firstofall,iwannaintroducemyself.iefromnanjinguniversityoftechnology,nanjingcity,china. p3
thecontentislistedasfollows. p4
allourresearchesareconductedbytheacademicthoughts.generallyspeaking,wearemittedtoporousmaterials.inordertoexplorehigh-performancefunctionalizedmaterialsforpilotexperimentsandscale-upproduction;wetunethestructure,suchaspositionandmorphologystepbystepandoptimizethemfurther.what’
smore,thepossiblesynthesismechanismsarealsoinvestigated.today,thepresentationisbasedontheright-handbranch. p5
itisknownthatmesoporoussilicahaveexcellentcharactersasthecatalystcarrier,suchas……..
butduetolackofactivesites,wehavetointroduceorganicorinorganicspeciesasactivesites.andthecatalyticperformanceneedtobefurtherimproved.
p6
asweknow,thethreefactorsincludingactivity,scaleanddiffusionfactorplaydecisiveroleinthecatalysis,affectingtheyield,selectivity,stabilitystrongly.inourpresentation,wemainlyfocusontheinfluenceofscalefactoronthecatalysis. p7
duetolackofactivesitesformesoporoussilica,twomainmethods(surfaceloading,modifiedframework)arewidelyreported,bywhichvariousorganicorinorganicactivesitescanbeimmobilizedonthesurfaceorincorporatedintotheframeworkofmesopooussilica. p8
thoughvariousmorphologiesofmesoporossilicawerewidelysynthesized,thesynthesisofthemesoporossilica,withthreesimultaneouscharacteristicsincludingdopedmetal,mesoporousstructureandspecificmorphology,isalwaysachallenge,whichisrarelyreported.
inotherwords,forourcaseexploringapropercondition,atwhichthesiliconandmetalsourcescansimultaneouslyhydrolyze,canensureadesiredmaterial.
p9 next,let’
slookatthesyntheticsteps.firstly,….then,….afterthat,….atlast,weobtainedthe products. p10
inthiswork,bychangingthesynthesisconditions,suchas…,andsoon,thepuremesoporoussilicawithdifferentmorphologiesweresynthesized,includingnanosphere,nanorod,helix,capsuleandnanotube.wewillfocusonthepreparationandcatalyticapplicationofmesoporoussilicawithnanotubemorphology. p11
thesemimagesofsamples:a1,a2,a3areshowninthefigure.itcanbeseenthatsamplea1isnanowire-likewithlengthofabout2μ
manddiameterofabout100nm.whentheamountof...is0.04g,themorphologyofsamplea2becametobeshortandthickrodsandthesizeisabout1μ
minlengthand400nmindiameter,respectively.withfurtherincreasingtheamountof...,thesamplea3anda4turnedtobesphericalmorphology.italsocanbeseenthatthediametersofsamplesa3anda4aresubs
tantiallythesameabout450nm.however,thesphericalmorphologyofa4ismoreregularthanthatofa3.
thexrdpatternsshowedfourreflectionpeaksattributedto(100),(110),(200)and(210),respectively,duetothehexagonalsructure. p12
then,wekeepthesameamountof...,increasingtheamountof....
wefoundthatthelengthincreasedgradually.thexrdpatternsalsoshowedthehexagonalsructureofsamplesb1,b2,b3,b4. p13
moreover,anadditionalproofofthehexagonalsymmetrystructureisgivenbytemandtheftpattern.then2adsorption-desorptionisothermsofthesamplesb1,b2,b3,b4exhibitatypicaltype-ivisotherm.
aordingtothetableofstructuralparameters,wecanfindthatthespecificsurfaceareaandtotalporevolumeincreasegradually,thethicknessofwalldecreaseandthereisnoobviouschangeindiameter. p14
furthermore,thepossiblesynthesismechanismofthemesoporoussil
icananotubeindualtemplatessystemwasproposed.wesuggestthatduetoelectrostaticrepulsionbetweenpositivelychargedammoniumionsfromhydratedammoniamoleculesandhydrophilicgroupsof...,especiallyinammonia(nh3,25wt.%)solution,thehighconcentratedammoniumionsprovideacrowdedandrepulsivespacetopreventtheconjunctionof...molecules,leadingtotheformationoftherod-likemicellesastemplatetoformporestructureinsteadofsphere-likeones.theroleofco-template...issuggestedtotunethelengthofrod-likemicellesbyarrangingitselfalongtheaxisofchannelwithpeoandppopartimmersedinthehydrophilicandthehydrophobicgroupofcta+respectively.asaresult,themesoporousnanotubewithdifferentlengthwillbesynthesized.however,thenon-polar...micellesarenotaffectedbypositivelychargedammonium.whentheamountofco-templateincreasedfurther,thenon-polar...micellestendtocontrolthemorphologyofmicelleswhicharesequentiallyfromnanotube,shortrodtosphere-likeones.itmybethereasonthatthenon-polar...micelleswouldprovidestrongerattractiveforcethantheelectrostaticrepulsionderivedfromthepeoblock,ammoniumionsandheadgroupof...,respectively. p15
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