Cobalt nanoparticles encapsulated in nitrogen-doped carbon for room-temperature selective hydrogenation of nitroarenes

Article abstract of DOI:10.1016/S1872-2067(17)62988-7

Here, we report cobalt nanoparticles encapsulated in nitrogen-doped carbon (Co@NC) that exhibit excellent catalytic activity and chemoselectivity for room-temperature hydrogenation of nitroarenes. Co@NC was synthesized by pyrolyzing a mixture of a cobalt

Full text of DOI:10.1016/S1872-2067(17)62988-7

ChineseꢀJournalꢀofꢀCatalysisꢀ39ꢀ(2018)ꢀ664–672
ꢀ
ꢀ ꢀ ꢀ
ꢀ ꢀ ꢀ ꢀ
a v a i l a b l e a t w w w . s c i e n c e d i r e c t . c o m
ꢀ
j o u r n a l h o m e p a g e : w w w . e l s e v i e r . c o m / l o c a t e / c h n j c
ꢀ
ꢀ
Article (Special Issue on Environmental and Energy Catalysis)
Cobaltꢀnanoparticlesꢀencapsulatedꢀinꢀnitrogen‐dopedꢀcarbonꢀforꢀ
room‐temperatureꢀselectiveꢀhydrogenationꢀofꢀnitroarenesꢀ
a,b
a,b
a
a,b
a,b
a,b,
RuijieꢀGaoꢀ ,ꢀLunꢀPanꢀ ,ꢀZhengwenꢀLiꢀ ,ꢀXiangwenꢀZhangꢀ ,ꢀLiꢀWangꢀ ,ꢀJi‐JunꢀZouꢀ *
ꢀ
aꢀKeyꢀLaboratoryꢀforꢀGreenꢀChemicalꢀTechnologyꢀofꢀtheꢀMinistryꢀofꢀEducation,ꢀSchoolꢀofꢀChemicalꢀEngineeringꢀandꢀTechnology,ꢀTianjinꢀUniversity,ꢀTianjinꢀ
00072,ꢀChinaꢀ
bꢀCollaborativeꢀInnovativeꢀCenterꢀofꢀChemicalꢀScienceꢀandꢀEngineeringꢀ(Tianjin),ꢀTianjinꢀ300072,ꢀChinaꢀ
3
A R T I C L E ꢀ I N F O ꢀ
A B S T R A C T ꢀ
Articleꢀhistory:ꢀ
Here,ꢀweꢀreportꢀcobaltꢀnanoparticlesꢀencapsulatedꢀinꢀnitrogen‐dopedꢀcarbonꢀ(Co@NC)ꢀthatꢀexhibitꢀ
excellentꢀ catalyticꢀ activityꢀ andꢀ chemoselectivityꢀ forꢀ room‐temperatureꢀ hydrogenationꢀ ofꢀ ni‐
troarenes.ꢀCo@NCꢀwasꢀsynthesizedꢀbyꢀpyrolyzingꢀaꢀmixtureꢀofꢀaꢀcobaltꢀsalt,ꢀanꢀinexpensiveꢀorganicꢀ
molecule,ꢀ andꢀ carbonꢀ nitride.ꢀ Usingꢀ theꢀ Co@NCꢀ catalyst,ꢀ aꢀ turnoverꢀ frequencyꢀ ofꢀ ~12.3ꢀ h ꢀ andꢀ
selectivityꢀforꢀ4‐aminophenolꢀofꢀ>99.9%ꢀwereꢀachievedꢀforꢀhydrogenationꢀofꢀ4‐nitrophenolꢀatꢀroomꢀ
Receivedꢀ29ꢀNovemberꢀ2017ꢀ
Acceptedꢀ22ꢀDecemberꢀ2017ꢀ
Publishedꢀ5ꢀAprilꢀ2018ꢀ
−1
temperatureꢀandꢀ10ꢀbarꢀH ꢀpressure.ꢀTheꢀexcellentꢀcatalyticꢀperformanceꢀcanꢀbeꢀattributedꢀtoꢀtheꢀ
2
Keywords:ꢀ
cooperativeꢀeffectꢀofꢀhydrogenꢀactivationꢀbyꢀelectron‐deficientꢀCoꢀnanoparticlesꢀandꢀenergeticallyꢀ
preferredꢀadsorptionꢀofꢀtheꢀnitroꢀgroupꢀofꢀnitroarenesꢀtoꢀelectron‐richꢀN‐dopedꢀcarbon.ꢀInꢀaddition,ꢀ
thereꢀisꢀelectronꢀtransferꢀfromꢀtheꢀCoꢀnanoparticlesꢀtoꢀN‐dopedꢀcarbon,ꢀwhichꢀfurtherꢀenhancesꢀtheꢀ
functionalityꢀ ofꢀ theꢀ metalꢀ centerꢀ andꢀ carbonꢀ support.ꢀ Theꢀ catalystꢀ alsoꢀ exhibitsꢀ stableꢀ recyclingꢀ
performanceꢀandꢀhighꢀactivityꢀforꢀnitroaromaticsꢀwithꢀvariousꢀsubstituents.ꢀ
Cobaltꢀnanoparticleꢀ
Nitrogen‐dopedꢀcarbonꢀ
Nitroarenesꢀ
Selectiveꢀhydrogenationꢀ
Hydrogenꢀactivationꢀ
Heterogeneousꢀcatalysis
©ꢀ2018,ꢀDalianꢀInstituteꢀofꢀChemicalꢀPhysics,ꢀChineseꢀAcademyꢀofꢀSciences.
PublishedꢀbyꢀElsevierꢀB.V.ꢀAllꢀrightsꢀreserved.
1
.ꢀ ꢀ Introductionꢀ
conditionsꢀ [5–13].ꢀ However,ꢀ noble‐metal‐freeꢀ catalystsꢀ areꢀ
preferredꢀinꢀindustryꢀbecauseꢀofꢀtheirꢀlowꢀcostꢀandꢀabundance.ꢀ
Inꢀ thisꢀ case,ꢀ transition‐metal‐ꢀ [14–22]ꢀ andꢀ carbon‐basedꢀ
[23–28]ꢀcatalystsꢀshowꢀpotentialꢀforꢀselectiveꢀhydrogenationꢀofꢀ
nitrobenzene,ꢀ butꢀ theyꢀ sufferꢀ fromꢀ lowꢀ activityꢀ andꢀ requireꢀ
harshꢀreactionꢀconditions.ꢀToꢀachieveꢀhighꢀactivityꢀandꢀselectiv‐
Selectiveꢀ hydrogenationꢀ ofꢀ nitroarenesꢀ isꢀ aꢀ promisingꢀ ap‐
proachꢀ toꢀ produceꢀ aromaticꢀ aminesꢀ andꢀ aminocyclohexanesꢀ
1,2].ꢀAromaticꢀaminesꢀareꢀimportantꢀbulkꢀchemicalsꢀinꢀmanyꢀ
[
fields,ꢀ includingꢀ productionꢀ ofꢀ fineꢀ chemicals,ꢀ commercialꢀ
products,ꢀandꢀ polymersꢀ[3,4].ꢀ Alongꢀwithꢀtheꢀ productsꢀofꢀhy‐
drogenationꢀ ofꢀ theꢀ nitroꢀ groups,ꢀ someꢀ byproductsꢀ areꢀ alsoꢀ
produced,ꢀsuchꢀasꢀnitrosoꢀandꢀazoꢀcompounds.ꢀForꢀsubstitutedꢀ
nitroarenesꢀ withꢀ reducibleꢀ groupsꢀ (e.g.,ꢀ –Cl,ꢀ –C=O,ꢀ andꢀ –CHOꢀ
groups),ꢀ selectiveꢀhydrogenationꢀofꢀtheꢀnitroꢀ groupꢀisꢀ aꢀgreatꢀ
challenge.ꢀNoble‐metal‐basedꢀcatalystsꢀhaveꢀbeenꢀusedꢀforꢀtheꢀ
chemicalꢀtransformationꢀofꢀnitrobenzeneꢀtoꢀaniline,ꢀandꢀexcel‐
lentꢀselectivitiesꢀandꢀactivitiesꢀhaveꢀbeenꢀachievedꢀunderꢀmildꢀ
ityꢀ underꢀ mildꢀ conditions,ꢀ bothꢀ theꢀ H
ꢀ moleculesꢀ andꢀ nitroꢀ
2
groupsꢀ mustꢀ beꢀ effectivelyꢀ activated,ꢀ whichꢀ isꢀ difficultꢀ toꢀ
achieveꢀwithꢀaꢀcatalystꢀcontainingꢀonlyꢀaꢀsingleꢀtypeꢀofꢀactiveꢀ
site.ꢀ
Forꢀbifunctionalꢀcatalystsꢀcomposedꢀofꢀaꢀcarbon‐basedꢀma‐
terialꢀ loadedꢀ withꢀ aꢀ transition‐metal‐basedꢀ catalyst,ꢀ theꢀ sup‐
portꢀmaterialꢀcanꢀnotꢀonlyꢀconfineꢀtheꢀmetalꢀatoms,ꢀbutꢀitꢀcanꢀ
alsoꢀmodifyꢀtheꢀelectronicꢀenvironmentꢀofꢀtheꢀmetalꢀnanoparti‐
*
ꢀCorrespondingꢀauthor.ꢀTel/Fax:ꢀ+86‐22‐27892340;ꢀE‐mail:ꢀjj_zou@tju.edu.cnꢀ
ThisꢀworkꢀwasꢀsupportedꢀbyꢀtheꢀNationalꢀNaturalꢀScienceꢀFoundationꢀofꢀChinaꢀ(U1462119)ꢀandꢀtheꢀTianjinꢀMunicipalꢀNaturalꢀScienceꢀFoundationꢀ
16JCQNJC05200).ꢀ
DOI:ꢀ10.1016/S1872‐2067(17)62988‐7ꢀ|ꢀhttp://www.sciencedirect.com/science/journal/18722067ꢀ|ꢀChin.ꢀJ.ꢀCatal.,ꢀVol.ꢀ39,ꢀNo.ꢀ4,ꢀAprilꢀ2018ꢀ ꢀ ꢀ
(

