MOF衍生碳基材料的电催化应用及其先进表征技术.pdf

Cite this:NewCarbonMaterials,2024,39(1):78-99DOI:10.1016/S1872-5805(24)60828-0MOF-derived nanocarbon materials for electrochemical catalysis andtheir advanced characterizationCHENXi1,LIMing-xuan1,YanJin-lun1,ZhangLong-li1,2,*（1.College of Chemistry and Chemical Engineering,China University of Petroleum(East China),Qingdao 266580,China;2.State Key Laboratory of Heavy Oil Processing,China University of Petroleum(East China),Qingdao 266580,China）Abstract：Becauseofthedemandforcleanandsustainableenergysources,nanocarbons,modifiedcarbonsandtheircompositematerialsderivedfrommetal-organicframeworks(MOFs)areemergingasdistinctcatalystsforelectrocatalyticenergyconversion.ThesematerialsnotonlyinherittheadvantagesofMOFs,likecustomizabledopantsandstructuraldiversity,butalsoeffectivelypre-venttheaggregationofnanoparticlesofmetalsandmetaloxidesduringpyrolysis.Consequently,theyincreasetheelectrocatalyticef-ficiency,improveelectricalconductivity,andmayplayapivotalroleingreenenergytechnologiessuchasfuelcellsandmetal-airbatteries.ThisreviewfirstexploresthecarbonizationmechanismoftheMOF-derivedcarbon-basedmaterials,andthenconsiders3keyaspects:intrinsiccarbondefects,metalandnon-metalatomdoping,andthesynthesisstrategiesforthesematerials.Wealsoprovideacomprehensiveintroductiontoadvancedcharacterizationtechniquestobetterunderstandthebasicelectrochemicalcatalys-isprocesses,includingmappingtechniquesfordetectinglocalizedactivesitesonelectrocatalystsurfacesatthemicro-tonano-scaleandin-situspectroscopy.Finally,weofferinsightsintofutureresearchconcerningtheiruseaselectrocatalysts.Ourprimaryobject-iveistoprovideaclearerperspectiveonthecurrentstatusofMOF-derivedcarbon-basedelectrocatalystsandencouragethedevelop-mentofmoreefficientmaterials.Key words:MOFs；Nanocarbonmaterials；Electrochemicalcatalysis；Advancedcharacterizations1IntroductionMetal-organicframeworks(MOFs)are crystal-linematerialscomposedofself-assembledmetalionsor clusters with organic ligands12.In recent years,MOFshavefoundwidespreadapplicationsinvariousfieldssuchasgasadsorptionandseparation,catalysis,chemicalsensing,energystorageandconversionduetotheirperiodiccrystalstructure,structuralflexibility,tunableporetopology,highsurfacearea,andtailor-able properties39.Notably,Zheng et al.have dis-coveredthatthein-depthexploration,precisedesign,andefficientsynthesisofMOFscannowbeachievedthroughthecollaborationofGPT-4chemistsandhu-manresearchers,enhancing the feasibility and effi-ciencyofresearchactivities,thusacceleratingthepro-gressinMOFmaterials10.Furthermore,BASF,asagroundbreakingdevelopment,hasannounceditsposi-tionasthefirstglobalproducerofMOFsonascaleofseveralhundredtonsperyear.TheseMOFs,particu-larlyzinc-triazole-oxalate-basedMOF(CALF-20,de-velopedfromUniversityofCalgary),havebeende-signedforcarbondioxidestorageandcanalsoadsorbgreenhousegasmethane,makingindustrial-levelcar-boncapturepossible.Thissignificantachievement,aspublishedinthejournalScience,signifiesthetruein-dustrializationofMOFsandthesuccessfulenhance-mentofeconomicbenefits6.However,the presence of weak coordinationbetweenmetalnodesandorganicligandsinthemajor-ity of MOFs leads to issues such as low catalyticactivityandchallengesincatalystrecoveryunderde-mandingreaction conditions.These conditions in-cludeorganic/watersolvents,acidicoralkalineenvir-onments,andhightemperatures,whichhavelimitedthepracticalapplicationofMOFsinthefieldofelec-trocatalysis.Onanothernote,highconductivityisan-other critical requirement for MOFs when used aselectrocatalysts.Nonetheless,duetothepresenceoftypicalorganiclinkerssurroundingredox-activesites,MOFsoftenexhibitpoorconductivity,renderingtheminsulatingmaterials.Additionally,theelectronicinter-actionsbetweenmetalnodesandorganiclinkersfur-theraffecttheconductivityofMOFs11.Carbon-basedReceived