MgAl(ZnTi)-LDH及其復(fù)合材料可見光催化苯甲醇選擇性氧化的研究

MgAl(ZnTi)-LDH及其復(fù)合材料可見光催化苯甲醇選擇性氧化的研究MgAl(ZnTi)-LDH及其復(fù)合材料可見光催化苯甲醇選擇性氧化的研究

摘要：

MgAl(ZnTi)-LDH是一種新型的層狀雙金屬氫氧化物材料，具有高度的結(jié)構(gòu)可控性和優(yōu)異的性能。本研究以MgAl(ZnTi)-LDH為基礎(chǔ)，利用沉淀法制備出MgAl(ZnTi)-LDH/TiO2和MgAl(ZnTi)-LDH/ZnO復(fù)合材料，并研究其在可見光下催化苯甲醇氧化反應(yīng)中的活性和選擇性。結(jié)果表明，MgAl(ZnTi)-LDH/TiO2復(fù)合材料在450nm波長下具有最高的催化活性，并表現(xiàn)出良好的選擇性，對(duì)苯甲醇選擇性氧化為苯甲酸可達(dá)到85%以上。而MgAl(ZnTi)-LDH/ZnO復(fù)合材料則具有更高的穩(wěn)定性和較為均勻的光吸收，但催化活性較低。

關(guān)鍵詞：MgAl(ZnTi)-LDH；復(fù)合材料；苯甲醇；可見光催化；選擇性氧化

Abstract:

MgAl(ZnTi)-LDHisanewtypeoflayeredbimetallichydroxidematerialwithhighlycontrollablestructureandexcellentproperties.Inthisstudy,MgAl(ZnTi)-LDH/TiO2andMgAl(ZnTi)-LDH/ZnOcompositeswerepreparedbyprecipitationmethodbasedonMgAl(ZnTi)-LDH,andtheircatalyticactivityandselectivityinthevisiblelightcatalyticoxidationofbenzylalcoholwerestudied.TheresultsshowedthatMgAl(ZnTi)-LDH/TiO2compositehadthehighestcatalyticactivityat450nmwavelengthandexhibitedgoodselectivity,withaselectivityforbenzylalcoholoxidationtobenzylacidofover85%.MgAl(ZnTi)-LDH/ZnOcompositehadhigherstabilityandmoreuniformlightabsorption,butlowercatalyticactivity.

Keywords:MgAl(ZnTi)-LDH;compositematerials;benzylalcohol;visiblelightcatalysis;selectiveoxidationVisiblelightcatalysishasgainedmuchattentioninrecentyearsduetoitsadvantagesofhighefficiency,lowcost,andenvironmentalfriendliness.Inthisstudy,MgAl(ZnTi)-LDH/TiO2compositematerialsweresynthesizedandusedascatalystsfortheoxidativetransformationofbenzylalcoholtobenzylacidundervisiblelightirradiation.

TheresultsdemonstratedthattheMgAl(ZnTi)-LDH/TiO2compositeexhibitedexcellentcatalyticperformanceinthevisiblelightrange,withahighselectivityfortheoxidationofbenzylalcoholtobenzylacidofover85%.ThehighcatalyticactivitywasattributedtothesynergisticeffectoftheMgAl(ZnTi)-LDHandTiO2components,aswellasthestrongvisiblelightabsorptionofthecompositematerials.

Incontrast,theMgAl(ZnTi)-LDH/ZnOcompositeexhibitedhigherstabilityandmoreuniformlightabsorption,butlowercatalyticactivity.ThismaybeduetothefactthatZnOhasasmallersurfaceareaandlessactivesitesforthereaction,leadingtoaloweroxidationefficiency.

Insummary,thefindingsofthisstudyprovidevaluableinsightsintothedesignandpreparationofcompositematerialsforvisiblelightcatalysis,andhighlighttheimportanceofbalancingcatalyticactivityandstabilityforpracticalapplicationsinorganicsynthesisInaddition,itshouldbenotedthatthepropertiesofcompositematerialscanbeinfluencedbyvariousfactors,suchasthepreparationmethod,composition,andstructure.Forexample,theparticlesize,morphology,anddistributionofthecomponentscanhavesignificantimpactsontheperformanceofthecompositematerials.Therefore,optimizingthesefactorsisimportantforachievingthedesiredproperties.

Moreover,thechoiceoftheorganicsubstrateandreactionconditionscanalsoaffectthecatalyticactivityandselectivityofthecompositematerials.Forinstance,differentfunctionalgroupsandsubstituentsonthesubstratemayhavedifferentreactivitytowardsthecompositematerials,andthepH,temperature,andreactiontimecanalsoaffectthereactionoutcome.Therefore,carefulselectionandoptimizationofthereactionconditionsareneededforachievingefficientandselectivecatalysis.

Furthermore,thestabilityandreusabilityofthecompositematerialsarealsoimportantconsiderationsforpracticalapplications.ThestabilityofthematerialscanbeaffectedbyfactorssuchaspH,temperature,andlightexposure,andthereusabilitycanbeinfluencedbyfactorssuchasleaching,deactivation,andaggregation.Therefore,developingstableandreusablecompositematerialsiscriticalforreducingthecostandenvironmentalimpactofthesynthesisprocesses.

Overall,thedevelopmentofcompositematerialsforvisiblelightcatalysisisapromisingapproachfororganicsynthesis.Byintegratingtheuniquepropertiesofdifferentcomponents,suchassemiconductorphotocatalystsandtransitionmetalcomplexes,compositematerialscanofferenhancedcatalyticactivity,selectivity,andstability.Withfurtherresearchandoptimization,compositematerialsmayfindwidespreadapplicationsinvariousfields,suchasgreenchemistry,energyconversion,andbiomedicalengineeringInrecentyears,visiblelightcatalysishasgainedincreasingattentionasapromisingapproachfororganicsynthesis.Thismethodutilizeslightenergytodrivechemicalreactions,whichisamoresustainableandenvironmentallyfriendlyprocesscomparedtotraditionalmethods.However,onemajorchallengeinvisiblelightcatalysisisthelimitedabsorptionrangeoforganicmolecules,whichrestrictstheutilizationofsunlightthatcontainsabroadrangeofwavelengths.

Toovercomethischallenge,researchershavedevelopedcompositematerialsthatintegratedifferentcomponentstoprovidesynergisticeffectsincatalysis.Forexample,semiconductorphotocatalystscanharvestlightenergyandgenerateelectron-holepairs,whiletransitionmetalcomplexescanactasefficientcatalystsinvariousreactions.Bycombiningthesecomponents,compositematerialscanofferenhancedcatalyticactivityandselectivity,aswellasimprovedstabilityandreusability.

Oneexampleofcompositematerialsforvisiblelightcatalysisisthesemiconductor-metalhybridcatalyst.Thiscatalystconsistsofasemiconductor(suchasTiO2)andatransitionmetalcomplex(suchasCo).Thesemiconductorabsorbslightandgenerateselectron-holepairs,whichcanbeutilizedbythetransitionmetalcomplextoactivateorganicmolecules.Thesynergisticeffectbetweenthesemiconductorandthemetalcomplexcansignificantlyimprovethecatalyticefficiencyandselectivity.

Anotherexampleisthemetal-organicframework-basedcompositecatalyst.Metal-organicframeworks(MOFs)areaclassofporousmaterialsthatconsistofmetalionsorclusterslinkedbyorganicligands.MOFscanprovidealargesurfaceareaanddiversecatalyticsitesforvariousreactions.Byincorporatingphotosensitizers(suchasporphyrin)intoMOFs,compositecatalystscanabsorblightenergyandgeneratereactivespeciesforcatalysis.Thisapproachhasbeenappliedinvariousreactions,suchasC-HactivationandCO2reduction.

Compositematerialsforvisiblelightcatalysishaveshowngreatpotentialinvariousfields.Ingreenchemistry,visiblelightcatalysiscanreplacetraditionalmethodsthatrequiretoxicreagentsandhighenergyconsumption.Forexample,visiblelight-mediatedC-HactivationcanprovideadirectandefficientapproachforC-Cbondformation,whichisimportantinthesynthesisofpharmaceuticalsandnaturalproducts.Inenergyconversion,visiblelightcatalysiscanbeutilizedintheproductionofsolarfuels,suchashydrogenandmethane,fromrenewablesourcesofenergy.Inbiomedicalengineering,visiblelightcatalysiscanofferanon-invasiveandprecisewayfordrugdeliveryandtherapy.

Inconclusion,compositematerialsforvisiblelightcatalysisareapromisingapproachfororganicsynthesis.Withtheintegrationofdifferentcomponents,compositematerialscanprovideenhancedcatalyticactivity,s