ꢀ
RuijieꢀGaoꢀetꢀal.ꢀ/ꢀChineseꢀJournalꢀofꢀCatalysisꢀ39ꢀ(2018)ꢀ664–672ꢀ
665ꢀ
clesꢀ (inꢀ aꢀ wayꢀsimilarꢀtoꢀhomogeneousꢀcatalystsꢀ withꢀorganicꢀ
ligands),ꢀ whichꢀ increasesꢀ theꢀ catalyticꢀ activity.ꢀ Recently,ꢀ
earth‐abundantꢀ metalsꢀ (e.g.,ꢀ Co)ꢀ haveꢀ beenꢀ usedꢀ forꢀ hydro‐
genationꢀofꢀnitrobenzeneꢀ[14,20].ꢀReducedꢀcobaltꢀcanꢀactꢀasꢀaꢀ
hydrogenꢀ acceptorꢀowingꢀtoꢀtheꢀelectron‐deficientꢀ stateꢀofꢀitsꢀ
surface,ꢀ whichꢀ promotesꢀ cleavageꢀ ofꢀ H–Hꢀ bonds.ꢀ However,ꢀ itꢀ
suffersꢀfromꢀlowꢀchemoselectivityꢀbecauseꢀofꢀcoadsorptionꢀofꢀ
twoꢀorꢀmoreꢀnitroarenes.ꢀInꢀthisꢀcase,ꢀcatalyticꢀcouplingꢀofꢀazoꢀ
compoundsꢀcanꢀoccur.ꢀHeteroatom‐dopedꢀcarbonꢀwithꢀanꢀad‐
justableꢀelectronꢀstructureꢀandꢀchemicalꢀstabilityꢀcanꢀstabilizeꢀ
metalꢀnanoparticlesꢀ[29–33].ꢀDopingꢀNꢀatomsꢀintoꢀtheꢀcarbonꢀ
matrixꢀcanꢀcauseꢀchargeꢀdelocalizationꢀ[34–36]ꢀandꢀaꢀhighꢀpos‐
itiveꢀchargeꢀdensityꢀonꢀtheꢀcarbonꢀatomsꢀnextꢀtoꢀtheꢀdopedꢀNꢀ
atoms,ꢀwhichꢀareꢀbeneficialꢀforꢀadsorptionꢀofꢀcompoundsꢀcon‐
tainingꢀaꢀnitroꢀgroup.ꢀN‐dopedꢀcarbonꢀhasꢀbeenꢀusedꢀasꢀaꢀcata‐
lystꢀ forꢀ hydrogenationꢀ ofꢀ nitrobenzeneꢀ becauseꢀ ofꢀ theꢀ strongꢀ
interactionꢀ betweenꢀ nitrobenzeneꢀ andꢀ carbonꢀ catalystsꢀ [37],ꢀ
atmosphere,ꢀandꢀmaintainedꢀatꢀthisꢀtemperatureꢀforꢀ2ꢀh.ꢀTheꢀ
as‐obtainedꢀblackꢀsolidꢀsamplesꢀwereꢀusedꢀforꢀcharacterizationꢀ
andꢀ theꢀ catalyticꢀ reactions.ꢀ Toꢀ furtherꢀ investigateꢀ theꢀ roleꢀ ofꢀ
N‐dopedꢀcarbon,ꢀCo@Cꢀwasꢀpreparedꢀbyꢀtheꢀconventionalꢀim‐
pregnationꢀmethodꢀusingꢀcommercialꢀcarbonꢀ(VX720R)ꢀasꢀtheꢀ
support.ꢀPureꢀN‐dopedꢀcarbonꢀwasꢀalsoꢀsynthesizedꢀbyꢀpyroly‐
sisꢀofꢀg‐C N .ꢀ
3 4
2.2.ꢀ ꢀ Characterizationꢀ
Transmissionꢀ electronꢀ microscopyꢀ (TEM)ꢀ wasꢀ performedꢀ
withꢀaꢀTecnaiꢀG2ꢀF20ꢀtransmissionꢀelectronꢀmicroscopeꢀatꢀ200ꢀ
kV.ꢀ Theꢀ crystalꢀ structuresꢀ wereꢀ determinedꢀ byꢀ aꢀ RigaKuꢀ
D/max‐2500ꢀX‐rayꢀdiffractometerꢀ(XRD)ꢀequippedꢀwithꢀaꢀCuꢀK ꢀ
α
irradiationꢀ source.ꢀ Elementalꢀ analysisꢀ wasꢀ performedꢀ withꢀ aꢀ
VarioꢀELꢀCubeꢀequippedꢀwithꢀaꢀMETTLERꢀx86ꢀinstrument.ꢀTheꢀ
elementalꢀcompositionꢀandꢀbondingꢀinformationꢀwereꢀobtainedꢀ
byꢀX‐rayꢀphotoelectronꢀspectroscopyꢀ(XPS)ꢀatꢀaꢀpassꢀenergyꢀofꢀ
187.85ꢀ eVꢀ (Physicalꢀ Electronicsꢀ PHIꢀ 1600ꢀ ESCAꢀ XPSꢀ systemꢀ
butꢀitsꢀactivityꢀisꢀstillꢀveryꢀlowꢀowingꢀtoꢀitsꢀpoorꢀabilityꢀforꢀH
ꢀ
2
activation.ꢀ Metalꢀ catalystsꢀ canꢀ alsoꢀ beꢀ activatedꢀ byꢀ car‐
bon‐nitride‐basedꢀmaterialsꢀ[38–40],ꢀwhereꢀtheꢀ electronꢀden‐
usingꢀaꢀmonochromatedꢀAlꢀK ꢀX‐rayꢀsource)ꢀusingꢀtheꢀCꢀ1sꢀpeakꢀ
α
sityꢀofꢀtheꢀmetalꢀcentersꢀchangesꢀbecauseꢀin‐latticeꢀNꢀatomsꢀactꢀ
asꢀelectron‐acceptingꢀgroups.ꢀTherefore,ꢀusingꢀN‐dopedꢀcarbonꢀ
asꢀaꢀsupportꢀforꢀmetal‐basedꢀnanocatalystsꢀisꢀexpectedꢀtoꢀen‐
hanceꢀtheirꢀcatalyticꢀactivity.ꢀ
atꢀ 284.6ꢀ eVꢀ asꢀ theꢀ internalꢀ standard.ꢀ Theꢀ nitrogenꢀ adsorp‐
tion–desorptionꢀisothermsꢀwereꢀdeterminedꢀwithꢀaꢀASAPꢀ2020ꢀ
physisorptionꢀanalyzerꢀatꢀ–196ꢀ°C,ꢀandꢀtheꢀspecificꢀsurfaceꢀare‐
asꢀ wereꢀ calculatedꢀ byꢀ theꢀ conventionalꢀ Brunauer–Emmett–
ꢀ
Inspiredꢀbyꢀtheꢀaboveꢀfindings,ꢀweꢀdevelopedꢀaꢀsynergeticꢀ
catalystꢀ composedꢀ ofꢀ Coꢀ nanoparticlesꢀ encapsulatedꢀ inꢀ
N‐dopedꢀcarbonꢀ(Co@NC)ꢀforꢀroom‐temperatureꢀselectiveꢀhy‐
drogenationꢀ ofꢀ nitroarenes.ꢀ Theꢀ N‐dopedꢀ carbonꢀ andꢀ cobaltꢀ
centerꢀplayꢀrolesꢀinꢀpreferentialꢀadsorptionꢀofꢀnitroareneꢀandꢀ
Tellerꢀ (BET)ꢀ method.ꢀ Theꢀ poreꢀ sizeꢀ distributionꢀ inꢀ theꢀ meso‐
