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Ag纳米催化剂的合成、表征及其催化性能的研究.docx

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Ag纳米催化剂的合成、表征及其催化性能的研究 Introduction Duetotherapidlyincreasingdevelopmentoftechnologyandindustry,thedemandforefficientandenvironmentallyfriendlycatalystsfordifferentchemicalreactionshasbeengrowing.Catalystsarewidelyusedinnumerousorganictransformationsandthus,thesearchfornewcatalyststhatcanenhancethekineticsandselectivityofchemicalreactionsinamoresustainablewayisfundamental.Overthepastdecades,nanotechnologyhasemergedasapromisingfieldincatalystdevelopment,offeringthepotentialtodesignandsynthesizematerialswithuniquepropertiesandhighcatalyticactivity.Amongthevarioustypesofnanomaterials,Agnanoparticleshavereceivedattentionaspossiblecatalystsduetotheirexcellentelectronicproperties,highsurfacearea,anduniqueopticalproperties. SynthesisofAgNanocatalysts TherearedifferentmethodstosynthesizeAgnanocatalysts,includingchemicalreductionmethods,photochemicalreductionmethods,sonochemicalmethods,andsoon.Inchemicalreductionmethods,silverionsarereducedtoAgnanoparticlesbyusingchemicalagentssuchassodiumborohydride(NaBH4),hydrazine,orcitrate.Amongthese,thecitratereductionmethodisthemostcommonlyusedandwasfirstintroducedbyFrens(1973).Thismethodinvolvestheuseofsodiumcitrateasbothreducingandstabilizingagents.ThesizeandshapeofAgnanoparticlescanbecontrolledbyadjustingthetemperature,pH,andconcentrationofthesilverionsandthereducingagent. AnotherfacilemethodforpreparingAgnanoparticlesisthephotochemicalreductionmethod.ThismethodinvolvesirradiatingasilvernitratesolutionwithUVlight,whichinducesreductionofsilverionstoAgnanoparticles.Thereactionistypicallycarriedoutinanaqueoussolutioninthepresenceofreducingagentslikesodiumborohydrideorascorbicacid.ThesizeandshapeofAgnanoparticlescanbecontrolledbyadjustingtheconcentrationofsilvernitrate,irradiationtime,pH,andthepresenceofsurfactants. CharacterizationofAgNanocatalysts ThecharacterizationofAgnanocatalystsisimportanttounderstandtheirphysicochemicalpropertiesandtorelatethemtotheircatalyticperformance.Severaltechniqueshavebeenemployedtocharacterizesilvernanop