Research Article One-Step Synthesis of Colloidal...

Hindawi Publishing CorporationJournal of NanoscienceVolume 2013 Article ID 804290 5 pageshttpdxdoiorg1011552013804290

Research ArticleOne-Step Synthesis of Colloidal Quantum Dots of Iron SelenideExhibiting Narrow Range Fluorescence in the Green Region

Pradyumna Mulpur Tanu Mimani Rattan and Venkataramaniah Kamisetti

Department of Physics Sri Sathya Sai Institute of Higher Learning Prasanthinilayam 515 134 India

Correspondence should be addressed to Venkataramaniah Kamisetti kvenkataramaniahsssihleduin

Received 24 August 2013 Revised 7 November 2013 Accepted 8 November 2013

Academic Editor Mingwang Shao

Copyright copy 2013 Pradyumna Mulpur et al This is an open access article distributed under the Creative Commons AttributionLicense which permits unrestricted use distribution and reproduction in any medium provided the original work is properlycited

The instantaneous isolation of green fluorescent colloidal quantum dots of iron selenide capped with biocompatible oleic acidis reported in this study These iron-containing quantum dots also serve as a safe alternative to the conventionally used metal-chalcogenide systems inwhich the heavymetal component is usually toxicThe isolated colored colloidal solutions exhibited intensegreen fluorescence on exposure to ultraviolet light which was also confirmed by photoluminescence spectroscopy The isolatedproduct was subjected to dynamic light scattering and transmission electron microscopy and the particles were found to exhibitspherical morphology with an average diameter of 6ndash8 nm confirming the isolation of quantum dots The isolated iron selenidequantum dots have promising potential towards bioimaging and sensing due to the biocompatible coating of oleic acid and ironwhich also allows possibility of further chemical derivatization

1 Introduction

Quantum dots (QDs) have emerged as one of the most fas-cinating systems in the new millenniumThey have garneredwidespread interest amongst a multitude of research groupsas they exhibit higher extinction coefficients higher quantumyields less photobleaching broad absorption and narrowemissions which can be tuned with size [1 2] Due to theseproperties they are used in infrared photodetectors solidstate lasers photovoltaics QD-LEDs medical imaging tar-geting therapy and sensing [3ndash6]The othermajor advantageof QDs is that they can be functionalized with a variety ofmolecules like antibodies aptamers proteins DNA and soforth to enable specificity for early and rapid detection [78] Moreover in comparison to organic fluorophores whichdisplay high photobleaching and low extinction coefficientsQDs are definitely the more suitable alternatives

The impressive investigations on these systems in almostevery discipline are reflected in the work being carried outglobally In addition to the important aspect of discover-ing novel materials attempts are constantly being madeto explore new routes of synthesis and functionalization

Several specific quantum dot systems have been fabricatedwith an aim towards targeting special applications Most ofthe synthesized systems fall under the category of metalchalcogenides and typically synthesized are the II-VI systems[9] They include cations of zinc cadmium and mercurycombined with anionic oxygen sulphur selenium or tel-lurium that exhibit a high degree of photoluminescence dueto the presence of a direct band gap [6] CdSe ZnSe PbSeCdTe HgTe PbS InP and ZnO are some of the extensivelystudied systems reported with a high quantum yield [6]

Motivated by the extraordinary benefit of these systemswe made efforts to isolate oleic acid capped iron selenidequantum dots via the hot injection route which has not beenreported previously Oleic acid has been previously reportedto be biocompatible [10] Iron selenide has interesting opticalelectronic and magnetic properties that could be used forbiological imaging or sensing It shows promising potentialas a QD system since iron has a well-defined magneticdomain structure [11] This would make iron selenide QDs aprobable candidate for targeted delivery under the influenceof a magnetic field It can even be used for applicationslike MRI for which quantum dot systems are already being

2 Journal of Nanoscience

tested [12] Moreover alternative quantum dots systems ofCd Pb and Hg are known to be toxic [13] The aim is toisolate stable surfactant capped iron selenide colloidal QDsas a possible biocompatible replacement for the harmfulfluorescent markers