poreꢀ rangeꢀ wasꢀ determinedꢀ byꢀ theꢀ Barrett–Joyner–Halendaꢀ
method.ꢀBeforeꢀperformingꢀtheꢀmeasurements,ꢀallꢀtheꢀsamplesꢀ
wereꢀ outgassedꢀ underꢀ vacuumꢀ atꢀ 200ꢀ °Cꢀ forꢀ 12ꢀ hꢀ untilꢀ theꢀ
pressureꢀwasꢀlessꢀthanꢀ0.66ꢀPa.ꢀTheꢀFourierꢀtransformꢀinfraredꢀ
spectroscopyꢀ(FTIR)ꢀspectraꢀwereꢀrecordedꢀwithꢀaꢀBioRadꢀFTSꢀ
6000ꢀspectrometer.ꢀRamanꢀspectroscopyꢀwasꢀperformedꢀwithꢀaꢀ
Ramanꢀ spectrometerꢀ (DXRꢀ Microscope)ꢀ usingꢀ aꢀ greenꢀ semi‐
conductorꢀlaserꢀ(532ꢀnm)ꢀasꢀtheꢀexcitationꢀsource.ꢀ
H
ꢀactivation,ꢀsoꢀtheirꢀsynergeticꢀeffectꢀleadsꢀtoꢀexcellentꢀactiv‐
2
ityꢀ andꢀ selectivity.ꢀ Theꢀ Co@NCꢀ catalystsꢀ wereꢀ synthesizedꢀ byꢀ
calciningꢀ aꢀ mixtureꢀ ofꢀ aꢀ cobaltꢀ salt,ꢀ anꢀ inexpensiveꢀ organicꢀ
molecule,ꢀandꢀcarbonꢀnitride.ꢀTheꢀoptimizedꢀCo@NC‐1ꢀcatalystꢀ
showsꢀ excellentꢀ activityꢀ andꢀ selectivityꢀ atꢀ roomꢀ temperature,ꢀ
whichꢀcannotꢀbeꢀachievedꢀusingꢀbareꢀN‐dopedꢀcarbonꢀorꢀpris‐
tine‐carbon‐supportedꢀCoꢀnanoparticleꢀcatalysts.ꢀ
2.3.ꢀ ꢀ Catalyticꢀhydrogenationꢀofꢀnitroarenesꢀ
Hydrogenationꢀwasꢀperformedꢀinꢀaꢀ50‐mLꢀautoclaveꢀwithꢀaꢀ
polytetrafluoroethyleneꢀ liningꢀ usingꢀ 0.5ꢀ mmolꢀ ofꢀ theꢀ ni‐
troarene,ꢀ 5ꢀmLꢀ ofꢀtheꢀ solvent,ꢀ andꢀ 30ꢀmgꢀofꢀtheꢀcatalyst.ꢀTheꢀ
2.ꢀ ꢀ Experimentalꢀ ꢀ
2.1.ꢀ ꢀ Catalystꢀsynthesisꢀ
autoclaveꢀwasꢀpurgedꢀwithꢀN
2
ꢀandꢀH ꢀ(15ꢀbar)ꢀthreeꢀtimesꢀandꢀ
2
thenꢀpressurizedꢀtoꢀ10ꢀbar.ꢀAfterꢀtheꢀreaction,ꢀtheꢀcatalystꢀwasꢀ
separatedꢀbyꢀcentrifugation,ꢀfollowedꢀbyꢀanalysisꢀofꢀtheꢀsampleꢀ
byꢀgasꢀchromatographyꢀ(GC)–massꢀspectroscopyꢀ(MS)ꢀ(Agilentꢀ
5975ꢀequippedꢀwithꢀaꢀHP‐5ꢀcapillaryꢀcolumn)ꢀandꢀGCꢀ(Agilentꢀ
7820ꢀequippedꢀwithꢀaꢀflameꢀionizationꢀdetectorꢀandꢀAT‐SE‐54ꢀ
capillaryꢀcolumn).ꢀ
Toꢀfabricateꢀcarbonꢀnitrideꢀ(g‐C
3
N ),ꢀmelamineꢀwasꢀplacedꢀ
4
inꢀaꢀcoveredꢀcrucible,ꢀheatedꢀtoꢀ550ꢀ°Cꢀforꢀ4ꢀhꢀunderꢀanꢀinertꢀ
environment,ꢀandꢀthenꢀmaintainedꢀatꢀ550ꢀ°Cꢀforꢀanotherꢀ4ꢀh.ꢀ
Theꢀ as‐synthesizedꢀ yellowꢀ solidꢀ wasꢀ groundꢀ intoꢀ aꢀ powder,ꢀ
whichꢀwasꢀusedꢀtoꢀproduceꢀN‐dopedꢀcarbon.ꢀTheꢀhomogeneousꢀ
cobalt‐containingꢀprecursorꢀsolutionꢀwasꢀpreparedꢀbyꢀdissolv‐
ingꢀ cobaltꢀ nitrateꢀ hexahydrateꢀ (1.168ꢀ g)ꢀ andꢀ triethyleneꢀ dia‐
3.ꢀ ꢀ Resultsꢀandꢀdiscussionꢀ ꢀ ꢀ
mineꢀ(1.92ꢀg)ꢀinꢀ40ꢀmLꢀofꢀdeionizedꢀwater.ꢀg‐C
.0ꢀgꢀforꢀCo@NC‐0.5,ꢀCo@NC‐1,ꢀorꢀCo@NC‐2,ꢀrespectively)ꢀwasꢀ
addedꢀtoꢀtheꢀaqueousꢀsolutionꢀunderꢀmagneticꢀstirring.ꢀOwingꢀ
toꢀtheꢀeffectꢀofꢀtheꢀCo–Nꢀbond,ꢀCo ꢀionsꢀcanꢀembedꢀinꢀtheꢀholesꢀ
ofꢀ carbonꢀ nitrideꢀ andꢀ triethyleneꢀ diamineꢀ moleculesꢀ preventꢀ
excessiveꢀgrowthꢀofꢀCoꢀparticlesꢀduringꢀtheꢀfollowingꢀpyrolysisꢀ
treatment.ꢀ Afterꢀ theꢀ solventꢀ wasꢀ removedꢀ byꢀ vacuumꢀ
freeze‐drying,ꢀtheꢀ solidꢀ powderꢀwasꢀtransferredꢀtoꢀaꢀ coveredꢀ
3
N
4
ꢀ(1.0,ꢀ2.0,ꢀorꢀ
4
Toꢀenableꢀlarge‐scaleꢀproductionꢀofꢀCo@NCꢀforꢀpossibleꢀuseꢀ
asꢀ aꢀ heterogeneousꢀ catalyst,ꢀ weꢀ developedꢀ aꢀ freeze‐dryingꢀ
methodꢀusingꢀcobaltꢀnitrateꢀasꢀtheꢀmetalꢀsaltꢀandꢀcarbonꢀnitrideꢀ
asꢀtheꢀNꢀprecursor.ꢀTheꢀsolidꢀmixtureꢀwasꢀcarbonizedꢀatꢀ900ꢀ°Cꢀ
underꢀ anꢀ inertꢀ atmosphereꢀ (Fig.ꢀ 1(a)).ꢀ Theꢀ X‐rayꢀ diffractionꢀ
(XRD)ꢀpatternsꢀindicateꢀformationꢀofꢀmetallicꢀcobaltꢀ[41]ꢀ(theꢀ
peaksꢀatꢀaboutꢀ44°ꢀandꢀ51°ꢀareꢀassignedꢀtoꢀtheꢀ(111)ꢀandꢀ(200)ꢀ
diffractionsꢀofꢀCoꢀnanoparticles)ꢀandꢀgraphiticꢀcarbonꢀ(theꢀpeakꢀ
2+
crucible,ꢀheatedꢀtoꢀ900ꢀ °Cꢀ atꢀ aꢀ rateꢀofꢀ 2.5ꢀ °C/minꢀunderꢀaꢀ N ꢀ
2

