doination

DOI:10.
1002/asia.
201000728AMechanisticStudyontheFormationofSilverNanoplatesinthePresenceofSilverSeedsandCitricAcidorCitrateIonsJieZeng,[a]JingTao,[b]WeiyangLi,[a]JenniferGrant,[c]PhyllisWang,[c]YimeiZhu,[b]andYounanXia*[a]DedicatedtoProfessorEiichiNakamuraontheoccasionofhis60thbirthdaySilvernanocrystalshavereceivedconsiderableattentioninrecentyearsowingtotheiruniquepropertiesandapplica-tions.
[1]Forexample,thankstotheirwell-establishedopticalpropertiesknownaslocalizedsurfaceplasmonresonance(LSPR),silvernanocrystalspossesawiderangeofapplica-tionsforuseasopticallabels,substratesforsurface-en-hancedRamanscattering(SERS),near-fieldopticalprobes,andcontrastagentsforbiomedicalimaging.
[2]Moreimpor-tantly,theopticalpropertiesofsilvernanocrystalscanbefinelytunedbycontrollingtheirshapesduringachemicalsynthesis.
[3]Aremarkableexampleisthatofsilvernano-plates,aclassofnanocrystalsthathavetwo-dimensionalani-sotropy.
[4]Thesenanoplatesexhibitfascinatingopticalprop-erties,suchasastrong,in-planedipoleresonancemodeinthevisibleregion.
Thepeakpositionofthisresonancemodehasbeenfoundtobehighlysensitivetothemorphologyofthenanostructure,includingthesizeandsharpnessofthecorners.
[5]Withregardtotheirsynthesis,silvernanoplateswerefirstreportedin2001byMirkinandco-workers,whousedapho-toinductionmethodtoconvertsilvernanospheresintotrian-gularnanoplates.
[6]Sincethen,anumberofdifferentsyn-theticrouteshavebeendemonstrated,includingthosebasedonphotoinducedorthermallyinducedtransformationandthosebasedondirectchemicalreduction.
[7]Suchmethods,andmodifiedversionsthereof,havebeenwidelyutilizedforpreparinguniformsamplesofsilvernanoplates,andmostoftheminvolvedtheuseofcitrateasacappingagentasitcanselectivelybindto{111}facets,thusrestrictinggrowthintheverticaldirectionstomaintainaplate-likeshape.
[7d,8]Despiteextensivestudiesofsilver-nanoplatesynthesis,verylittleisknownaboutthedetailsofnucleationinvolvedinthefor-mationofseedparticles.
[8b,9]Onebarriertounderstandingthismechanismisthedifficultytoresolvehowaprecursorsaltisreducedintoneutralatomsthatthenevolveintonanoscalecrystals.
Wehavepreviouslysuggestedthatmassspectrometrycouldprovideatoolforthesimpleidentifica-tionandcharacterizationofsilverspeciesbeforetheinitia-tionofareaction,whichmightdominatethenucleationofsilver.
[10]Basedonstructuralanalysisofseedparticlesandstudyofthemassspectrumoftheprecursorsolution,hereinweproposeaplausiblemechanisminwhichcitrateservesasadualfunctionalagent.
Specifically,citratenotonlyservesasacappingagenttoselectivelybind{111}facets,butalsocoordinateswithAg+ionstoformavarietyofcomplexes.
ThiscoordiredTag"style="COLOR:#000000;BACKGROUND-COLOR:#ffff00">nationeffectcansignificantlyreducetheconcen-trationoffreeAg+ions,thusslowingdownthereductionandenablingakineticcontrolthatfavorsnanoplateforma-tion.
Toseparatenucleationfromgrowthsothatwecanfocusourinvestigationonthenucleationstep,weemployedaseed-mediatedmethodthatcangeneratetriangularsilvernanoplatesinhighyields(fordetails,seetheExperimentalSection).
[5c,8a]Thatmethodinvolvedsilver-seed-catalyzedre-ductionofAgNO3byl-ascorbicacidinthepresenceofcit-rateandpoly(vinylpyrrolidone)(PVP).
