材料化学翻译

第1页共9页JournalofMaterialsChemistryA材料化学杂志PAPERViewArticleOnlineViewJournal|ViewIssueSynthesisandlithium-storagepropertiesofMnO/reducedgrapheneoxidecompositesderivedfromgrapheneoxideplusthetransformationofMn(VI)toMn(II)bythereducingpowerofgrapheneoxide一氧化锰的合成和锂存储特性减少了氧化石墨烯的复合材料，而后者源于氧化石墨烯以及Mn（VI)转化Mn(II)过程中，通过降低氧化石墨烯能量生出的转化物Inthisreport,anovelmethodisproposedtoprepareMnO/reducedgrapheneoxide(rGO)compositesviacalciningtheprecursors(i.e.d-MnO2/grapheneoxidecomposites)at500CinArusingnoexternalreducinggas,inwhichgrapheneoxide(GO)successfullyservesasareductantbyreleasingCOduringitsthermolysisforthefirsttime.BycontrollingtheinitialratiosofGOtoKMnO4,differentlycomposedprecursorscanbeobtainedviatheredoxreactionbetweenGOandKMnO4,thenleadingtotheformationofcompositeswithdifferentMnO/rGOratiosanddispersionofMnOontherGOsurface(denotedasMGC1andMGC2).Whenappliedasanactivematerialinlithiumionbatteries,MGC1showsexcellentcyclingperformanceandcapacityretention.Under100and200mAg-1,MGC1coulddeliverreversiblecapacitiesashighas900and750mAhg1,respectively,aftermorethan100cycles.Consideringthesimpleoperationandlowenergyconsumptioninthewholematerialsynthesisprocesses,thepresentstrategyisfeasibleandeffectiveforpracticalapplication.Evenmoreimportantly,thereductibilityofgrapheneoxideuponthermolysisisutilizedforthefirsttime,whichismeaningfulforitsextensioninsynthesisoffunctionalnanomaterials.在这份报告中，提出了制备一氧化锰/还原氧化石墨烯复合材料的一种新方法，.通过在氩气中，500℃的条件下使用没有外部的还原性气体，煅烧前驱体（i.e.d-二氧化锰/氧化石墨烯复合材料）,在此过程中，氧化石墨烯完全可以胜任还原剂的功能，首次热解，释放一氧化碳..控制氧化石墨烯（GO）和KMnO4的初始比KMnO4，通过氧化石墨烯（GO）和KMnO4氧化还原反应获得不同组成的前体，形成的复合材料具有不同MnO/rGO比率和MnO，rGO表面不同的色散(用MGC1和MGC2表示)。当应用于锂离子电池的活性材料时，MGC1具有优异的循环性能和容量保持率。在100和200mAg-1下，MGC1可以提供可逆容量高达900和750mAhg-1，分别在100次以上。考虑到在整个材料合成工艺操作简单、能耗低，目前的策略是可行的和有效的实际应用。更重要的是，氧化石墨烯对热解还原是首次利用，这是其在功能纳米材料的合成延伸意义。Withtheincreasingpowerandenergydemandinportableelectronicvehiclesanddevices,greatefforthasbeenmadeindevelopingnewhigh-performanceelectrodematerialsforhigh-powerrechargeablelithium-ionbatteries(LIBs).1–5Transitionmetaloxides,suchasSnO2,6–8TiO2,9MoOx,10,11andMnO2,12,13havebeenwidelystudiedasanodematerialsinLIBssincerstproposedin2000byPoizotetal.14Amongthesetransitionmetaloxides,manganeseoxides(MnOx)wereapromisingcandidateseriesbecauseoftheirrelativelylowthermodynamicequilib-riumvoltageversusLi/Li+,15–17andlowelectromotiveforce,18–20aswellastheirenvironmentalbenignityandlowcost.However,therearestillseveraldrawbackssuchas:(1)thelargevolumechangeandgradualagglomerationofmetalgrains21,22duringthedischarge/chargereactionand(2)intrinsicallylowelec-tronicconductivity,bothofwhichresultintherapidfadingofcapacitiesduringthecyclingprocess.23Toovercomethesechallenges,manyresearchstudieswerefocusedontheincor-porationofcarbonnanomaterialssuchascarbonnano-tubes24–26andcarbonnanobers27intoMnOxtosuppressthepulverizationandcapacityfading.