666ꢀ
RuijieꢀGaoꢀetꢀal.ꢀ/ꢀChineseꢀJournalꢀofꢀCatalysisꢀ39ꢀ(2018)ꢀ664–672ꢀ
(
a)
b)
pyrolysis
Co@NC-2
(
Co@NC-1
Co@NC-0.5
Co@C
(c)
c)
1
00 nm
20
30
40
50
60
2
(d)
(e)
(f)
5
nm
1
00 nm
100 nm
0.205 nm
Co(111)
0
.205 nm
0
.205 nm
Co(111)
Co(111)
2+
Fig.ꢀ1.ꢀ(a)ꢀProposedꢀsyntheticꢀprotocolꢀforꢀpreparationꢀofꢀCo@NCꢀcatalystsꢀfromꢀmetalꢀandꢀorganicꢀprecursorsꢀ(Co ꢀcationsꢀandꢀtriethyleneꢀdiamine)ꢀ
andꢀbulkꢀcarbonꢀnitride.ꢀCarbonꢀatomsꢀareꢀgray,ꢀnitrogenꢀatomsꢀareꢀblue,ꢀcobaltꢀatomsꢀareꢀpurple,ꢀandꢀhydrogenꢀatomsꢀareꢀwhite.ꢀ(b)ꢀXRDꢀpatternsꢀof
theꢀCo@NCꢀandꢀCo@Cꢀcatalysts.ꢀ(c)ꢀTypicalꢀTEMꢀandꢀ(d)ꢀHRTEMꢀimagesꢀofꢀCo@NC‐1ꢀ(scaleꢀbarꢀ2ꢀnm).ꢀTypicalꢀTEMꢀandꢀHRTEMꢀimagesꢀofꢀCo@NC‐0.5ꢀ
(e)ꢀandꢀCo@NC‐2ꢀ(scaleꢀbarꢀ2ꢀnm)ꢀ(f).ꢀ
2
−1
atꢀaboutꢀ26°)ꢀ[42,43]ꢀ(Fig.ꢀ1(b)),ꢀandꢀalsoꢀexcludeꢀcoexistenceꢀ
ofꢀdetectableꢀamountsꢀofꢀcobaltꢀoxides,ꢀnitrides,ꢀandꢀcarbides.ꢀ
Theꢀ carbonꢀ peakꢀ becomesꢀ moreꢀ intensiveꢀ withꢀ additionꢀ ofꢀ
graphiticꢀcarbonꢀnitride.ꢀAllꢀofꢀtheꢀTEMꢀimagesꢀ(Fig.ꢀ1(c)–(f))ꢀ
showꢀthatꢀtheꢀCoꢀnanoparticlesꢀinꢀCo@NCꢀhaveꢀaꢀsimilarꢀaver‐
ageꢀsizeꢀofꢀ~10ꢀnm,ꢀindicatingꢀthatꢀtheꢀamountꢀofꢀcarbonꢀnitrideꢀ
doesꢀ notꢀ influenceꢀ theꢀ sizeꢀ ofꢀ theꢀ Coꢀ nanoparticles.ꢀ Further‐
more,ꢀ theꢀ high‐resolutionꢀ TEMꢀ (HRTEM)ꢀ imageꢀ ofꢀ Co@NCꢀ
showsꢀ aꢀ highlyꢀ integratedꢀ nanostructureꢀ ofꢀ layeredꢀ car‐
bon‐coatedꢀCoꢀnanoparticlesꢀ(Fig.ꢀ1(d)).ꢀTheꢀlatticeꢀspacingꢀofꢀ
allꢀ ofꢀ theꢀ catalystsꢀ isꢀ 0.205ꢀ nmꢀ (Fig.ꢀ 1(d)–(f)),ꢀ whichꢀ isꢀ at‐
tributedꢀtoꢀtheꢀ(111)ꢀplaneꢀofꢀmetallicꢀcobaltꢀ[41].ꢀTheꢀcarbonꢀ
layersꢀcanꢀactꢀasꢀaꢀshellꢀtoꢀprotectꢀtheꢀmetallicꢀCoꢀnanoparticlesꢀ
fromꢀ aggregationꢀ andꢀ oxidationꢀ duringꢀ pyrolysisꢀ andꢀ theꢀ fol‐
lowingꢀ reactionꢀ processes.ꢀ Theꢀ porosityꢀ ofꢀ theꢀ synthesizedꢀ
Co@NCꢀ catalystsꢀ wasꢀ evaluatedꢀ byꢀ nitrogenꢀ adsorp‐
tion–desorptionꢀ(Fig.ꢀ2(a)).ꢀWithꢀincreasingꢀamountꢀofꢀcarbonꢀ
nitride,ꢀtheꢀBETꢀsurfaceꢀareaꢀofꢀtheꢀcatalystꢀdoesꢀnotꢀsignificantꢀ
changeꢀ (80.78,ꢀ 81.46,ꢀ andꢀ 86.31ꢀ m ꢀ g ꢀ forꢀ Co@NC‐0.5,ꢀ
Co@NC‐1,ꢀ andꢀ Co@NC‐2,ꢀ respectively).ꢀ XPSꢀ andꢀ elementalꢀ
analysisꢀ wereꢀ performedꢀ toꢀ obtainꢀ furtherꢀ informationꢀ aboutꢀ
theꢀchemicalꢀcompositionsꢀofꢀtheꢀcatalystsꢀ(Fig.ꢀ2(b)ꢀandꢀTableꢀ
1).ꢀTheꢀresultsꢀindicateꢀthatꢀtheꢀNꢀconcentrationꢀinꢀtheꢀbulkꢀisꢀ
veryꢀ closeꢀ toꢀ thatꢀ onꢀ theꢀ surfaceꢀ andꢀ theꢀ Nꢀ concentrationꢀ in‐
creasesꢀwithꢀincreasingꢀcarbonꢀnitrideꢀadditionꢀ(1.75ꢀandꢀ3.62ꢀ
at%ꢀ forꢀ Co@NC‐0.5ꢀ andꢀ Co@NC‐1,ꢀ respectively).ꢀ Furtherꢀ in‐
creasingꢀtheꢀamountꢀofꢀcarbonꢀnitrideꢀpowderꢀdoesꢀnotꢀsignifi‐
cantlyꢀ increaseꢀ theꢀ nitrogenꢀ concentrationꢀ (3.73ꢀ at%ꢀ forꢀ
Co@NC‐2).ꢀ Theꢀ Ramanꢀ spectraꢀ (Fig.ꢀ 2(c))ꢀ showꢀ twoꢀ distinctꢀ
−1
signalsꢀ atꢀ 1350ꢀ andꢀ 1590ꢀ cm ,ꢀ whichꢀ areꢀ assignedꢀ toꢀ defec‐
tive/disorderedꢀ sp ꢀ hybridizedꢀ carbonꢀ (Dꢀ band)ꢀ andꢀ crystal‐
lizedꢀ graphiticꢀ sp ꢀ carbonꢀ (Gꢀ band),ꢀ respectively.ꢀ Theꢀ ratioꢀ ofꢀ
theꢀintensityꢀofꢀtheꢀDꢀbandꢀtoꢀtheꢀintensityꢀofꢀtheꢀGꢀbandꢀI
increasesꢀ fromꢀ 0.908ꢀ (Co@NC‐0.5)ꢀ toꢀ 1.0ꢀ (Co@NC‐1)ꢀ uponꢀ
increasingꢀtheꢀaddedꢀamountꢀofꢀcarbonꢀnitride.ꢀ
3
2
D G
/I ꢀ
Theꢀ Co@NCꢀ catalystsꢀ wereꢀ appliedꢀ toꢀ hydrogenationꢀ ofꢀ