Thesilverseedswere,inturn,preparedbyreducingAgNO3withNaBH4inthepresenceofcitrateandPVP.
AsshownintheSupportingInformation,FigureS1a,sol-utionswithdifferentcolorsfromyellowtoorange,red,purple,blue,andfinallycyan,wereeasilyobtainedbycon-[a]Dr.
J.
Zeng,W.
Li,Prof.
Y.
XiaDepartmentofBiomedicalEngineeringWashingtonUniversity,St.
Louis,Missouri63130(USA)Fax:(+1)314-935-7448E-mail:xia@biomed.
wustl.
edu[b]Dr.
J.
Tao,Dr.
Y.
ZhuCondensedMatterPhysics&MaterialsScienceDepartmentBrookhavenredTag"style="COLOR:#000000;BACKGROUND-COLOR:#ffff00">NationalLaboratory,Upton,NewYork11973(USA)[c]J.
Grant,P.
WangDepartmentofEnergy,EnvironmentalandChemicalEngineeringWashingtonUniversity,St.
Louis,Missouri63130(USA)SupportinginformationforthisarticleisavailableontheWWWunderhttp://dx.
doi.
org/10.
1002/asia.
201000728.
3762011Wiley-VCHVerlagGmbH&Co.
KGaA,WeinheimChem.
AsianJ.
2011,6,376–379COMMUNICATIONtrollingthequantityofsilverseedsaddedintothegrowthsolution.
Ingeneral,themajorLSPRpeakwassignificantlyred-shiftedasthequantityofseedsolutionwasreduced(seetheSupportingInformation,FigureS1b).
ThreeLSPRpeakswereobservedforallofthesamplesexcepttheseedsolution,thusindicatingtheformationofaplate-likestruc-tureoncetheseededgrowthwasinitiated.
Takingthecyansolutionasanexample,weassignedtheextinctionpeaksat335nm,470nm,and735nmtotheout-of-planequadrupole,in-planequadrupole,andin-planedipoleplasmonresonan-cesofananoplate,respectively.
[7b]Figure1aandbshowtransmissionelectronmicroscopy(TEM)imagesofthesilvernanoplatesattwodifferentori-entationsforthesampleobtainedwhen20mLoftheseedsolutionwasintroduced.
AsshowninFigure1a,thenano-platesweretriangularinshapewithslighttruncationatthecorners.
Theedgelengthvariedfrom30to60nm.
InFig-ure1b,almostallofthenanoplateslayontheTEMgridagainstoneoftheirsidefaces.
Aninterestingfeatureofsilvernanoplateswasthattheytendedtostackuponeachotherface-to-faceandstandverticallyontheiredges.
[5c]FromtheTEMimageinFigure1b,weobtainedanaveragethicknessof~5nmfortheplates.
TheTEMstudyalsocon-firmedourconclusionsregardingtheparticlemorphologydeducedfromtheextinctionspectrainFigureS1b.
Toobtainstructuralinformationaboutthesilvernano-plates,weconductedhigh-resolutionTEMstudieswithsilvernanoplatesatthetwodifferentorientations,showninFigure1aandb.
Figure1canddshowtwoimagestakenperpendiculartotheflatfacesofanindividualnanoplatealongthe["111]zoneaxis.
Thefringesseparatedby2.
5couldbeassignedtothe1/3ACHTUNGTRENNUNG{422}reflection,whichwasgen-erallyforbiddenforaface-centeredcubic(fcc)lattice.
Meanwhile,the{220}fringeswithaseparationof1.
4werealsoobserved.
TheinsetinFigure1cshowsatypicalselect-edareaelectrondiffraction(SAED)patternrecordedbydi-rectingtheelectronbeamperpendiculartotheflatfacesofanindividualnanoplate.
Thesix-foldrotationalsymmetrydisplayedbythespotsimpliesthattheflatfaceswereboundby{111}planes.
Threesetsofspotswereidentifiedbasedonthed-spacing.
Firstly,thesetwithaspacingof1.
