au by using Stobermethod (16.75ml) ethanol
and (24.75ml)water, (9ml)NH3 H2O under vigorous stir.(2)In another glass , we put (45ml)ethanol and (4.5ml) TEOS
and added them to the first step for two hours then wewashed them 6 times : the first three times using water and the last
three times using ethanol.Thenwe added ethanol to the SiO2to get a total size of 50 ml andadded 0.2 ml of C9H23NO3Si
for 12 hours and washed it 7 times using ethanol.(3) We took 50 ml of water and 1ml of HAucl4 in sequence under
vigorous stir (4) We put 0.1381g of C6H5Na3O7.2H2O in 12ml of water and added 2 ml to step 3 and another 10 ml to it
0.0078g from NaBH4and took 1ml of it and added it to step 3.After 5 min, we took 0.5 mlof SiO2and added it to the
solution then we washed it four times using water. (5) We took (25ml) of water and 0.6 of SiO2 @Au from step 4 under
vigorous stir after 5 min and added 0.7g of potassium sodium tartrate, 0.2 g of CuSO4•5H2O.After thatwe added 0.1g
NaOH in 5 ml water, then we took 0.1 ml of formaldehyde solution in 6 ml water and 0.5 in sequence
underrigorousstirindifferenttimes :45min,90min,225min.We measured the absorption by UV and the morphoto using the
scanning electron Microscope ( SEM).
Volume 3, Issue 7, July 2014
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International Journal of Application or Innovation in Engineering & Management (IJAIEM)
Web Site: www.ijaiem.org Email: editor@ijaiem.org
Volume 3, Issue 7, July 2014
ISSN 2319 - 4847
3. RESULT AND DISCUSSIONS
Table (1) shows the effect of changing reaction time(45,90,225 min) on the absorption value when the amount of NaOH
s fixed (0.1g)
Sample
Reaction time
High Absorption value
Amount of NaOH
1
45 min
0.8
0.1g
2
90 min
1.1
0.1g
3
225min
2.5
0.1g
Table (2) Effect of changing the amount of NaOH (0.1,0.5,0.7 g) on the absorption value when reaction time is fixed
(45min)
Sample
Reaction time
High Absorption value
Amount of NaOH
4
45 min
0.8
0.1g
5
45 min
1.3
0.5g
6
45 min
1.4
0.7g
Table ( 3) illustrates the effect of changing reaction time (45,90,225 min) on the absorption value when the amount of
NaOH is fixed (0.5g)
Sample
Reaction time
High Absorption value
Amount of NaOH
7
45 min
1.1
0.5g
8
90 min
1.0
0.5g
9
225min
0.4
0.5g
We investigate the influence of the reaction time, the amount of NaOH on the products as seen inTables 1, 2 and 3.One
can see that the absorption values alter when the NaOH values and the reaction time change. In table 1, we observe that
the fixed value of NaOH 0.1g and the changing reaction time have led to alteration in absorption which changes
proportionally with the reaction time, i.e. Any increase in the reaction time leads to an increase in the absorption for the
materials, suggesting that enhancement of the absorption surface remains longer time to form the absorptive particles. As
for table 2, we notice that the NaOH values are different at a fixed reaction time ( 45 minutes ) and we also get an
increase in the absorption value. The reason is that the NaOH increases the copper sulfate ( CuSO4)on the surface of the
SiO2@Au, which leads to an increase in the number of the absorptive molecules.However, we see that the results in
Table 3 are in contrast with the results in Table1, because increase of both NaoOH and reaction time results inan
increasein the oxidativestressofreactivematerials.
1.0
(1)
(2)
(3)
Absorbance (a.u)
0.8
0.6
0.4
0.2
0.0
300
400
500
600
700
800
900
W avelenght (nm)
Fig (1-a) UV absorption spectra of SiO2@Au-Cu nanoparticles samples (1,2,3) are different at differentreaction times
(45,90,225min) sequentially with fixed NaOH amount (0.1g)
We study the kinetic of the absorption for the multi-metals alloy collides prepared with gold and copper solution in 3
different cases as seen in Fig. (1-a),where fixed the amount of NaoH at about 0.1g and avariation ofreaction time (45, 90,
225 min), obtained three different curves according to different reaction time; the curve value of absorption changes
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International Journal of Application or Innovation in Engineering & Management (IJAIEM)
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Volume 3, Issue 7, July 2014
ISSN 2319 - 4847
when reaction times change and the relation is direct and proportional.Sample 1(45 min) has a peak of about 532 nm
which is close to that of Au absorption at 521nm which is consistent with the SPR of gold metal particles with size in the
nanometer rang[16].Sample 3 (225 min) also has a peak of about 542, which is close to the absorption band of copper 572
[22]. For the dispersions of Au/Cu composite bimetallic nanoparticles, only a single SPR absorption band is revealed, and
the peak position is different from the peak positions of monometallic Au and monometallic Cu nanoparticles. The
absorption curve of the alloy dispersion could not be obtained by a sample overlapping of the absorption curves of