ꢀ
RuijieꢀGaoꢀetꢀal.ꢀ/ꢀChineseꢀJournalꢀofꢀCatalysisꢀ39ꢀ(2018)ꢀ664–672ꢀ
667ꢀ
(a)
(
b)
C
(c)
Co@NC-2
Co@NC-1
Co@NC-0.5
G
Co@NC-2
Co@NC-1
Co@NC-0.5
D
200
160
120
D
G
I /I = 0.908
I /I
D G
= 1.0
N
8
0
0
0
O
I /I
D G
= 0.987
4
Co@NC-2
Co@NC-1
Co@NC-0.5
0.0
0.2
0.4
0.6
0.8
1.0
600
400
200
0
800
1000
1200
1400
1600
1800
2000
Relative pressure (P/P
0
)
-1
Binding energy (eV)
Raman shift (cm )
Fig.ꢀ2.ꢀN ꢀadsorptionꢀisothermsꢀ(a),ꢀXPSꢀspectraꢀ(b),ꢀandꢀRamanꢀspectraꢀ(c)ꢀofꢀtheꢀCo@NCꢀcatalysts.ꢀ
2
4
‐nitrophenolꢀtoꢀtestꢀtheirꢀcatalyticꢀactivity.ꢀTheꢀhydrogenationꢀ
reactionsꢀ [41],ꢀ especiallyꢀ hydrogenationꢀ ofꢀ nitrobenzeneꢀ
[14,42].ꢀ Oneꢀ importantꢀ factorꢀ isꢀ theꢀ interactionꢀ betweenꢀ theꢀ
nitroꢀgroupꢀandꢀtheꢀpolarꢀsolventꢀbyꢀOH···NꢀandꢀOH···Oꢀhydro‐
genꢀbonds,ꢀwhichꢀacceleratesꢀpolarizationꢀofꢀN=OꢀandꢀN–Oꢀandꢀ
weakensꢀtheꢀbondꢀstrengthꢀ[46,47].ꢀAnotherꢀimportantꢀfactorꢀisꢀ
theꢀeasyꢀofꢀadsorptionꢀandꢀdissociationꢀofꢀhydrogenꢀonꢀtheꢀcat‐
alystꢀ surfaceꢀ inꢀ theꢀ polarꢀ solventꢀ [48].ꢀ Asꢀ shownꢀ inꢀ Tableꢀ 2,ꢀ
reactionsꢀ wereꢀ performedꢀ atꢀ roomꢀ temperatureꢀ underꢀ aꢀ H
pressureꢀofꢀ10ꢀbar.ꢀWhenꢀN‐dopedꢀcarbonꢀwasꢀusedꢀasꢀtheꢀcat‐
2
ꢀ
alyst,ꢀ noꢀ catalyticꢀ hydrogenationꢀ productꢀ wasꢀ obtainedꢀ evenꢀ
afterꢀ reactingꢀ forꢀ 12ꢀ h,ꢀ demonstratingꢀ theꢀ inertꢀ natureꢀ ofꢀ
N‐dopedꢀcarbonꢀforꢀhydrogenationꢀofꢀ4‐nitrophenolꢀunderꢀmildꢀ
reactionꢀconditions,ꢀwhichꢀisꢀbecauseꢀofꢀitsꢀpoorꢀabilityꢀforꢀhy‐
drogenꢀ activation.ꢀ Theꢀ catalyticꢀ behaviorꢀ ofꢀ theꢀ Co@NCꢀ cata‐
lystsꢀisꢀshownꢀinꢀFig.ꢀ3(a),ꢀwhereꢀconversionꢀofꢀ4‐nitrophenolꢀisꢀ
plottedꢀasꢀaꢀfunctionꢀofꢀtheꢀreactionꢀtime.ꢀCo@NC‐0.5ꢀcanꢀiniti‐
ateꢀ hydrogenationꢀ ofꢀ 4‐nitrophenol,ꢀ withꢀ totalꢀ conversionꢀ ofꢀ
higherꢀ reactionꢀ temperatureꢀ andꢀ H
2
ꢀ pressureꢀ accelerateꢀ theꢀ
reaction.ꢀ
Theꢀ controlꢀ experimentsꢀ indicateꢀ thatꢀ Co@NC‐1ꢀ hasꢀ veryꢀ
highꢀ catalyticꢀ activityꢀ andꢀ excellentꢀ chemoselectivityꢀ forꢀ hy‐
drogenationꢀofꢀ4‐nitrophenol.ꢀToꢀdetermineꢀhowꢀN‐dopedꢀcar‐
bonꢀandꢀCoꢀnanoparticlesꢀsynergisticallyꢀcatalyzeꢀselectiveꢀhy‐
drogenationꢀ ofꢀ 4‐nitrophenol,ꢀ furtherꢀ characterizationsꢀ ofꢀ
Co@NC‐1ꢀ wereꢀ performed.ꢀ Theꢀ similarꢀ morphologiesꢀ ofꢀ theꢀ
Co@NCꢀcatalystsꢀmeanꢀthatꢀitꢀisꢀnotꢀtheꢀcobaltꢀcontent,ꢀparticleꢀ
size,ꢀorꢀnanostructureꢀofꢀtheꢀCoꢀnanoparticlesꢀthatꢀaffectsꢀtheꢀ
catalyticꢀactivity.ꢀTheꢀsurfaceꢀareaꢀcanꢀalsoꢀbeꢀexcludedꢀbecauseꢀ
Co@NC‐1,ꢀCo@NC‐0.5,ꢀandꢀCo@NC‐2ꢀhaveꢀsimilarꢀsurfaceꢀare‐
as,ꢀasꢀshownꢀinꢀFig.ꢀ2(a).ꢀAsꢀshownꢀinꢀtheꢀNꢀ1sꢀspectraꢀ(Fig.ꢀ4(a)ꢀ
andꢀ(b)),ꢀtheꢀdopedꢀNꢀatomsꢀareꢀmainlyꢀgraphiticꢀandꢀpyridinicꢀ
Nꢀ [30]ꢀ (theꢀ peaksꢀ centeredꢀ atꢀ aboutꢀ 401.5ꢀ andꢀ 399.0ꢀ eV,ꢀ re‐
spectively).ꢀTheꢀshiftsꢀofꢀtheꢀtypicalꢀCoꢀ2pꢀXPSꢀpeaksꢀtoꢀhigherꢀ
energyꢀandꢀNꢀ1sꢀXPSꢀpeaksꢀtoꢀlowerꢀenergyꢀindicateꢀaꢀdecreaseꢀ
inꢀ theꢀ electronꢀ densityꢀ ofꢀ theꢀ Coꢀ nanoparticlesꢀ inꢀ Co@NC‐1ꢀ
comparedꢀwithꢀCo@NC‐0.5,ꢀwhichꢀconfirmsꢀelectronꢀtransferꢀatꢀ
theꢀinterfaceꢀofꢀCoꢀandꢀN‐dopedꢀcarbonꢀ(Fig.ꢀ4(c)).ꢀ