4(trian-gle)wasindexedtothe{220}Braggreflection.
Second,theoutersetwithalatticespacingof0.
8(square)originatedfromthe{422}reflection.
Thesetwosetsofreflectionswerebothallowedforanfcclattice.
Third,theinnersetwithaspacingof2.
5(circle)wasduetothe1/3ACHTUNGTRENNUNG{422}reflection.
Thisforbiddenreflectionwasalsopreviouslyobservedforbothsilverandgoldnanoplates.
[7d,11]Figure1eandfshowhigh-resolutionTEMimagesofthesidefacerecordedinthe[011]orientation.
Thefringescouldbeindexedto{111}or{200}reflections,thusimplyingthatthesidefacewasboundbyoneofthe{100}planes.
Thisas-signmentcorrespondedtoageometricalmodel,inwhicheachnanoplatewasenclosedbytwo{111}planesasthetopandbottomfaces,andbyamixof{100}and{111}planesasthesidefaces.
[12]Ahigh-resolutionTEMstudyalsorevealedthateachnanoplatecontained{111}twindefectsparalleltotheirflatfaces(Figure1f).
The{111}twinplaneswerepre-sumablyresponsiblefortheappearanceoftheforbidden1/3ACHTUNGTRENNUNG{422}reflection.
[11a]Asamajoradvancementoverpreviouswork,weanalyzedthestructureofthesilverseedsbyTEMimaging.
AsshowninFigure2a,thesizeofseedparticleswasestimatedtobeFigure1.
TEMandhigh-resolutionTEMimagesoftriangularsilvernano-plates.
(a,b)TEMimagesofsilvernanoplateswithtwodifferentorienta-tions.
Thescalebarsoftheinsetsin(a)and(b)areboth10nm.
(c,d)High-resolutionTEMimagesofsilvernanoplatestakenfromtheflattopface.
Theinsetof(c)showstheSAEDpatterntakenfromthisparti-cle.
Thespots(triangle,square,andcircle)couldbeindexedtotheal-lowed{220}reflection,theallowed{422}reflection,andtheformallyfor-bidden(1/3)ACHTUNGTRENNUNG{422}reflection,respectively.
(e,f)High-resolutionTEMimagesofsilvernanoplatestakenfromthesideface.
Figure2.
(a)TEMand(b)high-resolutionTEMimagesofthesilverseedparticles.
Thefringespacingof2.
4,2.
0,and1.
4correspondtothe{111}planes,the{200}planes,andthe{220}planes,respectively.
The{111}twinplanesareindicatedbytwoarrows.
Chem.
AsianJ.
2011,6,376–3792011Wiley-VCHVerlagGmbH&Co.
KGaA,Weinheimwww.
chemasianj.
org3772.
10.
3nm.
Figure2bshowshigh-resolutionTEManalysisofatypicalseedparticlewithclearcrystallinelatticefringes.
Thefringespacingof2.
4,2.
0,and1.
4correspondedtothe{111},{200},and{220}planes,respectively.
Thela-beledanglebetweentwolatticefringeswas54.
78,whichwasidenticaltothetheoreticalvaluefortheanglebetweenthe{111}and{200}planesinanfcccrystal.
Wealsoobservedtwo{111}twinplanesinthisparticle(asindicatedbythearrows),whichmightimplythegrowthmechanismfortheresultingsilvernanoplates.
Wesuggestedthatthegenerationof{111}twinplanesandstackingfaultsinseedparticleswerekeyfactorsgoverningplategrowth.
Ingeneral,theadatomstendtoattachtothetwin-createdreentrantgroovesinordertolowerthelocalnucleationenergywhenforminganewatomiclayer.
[13]Therefore,particlegrowthwasacceleratedinthelateraldirectionparalleltothetwinplanes,whichcouldkeepdrivingtheparticletogrowto-wardsawell-definedplatestructure.
Positive-modemassspectrometrywasusedtostudythecoordiredTag"style="COLOR:#000000;BACKGROUND-COLOR:#ffff00">nationeffectofcitrateandAgNO3sourcebeforetheinitiationofAg+reduction.
Figure3showsatypicalspec-trumofanaqueoussolutioncontaining1mmofAgNO3and18mmofcitricacid.
Surprisingly,thedoubletpeaksofiso-latedAg+ions(locatedatm/z107and109)werequiteweakwhilstseveralsetsofpeaksinthem/zrangefrom150to1000exhibiteddistinctisotopepatterns.
Accordingtotheisotopepatternsandtheircorrespondingm/zratios(seetheSupportingInformation,FigureS2),thesepeakscanbeas-signedtoH+·CAH,[Ag·CAH]+,[Ag·CAH2]+,[Ag2·CAH·CA]+,[Ag3·CA2]+,[Ag2·CAH2·CA]+,and[Ag3·CAH·CA2]+species,whereCAHrepresentscitricacidandCArepresentsthecitrateion.
ItseemsthatbothCAHandCAcoordinatedstronglywithAg+ions,possiblythroughthecarboxylategroup.
[14]Inthiscase,thecoordina-tioneffectsignificantlyreducedtheconcentrationoffree,isolatedAg+ions,andthussloweddownthereductionofAg+ionsandthesubsequentformationrateofsilveratoms,thusleadingtokineticcontroloverthenanocrystalgrowth.
Ourpreviousstudiesrevealedthatkineticallycontrolledprocessesmightbethekeytoachievingseedswithstackingfaultsandnanocrystalswiththermodynamicallyunfavorableshapes.
[11b]WealsonotedthateachcoordiredTag"style="COLOR:#000000;BACKGROUND-COLOR:#ffff00">nationcomplexcouldcon-tainone,two,orthreeAg+species.
Areductant(NaBH4inthecaseofseedpreparation)mayfirstreducetheAg+ionsinthesecomplexestoformAg1atoms,Ag2dimers,andAg3trimers.
Inakineticallycontrolledprocess,theseatomicspe-ciesandsmallclusterswouldthenaggregateintobiggerclusters,thusformingseedparticles.
AproposedmechanismforseedformationisschematicallyshowninFigure4a.
Asfortheseededgrowthofnanoplates,l-ascorbicacidservesasanewreductanttoreducethecoordiredTag"style="COLOR:#000000;BACKGROUND-COLOR:#ffff00">nationcomplexes.
Afterreduction,thenewlyformedatomsandclusterswouldattachtothesurfaceofpre-existingseedparticles,thusre-sultinginnanoplategrowth(Figure4b).
Atthesametime,citratewouldactasaselectivecappingagentthatbindsto{111}facets,thusrestrictinggrowthintheverticaldirectionsandonlyallowingpreferentialgrowthinthelateraldirec-tions.
Thismechanismisconsistentwithourdata,inwhichtheedgelengthincreasedfrom2.
1nmto30–60nmoverthecourseofthesynthesiswhilstthethicknessonlygrewfrom2.
1nmto5.
0nm.
Insummary,wehaveidentifiedthecoordiredTag"style="COLOR:#000000;BACKGROUND-COLOR:#ffff00">nationcom-plexesofAg+andcitrateionsasthedominantspecieswhencitratewasmixedwithAgNO3inanaqueoussolution.
SuchacoordiredTag"style="COLOR:#000000;BACKGROUND-COLOR:#ffff00">nationeffectwasdemonstratedtoenableakineticcontrolduringtheformationofsilverseedswithstackingfaults.
Thisworkexplainswhycitrateisnecessaryforgener-atingsilvernanoplates:itnotonlyservesasaselectivecap-pingagentsfor{111}facets,butalsoactsasastrongcoordi-redTag"style="COLOR:#000000;BACKGROUND-COLOR:#ffff00">nationligandwithAg+ions.
Inadditiontothemechanisticunderstanding,thisworkalsocontributestoourcontroloverthenucleationstepinvolvedintheformationofsilvernanocrystals.
Thereisnodoubtthatabetterunderstandingofthenucleationstepholdsthekeytobettercontrolovertheshapeandsizeofnanocrystals.