monometallic Au and monometallic Cu colloidal dispersions. We state that the wavelength 542 nm (obtained for
bimetallic alloy dispersions) is nearly the arithmetic mean value of 521 nm and 572 nm. Therefore, based on these
spectra, it is reasonable to determine that the Au/Cu composite bimetallic nanoparticles are homogeneous alloy ones ; the
novel absorption band, 542 nm, for Au/Cu composite is attributed to the SPR band of Au/Cu composite nanoparticles
4.0
(4)
(5)
(6)
Absorbance (a.u)
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0.0
300
400
500
600
700
800
900
Wavelenght (nm)
FIG (1-b) UV absorption spectra of SiO2@Au-Cu nanoparticles for samples (4,5,6) are different at different amounts of
NaOH (0.1, 0.5, 0.7 g) sequentially with fixed time reaction 45 min
Figure(1-b) shows the absorption spectra for another three kinds of SiO2@Au-Cu composite nanoparticleswhen the
reaction time is a constant of 45 min. We found different absorption spectra according to different amounts of
NaOH,whereincreasing the amount of NaOH (0.1, 0.5, 0.7 g) hasled to increase in the absorption value, but there is no
peak in amounts (0.5,0.7g) of NaOH.Simple 5and 6 lines indicatethe absence of any observable Plasmon peak and this is
most likely due to the small dimensionsbetween the particles. It is consistent with (20) where particles appear close to
each other and this is evident in the samples 5and6,but we have a small peak in sample 4 (0.1g) NaOH (45 min) about
532 nm and that is due to the increase of cu particles that cover gold because this value of a peak islocated between the
value of the top of the copper and gold, but it iscloser to the gold peak than that of the copper.
(7)
(8)
(9)
1.4
Absorbance (a.u)
1.2
1.0
0.8
0.6
0.4
0.2
0.0
300
400
500
600
700
800
900
Wavelenght (nm)
FIG (1-C) - UV absorption spectra of SiO2@Au-Cu nanoparticles for samples (7,8,9) are different at reaction
times(45,90,225min )Sequentially with a fixed NaOH amount(0.5g)
In Fig 3, also study different absorptions for composite with different reaction times (45, 90, 225 min) and a fixed NaOH
amount (0.5g).We have three samples: 7, 8 and 9; the absorptions in samples 7 and 9 curvesdecrease with time
increase,the UV/ spectrum does not display any absorption peak (or shoulder), even after 225 min from i interaction. The
Volume 3, Issue 7, July 2014
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International Journal of Application or Innovation in Engineering & Management (IJAIEM)
Web Site: www.ijaiem.org Email: editor@ijaiem.org
Volume 3, Issue 7, July 2014
ISSN 2319 - 4847
copper nanoparticles have too small size to show the plasmon peak (572 nm) because of the low concentration of copper
ion used in the starting solution where adding more NaOH leads to the oxidationof copper and an increase in the reaction
time. This means growing oxidation and a very small size of copper. The same phenomenon has been observed by
Lisiecki et al. [11]. Moreover, we found that the kinetics of copper particle growth has been much slower than that of gold
nanoparticles
Figs 2 (a, b ,c) SEM compositeSiO2@Au- Cu for different reaction times (45, 90, 225 min) sequentially with a fixed
amount of NaOH ( about 0.1g )
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Figs 2 (d, e, f) SEM compositeSiO2@Au-Cu for different reaction times (45, 90, 225 min) sequentially with a fixed
amount of NaOH ( about 0.5g )
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Fig (2-g) SEM compositeSiO2@Au-Cu for t reaction time (45min) with an amount of NaOH ( about 0.7g)
The growth and optical properties of incomplete copper layers on silica@ gold nanostructure (500 nm) are studied using
Scanning electron microscope SEM as shown in Figs. 2a-2g. Cu nanoparticles do not have continuous single-crystalline
shell structures, which issimilar to Zhang [20]. The optical properties of these systems are different from those of
complete copper nanoshellsduring the growth process of the individual Cu particles.The most pronounced change appears
to occur from Fig2a to 2g,wherenot only the size of the Cu particles on the surface increases, as one would expect, but it is
evident by inspection, the number of Cu particles greatly decreases or increases.In Figs2(a, b, c, g) ,we can see a lot of
particles from SiO2@Au@Cu that look close to each other and havequantities ofparticlesof
coppernanoparticleswhoseshapesgradually increase and this is consistent with UV test.As for Figs 2(d, e, f), the particles
have the samepreviousshapes but they are closer to each other,thecopperparticlesbecomemuchless in number,theamount of
NaOH increases withthe increaseof time, which leads to arisein the oxidative stressand thereforeabsorbentparticles
decrease.This is reinforced by the planned number UVtest, which means when we add more NaOH we get the best
absorption but for a limited amount.
4.CONCLUSION
The effects of alteration in reaction time to form composite SiO2@Au-Cu, when thevalues of allthe materials used are
fixed, arefunctional to mutation geometry of SiO2@ Au-Cu nanoparticles and functionalin changingthe values
ofabsorbance where the absorption increases with the time reaction proportionally in case the amount of NaoH is 0.1g, but
when the amount is increased to 0.5g and reaction time,we seethe oppositeand theabsorbance value decreases.The reason
is that increasing thesefactorshas led to theexpansion ofoxidative stress. Concerning the effects of transposition value of
NaoH to form SiO2@ Au-Cu nanoparticles when the reaction time is fixed, it has been found that this material functions
to change geometry of SiO2@ Au-Cu nanoparticles and functions to mutate the values of absorbance, and thisin
turnleadstogreaterexcitement in the particle surface and the fluctuation collective of electronsby thenwill be
composedsurfaceplasmons( and the collective fluctuation of electrons will be, by then, composed of surface plasmon). The
best result was obtained when the amount of NaoH was fixed (0.1 g ) and reaction time was changed, SPR was weakdue
to the lack of copper.The reasonbehind many of theapplications ofAu-Cu nanoparticles and thegrowing interest in
potential large-scale or large-area applications relative to their Au and Ag counterparts is the significantly reduced
relative cost of the constituent metal.
REFERENCES
[1] V. Biju, T. Itoh, A. Anas, A. Sujith and M. Ishikawa, Anal. Bioanal. Chem., 2008, 391, 2469 ; S. Besner, A. V.
Kabashin, F. M. Winnik and M. Meunier, Appl. Phys.: A, 2008, 93, 955 M. Grzelczak, J. Pérez-Juste, P.
Mulvaney and L. M. Liz-Marza, Chem. Soc. Rev., 2008, 37, 1783
[2] R. J. White, R. Luque, V. L. Budarin, J. H. Clark and D. J. Macquarrie, Chem. Soc. Rev., 2009, 38, 481 In addition to
nanoparticle geometry, the optical properties of plasmonic nanoparticles can also be strongly influenced by the
electronic structure of the constituent metal, which determines the metal’s dielectric function.
[3] S. Link, C. Burda, Z.L. Wang, M.A. El-Sayed: J. Chem. Phys. 11, 1255(1999)
[4] M.Jos´e-Yacam´an, J.A. Ascencio, S. Tehuacanero, M. Marin: Top. Catal.18, 167 (2002)
[5] A. Ruiz, J. Arbiol, A. Cirera, A. Cornet, J.R. Morante: Mater. Sci. Eng.C19, 105 (2002)
Volume 3, Issue 7, July 2014
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[6] R.J. De Meijer, C. Stapel, D.G. Jones, P.D. Roberts, A. Rozendaal,W.G. Macdonald, K.Z. Chen, Z.K. Zhang, Z.L.
Cui, D.H. Zuo,D.Z. Yang: Nanostruct. Mater. 8, 205 (1997)
[7] Y.M. Cheng, H.K. Rhee: Catal. Lett. 85, 159 (2003)
[8]- P. del Angel, J.M. Dominguez, G. del Angel, J.A. Montoya, J. Capilla,E. Lamy-Pitara, J. Barbier: Top. Catal. 18,
183 (2002
[9] M. Zheng, Z. Li and X. Huang, Langmuir, 2004, 20(10), 4226
[10] S. Jeong, K. Woo, D. Kim, S. Lim, J.S. Kim, H. Shin, Y. Xia, J.Moon, Adv. Funct. Mater. 18, 679 (2008).
doi:10.1002/ adfm.200700902
[11] I. Lisiecki, M.P. Pileni, J. Am. Chem. Soc. 115, 3887 (1993). doi:10.1021/ja00063a0069. N.A. Dhas, C.P. Raj, A.
Gedanken, Chem. Mater. 10, 1446
[12] N.A. Dhas, C.P. Raj, A. Gedanken, Chem. Mater. 10, 1446 (1998). doi:10.1021/cm9708269
[13] R.V. Kumar, Y. Mastai, Y. Diamant, A. Gedanken, J. Mater.Chem. 11, 1209 (2001). doi:10.1039/b005769j
[14] G. Vitulli, M. Bernini, S. Bertozzi, E. Pitzalis, P. Salvadori, S.Coluccia, G. Martra, Chem. Mater. 14, 1183 (2002).
doi:10.1021/cm011199x
[15] H.H. Huang, F.Q. Yan, Y.M. Kek, C.H. Chew, G.Q. Xu, W. Ji,P.S. Oh, S.H. Tang, Langmuir 13, 172 (1997).
doi:10.1021/la9605495
[16] S.H. Wu, D.H. Chen, J. Colloid. Interface Sci. 273, 165 (2004).doi:10.1016/j.jcis.2004.01.071
[17] B.K. Park, S. Jeong, D. Kim, J. Moon, S. Lim, J.S. Kim, J.Colloid. Interface Sci. 311, 417 (2007).
doi:10.1016/j.jcis.2007.03.039
[18] Z.W. Liu, Y. Bando, Adv. Mater. 15, 303 (2003). doi:10.1002/adma.200390073
[19] I.G. Casella, T.R.I. Cataldi, A. Guerrieri, E. Desimoni, Anal.Chim. Acta 335, 217 (1996). doi:10.1016/S00032670(96)00351
[20] Cuprous Oxide Nano shellswith Geometrically Tunable Optical PropertiesLi Zhang and Hui Wang*Department of
Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208, United States
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