Theoreticalꢀ investigationꢀ suggestsꢀ thatꢀ introductionꢀ ofꢀ do‐
pantsꢀ intoꢀ theꢀ carbonꢀ frameworkꢀ canꢀ makeꢀ theꢀ electronicꢀ
structureꢀnegativeꢀ[34–36].ꢀTheꢀnitroꢀgroup,ꢀwhichꢀisꢀaꢀstrongꢀ
electron‐withdrawingꢀ group,ꢀ willꢀ haveꢀ aꢀ strongꢀ interactionꢀ
withꢀtheꢀelectron‐richꢀsites.ꢀConsequently,ꢀN‐dopedꢀcarbonꢀhasꢀ
beenꢀusedꢀforꢀcatalyticꢀhydrogenationꢀofꢀnitrobenzeneꢀ[37].ꢀForꢀ
Co@NC‐1,ꢀtheꢀrelativelyꢀhighꢀNꢀdopingꢀconcentrationꢀresultsꢀinꢀ
electronꢀredistributionꢀatꢀtheꢀinterfaceꢀofꢀcobaltꢀandꢀN‐dopedꢀ
carbon,ꢀwhichꢀenrichesꢀtheꢀpositiveꢀchargesꢀonꢀtheꢀmetallicꢀCoꢀ
nanoparticleꢀ sideꢀ andꢀ theꢀ negativeꢀ chargesꢀ onꢀ theꢀ N‐dopedꢀ
carbonꢀside,ꢀasꢀindicatedꢀbyꢀtheꢀXPSꢀresultsꢀ(Fig.ꢀ4).ꢀAlthoughꢀ
bothꢀcarbonꢀwithꢀaꢀhighꢀconcentrationꢀofꢀNꢀatomsꢀandꢀmetallicꢀ
Coꢀcanꢀactꢀasꢀadsorptionꢀsitesꢀforꢀnitroꢀgroups,ꢀadsorptionꢀtoꢀ
electron‐richꢀN‐dopedꢀcarbonꢀisꢀpreferred.ꢀInꢀaddition,ꢀtheꢀme‐
4
4
‐nitrophenolꢀ inꢀ 5ꢀ hꢀ butꢀ withꢀ poorꢀ chemoselectivityꢀ forꢀ
‐aminophenolꢀ (78.1%).ꢀ Co@NC‐1ꢀ exhibitsꢀ theꢀ bestꢀ perfor‐
manceꢀamongꢀtheꢀcatalystsꢀtested,ꢀgivingꢀcompleteꢀconversionꢀ
ofꢀ4‐nitrophenolꢀinꢀ3ꢀhꢀandꢀaꢀturnoverꢀfrequencyꢀ(TOF)ꢀbasedꢀ
−1
onꢀtheꢀamountꢀofꢀCoꢀatꢀ30ꢀminꢀofꢀ12.3ꢀh .ꢀMoreꢀimportantly,ꢀ
theꢀ chemoselectivityꢀ forꢀ 4‐aminophenolꢀ isꢀ >99.9%ꢀ andꢀ theꢀ
amountsꢀofꢀtheꢀbyproductsꢀareꢀbelowꢀtheꢀdetectionꢀlimitationꢀ
ofꢀGC–MSꢀandꢀGCꢀ(Fig.ꢀ3(b)ꢀandꢀ(c)).ꢀCo@NC‐2ꢀdoesꢀnotꢀper‐
formꢀ betterꢀ thanꢀ Co@NC‐1ꢀ becauseꢀ aꢀ furtherꢀ increaseꢀ inꢀ theꢀ
amountꢀofꢀg‐C
3
N ꢀdoesꢀnotꢀfurtherꢀincreaseꢀtheꢀNꢀdopingꢀcon‐
4
centration.ꢀToꢀunderstandꢀtheꢀimportantꢀroleꢀofꢀN‐dopedꢀcar‐
bon,ꢀ commercialꢀ carbon‐supportedꢀ Coꢀ nanoparticlesꢀ (Co@C)ꢀ
wereꢀ synthesizedꢀ andꢀ appliedꢀ forꢀ hydrogenationꢀ ofꢀ 4‐
phenolꢀ underꢀ theꢀ sameꢀ conditions.ꢀ Afterꢀ 3ꢀ h,ꢀ conversionꢀ ofꢀ
‐nitrophenolꢀ wasꢀ onlyꢀ 5.6%ꢀ andꢀ itꢀ didꢀ notꢀ significantlyꢀ in‐
ꢀ
nitro‐
4
creaseꢀevenꢀforꢀaꢀprolongedꢀreactionꢀperiod.ꢀFurthermore,ꢀlargeꢀ
amountsꢀofꢀbyproductsꢀ(i.e.,ꢀazoxyꢀcompounds)ꢀwereꢀproducedꢀ
andꢀtheꢀselectivityꢀforꢀ4‐aminophenolꢀwasꢀonlyꢀ67.1%.ꢀ
Differentꢀ solventsꢀ (water,ꢀ tetrahydrofuranꢀ (THF),ꢀ andꢀ cy‐
clohexane)ꢀwereꢀtestedꢀusingꢀCo@NC‐1ꢀasꢀtheꢀcatalystꢀ(Tableꢀ
2).ꢀ Theꢀ activityꢀ improvesꢀ withꢀ increasingꢀ polarityꢀ ofꢀ theꢀ sol‐
vent.ꢀTheꢀpolarityꢀofꢀtheꢀsolventꢀhasꢀaꢀsignificantꢀeffectꢀonꢀmanyꢀ
Tableꢀ1ꢀ
CompositionsꢀofꢀtheꢀCo@NCꢀcatalystsꢀdeterminedꢀbyꢀXPSꢀandꢀelementalꢀ
analysis.ꢀ
Coꢀ(at%)ꢀ
Cꢀ(at%)ꢀ
a/bulk
Nꢀ(at%)ꢀ
Oꢀ(at%)ꢀ
Catalystꢀ
b
a/bulk
bꢀ Surface
a/bulkb
Surface
ꢀ
aꢀ Surface
ꢀ
ꢀ
Surface
ꢀ
ꢀ
ꢀ
ꢀ
Co@NC‐0.5ꢀ
Co@NC‐1ꢀ
Co@NC‐2ꢀ
0.76ꢀ
0.75ꢀ
0.73ꢀ
94.15/95.28ꢀ
93.46/95.10ꢀ
92.17/93.41ꢀ
1.76/1.75ꢀ
3.82/3.62ꢀ
3.68/3.73ꢀ
3.33/2.97ꢀ
1.97/1.28ꢀ
3.42/2.86ꢀ
tallicꢀphaseꢀprovidesꢀactiveꢀsitesꢀforꢀH
2
ꢀactivationꢀandꢀpromotesꢀ
aꢀ
CalculatedꢀfromꢀXPSꢀmeasurements.ꢀ ꢀ
Calculatedꢀfromꢀelementalꢀanalysis.ꢀ
cleavageꢀ ofꢀ H–Hꢀ bondsꢀ owingꢀ toꢀ itsꢀ goodꢀ electrophilicity.ꢀ
bꢀ

