graphvcpd

NanoRes.
ElectronicSupplementaryMaterialIn-situprobingofthermaldesorptionofvapormoleculesonananowireviaworkfunctionvarianceKovurPrashanthi(),JohnEricHawk,RyanMcGee,RaviGaikwad,andThomasThundat()IngenuityLab,DepartmentofChemicalandMaterialsEngineering,UniversityofAlberta,Edmonton,ABT6G2V4,CanadaSupportinginformationtoDOI10.
1007/s12274-016-1210-yFigureS1XRDpatternobservedforplatinumnanowiresshowingitspolycrystallinenature.
FigureS2Surfacepotentialforplatinumnanowiresobtainedatroomtemperaturewithandwithoutmethanolvapors.
ThisfigureisthegraphobtainedforadifferentlocationofthesameKPFMimageofthesamenanowireasFigs.
2(c1)and2(d1)reportedinthemanuscript.
AddresscorrespondencetoKovurPrashanthi,kovur@ualberta.
ca;ThomasThundat,thundat@ualberta.
ca|www.
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aspNanoRes.
FigureS3(a1)–(f2)Surfacepotentialmappingandcorrespondingcross-sectionalprofilesobtainedforPtnanowireatvarioustemperaturewithoutmethanolvapors.
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theNanoResearch.
com∣www.
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com/journal/12274|NanoResearchNanoRes.
FigureS4(a1)–(f2)Surfacepotentialmappingandcorrespondingcross-sectionalprofilesobtainedforPtnanowireatvarioustemperaturewithmethanolvapors.
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aspNanoRes.
FigureS5(a)AbsolutecontactpotentialobtainedforPtnanowiresatdifferenttemperatureswithandwithoutmethanolvapors.
(b)Therelativechange,ΔVCPDobtainedforPtnanowiresatdifferenttemperaturesduetomethanoladsorption.
(c)ThederivateofVCPD,d(ΔVCPD)/dTplottedasfunctionoftemperature.
SurfaceareacalculationsforPtnanowireThesurfaceareaofthecylindricalnanowire,SANW=2πRL,whereRistheradiusofthenanowire(50nm)andListhelength(20μm).
SANW=6.
28*10–8cm2.
WehavealsoconsideredtheroughnessandtheporosityofPtnanowireduringthesurfaceareacalculation.
Ther.
m.
sroughnesscalculatedfromAFMmeasurementsis~4nm.
ThecrystallitesizeofPtnanowiremeasuredbyTEMis~20nm.
Inordertofindthesurfaceareaoftheroughenednanowire,itisfirstnecessarytofindthenumberofspheresthatcanbeinscribedinsideacircleofradiusR,whiletouchingboththenearestsphere(s)andRatatangentpoint.
SeeFig.
S6(a)whichreducestoFig.
S6(b).
Usingr=Grainboundary2=10nmandR=50nm,onefindsthatn=12.
4=thenumberofspheresthatwillpackinsidethewirewhilemaintainingthemeasuredwireradiusof50nm.
Numberofspheresthatwillpackalongthelengthofthewire,1,0002Lr.
Sinceafractionalsphereisnotallowed,wewillassumethatn=12,andthetotalnumberofspherespackedintotheradiusandlengthofthewireare12,000.
Assumingthatonlyahemisphereofeachspherewillcontributetoadsorption,thetotalsurfaceareaoftheroughenedwireisfoundtobeSArough=(2πr2)(12000)=7.
54*10–8cm2.
Itshouldbenotedthatthisisonlyafirstorderapproximationinwhichonlyahemisphereofeachpackedspherecontributestotheadsorptionprocess.
Ifoneweretoallowfortheporosityoftheroughenedstructureandcontributionfromalargerportionofthesurfaceareatocontributetotheadsorptionprocess,thisnumberwouldincreasetoamaximumof2SArough=1.
51*10–7cm2.
Anycontributiontoadsorptionbyanyfurtherinscribedspheres(thoseinscribedinsidetheoutermostringofspheres)isnotincludedasitisimpossibletospeakastotheradiusofthosespheressincetheyaresubsurfacetotheroughenedwireandthusunavailabletoanymeasurementschemeandassumedexcludedfromanysorptionprocess.
FigureS6(a)Schematicofnanowirewithroughnessinradialdirectionand(b)surfaceareacalculationforeachhemisphere.