Environmentally Friendly Synthetic Route to the Monodispersed ZnO Nanoparticles on Large-scale

8/17/2019 Environmentally Friendly Synthetic Route to the Monodispersed ZnO Nanoparticles on Large-scale

1/4

Environmentally friendly synthetic route to the monodispersed ZnOnanoparticles on large-scale

Yan-Ming Chen n, Hong-Wei JiaSchool of Petrochemical Engineering, Shenyang University of Technology, Liaoyang 111003, PR China

a r t i c l e i n f o

Article history:

Received 20 May 2014

Accepted 19 June 2014Available online 27 June 2014

Keywords:

NanoparticlesMicrostructureCrystal growth

a b s t r a c t

Monodispersed spherical ZnO nanoparticles with narrow size distribution have been synthesized byenvironmentally friendly wet-chemical route. The synthesis utilizes zinc acetate as precursor, which is

hydrolyzed in the ethanol-2% H2O solution to form the ZnO nanoparticles. Sodium oleate was employedas surface capping agent to control the size at 5–200 nm and to improve the dispersion properties of ZnOnanoparticles. The blue-shift of the adsorption peaks at about 360 nm could be detected obviously byincreasing the Naþ:Zn2þ molar ratio. The X-ray diffraction (XRD) results indicated that the synthesizedZnO had a pure hexagonal wurtzite structure. The photoluminescence spectrum (PL) gave two mainemission peaks centering at 410 nm and 550 nm. Complicated procedure or high temperature was notrequired in this reaction process. And the expansion experiment was conducted, which coulddemonstrate that yield of ZnO products could be up-scaled to the gram-scale or even more withoutaffecting the property of nanoparticles. Moreover, the recycling solution was also available in thisreaction system, which made it environmental friendly and improved the solutions' reusability rate.As their good long carbon-chain surface coating, the ZnO nanoparticles are well suitable for theapplications in polymer nanocomposites and related elds.

& 2014 Elsevier B.V. All rights reserved.

1. Introduction

Inorganic semiconductor ZnO nanoparticles have attractedmore interest due to their size-dependent properties [1,2] andits wide variety of applications in laser diodes [3], piezoelectricnanogenerator [4], cell labeling [5], antibacterial agent [6], self-cleaning materials [7,8] and catalyzers [9]. Consequently, thediversied applications requires the reproducible synthesis of monodisperse ZnO nanoparticles on large scale. To date, varioussynthetic approaches have been developed to synthesize ZnOnanoparticles such as sol–gel method [10], thermal decomposi-tion method [2,11], chemical vapor method [12] and hydrolysis

method [13]. Nonetheless, in most of the syntheses above, theyield of nano-ZnO was milligram scale or even less, and thesolution was unrecyclable.

Recently, Liu and Zhou [14] used seed-mediated method tosynthesize ZnO nanoparticles. The morphology of the particles wasmodied by the polymer capping agent PEG . Hu [15] obtained highlyphoto-catalytically active ZnO nanoparticles by sol–gel methodwith the assistance of cetyltrimethylammonium bromide (CTAB).

The parameters and the microscopy were altered by the surfactant(CTAB). Cozzoli et al. [2] reported a non-hydrolytic route to ZnOnanoparticles by means of thermal decomposition of zinc acetatein alkylamines, in the presence of tert -butylphosphonic acid(TBPA) as a stabilizer. Kulyk et al. [16] synthesized the ZnO/PMMAnanocomposite lms through a spin coating method, and theresults showed that the polymer matrix plays a principal role inthe photoinduced nonlinear optical properties. According to thereports above, the capping agents play an important role informing the monodisperse ZnO nanoparticles because they canhelp to control the size-dependent properties of nanoparticles andenhance interfacial compatibility between inorganics and inor-

ganics. As the high-performance and the cheap commercialproduction, sodium oleate has been applied in the preparation of ZnO nanoparticles. For example, Ehlert et al. [17]and Xu et al. [18]synthetized nano-ZnO materials by using sodium oleate as cap-ping agent successfully. However, problems of the fabricationincluding the complicated process and the high resource con-sumption are still waiting for the solution.

Aiming at systematic resolution of the problems above, wepresent a facile and environmentally friendly route to synthesizethe monodisperse ZnO nanoparticles. Zinc acetate was used asprecursor; sodium oleate was added as surface capping agentsinto the solution; the size of the nanoparticles was effectively

Contents lists available at ScienceDirect

journal homepage: www.elsevier.com/locate/matlet

Materials Letters

http://dx.doi.org/10.1016/j.matlet.2014.06.1180167-577X/& 2014 Elsevier B.V. All rights reserved.

n Corresponding author. Tel.: þ 86 419 5319236; fax: þ 86 419 5311989.E-mail address: [email protected] (Y.-M. Chen).

Materials Letters 132 (2014) 389–392

http://www.sciencedirect.com/science/journal/0167577Xhttp://www.elsevier.com/locate/matlethttp://dx.doi.org/10.1016/j.matlet.2014.06.118mailto:[email protected]://dx.doi.org/10.1016/j.matlet.2014.06.118http://dx.doi.org/10.1016/j.matlet.2014.06.118http://dx.doi.org/10.1016/j.matlet.2014.06.118http://dx.doi.org/10.1016/j.matlet.2014.06.118mailto:[email protected]://crossmark.crossref.org/dialog/?doi=10.1016/j.matlet.2014.06.118&domain=pdfhttp://crossmark.crossref.org/dialog/?doi=10.1016/j.matlet.2014.06.118&domain=pdfhttp://crossmark.crossref.org/dialog/?doi=10.1016/j.matlet.2014.06.118&domain=pdfhttp://dx.doi.org/10.1016/j.matlet.2014.06.118http://dx.doi.org/10.1016/j.matlet.2014.06.118http://dx.doi.org/10.1016/j.matlet.2014.06.118http://www.elsevier.com/locate/matlethttp://www.sciencedirect.com/science/journal/0167577X


2/4

controlled and the solution could be recycled without impactingthe properties of products. The process can be up-scaled to thegram-scale or even more with the better repeatability.

2. Experimental section

Materials: The following reagents were used: zinc acetate

dehydrate(Zn(Ac)2

2H2O), AR, Tianjin Mei Yu Chemical Co., Ltd.,China; ethanol, AR, Liaoning Xin Xing Chemical Co., Ltd., China;sodium oleate, CP, Sinopharm Chemical Reagent Co., Ltd., China;deionized water, commercially available. All chemicals were usedas received without further purication.

Synthesis: All manipulations were performed under an open-aircondition. The solution of zinc acetate precursor was prepared bydissolving 10.975 g zinc acetate dihydrate into 100 ml distilledwater under constant stirring, which resulted in a clear solution.

98 mL ethanol and 1.218 g (4 mmol) sodium oleate were set in adual port 250 mL round bottom ask under vigorous stirring at80 1C, this resulted in a homogenous solution of sodium oleate inthe ethanol. In addition, 2 mL of zinc acetate precursor (0.5 mol/L)was rapidly injected through pipettor and time response wasnoted at this moment. After being kept for 0.5 h, the productwere ltered, washed with ethanol and deionized water threetimes, and then dried at 80 1C for 1 h to obtain the nal ZnO

samples. 0.005 g white precipitate was dispersed in 10 mL tolueneto form the stable solution and then tested. The further expansionexperiment was conducted by scaling up the volume of thereaction parameter (The reaction parameter were same as aboveexcluding those listed in Table 1.). The details about the expansionexperiment are summarized in Table 1.

Characterization: UV –vis absorption spectroscopy and photolumi-nescence spectra were measured separately by using a PE Lambda25ultraviolet–visible spectrophotometer and a PE LS-55 uorescencespectrophotometer at room temperature. Transmission electronmicroscopy images were obtained by using the JEOL JEM-2010microscope. The X-ray pattern was measured by using Cu Kα( λ¼1.54 Å ) radiation on a SHIMADZU-7000 X-ray diffractometer.

3. Results and discussion

In this work, we tuned Naþ:Zn2þ molar ratio by changing theaddition amount of sodium oleate, at the same time, it kept theconcentration of Zn2þ as a constant value (1 102mol/L) in thisreaction system. During the preparations of ZnO colloids, we foundthat spontaneous hydrolysis of zinc acetate dehydrate takes placein ethanol at 80 1C, leading to the formation of ZnO nanoparticles.The size and morphology of obtained samples were characterizedby using TEM images. Fig. 1 shows the TEM images of the samples

Table 1

Details of synthesis conditions in the expansion experiment.