668ꢀ
RuijieꢀGaoꢀetꢀal.ꢀ/ꢀChineseꢀJournalꢀofꢀCatalysisꢀ39ꢀ(2018)ꢀ664–672ꢀ
(
a)
(b)
1
00
99.9
9
8.7
100
8
6
4
2
0
0
0
0
0
7
8.1
8
6
4
2
0
0
0
0
0
6
7.1
Co@NC-2
Co@NC-1
Co@NC-0.5
Co@C
NC
0
1
2
3
4
5
12
Time (h)
(
c)
t = 2.12 min
0
20
40
60
80
100
120
t = 2.86 min
1
2
3
4
5
6
7
8
9
0
20
40
60
80
m/z
100
120
140
Time (min)
Fig.ꢀ3.ꢀCatalyticꢀactivityꢀandꢀchemoselectivityꢀofꢀvariousꢀcatalystsꢀforꢀhydrogenationꢀofꢀ4‐nitrophenol.ꢀ(a)ꢀConversionꢀofꢀ4‐nitrophenolꢀwithꢀtime.ꢀ(b)ꢀ
Chemoselectivityꢀforꢀ4‐aminophenolꢀusingꢀvariousꢀcatalystsꢀ(reactionꢀconditions:ꢀ0.5ꢀmmolꢀ4‐nitrophenol,ꢀ30ꢀmgꢀcatalyst,ꢀ5ꢀmLꢀethanol,ꢀroomꢀtem‐
perature,ꢀandꢀ10ꢀbarꢀH ).ꢀ(c)ꢀGCꢀspectrumꢀofꢀtheꢀreactionꢀproductꢀmixtureꢀafterꢀ1ꢀhꢀhydrogenationꢀofꢀ4‐nitrophenolꢀcatalyzedꢀbyꢀCo@NC‐1ꢀandꢀtheꢀ
2
correspondingꢀmassꢀspectra.ꢀ
Tableꢀ2ꢀ
Effectꢀofꢀtheꢀreactionꢀconditionsꢀonꢀhydrogenationꢀofꢀ4‐nitrophenol.ꢀ
ꢀ
Entryꢀ
Solventꢀ
Ethanolꢀ
THFꢀ
Timeꢀ(h)ꢀ
Temperatureꢀ(°C)ꢀ
Pressureꢀ(bar)ꢀ
Conversionꢀ(%)ꢀ
ꢀ 68.3ꢀ
Selectivityꢀ(%)ꢀ
>99.0ꢀ
1
ꢀ
1ꢀ
1ꢀ
1ꢀ
1ꢀ
1ꢀ
1ꢀ
1ꢀ
1ꢀ
1ꢀ
3ꢀ
25ꢀ
25ꢀ
25ꢀ
25ꢀ
40ꢀ
60ꢀ
25ꢀ
25ꢀ
25ꢀ
25ꢀ
10ꢀ
10ꢀ
10ꢀ
10ꢀ
10ꢀ
10ꢀ
ꢀ 5ꢀ
20ꢀ
30ꢀ
10ꢀ
2
ꢀ
ꢀ 44.5ꢀ
ꢀ 88.1ꢀ
ꢀ 10.1ꢀ
ꢀ 84.2ꢀ
>99.0ꢀ
ꢀ 95.7ꢀ
>99.0ꢀ
>99.0ꢀ
3
ꢀ
2
H Oꢀ
4
ꢀ
Cyclohexaneꢀ
Ethanolꢀ
Ethanolꢀ
Ethanolꢀ
Ethanolꢀ
Ethanolꢀ
Ethanolꢀ
5ꢀ
6
ꢀ
100.0ꢀ
ꢀ 23.5ꢀ
ꢀ 77.6ꢀ
ꢀ 91.2ꢀ
>99.0ꢀ
>99.0ꢀ
>99.0ꢀ
>99.0ꢀ
7
ꢀ
8
ꢀ
9
ꢀ
10ꢀ
100.0ꢀ
>99.0ꢀ
Reactionꢀconditions:ꢀ30ꢀmgꢀCo@NC‐1,ꢀ0.5ꢀmmolꢀ4‐nitrophenol,ꢀandꢀ5ꢀmLꢀsolvent.ꢀ
Therefore,ꢀforꢀCo@NC‐1,ꢀtheꢀelectron‐transferꢀeffectꢀacceleratesꢀ
sorbedꢀnitroꢀgroupsꢀareꢀthenꢀreducedꢀbyꢀtheꢀsurfaceꢀhydrogenꢀ
species,ꢀwhichꢀisꢀdescribedꢀasꢀtheꢀsynergisticꢀeffectꢀofꢀCoꢀnano‐
particlesꢀandꢀN‐dopedꢀcarbon.ꢀ
ToꢀbetterꢀunderstandꢀtheꢀexcellentꢀselectivityꢀofꢀCo@NC‐1,ꢀ
theꢀadsorptionꢀmodeꢀofꢀ4‐nitrophenolꢀonꢀdifferentꢀcatalystꢀsur‐
H ꢀ activationꢀ overꢀ theꢀ Coꢀ nanoparticlesꢀ andꢀ deprotonationꢀ ofꢀ
2
theꢀH–metalꢀintermediates,ꢀwhichꢀgeneratesꢀcatalyticallyꢀactiveꢀ
sitesꢀtoꢀpromoteꢀtheꢀwholeꢀreactionꢀprocess.ꢀHere,ꢀweꢀpresumeꢀ
thatꢀ 4‐nitrophenolꢀ adsorbsꢀ toꢀ N‐dopedꢀ carbonꢀ andꢀ theꢀ ab‐