随着便携式电子车辆和设备对功率和能源的需求，努力开发新的高性能的电极材料为高功率可充电的锂离子电池（LIBS）。一些过渡金属氧化物，如SnO2，MoOx，和MnO2，在作为锂离子电池的阳极材料被广泛研究，锰氧化物（MnOx）是一种很有前途的候选系列,因为其相对于Li/Li+相对较低的热力学平衡电压，和低电势，以及其环境友好、成本低。然而，仍有一些缺点如：（1）大的体积变化和充放电反应过程中金属颗粒逐渐集聚，（2）本质上低的电子电导率，这两者导致在循环过程中迅速衰败的能力，第2页共9页为克服这些挑战，许多研究都集中在碳纳米材料如把碳纳米管和碳纳米纤维加到MnOx中抑制粉化和容量衰减.Afterthediscoveryofgra-phene,muchinterestwaspaidtographene/MnOxnano-compositesforLIBswithhighcapacityandlong-life.23,28–30However,manyofthesecompositesweresynthesizedundersevereconditionsandusuallyneededhighercostforcalcina-tion.Forexample,inSunetal.'sreport,bymixingMn(CH3-COO)2andGOsolutions,andaddinghydrazinehydrate,aMn-precursor/grapheneintermediatewasobtained,whichwasthenannealedat500Cina5%H2/Aratmospherefor5htoobtainthenalMnO/graphenecomposite.31AsimilarstrategywasusedforaN-dopedMnO/graphenehybridbycalciningaprecursor,i.e.Mn3O4/graphene,at800℃for5hunderaNH3atmosphere.32InQian'sgroup,theprecursorsMnOOHnano-wireswererstsynthesizedthroughahydrothermalprocedureandaerthefollowingcalcinationinair,Mn2O3nanowireswereobtained.ThefinalMnO@Ccore–shellnanowireswereproducedbyexposingtheseMn2O3nanowirestoargonandanacetylene/argongasmixtureat500℃.石墨烯被发现后，更多的关注放在石墨烯/氧化锰纳米复合材料具有高容量、长寿命的锂离子电池上。然而，这些复合材料的合成需要在苛刻条件下，通常需要更高的成本。例如，在太阳等人的报告，通过混合Mn(CH3-COO)2和氧化石墨烯来解决，加入水合肼，Mn前驱体/石墨烯得到中间物，然后在500℃5%H2／Ar气流中煅烧5小时得到复合材料，类似的方法被用于掺杂一氧化锰/石墨烯混合煅烧前驱体获得最终的一氧化锰/石墨烯复合材料，即Mn3O4/石墨烯，在800℃5h下氨气流中.在前组，前体MnOOH纳米线首先通过水热法合成了33和一个二以下在空气中煅烧，得到纳米三氧化二锰。最后的MnO@C核壳纳米线的–暴露这些Mn2O3纳米线在500℃时在氩气和乙炔/氩气混合气体中产生.Differentfrommanyofthereportedstudies,wehereinintroduceMnO/rGOcompositesviaaquitedifferentsynthesisapproach.Asreportedinmanypublications,34,35theoreticalandexperimentalproofhasprovedthatthermalreductionofgrapheneoxidewouldreleaseCOandCO2,andtheCO–CO2ratiosweredependentonthethermalconditions.Therefore,inthiswork,wetriedtoutilizethereductiveCOreleasedfromGOtoinsitureduceMnO2intheMnO2/GOcompositestoobtainMnO/rGOcompositeswithoutusinganyexternalreductivegases,suchasH2andCO,whichmakesthesynthesisprocesswithlesscostandmoresafety.Whatismoreimportant,GOisutilizedasasolidreductantforthefristtimeandthisvaluablendingwillarousemuchinterestintheGOresearchformaterialsynthesis.不同于许多研究报道,我们这里介绍MnO/rGO复合材料通过一个完全不同的合