Samplenumber

The sodiumoleate

addition (g)

The addition of thezinc acetate

precursor (mL)

Theethanol

addition(mL)

The ethanol source

1 1.218 2 98 purchased directly2 2.435 4 196 purchased directly3 6.088 10 490 purchased directly4 6.088 10 490 recycled through

ltration anddistillation once

5 6.088 10 490 recycled throughltration anddistillation twice

Fig. 1. TEM images for the as-synthesized ZnO nanoparticles (A) Naþ

:Zn2þ

¼1:2; (B) Naþ

:Zn2þ

¼1:1; C Naþ

:Zn2þ

¼4:1; D Naþ

:Zn2þ

¼8:1.

Y.-M. Chen, H.-W. Jia / Materials Letters 132 (2014) 389 – 392390


3/4

with different Naþ:Zn2þ molar ratios, indicating that the nano-particles are monodispersed and nearly spherical with a narrowsize distribution. The size of ZnO nanoparticles was easily con-trolled by varying the Naþ:Zn2þ molar ratio. The diameter of particles was about 200 nm when Naþ:Zn2þ molar ratio were 1:2and 1:1. However, the nanoparticles' sizes reduced to 5–10 nmwhen the molar ratios were 4:1 and 8:1. Meanwhile, it is clear thatsodium oleate absorbed on the surface of the ZnO nanoparticles

to prevent the appearance of aggregation (Fig. 1(A) and (B)). TheUV –vis spectra results are consistent with the ones of TEM image.As shown in Fig. 2, the characteristic absorption peaks of ZnO canbe observed at about 360 nm. Moreover, the blue-shift of peakswith the increasing Naþ:Zn2þ molar ratio was detected. Accordingto the quantum size effect, it is undoubtable that the smaller sizeof the nanoparticles has the shorter absorption wavelength.Regarding all the above results, it is clear that sodium oleate playsthe key role in controlling the particle size.

X-ray diffraction patterns were collected in order to identify thecrystal phase of the as-synthesized ZnO nanoparticles. As shownin Fig. 3, all the diffraction peaks can be indexed as hexagonalwurtzite phase reported in JCPDS Card no. (36-1451, P63mc,a¼3.250 Å, c ¼5.207 Å, the lowest part of Fig. 3). No peaks fromother crystalline phases were observed, indicating the formationof pure ZnO products.

The PL property of the ZnO nanoparticles was investigated byphotoluminescence spectra. Two main emission peaks wereobserved centering at 410 nm and 550 nm in Fig. 4. The emissionpeak at 410 nm originates from the exciton recombination radia-tion. While for the emission at 550 nm, the surface oxygen vacancywas supposed to be main reason, which results from the recombi-nation of an electron in or near the conduction band with a hole atthe defect site.

To investigate the stability of this reaction system, the expan-sion experiments were conducted. As shown in Fig. 2(B), nearlyidentical absorption peaks were given. It may demonstrate that,there is little or no effect on the property of as-synthesized ZnOnanoparticles with the expansion of the experiment. And the yield

of ZnO nanoparticles can be up-scaled easily. For the present work,the yield was upto 3 g per batch. Even more signicantly, we foundthat the solution could be recycled without affecting the perfor-mance of the obtained ZnO nanoparticles (Fig. 2(B) d, e). It ishelpful to protect the environment and improve the solution reuserate. According to our results, it is believable that the nano-ZnOyield of the certain value solution can be further improvedthrough the simple distillation process. Furthermore, the long

carbon-chain of the sodium oleate was capped around the surfaceof ZnO nanoparticles (Fig. 1(A) and (B)) which may benet itsapplication in the polymer nanocomposites and related elds.

Fig. 2. UV –vis absorption spectra of as-synthesized ZnO nanoparticles (A) a Naþ:Zn2þ¼1:2; b Naþ:Zn2þ¼1:1; c Naþ:Zn2þ¼4:1; d Naþ:Zn2þ¼8:1; (B) expansion

experiment, a sample 1; b sample 2; c sample 3; d sample 4; e sample 5.

Fig. 3. Powder X-ray diffraction patterns of as-synthesized ZnO nanoparticles

(Naþ:Zn2þ¼4:1).

Fig. 4. PL emission spectra of as-synthesized ZnO nanoparticles (Naþ:Zn2þ¼4:1, λex¼325 nm).

Y.-M. Chen, H.-W. Jia / Materials Letters 132 (2014) 389 – 392 391


4/4

Further research works on the as-synthesized ZnO nanoparticles/polymer composite materials in our workgroup are in progress.

4. Conclusion

A large-scale and environmental friendly synthetic method of monodispersed ZnO nanoparticles has been presented by usingzinc acetate as precursor and sodium oleate as the capping agentin the ethanol-2% H2O solution. The as-synthesized ZnO nanopar-ticles were nearly spherical with high purity of hexagonal wurtzitestructure. With the increasing Naþ:Zn2þ molar ratio, the size of the particles could be controlled easily from 5 to 200 nm, mean-while, the UV –vis spectrum gave blue-shift of the adsorptionpeaks at about 360 nm, which resulted from the quantum sizeeffect. The PL property of the ZnO nanoparticles was investigatedby photoluminescence spectra, and two main emission peakscentering at 410 nm and 550 nm could be detected obviously.No complicated procedures or high temperature was required inthis reaction process. The properties of nanoparticles were stablewith the expansion of the reaction system. The yield of the ZnOnanoparticles is gram-scale per bath and it can be simplyincreased by scaling up the parameters. More notably, the solution

can be recycled which makes possible the environmental protec-tion and enhances the solution utilization. Because of their goodstabilization and long carbon chain surface coating, the ZnOnanoparticles are well suitable for the applications in polymernanocomposites and related elds.

Acknowledgment

This work was supported by Liaoning province Dr Fund project“the synthesis of doped semiconductor nanoparticles ", the projectnumber: 200644.

References

[1] Luo B, Rossini JE, Gladfelter WL. Langmuir 2009;25:13133–341.[2] Cozzoli PD, Curri ML, Agostiano A, Leo G, Lomascolo M. J Phys Chem B

2003;107:4756–62.[3] Liu CH, Zapien JA, Yao Y, Meng XM, Lee CS, Fan SS, et al. Adv Mater

2003;15:838–41.[4] Wang ZL, Song J. Science 2006;312:242–6.[5] Tang X, Choo ESG, Li L, Ding J, Xue J. Langmuir 2009;25:5271–5.[6] Stanković A, Dimitrijević S, Uskoković D. Colloid Surf B 2013;102:21–8.[7] Tarwal NL, Patil PS. Appl Surf Sci 2010;256:7451–6.[8] Joo J, Lee D, Yoo M, Jeon S. Sens Actuators B 2009;138:485–90.[9] Pineda M, Palacios JM, Alonso L, Garc´ıa E, Moliner R. Fuel 2000;79:885–95.

[10] Carnes CL, Klabunde KJ. Langmuir 2000;16:3764–72.[11] Choi SH, Kim EG, Park J, An K, Lee N, Kim SC, et al. J Phys Chem B

2005;109:14792–4.[12] Ali M, Friedenberger N, Spasova M, Winterer M. Chem Vap Depos

2009;15:192–8.[13] Hu X, Masuda Y, Ohji T, Kato K. Langmuir 2008;24:7614–7.[14] Liu XM, Zhou YC. J Crys Growth 2004;270:527–34.[15] Hu W. Mater Lett 2013;91:301–3.[16] Kulyk B, Sahraoui B, Krupka O, Kapustianyk V, Rudyk V, Berdowska E, et al. J

Appl Phys 2009;106:093102.[17] Ehlert S, Lunkenbein T, Breu J, Förster S. Colloid Surf A 2014;444:76–80.[18] Xu J, Zhu Y, Huang H, Xie Z, Chen D, Shen G. CrystEngComm 2011;13:2629–35.

Y.-M. Chen, H.-W. Jia / Materials Letters 132 (2014) 389 – 392392
http://refhub.elsevier.com/S0167-577X(14)01167-7/sbref1http://refhub.elsevier.com/S0167-577X(14)01167-7/sbref1http://refhub.elsevier.com/S0167-577X(14)01167-7/sbref1http://refhub.elsevier.com/S0167-577X(14)01167-7/sbref1http://refhub.elsevier.com/S0167-577X(14)01167-7/sbref2http://refhub.elsevier.com/S0167-577X(14)01167-7/sbref2http://refhub.elsevier.com/S0167-577X(14)01167-7/sbref2http://refhub.elsevier.com/S0167-577X(14)01167-7/sbref2http://refhub.elsevier.com/S0167-577X(14)01167-7/sbref2http://refhub.elsevier.com/S0167-577X(14)01167-7/sbref3http://refhub.elsevier.com/S0167-577X(14)01167-7/sbref3http://refhub.elsevier.com/S0167-577X(14)01167-7/sbref3http://refhub.elsevier.com/S0167-577X(14)01167-7/sbref3http://refhub.elsevier.com/S0167-577X(14)01167-7/sbref3http://refhub.elsevier.com/S0167-577X(14)01167-7/sbref4http://refhub.elsevier.com/S0167-577X(14)01167-7/sbref4http://refhub.elsevier.com/S0167-577X(14)01167-7/sbref4http://refhub.elsevier.com/S0167-577X(14)01167-7/sbref4http://refhub.elsevier.com/S0167-577X(14)01167-7/sbref5http://refhub.elsevier.com/S0167-577X(14)01167-7/sbref5http://refhub.elsevier.com/S0167-577X(14)01167-7/sbref5http://refhub.elsevier.com/S0167-577X(14)01167-7/sbref5http://refhub.elsevier.com/S0167-577X(14)01167-7/sbref6http://refhub.elsevier.com/S0167-577X(14)01167-7/sbref6http://refhub.elsevier.com/S0167-577X(14)01167-7/sbref6http://refhub.elsevier.com/S0167-577X(14)01167-7/sbref6http://refhub.elsevier.com/S0167-577X(14)01167-7/sbref6http://refhub.elsevier.com/S0167-577X(14)01167-7/sbref6http://refhub.elsevier.com/S0167-577X(14)01167-7/sbref6http://refhub.elsevier.com/S0167-577X(14)01167-7/sbref6http://refhub.elsevier.com/S0167-577X(14)01167-7/sbref6http://refhub.elsevier.com/S0167-577X(14)01167-7/sbref6http://refhub.elsevier.com/S0167-577X(14)01167-7/sbref7http://refhub.elsevier.com/S0167-577X(14)01167-7/sbref7http://refhub.elsevier.com/S0167-577X(14)01167-7/sbref7http://refhub.elsevier.com/S0167-577X(14)01167-7/sbref7http://refhub.elsevier.com/S0167-577X(14)01167-7/sbref8http://refhub.elsevier.com/S0167-577X(14)01167-7/sbref8http://refhub.elsevier.com/S0167-577X(14)01167-7/sbref8http://refhub.elsevier.com/S0167-577X(14)01167-7/sbref8http://refhub.elsevier.com/S0167-577X(14)01167-7/sbref9http://refhub.elsevier.com/S0167-577X(14)01167-7/sbref9http://refhub.elsevier.com/S0167-577X(14)01167-7/sbref9http://refhub.elsevier.com/S0167-577X(14)01167-7/sbref9http://refhub.elsevier.com/S0167-577X(14)01167-7/sbref9http://refhub.elsevier.com/S0167-577X(14)01167-7/sbref9http://refhub.elsevier.com/S0167-577X(14)01167-7/sbref9http://refhub.elsevier.com/S0167-577X(14)01167-7/sbref10http://refhub.elsevier.com/S0167-577X(14)01167-7/sbref10http://refhub.elsevier.com/S0167-577X(14)01167-7/sbref10http://refhub.elsevier.com/S0167-577X(14)01167-7/sbref10http://refhub.elsevier.com/S0167-577X(14)01167-7/sbref11http://refhub.elsevier.com/S0167-577X(14)01167-7/sbref11http://refhub.elsevier.com/S0167-577X(14)01167-7/sbref11http://refhub.elsevier.com/S0167-577X(14)01167-7/sbref11http://refhub.elsevier.com/S0167-577X(14)01167-7/sbref11http://refhub.elsevier.com/S0167-577X(14)01167-7/sbref12http://refhub.elsevier.com/S0167-577X(14)01167-7/sbref12http://refhub.elsevier.com/S0167-577X(14)01167-7/sbref12http://refhub.elsevier.com/S0167-577X(14)01167-7/sbref12http://refhub.elsevier.com/S0167-577X(14)01167-7/sbref12http://refhub.elsevier.com/S0167-577X(14)01167-7/sbref13http://refhub.elsevier.com/S0167-577X(14)01167-7/sbref13http://refhub.elsevier.com/S0167-577X(14)01167-7/sbref13http://refhub.elsevier.com/S0167-577X(14)01167-7/sbref13http://refhub.elsevier.com/S0167-577X(14)01167-7/sbref14http://refhub.elsevier.com/S0167-577X(14)01167-7/sbref14http://refhub.elsevier.com/S0167-577X(14)01167-7/sbref14http://refhub.elsevier.com/S0167-577X(14)01167-7/sbref14http://refhub.elsevier.com/S0167-577X(14)01167-7/sbref15http://refhub.elsevier.com/S0167-577X(14)01167-7/sbref15http://refhub.elsevier.com/S0167-577X(14)01167-7/sbref15http://refhub.elsevier.com/S0167-577X(14)01167-7/sbref15http://refhub.elsevier.com/S0167-577X(14)01167-7/sbref16http://refhub.elsevier.com/S0167-577X(14)01167-7/sbref16http://refhub.elsevier.com/S0167-577X(14)01167-7/sbref16http://refhub.elsevier.com/S0167-577X(14)01167-7/sbref17http://refhub.elsevier.com/S0167-577X(14)01167-7/sbref17http://refhub.elsevier.com/S0167-577X(14)01167-7/sbref17http://refhub.elsevier.com/S0167-577X(14)01167-7/sbref17http://refhub.elsevier.com/S0167-577X(14)01167-7/sbref18http://refhub.elsevier.com/S0167-577X(14)01167-7/sbref18http://refhub.elsevier.com/S0167-577X(14)01167-7/sbref18http://refhub.elsevier.com/S0167-577X(14)01167-7/sbref18http://refhub.elsevier.com/S0167-577X(14)01167-7/sbref18http://refhub.elsevier.com/S0167-577X(14)01167-7/sbref17http://refhub.elsevier.com/S0167-577X(14)01167-7/sbref16http://refhub.elsevier.com/S0167-577X(14)01167-7/sbref16http://refhub.elsevier.com/S0167-577X(14)01167-7/sbref15http://refhub.elsevier.com/S0167-577X(14)01167-7/sbref14http://refhub.elsevier.com/S0167-577X(14)01167-7/sbref13http://refhub.elsevier.com/S0167-577X(14)01167-7/sbref12http://refhub.elsevier.com/S0167-577X(14)01167-7/sbref12http://refhub.elsevier.com/S0167-577X(14)01167-7/sbref11http://refhub.elsevier.com/S0167-577X(14)01167-7/sbref11http://refhub.elsevier.com/S0167-577X(14)01167-7/sbref10http://refhub.elsevier.com/S0167-577X(14)01167-7/sbref9http://refhub.elsevier.com/S0167-577X(14)01167-7/sbref8http://refhub.elsevier.com/S0167-577X(14)01167-7/sbref7http://refhub.elsevier.com/S0167-577X(14)01167-7/sbref6http://refhub.elsevier.com/S0167-577X(14)01167-7/sbref5http://refhub.elsevier.com/S0167-577X(14)01167-7/sbref4http://refhub.elsevier.com/S0167-577X(14)01167-7/sbref3http://refhub.elsevier.com/S0167-577X(14)01167-7/sbref3http://refhub.elsevier.com/S0167-577X(14)01167-7/sbref2http://refhub.elsevier.com/S0167-577X(14)01167-7/sbref2http://refhub.elsevier.com/S0167-577X(14)01167-7/sbref1

Environmentally Friendly Synthetic Route to the Monodispersed ZnO Nanoparticles on Large-scale

Documents

Transcript of Environmentally Friendly Synthetic Route to the Monodispersed ZnO Nanoparticles on Large-scale