ꢀ
RuijieꢀGaoꢀetꢀal.ꢀ/ꢀChineseꢀJournalꢀofꢀCatalysisꢀ39ꢀ(2018)ꢀ664–672ꢀ
669ꢀ
(b)
Co@NC-1
Co@NC-1
Co@NC-0.5
(
a)
Graphitic N
Co 2p3/2
Co@NC-0.5
Pyridinic N
Co 2p1/2
4
06
404
402
400
398
396
800
796
792
788
784
780
776
Binding energy (eV)
Binding energy (eV)
c)
H
H2
e-
N-carbon
Co
Fig.ꢀ4.ꢀNꢀ1sꢀ(a)ꢀandꢀCoꢀ2pꢀ(b)ꢀXPSꢀspectraꢀofꢀCo@NC‐1.ꢀ(c)ꢀSchematicꢀillustrationꢀofꢀtheꢀelectron‐transferꢀeffectꢀatꢀtheꢀinterface.ꢀ
(d)
(
a)
Before adsorption
(b)
Before adsorption
(c)
Before adsorption
After adsorption
Before adsorption
After adsorption
After adsorption
After adsorption

1
1
210 cm

1
1
460 cm

1
1
210 cm


1
460 cm

1
1
540 cm

1
1
540 cm
1
750
1500
1250
1750
1500
1250
1
1750
1500
1250
1
1
750
1500
1250
1

1
Wavenumber (cm )
Wavenumber (cm )
Wavenumber (cm )
Wavenumber (cm )
Fig.ꢀ5.ꢀFTIRꢀspectraꢀofꢀN‐dopedꢀcarbonꢀ(a),ꢀtheꢀcarbonꢀsupportꢀ(b),ꢀCo@NC‐1ꢀ(c),ꢀandꢀCo@Cꢀ(d)ꢀbeforeꢀandꢀafterꢀadsorptionꢀofꢀ4‐nitrophenol.ꢀ
facesꢀ wasꢀ investigatedꢀ byꢀ FTIRꢀ spectroscopyꢀ (Fig.ꢀ 5).ꢀ Forꢀ
N‐dopedꢀcarbon,ꢀthereꢀareꢀthreeꢀcharacteristicꢀpeaksꢀatꢀ1210,ꢀ
N‐dopedꢀcarbon.ꢀ
Theꢀ catalyticꢀ stabilityꢀ isꢀ alsoꢀ aꢀ veryꢀ importantꢀ criterionꢀ toꢀ
evaluateꢀtheꢀ potentialꢀofꢀ aꢀcatalyst.ꢀ Co‐basedꢀ catalystsꢀ canꢀbeꢀ
easilyꢀrecycledꢀusingꢀanꢀexternalꢀmagneticꢀfieldꢀandꢀreusedꢀupꢀ
toꢀ tenꢀ times.ꢀ Asꢀ shownꢀ inꢀ Fig.ꢀ 6(a),ꢀ bothꢀ theꢀ conversionꢀ ofꢀ
4‐nitrophenolꢀandꢀselectivityꢀforꢀ4‐aminophenolꢀareꢀunchangedꢀ
forꢀ tenꢀ cycles.ꢀ Theꢀ unchangedꢀ structuralꢀ featuresꢀ furtherꢀ
demonstrateꢀtheꢀ excellentꢀ catalyticꢀ stabilityꢀofꢀCo@NC‐1ꢀ (Fig.ꢀ
6(b)).ꢀ
−1
1
460ꢀandꢀ1540ꢀcm ꢀafterꢀadsorptionꢀofꢀ4‐nitrophenol,ꢀwhichꢀ
areꢀ assignedꢀ toꢀ theꢀ stretchingꢀ vibrationꢀ ofꢀ C–OH,ꢀ frameworkꢀ
vibrationꢀ ofꢀ benzene,ꢀ andꢀ asymmetricalꢀ stretchingꢀ ofꢀ –NO ,ꢀ
2
respectively.ꢀInꢀcontrast,ꢀthereꢀareꢀnoꢀcharacteristicꢀpeaksꢀforꢀ
theꢀcarbonꢀsupportꢀbeforeꢀandꢀafterꢀadsorption.ꢀThisꢀconfirmsꢀ
thatꢀ4‐nitrophenolꢀadsorbsꢀonꢀN‐dopedꢀcarbonꢀbutꢀnotꢀonꢀpureꢀ
carbon,ꢀ whichꢀ isꢀ becauseꢀ theꢀ pureꢀ carbonꢀ supportꢀ isꢀ nearlyꢀ
inertꢀforꢀadsorptionꢀofꢀbothꢀnitroꢀandꢀhydroxylꢀgroups.ꢀHowev‐
er,ꢀCo@NC‐1ꢀshowsꢀsimilarꢀsignalsꢀtoꢀN‐dopedꢀcarbon,ꢀindicat‐
ingꢀ thatꢀ 4‐nitrophenolꢀ moleculesꢀ preferentiallyꢀ adsorbꢀ onꢀ
Weꢀ alsoꢀ investigatedꢀ hydrogenationꢀ ofꢀ eightꢀ otherꢀ substi‐
tutedꢀ nitroarenesꢀ usingꢀ theꢀ Co@NC‐1ꢀ catalyst.ꢀ Theꢀ corre‐
spondingꢀanilinesꢀwereꢀobtainedꢀinꢀexcellentꢀyieldsꢀwithꢀhighꢀ

670ꢀ
RuijieꢀGaoꢀetꢀal.ꢀ/ꢀChineseꢀJournalꢀofꢀCatalysisꢀ39ꢀ(2018)ꢀ664–672ꢀ
(
a)
(b)
1
00
100
8
6
4
2
0
0
0
0
0
80
60
40
20
0
After recycling test
Before recycling test
0
2
4
6
8
10
20
30
40
50
60
70
80
Cycles
o
2
( )
Fig.ꢀ6.ꢀ(a)ꢀCatalyticꢀstabilityꢀandꢀselectivityꢀofꢀCo@NC‐1ꢀafterꢀ3ꢀhꢀreactionꢀtimeꢀ(reactionꢀconditions:ꢀ0.5ꢀmmolꢀ4‐nitrophenol,ꢀ30ꢀmgꢀcatalyst,ꢀ5ꢀmLꢀ
ethanol,ꢀroomꢀtemperature,ꢀandꢀ10ꢀbarꢀH ).ꢀ(b)ꢀXRDꢀpatternsꢀofꢀfreshꢀandꢀusedꢀCo@NC‐1ꢀafterꢀtheꢀrecyclingꢀtest.ꢀ
2
selectivitiesꢀ (Tableꢀ 3).ꢀ Co@NC‐1ꢀ selectivelyꢀ hydrogenatesꢀ theꢀ
nitroꢀ groupꢀ whileꢀ otherꢀ functionalꢀ groups,ꢀ suchꢀ asꢀ –CHO,ꢀ
thatꢀCo@NC‐1ꢀisꢀaꢀversatileꢀcatalystꢀforꢀselectiveꢀhydrogenationꢀ
ofꢀsubstitutedꢀnitroarenes.ꢀ
–COOH,ꢀ andꢀ –C≡C,ꢀ areꢀ unaffected.ꢀ Forꢀ differentꢀ substitutedꢀ
nitroarenes,ꢀdifferentꢀtimesꢀareꢀrequiredꢀtoꢀachieveꢀfullꢀconver‐
sion.ꢀ 4‐Nitrostyreneꢀ takesꢀ 0.5ꢀ hꢀ moreꢀ thanꢀ 4‐nitrophenolꢀ be‐
causeꢀtheꢀπ–πꢀconjugativeꢀeffectꢀofꢀtheꢀ–C=Cꢀgroupꢀandꢀbenzeneꢀ
ringꢀ makesꢀ aꢀ relativelyꢀ difficultꢀ forꢀ nitrostyreneꢀ toꢀ adsorbꢀ toꢀ
theꢀ catalyst.ꢀ Forꢀ 3‐nitrophenol,ꢀ theꢀ nitroꢀ groupꢀ isꢀ difficultