Silver nanocrystals by hyperbranched polyurethane-assisted p(2)
时间:2025-04-07
时间:2025-04-07
H.W.Luetal./MaterialsChemistryandPhysics81(2003)104–107
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stableanddidnotprecipitatewithin3months.Theresultingsolutionwascastedonaglasssubstrateanddriedatroomtemperaturefor12h,thenat30 Cinvacuumfor12h.Black lmswerepeeledoffforcharacterization.
剥离
TheX-raypowderdiffraction(XRD)patternswererecordedatascanningrateof4 min 1inthe2θrangeof20–60 usingaRigakuD/max AX-raydiffractome-terwithCuK radiation(λ=1.54178Å).Transmissionelectronmicroscopic(TEM)photographsweretakenonaHitachiS-530TEM.Ultraviolet-visible(UV-Vis)spec-traweremeasuredonaPerkin-ElmerLambda20UV-Visspectrophotometer.APerkin-ElmerParagon1000FTIRspectrophotometerwasusedforFTIRmeasurement.3.Resultsanddiscussion3.1.XRDanalysis
Fig.1showedthetypicalXRDpatternsoftheobtainedsamples.Allthediffractionpeakscouldbeindexedtoface-centeredcubicsilverphasewithcellconstantsa0=4.1Å.ThevalueswereclosetothoseintheJCPDScard(cardno.4-783).Theaveragecrystallinesize,whichwasdeterminedfromthehalf-widthofthediffractionusingtheDebye–Scherrerequation,approximately8nm.
Fig.2.TEMmicrographofsilvernanoparticlesobtainedinthepresenceofHPafter24hirradiationtime.
3.3.UV-Visspectra
Thegenerationofsilvernanoparticlescouldalsobeiden-ti edfromboththecolorchangeandtheUV-Visspectrumoftheas-preparedproducts.UponirradiationofthesolutioncontainingHPandAg+,colorationwasobserved.Fig.3showedtheUV-Visabsorptionspectraofthesilvernanopar-ticlesobtainedinthepresenceofHPwithdifferentirradia-tiontime.PureHPsolutionexhibitednearlynoabsorptionintheselectedregion.Theabsorptionbandatabout430nmmaybeattributedtothecharacteristicsurfaceplasmonres-onanceofsilvernanoparticles[17].Byincreasingtheirra-diationtime,thepeaksaround430nmshiftedtothelower
3.2.TEManalysis
Fig.2showedtheTEMmicrographsoftheas-preparedsilvernanoparticles.TheobtainedsilvernanoparticleswerewelldispersedinHP,withdifferentdiametersof5–10nmand15–20nm,respectively.Thesizeofthesmallerparticles(5–10nm)wasconsistentwithXRDresults.Thelargersilverparticles(15–20nm)wereprobablytheaggregatesofthesmallerones,duetothehighsurfaceenergyofthenanosized
crystals.
Fig.1.XRDpatternofsilvernanoparticlesobtainedinthepresenceofHPafter24hirradiation
time.
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