Figure3.
Positive-modemassspectrumtakenfromanaqueoussolutioncontaining1mmofAgNO3and18mmofcitricacid.
CAH=citricacid,CA=citrateion.
Figure4.
Schematicsillustrating(a)theformationofsilverseedsand(b)thegrowthofsilverseedsintotriangularsilvernanoplates.
Thestack-ingfaultswereindicatedbywhitearrows.
378www.
chemasianj.
org2011Wiley-VCHVerlagGmbH&Co.
KGaA,WeinheimChem.
AsianJ.
2011,6,376–379COMMUNICATIONY.
Xiaetal.
ExperimentalSectionChemicalsSilvernitrate(AgNO3,Aldrich,209139-100g),sodiumborohydride(NaBH4,Fisher,S678-10g),poly(vinylpyrrolidone)(PVP,MW=29,000,Aldrich,234257-100g),sodiumcitrate(Na3CA,Aldrich,S1804-500g),andl-ascorbicacid(Aldrich,255564-100g)wereallusedasreceivedwithoutfurtherpurification.
Ultrapurewater(18.
2MW)wasusedforallsolu-tions.
PreparationofSilverSeedsInatypicalsynthesisofAgseeds,11mLofanaqueoussolutioncontain-ing0.
11mmAgNO3and2.
05mmNa3CAwasprepared.
Undermagneticstirring,anaqueoussolutionofNaBH4(0.
3mL,5mm)wasaddedinonegoandthemixturewasstirredfor10min.
Thisseedsolutionwasthenagedatroomtemperaturefor5hpriortofutureuse.
[8a]Theseedswerethenusedforthegrowthstepwithoutfurtherseparationorpurification.
SynthesisofSilverNanoplatesThetriangularAgnanoplateswerepreparedasfollows:9.
25mLofultra-purewaterwasmixedwith0.
25mLaqueousAgNO3(5mm),0.
75mLaqueousPVP(0.
7mmintermsoftherepeatingunit),0.
75mLaqueousNa3CA(30mm),andvariousquantities(640mL,320mL,160mL,80mL,40mLor20mL)oftheas-preparedseedsolution,followedbyslowdrop-pinginto6.
25mLaqueousl-ascorbicacid(1mm)undermagneticstir-ring.
Thecolorofthesolutionchangedgraduallyduringtheadditionofl-ascorbicacidandfinallybecamestable15minafterallofthel-ascor-bicacidhadbeenadded.
Theproductswerecleanedbycentrifugationandwashingwithwatertwiceat48CtogetridofexcessPVPandNa3CA,andthenre-dispersedinwaterforfuturecharacterization.
CharacterizationTEMimageswerecapturedusingaPhillips420microscopeoperatedat120kV.
High-resolutionTEMimagesandSAEDpatternsweretakenonaJEOL3000Ftransmissionelectronmicroscopeoperatedat300kV.
ThesamplesforTEMstudieswerepreparedbydryingadropoftheaqueoussuspensionofnanoparticlesonacarbon-coatedcoppergrid(TedPella,Redding,CA)underambientconditions.
Thegridwasthentransferredontoagravity-fedflowcellandwashedfor1hwithdeionizedwatertoremoveexcessPVPandcitrate.
Finally,thesamplewasdriedandstoredundervacuumforTEMcharacterization.
TheUV/VisextinctionspectrawereobtainedusingaVarianCary50UV/Visspectrophotometer.
Massspectraweretakenfromanaqueoussolutioncontaining1mmofAgNO3and18mmofcitricacid,usingaBrukerEsquireLC-iontrapmassspec-trometerwithanelectrosprayionsourceoperatinginapositivemode.
AcknowledgementsThisworkwassupportedinpartbyaresearchgrantfromtheNSF(DMR-0804088)andstart-upfundsfromWashingtonUniversityinSt.
Louis.
Y.
X.
wasalsopartiallysupportedbytheWorldClassUniversity(WCU)programthroughtheredTag"style="COLOR:#000000;BACKGROUND-COLOR:#ffff00">NationalResearchFoundationofKoreafundedbytheMinistryofEducation,ScienceandTechnology(R32-20031).
PartoftheresearchwasperformedattheNanoResearchFacility(NRF),amemberoftheredTag"style="COLOR:#000000;BACKGROUND-COLOR:#ffff00">NationalNanotechnologyInfrastructureNet-work(NNIN),whichisfundedbytheNSFunderawardno.
ECS-0335765.
WorkatBNLwassupportedbytheU.
S.
DOE/BESunderCon-tractNo.
DE-AC02-98CH10886.
Keywords:citrate·coordiredTag"style="COLOR:#000000;BACKGROUND-COLOR:#ffff00">nation·kineticcontrol·nanoplates·silver[1]a)X.
M.
Lu,M.
Rycenga,S.
E.
Skrabalak,B.
Wiley,Y.
Xia,Annu.
Rev.
Phys.
Chem.
2009,60,167–192;b)A.
R.
Tao,S.
Habas,P.
D.
Yang,Small2008,4,310–325;c)M.
Rycenga,C.
M.
Cobley,J.
Zeng,W.
Li,C.
Moran,Q.
Zhang,D.
Qin,Y.
Xia,Chem.
Rev.
2011,DOI:cr-2010-00275d.
[2]a)S.
M.
Nie,S.
R.
Emery,Science1997,275,1102–1106;b)O.
D.
Velev,E.
W.
Kaler,Langmuir1999,15,3693–3698;c)S.
R.
Nice-warner-Pena,R.
G.
Freeman,B.
D.
Reiss,L.
He,D.
J.
Pena,I.
D.
Walton,R.
Cromer,C.
D.
Keating,M.
J.
Natan,Science2001,294,137–141;d)Y.
W.
C.
Cao,R.
C.
Jin,C.
A.
Mirkin,Science2002,297,1536–1540;e)L.
A.
Dick,A.
D.
McFarland,C.
L.
Haynes,R.
P.
VanDuyne,J.
Phys.
Chem.
B2002,106,853–860;f)P.
Alivisatos,Nat.
Biotechnol.
2004,22,47–52.
[3]a)T.
Jensen,L.
Kelly,A.
Lazarides,G.
C.
Schatz,J.
ClusterSci.
1999,10,295–317;b)J.
P.
Kottmann,O.
J.
F.
Martin,D.
R.
Smith,S.
Schultz,Phys.
Rev.
B2001,64,235402;c)I.
O.
Sosa,C.
Noguez,R.
G.
Barrera,J.
Phys.
Chem.
B2003,107,6269–6275;d)B.
J.
Wiley,S.
H.
Im,Z.
Y.
Li,J.
McLellan,A.
Siekkinen,Y.
Xia,J.
Phys.
Chem.
B2006,110,15666–15675.
[4]a)K.
L.
Kelly,E.
Coronado,L.
L.
Zhao,G.
C.
Schatz,J.
Phys.
Chem.
B2003,107,668–677;b)L.
J.
Sherry,R.
C.
Jin,C.
A.
Mirkin,G.
C.
Schatz,R.
P.
VanDuyne,NanoLett.
2006,6,2060–2065;c)I.
Pastoriza-Santos,L.
M.
Liz-Marzan,J.
Mater.
Chem.
2008,18,1724–1737;d)J.
E.
Millstone,S.
J.
Hurst,G.
S.
Metraux,J.
I.
Cutler,C.
A.
Mirkin,Small2009,5,646–664.
[5]a)G.
S.
Mtraux,C.
A.
Mirkin,Adv.
Mater.
2005,17,412–415;b)Q.
Zhang,J.
P.
Ge,T.
Pham,J.
Goebl,Y.
X.
Hu,Z.
Lu,Y.
D.
Yin,Angew.
Chem.
2009,121,3568–3571;Angew.
Chem.
Int.
Ed.
2009,48,3516–3519;c)J.
Zeng,S.
Roberts,Y.
Xia,Chem.
Eur.
J.
2010,16,12559–12563.
[6]R.
C.
Jin,Y.
W.
Cao,C.
A.
Mirkin,K.
L.
Kelly,G.
C.
Schatz,J.
G.
Zheng,Science2001,294,1901–1903.
[7]a)I.
Pastoriza-Santos,L.
M.
Liz-Marzan,NanoLett.
2002,2,903–905;b)R.
C.
Jin,Y.
C.
Cao,E.
C.
Hao,G.
S.
Metraux,G.
C.
Schatz,C.
A.
Mirkin,Nature2003,425,487–490;c)D.
Aherne,D.
M.
Led-with,M.
Gara,J.
M.
Kelly,Adv.
Funct.
Mater.
2008,18,2005–2016;d)Y.
G.
Sun,B.
Mayers,Y.
Xia,NanoLett.
2003,3,675–679;e)S.
H.
Chen,D.
L.
Carroll,NanoLett.
2002,2,1003–1007;f)Y.
G.
Sun,Y.
Xia,Adv.
Mater.
2003,15,695–699.
[8]a)J.
Zeng,X.
Xia,M.
Rycenga,P.
Henneghan,Q.
Li,Y.
Xia,Angew.
Chem.
Int.
Ed.
2010,DOI:10.
1002/anie.
201005549;b)C.
Xue,G.
S.
Metraux,J.
E.
Millstone,C.
A.
Mirkin,J.
Am.
Chem.
Soc.
2008,130,8337–8344.
[9]a)X.
M.
Wu,P.
L.
Redmond,H.
T.
Liu,Y.
H.
Chen,M.
Steigerwald,L.
Brus,J.
Am.
Chem.
Soc.
2008,130,9500–9506;b)J.
Zhang,M.
R.
Langille,C.
A.
Mirkin,J.
Am.
Chem.
Soc.
2010,132,12502–12510.
[10]Y.
Xiong,I.
Washio,J.
Chen,M.
Sadilek,Y.
Xia,Angew.
Chem.
2007,119,5005–5009;Angew.
Chem.
Int.
Ed.
2007,46,4917–4921.
[11]a)I.
Washio,Y.
J.
Xiong,Y.
D.
Yin,Y.
Xia,Adv.
Mater.
2006,18,1745–1749;b)Y.
J.
Xiong,A.
R.
Siekkinen,J.
G.
Wang,Y.
D.
Yin,M.
J.
Kim,Y.
Xia,J.
Mater.
Chem.
2007,17,2600–2602;c)Y.
J.
Xiong,I.
Washio,J.
Y.
Chen,H.
G.
Cai,Z.
Y.
Li,Y.
Xia,Langmuir2006,22,8563–8570;d)V.
Germain,J.
Li,D.
Ingert,Z.
L.
Wang,M.
P.
Pileni,J.
Phys.
Chem.
B2003,107,8717–8720.
[12]Z.
L.
Wang,J.
Phys.
Chem.
B2000,104,1153–1175.
[13]a)J.
L.
Elechiguerra,J.
Reyes-Gasga,M.
J.
Yacaman,J.
Mater.
Chem.
2006,16,3906–3919;b)C.
Lofton,W.
Sigmund,Adv.
Funct.
Mater.
2005,15,1197–1208;c)T.
C.
R.
Rocha,D.
Zanchet,J.
Phys.
Chem.
C2007,111,6989–6993;d)C.
Salzemann,J.
Urban,I.
Li-siecki,M.
P.
Pileni,Adv.
Funct.
Mater.
2005,15,1277–1284.
[14]C.
H.
Munro,W.
E.
Smith,M.
Garner,J.
Clarkson,P.
C.
White,Langmuir1995,11,3712–3720.
Received:October6,2010Publishedonline:November24,2010Chem.
AsianJ.
2011,6,376–3792011Wiley-VCHVerlagGmbH&Co.
KGaA,Weinheimwww.
chemasianj.
org379AMechanisticStudyontheFormationofSilverNanoplates