Several methods of synthesis for such quantum dotsystems are described in the literature which are generallychosen so as to have the following properties monodisper-sity chemical integrity and specificity possibility of furtherfunctionalization and high degree of crystallinity withoutany defects [14] Our present work is based on the precursorroute where the principal synthetic strategy of arrestedprecipitation is used [14] It is a one pot synthesis routewhere all the precursors prepared in solvents are added inone vessel at elevated temperatures This is also known asthe hot injection route which minimizes the number of stepsproducing the product instantaneously At some stage of thegrowth the surface is stabilized by making use of surfactantsor capping agents Further growth is thereby controlled orarrested as the surfactants selectively bind to the surfaceof the growing nanocrystal [15] In our procedure we havesuitably modified the precursor route by incorporating areducing agent hydrazine monohydrate The reducing agentis added to prevent the susceptible oxidation of iron whichmay otherwise prevent the formation of quantum dots Moreimportantly hydrazine hydrate can also form complexes withthe precursors a critical step in the product formation asdiscussed in the subsequent sections

The final isolated product was characterized by UV PLDLS TEM and FT-Raman to ascertain the optical propertiessize and chemical composition

2 Experimental

21 Chemicals FeCl3 98 Otto (Chemika Biochemika

Reagents) 1-octadecene 95 trioctyl phosphine (TOP) 90Sigma Aldrich oleic acid pure Merck hydrazine monohy-drate 99 Alfa Aesar and Selenium powder HiMedia

22 Synthesis of Iron Selenide Quantum Dots About 30mgof selenium powder was added to a beaker containing 5mLof 1-octadecene Subsequently 04mL of TOP was addedto this mixture using a glass syringe The entire mixturewas subjected to mild heating with simultaneous magneticstirring until a clear solution was obtained The solventchosen for thiswasTOPbecause it has a high thermal stabilityand can coordinate with inorganic surfaces easily [16] therebyforming the selenium precursor

In the modified hot injection route 13mg of FeCl3is

weighed and added into a three-necked round bottom flask(250mL)This is followed by the addition of 06mLoleic acid02mL hydrazine monohydrate and 10mL octadecene Theround bottom flask is heated to 225∘C on a heating mantleThe entire working apparatus is set up in a fume hood

At this temperature 1mL of the prepared Se precursorsolution is injected into the round bottom flask On contactof the Se precursor with themixture already containedwithinthe flask an instantaneous colour change is observed An

aliquot of the sample in the flask is immediately drawn andtransferred into a storage vial The drawing of the aliquots isperformed repeatedly every 5 seconds until the solution in theround bottom flask is exhausted Rapid cold quenching of theisolated aliquots after hot injection is performed in crushedice This process immediately arrests the reaction therebycontrolling the particle growth and nucleation preventingfurther aggregation

23 Characterization The UV-Vis spectroscopy analysiswas performed using the instrument model UV-2450 Shi-madzu (Scientific Instruments Corp) under the photometricabsorbance mode The photoluminescence (PL) analyseswere performed using the model LS 55 spectrometer 120V from PerkinElmer The preliminary particle size analysesfor the samples were performed with the dynamic lightscattering technique (DLS) using the instrument ZetasizerNano (Malvern Nano ZS) involving the advantageous non-invasive backscatter detection at 173∘ The particle size andmorphology was determined using TEM JEOL JEM 2000 FXII The analysis of the formed product was carried out usingFT-Raman spectroscopy (Thermo Nicolet 6700)

3 Results and Discussion

The colorless mixture on addition of the Se precursor at225∘C immediately transformed to pale yellow A total of12 aliquots (with a 5-second interval between drawing thesuccessive aliquots) were drawn from the mother solutionin the flask The samples ranged visibly from a pale yellowcolor of the first aliquot to a dark brown of the last aliquot asshown in Figure 1(a)The isolated aliquotswhenplaced underUV light exhibited a distinct uniform green fluorescence(Figure 1(b)) This was the first indication of an iron basedproduct displaying narrow range fluorescence in the greenregion The entire experiment when repeated several timesproduced concordant results and the synthesized sampleswere found to be very stable at room temperature

In UV-Vis spectrometry the 1st aliquot displayed maxi-mum absorbance at around 315 nm the 6th at 325 nm andthe 12th at around 330 nm as shown in Figure 2(a) Since theabsorption peaks were not separated by a significant shiftit led us to ascertain that the synthesis yielded productsexhibiting a fairly monodisperse size range