date：2023-10-15；Revised date：2023-11-23Corresponding author：ZHANGLong-li,Professor.E-mail:Author introduction：CHENXi,Lecturer.E-mail：Homepage:http:/ in electrochemical reduction reac-tion,chemicalstability,cost-effectivenessandenvir-onmentalcompatibilityinresearchapplications.Fromeconomic and environmental perspectives,carbon-basednanomaterialsoffercertainadvantagesduetotheirabundantresourcesandeco-friendlynaturecom-paredtometal-basedcatalyticmaterials.Theseattrib-uteshavegarneredsignificantattentionforpotentialapplicationsacrossvariousdomainsforamultitudeofcarbon-basedmaterials.Thecarbonallotropefamilyprimarilyconstitutesofavast,periodicallyarrangedsp2lattice,forminganextensive-conjugatedsystemthatoffersenhancedthermalandelectricalconductiv-ity.Throughtheeffortsofnumerousscholars,modi-ficationstothelatticestructureofcarbon-basedma-terialshave been accomplished utilizing both cova-lentandnon-covalentmethods,alteringtheirintrinsicpropertiesandtailoringdesiredmaterialcharacterist-ics.Particularlyinoxygenreductionreaction(ORR)andoxygen evolution reaction(OER),typical elec-tron-demandingreactions,thedirectutilizationoftheinertelectronswithincarbon-basedmaterialsposessignificant challenges.Currently,the most directstrategyinvolves manipulating the electronic struc-tureofcarbon-basedmaterialcatalyststhroughthein-troductionofheteroatoms.Hence,thepreparationofnanoscale carbon-based derivatives from MOFs asprecursor materials offers an effective means toachievethesetargets.Overthepastdecade,remark-ableprogresshasbeenachievedinboththesynthesisstrategies and electrocatalytic activities of carbon-basedelectrocatalystsderivedfromMOFs1216.MOFsarerenownedfortheirorderedstructures,uniformcompositions,andrelativelyhighcarboncon-tent1617.Theyareconsideredappropriatesacrificialtemplates and metal precursors for the synthesis ofcarbonmaterials.Incomparisontoconventionalpor-ousmaterials,thesematerialsderivedfromMOFsof-tenexhibitarangeofuniqueadvantages.MOFscanbe transformed into carbon-based porous materialsthat exhibit greater stability than their precursorMOFs,retainingcharacteristicssuchasahighsurfacearea,structuraldiversityandabundantporosity.Thus,MOF-derivedmaterialsnotonlyoffertheadvantagesofporouscarbonbutalsoenhancethestabilityoftheparentMOFs.Additionally,theyexhibitgreaterresili-enceandrecyclabilityunderdemandingreactioncon-ditions.For ORR or OER,the metal ions/clusterswithinMOFsrepresentpotentiallywell-definedmetalactive centers.However,their poor conductivityseverelyhinderstheirORRcatalyticactivity.Toad-dressthisissue,thethermaldecompositionofMOFstopreparecarbon-basedcatalystshasproventobeaneffective solution.In the context of electrochemicalwatersplitting,MOFsareamongthebestsupportsys-temsforenhancingthecathodichydrogenevolutionreaction(HER)12.MOF-derived carbon compoundsnotonlyexhibitgoodconductivityandstabilitybutalso successfully maintain porosity while inheritingthesubstantialsurfaceareaoftheMOFprecursors18.Thestructureandsizeofthesematerialscanalsobemodifiedthroughcarefullyplannedsynthesisforop-timaluseinenergyapplications.Thus,continuousim-provementinthepreparationstrategiesforMOF-de-rivedmaterialsholdssignificantimplicationsfortheirapplicationinvariouscatalyticfields,contributingtothefutureofindustrialdevelopment.At present,several excellent reviews haveprovideddetaileddiscussionsregardingthemajorin-fluenceofcomposition,structure,ormorphologyonMOF-derived carbon-based materials in the field ofelectrocatalysis12,16.However,asystematicsummaryanddiscussionofadvancedcharacterizationmethodsspecific to these materials are currently lacking.Therefore,we hope that this review will assist re-searchers in gaining a quicker understanding of thelatestdevelopments in MOF-derived carbon elec-trocatalysts,designing and synthesizing higher-per-formanceelectrocatalysts,andgainingadeeperunder-standing of advanced characterization methods forMOF-derivedcarbon-basedmaterials.Inthisreview,we first discuss the carbonization mechanisms ofMOF-derived carbon-based materials.Subsequently,wefocusonpromotionstrategiesfrom3aspects(in-trinsiccarbon defects,metal and non-metal het-eroatomdoping)andsystematicallyintroducevariousadvanced characterization methods(in-situ mapping第1期CHENXietal:MOF-derivednanocarbonmaterialsforelectrochemicalcatalysisandtheir79and in-situ spectroscopy).Finally,we provide ourconclusions and prospects for future research onMOF-derivedcarbon-based materials as electrocata-lysts.This review aims to provide a clearer under-standingofthecurrentstatusofMOF-derivedcarbon-basedelectrocatalysts,offering insights into the ex-plorationofmoreefficientelectrocatalyticmaterials.2CarbonizationstrategiesMOFsexhibitawiderangeofcompositionsandstructuraltunability,renderingthemidealprecursorsforcraftingporouscarbonnanomaterials1719.Tocre-atethesematerials,MOFsaresubjectedtocarboniza-tion,involvingthepyrolysisofself-ligands,adsorbedorganic solvents,or guest molecules2021.This pro-cess involves inter-/intramolecular dehydrogenation,deoxygenation,polymerization,arylation and func-tional group carbonization,ultimately yielding nanocarbonmaterials2223.Commonpreparationmethodsincludepyrolysisorsolutionpermeationwithincon-trolledatmosphereslikeAr,N2,H2orair24.ThroughtherationaldesignofMOFsprecursorsandmeticu-louscontrolofthesynthesisprocess(e.g.gasenviron-ment,pyrolysis temperature,duration,heating rateandprecursoraddition),adiversearrayofmaterialsderivedfromMOFscanbeprepared2526.Thesema-terials often retain certain characteristics inheritedfromtheMOFsprecursors,suchasporesizes,mor-phology,compositionsandproperties2728.ThisbroadspectrumofMOFs-derivednanocarbonmaterialsen-compassescarbonquantumdots20,29,porouscarbons28,30,metal nanoparticles31,metal compo-unds32,andtheirvariousnanoscalecomposites3,7,33.MOFs-derivednanocarbonmaterialsofferkeyadvant-ages:(1)Diversityandtunability:Theyleveragethevaried metal ions and organic ligands found inMOFs3,34.(2)Preservation of porous and orderedstructures:Theordered,porousMOFstructureeffect-ively prevents metal nanoparticle formation duringpyrolysis and the creation of metal oxides19,26.(3)Simplepreparation:MOFsareeasilypreparedundermild conditions,exemplified by ZIF-67,ZIF-8 andHKUST-1,whichcanbesynthesizedatroomtemper-ature and ambient pressure14,35.The utilization ofnanocarbonmaterials derived from MOFs in elec-trocatalysispresents several advantages:(1)En-hancedactivesites3536:Carefulcontrolofnanocar-bonmaterialmorphologyandporosityincreasesthenumber of exposed active sites,thereby enhancingelectrocatalyticefficiency.(2)Improvedmetaldisper-sion3738:The coordination environment betweenmetal ions and ligands in MOFs ensures well-dis-persedmetalsincarbonnanomaterialsboostingutiliz-ation efficiency.(3)Heteroatom introduction3940:The incorporation of heteroatoms makes doped-car-bonmaterials more receptive to well-defined het-eroatomfunctionalgroups,customizedpolarity,andinherent redox-active sites.The synthesis strategiesoutlinedinthispaperforMOFs-derivedcarbonnanomaterialscanbecategorizedinto3keyaspects.2.1 Direct pyrolysisThis is the simplest method to prepare porouscarbonmaterialsbydirectpyrolysisofMOFsprecurs-ors14,40.Theactivatedcarbonproducedbythismeth-odhasanorderedporestructurecomparedtocom-mercialactivatedcarbon.Forthepreparationofmetal-freecarbon,theMOFsprecursorsaregenerallysub-jectedtohigh-temperaturecarbonizationunderanin-ertatmosphere(e.g.,Ar,N2),whichleadstothede-composition of the organic skeleton,and the metalspeciescansubsequentlyberemovedbyin-situevap-orationoracidetching,andtheremovalofthemetalspecies increases the specific surface area and porevolumeofthematerial7,14.Forexample,Zhangetal14.synthesizednitrogen-dopedgraphiticporouscarbons(NGPCs)byusingazeolite-typenano-metallicorgan-ic skeleton(ZIF-8)as a self-sacrificing template,which was directly subjected to a high-temperaturecarbonizationprocessunderaninertN2atmosphere,followedbyfurtherremovalofmetalliczincparticlesbyacid etching,and consequently the ligand im-idazoleusedintheMOFactedasbothacarbonsourceand nitrogen source in the carbonization process(Fig.1a,b).Asshownbythetransmissionelectronmicroscope(TEM)images,the NGPCs retained thenanopolyhedral morphology of the parent ZIF-880新型炭材料（中英文）第39卷(Fig.1c-e),andhadabundantnitrogen,highspecificsurfaceareaandhierarchicalporositywithgoodelec-tricalconductivitynetwork,whichhasgreatpotentialas metal-free electrocatalysts for the ORR in fuelcells.Lietal30.usedZIF-67asaprecursortocontrolthe formation of high graphitized carbon shell-en-closedmesoporousmaterial(CN)frominsitu-gener-atedConanoparticlesthroughacidetchingbyadjust-ingthecalcinationtemperature,whichexhibitedex-cellentcatalyticperformanceintheaerobicoxidationofcyclohexaneandtolueneaswellasintheoxidativecouplingreactionofamineandimine.2.2 Co-pyrolysisDuetothelowcarboncontentinsomeMOFsortheanisotropic contraction during pyrolysis,the de-rivedcarbonporesmayswellorshowthephenomen-on of cavity collapse,and the direct pyrolysis ofMOFsformsalimitednumberofactivecentersforcatalysts7.In order to maintain the stability of theporestructure,theco-pyrolysisofMOFsastemplat-ingagentswithdifferentcarbonsourcescanbeusedtopreparecarbonmaterialswithhighspecificsurfacearea,homogeneousparticlesizesandgoodmorpho-logy.TheincorporationofguestspeciesintoMOFsfollowed by pyrolysis as an effective strategy is ofgreatinterestthepreparationofMOF-derivedporousmaterials11,28.The most commonly used externallyaddedcarbonsourceinthecarbonizationprocessofMOFsisfurfurylalcohol(FA),andthepolymeriza-tionofFAinMOFswiththelossofweightinthepyrolysisprocesscanleadtothederivationofporousstructures(Fig.1f).Liuetal17.subjectedFA/MOF-5compositestolow-temperature(98%after500cyclesat1C,withacommercial-gradereversiblecapacity of 2.3 mAh cm2.An SEM image of thecross-section of the HAGO/CoCN material isshowninFig.2d,whichshowsahierarchicalstruc-tureofhorizontallyalignedGO/CoCNnanosheetswithgapsbetweenneighboringGO/CoCNlayersofabout 20 m.The selected area electron diffraction(SAED)(Fig.2e)coincidewellwiththelatticeplanesofCo(111),(200),(220)andgraphiticcarbon(002).Itcan be expected that the HAGO/CoCN elec-trodeswillexposeadditionalactivesitesandthusim-prove the electrochemical performance.In addition,differentstructuresandpropertiesofcarbonnanoma-terial derivatives can be obtained by regulating thepyrolysistemperatureandatmosphere.Zhangetal34.foundthat similar ZIF-67/GO composites can pro-duce the three-dimensional porous hybrid materialCoN-HCCsNG by using the low-temperature(a)(f)(g)(i)(j)(d)(e)Co(220)Co(111)Co(200)C(002)(h)(b)(c)GO/CoCN electrodeHAGO/CoCN electrodeGO/CoCNGO/CoCNelectrodeevaporation80 CGOCCNHollow carbonnanocapsuleCo nanoparticleCoN-HCCsNGCarbonizationAcid etchingZIF-67ZIF-67/GOGO/ZIF-67Commercial GOLimited iontransportUnstablestructureZIF-67ZIF-67CoCNRandomly aligned sheetsHorizontally aligned sheetsRapid iontransportStrongstructureLi+Deposition600 CAnnealing100 m2 1/nm50 nm100 nm5 nm5 1/nm(200)(002)(111)Channel0.34 nmC(002)Fig.2(a)SyntheticprocessoftheGO/ZIF-67compositesandGO/CoCNnanosheets.(b)RandomlyalignedGO/CoCNnanosheetswithelectrode.(c)HorizontallyalignedGO/CoCNnanosheetswithelectrode.(d)Thecross-sectionalSEMimageand(e)SAEDpatternoftheHAGO/CoCNelectrodes19.R