The photoluminescence study of the above aliquots wasperformed using hexane as the solvent The three aliquotswere subject to excitation at 300 nm and the emission spec-trum was recorded The 1st and 6th aliquots displayed max-imum emission exhibiting two prominent peaks at around510 nm and 530 nm corresponding to a bluish green and abright green fluorescence respectively The intensity of the510 nm peak was higher than that of the 530 nm peak The6th aliquot displayed a very minute red shift in peak positionand less difference between the two peak intensitiesThe 12thaliquot however displayed a single prominent peak whichwas broader encompassing the range between 500 nm to550 nm centered at 515 nm corresponding to green color offluorescence (Figure 2(b))

Journal of Nanoscience 3

1 6 12

(a)

1 6 12

(b)

Figure 1 Photograph of the isolated colloidal aliquots of iron selenide under (a) white light and (b) UV light

Abso

rban

ce (a

u)

280 300 320 340 360 380 400Wavelength (nm)

Aliquot 1Aliquot 6Aliquot 12

(a)


Inte

nsity

(au

)

480 500 520 540 560 580 600Wavelength (nm)

(b)

Figure 2 (a) UV-Vis absorption spectra of isolated colloidal aliquots 1 6 and 12 (b) photoluminescence spectra of isolated colloidal aliquots1 6 and 12 at 120582ex = 300 nm

The profile of the peaks can be attributed to the dynamicsof the reaction of synthesis that is hot injection routeThe presence of two prominent peaks for the first aliquotindicates the presence of the product of two different sizesdue to the rapid dynamics at the inception of the reactionThe reduced difference in intensity between the two peaksin the 6th aliquot is indicative of a reaction undergoingstabilization Due to the presence of the surfactant oleic acidthe newly formed nuclei are capped immediately leading tothe growth of the clusters to an optimal size and the reactionstabilizes This is clearly illustrated in the emission peak ofthe final aliquot which is in the form of a broad profileand indicative of a stabilized reaction The nanocrystalssynthesized via this route undergoOstwald ripening resultingin the production of monodisperse particles in the quantumdot regime which can be ascertained from the well-defined

PL peaks [15 17] Moreover since the shift between the peakswas minimal from the first to the last aliquot with all theisolated aliquots displaying similar colors of fluorescence itwas confirmed that the synthesized systems exhibit ldquonarrowrange fluorescencerdquo

The size of the particles in the colloidal system wasascertained by dynamic light scattering method The particlesize distribution bynumber data as shown inFigure 3 displaysan average size distribution of about 5 nmThis substantiatesthe formation of stable quantum dots of the iron selenidecompound

To acquire a more resolved image displaying the size andmorphology of the iron selenide particles we performed aTEM analysis on the sampleThe TEM images clearly displayquantum dots as dark spots enveloped in a surfactantmatrixpossessing spherical morphology and diameter ranging from


1 10 1000

10

20

30

Size d (nm)

Num

ber (

)

d = 48nm

Figure 3 DLS data displaying the hydrodynamic radius of ironselenide

20nm

Figure 4 TEM image displaying iron selenide quantum dots withan average diameter of 6ndash8 nm

about 5 to 15 nm with a mean diameter of about 6ndash8 nmdisplayed in Figure 4 which is also in close accordance withthe DLS data

The chemical nature of the isolated quantum dots wasestablished using FT-Raman spectroscopy The spectra ofthe solvents display peaks from about 3500 cmminus1 to about1000 cmminus1 while the sample spectra displayed an additionaldistinct band centered at the 220 cmminus1 as observed inFigure 5The line at around 220 cmminus1 can be attributed to Fe-Se bond vibrations corresponding to the 120573-FeSe phase of thefluorescent iron selenide QDs [18]

The formation of FeSe can be probably explained bythe reaction mechanism involving hydrazine hydrate In themodified hot injection route we use hydrazinemonohydratewhich as a reducing agent effectively reduces Fe3+ from theiron salt to Fe2+ and the chalcogen to chalcogenide anionsthat is Se to Se2minus [19] In aqueous solution hydrazine exists

100 200 300 400 500 600 700 800

Inte

nsity

(au

)

220

Raman shift (cmminus1)

Figure 5 FT-Raman spectra of iron selenide quantum dots display-ing the characteristic 220 cmminus1 band corresponding to the 120573-FeSephase

as hydrazinium and hydroxyl ions as shown in (1) In thisexperiment the concentration of hydrazine monohydrate isoptimized to first reduce the iron salt enabling the formationof Fe2+

N2H4sdotH2O 997888rarr N

2H5

++OHminus (1)

N2H5

++ Fe3+ 997888rarr Fe2+ +NH

4

++H+ + 1

2N2 (2)

The acidic conditions generated in the reaction vesselfurther initiate the reduction of selenium

Se + 2N2H5

+997888rarr Se2minus + N

2+ 2NH

4

++ 2H+ (3)

In this manner the reaction conditions in the hot injec-tion route aided by the usage of hydrazine monohydrate asthe reducing agent and oleic acid as a capping agent led tothe formation of stable colloidal FeSe quantum dots whichare biocompatible

4 Conclusions

Quantum dots have myriad applications chief among thembeing their role in the delivery of therapeutic agents andimaging of cells and tissuesThus far the conventionally usedmetal-chalcogenide systems are reported to be toxic due tothe presence of heavy metals (Cd Hg and Pb) which leachout of the QD system on UV exposure These led to systemictoxicity in the healthy cells and tissues In our study we havebeen able to isolate green fluorescent iron selenide QDs ina single step The isolated FeSe quantum dots display stronggreen fluorescence and have been advantageously renderedbiocompatible due to oleic acid capping in addition to thenontoxic nature of iron in biological systems Consequentlythese QDs have promising applications towards in vitro or invivo imaging and sensing protocols in biosystems


Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

Acknowledgments

The authors are grateful to Bhagawan Sri Sathya Sai BabaFounder Chancellor Sri Sathya Sai Institute of Higher Learn-ing for being a source of constant motivation and inspirationin all their activities The authors also thank the supportfrom the Department of Science amp Technology (DST InspireFellowship Program) Ministry of Science and TechnologyGovernment of India

References

[1] L Spanhel M Haase HWeller and A Henglein ldquoPhotochem-istry of colloidal semiconductors 20 Surface modification andstability of strong luminescing CdS particlesrdquo Journal of theAmerican Chemical Society vol 109 no 19 pp 5649ndash5655 1987

[2] A P Alivisatos ldquoSemiconductor clusters nanocrystals andquantum dotsrdquo Science vol 271 no 5251 pp 933ndash937 1996

[3] M Grundmann ldquoPresent status of quantum dot lasersrdquo PhysicaE vol 5 no 3 pp 167ndash184 1999

[4] T J Bukowski and J H Simmons ldquoQuantum dot researchcurrent state and future prospectsrdquo Critical Reviews in SolidState and Materials Sciences vol 27 no 3-4 pp 119ndash142 2002

[5] A M Smith X Gao and S Nie ldquoQuantum dot nanocrystalsfor in vivomolecular and cellular imagingrdquo Photochemistry andPhotobiology vol 80 no 3 pp 377ndash385 2004

[6] B Debasis L Qian T-K Tseng and P H Holloway ldquoQuantumdots and theirmultimodal applications a reviewrdquoMaterials vol3 pp 2260ndash2345 2010

[7] S Dwarakanath J G Bruno A Shastry et al ldquoQuantumdot-antibody and aptamer conjugates shift fluorescence uponbinding bacteriardquo Biochemical and Biophysical Research Com-munications vol 325 no 3 pp 739ndash743 2004

[8] V Bagalkot L Zhang E Levy-Nissenbaum et al ldquoQuantumdot-aptamer conjugates for synchronous cancer imaging ther-apy and sensing of drug delivery based on Bi-fluorescenceresonance energy transferrdquoNano Letters vol 7 no 10 pp 3065ndash3070 2007

[9] J G Brennan T Siegrist P J Carroll et al ldquoBulk and nanostruc-ture group II-VI compounds from molecular organometallicprecursorsrdquo Chemistry of Materials vol 2 no 4 pp 403ndash4091990

[10] J Zhang X G Chen L Huang J T Han and X F Zhang ldquoSelf-assembled polymeric nanoparticles based on oleic acid-graftedchitosan oligosaccharide biocompatibility protein adsorptionand cellular uptakerdquo Journal of Materials Science pp 1ndash9 2012

[11] M Akhtar J Akhtar M A Malik F Tuna M Helliwelland P OrsquoBrien ldquoDeposition of iron selenide nanocrystalsand thin films from tris(NN-diethyl-N[prime or minute]-naphthoylselenoureato)iron(iii)rdquo Journal of Materials Chem-istry vol 22 pp 14970ndash14975 2012

[12] R Koole W J M Mulder M M van Schooneveld G JStrijkers AMeijerink andKNicolay ldquoMagnetic quantumdotsfor multimodal imagingrdquoWiley Interdisciplinary Reviewsy vol1 no 5 pp 475ndash491 2009

[13] A Hoshino K Fujioka T Oku et al ldquoPhysicochemical prop-erties and cellular toxicity of nanocrystal quantum dots dependon their surface modificationrdquo Nano Letters vol 4 no 11 pp2163ndash2169 2004

[14] T Pradeep Nano The Essentials McGraw-Hill 2008[15] C De Mello Donega P Liljeroth and D Vanmaekelbergh

ldquoPhysicochemical evaluation of the hot-injection method asynthesis route formonodisperse nanocrystalsrdquo Small vol 1 no12 pp 1152ndash1162 2005

[16] D V Talapin A L Rogach A Kornowski M Haaseand H Weller ldquoHighly luminescent monodisperse CdSe andCdSeZnS nanocrystals synthesized in a hexadecylamine-trioctylphosphine oxide-trioctylphospine mixturerdquo Nano Let-ters vol 1 no 4 pp 207ndash211 2001

[17] Ventra Introduction to Nanoscale Science and TechnologySpringer New York NY USA 2004

[18] C E M Campos J C De Lima T A Grandi K D Machadoand P S Pizani ldquoStructural studies of iron selenides preparedby mechanical alloyingrdquo Solid State Communications vol 123no 3-4 pp 179ndash184 2002

[19] SchmidtHydrazine and Its Derivatives Preparation PropertiesApplications John Wiley amp Sons New York NY USA 2ndedition 2001

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Smart Materials Research



MetallurgyJournal of


BioMed Research International

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Nano

materials


Journal ofNanomaterials


tested [12] Moreover alternative quantum dots systems ofCd Pb and Hg are known to be toxic [13] The aim is toisolate stable surfactant capped iron selenide colloidal QDsas a possible biocompatible replacement for the harmfulfluorescent markers

Several methods of synthesis for such quantum dotsystems are described in the literature which are generallychosen so as to have the following properties monodisper-sity chemical integrity and specificity possibility of furtherfunctionalization and high degree of crystallinity withoutany defects [14] Our present work is based on the precursorroute where the principal synthetic strategy of arrestedprecipitation is used [14] It is a one pot synthesis routewhere all the precursors prepared in solvents are added inone vessel at elevated temperatures This is also known asthe hot injection route which minimizes the number of stepsproducing the product instantaneously At some stage of thegrowth the surface is stabilized by making use of surfactantsor capping agents Further growth is thereby controlled orarrested as the surfactants selectively bind to the surfaceof the growing nanocrystal [15] In our procedure we havesuitably modified the precursor route by incorporating areducing agent hydrazine monohydrate The reducing agentis added to prevent the susceptible oxidation of iron whichmay otherwise prevent the formation of quantum dots Moreimportantly hydrazine hydrate can also form complexes withthe precursors a critical step in the product formation asdiscussed in the subsequent sections

The final isolated product was characterized by UV PLDLS TEM and FT-Raman to ascertain the optical propertiessize and chemical composition

2 Experimental

21 Chemicals FeCl3 98 Otto (Chemika Biochemika

Reagents) 1-octadecene 95 trioctyl phosphine (TOP) 90Sigma Aldrich oleic acid pure Merck hydrazine monohy-drate 99 Alfa Aesar and Selenium powder HiMedia

22 Synthesis of Iron Selenide Quantum Dots About 30mgof selenium powder was added to a beaker containing 5mLof 1-octadecene Subsequently 04mL of TOP was addedto this mixture using a glass syringe The entire mixturewas subjected to mild heating with simultaneous magneticstirring until a clear solution was obtained The solventchosen for thiswasTOPbecause it has a high thermal stabilityand can coordinate with inorganic surfaces easily [16] therebyforming the selenium precursor

In the modified hot injection route 13mg of FeCl3is

weighed and added into a three-necked round bottom flask(250mL)This is followed by the addition of 06mLoleic acid02mL hydrazine monohydrate and 10mL octadecene Theround bottom flask is heated to 225∘C on a heating mantleThe entire working apparatus is set up in a fume hood

At this temperature 1mL of the prepared Se precursorsolution is injected into the round bottom flask On contactof the Se precursor with themixture already containedwithinthe flask an instantaneous colour change is observed An

aliquot of the sample in the flask is immediately drawn andtransferred into a storage vial The drawing of the aliquots isperformed repeatedly every 5 seconds until the solution in theround bottom flask is exhausted Rapid cold quenching of theisolated aliquots after hot injection is performed in crushedice This process immediately arrests the reaction therebycontrolling the particle growth and nucleation preventingfurther aggregation

23 Characterization The UV-Vis spectroscopy analysiswas performed using the instrument model UV-2450 Shi-madzu (Scientific Instruments Corp) under the photometricabsorbance mode The photoluminescence (PL) analyseswere performed using the model LS 55 spectrometer 120V from PerkinElmer The preliminary particle size analysesfor the samples were performed with the dynamic lightscattering technique (DLS) using the instrument ZetasizerNano (Malvern Nano ZS) involving the advantageous non-invasive backscatter detection at 173∘ The particle size andmorphology was determined using TEM JEOL JEM 2000 FXII The analysis of the formed product was carried out usingFT-Raman spectroscopy (Thermo Nicolet 6700)

3 Results and Discussion

The colorless mixture on addition of the Se precursor at225∘C immediately transformed to pale yellow A total of12 aliquots (with a 5-second interval between drawing thesuccessive aliquots) were drawn from the mother solutionin the flask The samples ranged visibly from a pale yellowcolor of the first aliquot to a dark brown of the last aliquot asshown in Figure 1(a)The isolated aliquotswhenplaced underUV light exhibited a distinct uniform green fluorescence(Figure 1(b)) This was the first indication of an iron basedproduct displaying narrow range fluorescence in the greenregion The entire experiment when repeated several timesproduced concordant results and the synthesized sampleswere found to be very stable at room temperature

In UV-Vis spectrometry the 1st aliquot displayed maxi-mum absorbance at around 315 nm the 6th at 325 nm andthe 12th at around 330 nm as shown in Figure 2(a) Since theabsorption peaks were not separated by a significant shiftit led us to ascertain that the synthesis yielded productsexhibiting a fairly monodisperse size range

The photoluminescence study of the above aliquots wasperformed using hexane as the solvent The three aliquotswere subject to excitation at 300 nm and the emission spec-trum was recorded The 1st and 6th aliquots displayed max-imum emission exhibiting two prominent peaks at around510 nm and 530 nm corresponding to a bluish green and abright green fluorescence respectively The intensity of the510 nm peak was higher than that of the 530 nm peak The6th aliquot displayed a very minute red shift in peak positionand less difference between the two peak intensitiesThe 12thaliquot however displayed a single prominent peak whichwas broader encompassing the range between 500 nm to550 nm centered at 515 nm corresponding to green color offluorescence (Figure 2(b))


1 6 12

(a)

1 6 12

(b)


Abso

rban

ce (a

u)

280 300 320 340 360 380 400Wavelength (nm)


(a)


Inte

nsity

(au

)

480 500 520 540 560 580 600Wavelength (nm)

(b)







1 10 1000

10

20

30

Size d (nm)

Num

ber (

)

d = 48nm


20nm





100 200 300 400 500 600 700 800

Inte

nsity

(au

)

220





2H5

++OHminus (1)

N2H5

++ Fe3+ 997888rarr Fe2+ +NH

4

++H+ + 1

2N2 (2)


Se + 2N2H5


2+ 2NH

4

++ 2H+ (3)


4 Conclusions





Acknowledgments


References



























CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




1 6 12

(a)

1 6 12

(b)


Abso

rban

ce (a

u)

280 300 320 340 360 380 400Wavelength (nm)


(a)


Inte

nsity

(au

)

480 500 520 540 560 580 600Wavelength (nm)

(b)







1 10 1000

10

20

30

Size d (nm)

Num

ber (

)

d = 48nm


20nm





100 200 300 400 500 600 700 800

Inte

nsity

(au

)

220





2H5

++OHminus (1)

N2H5

++ Fe3+ 997888rarr Fe2+ +NH

4

++H+ + 1

2N2 (2)


Se + 2N2H5


2+ 2NH

4

++ 2H+ (3)


4 Conclusions





Acknowledgments


References



























CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




1 10 1000

10

20

30

Size d (nm)

Num

ber (

)

d = 48nm


20nm





100 200 300 400 500 600 700 800

Inte

nsity

(au

)

220





2H5

++OHminus (1)

N2H5

++ Fe3+ 997888rarr Fe2+ +NH

4

++H+ + 1

2N2 (2)


Se + 2N2H5


2+ 2NH

4

++ 2H+ (3)


4 Conclusions





Acknowledgments


References



























CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials






Acknowledgments


References



























CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials










CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials



Research Article One-Step Synthesis of Colloidal...

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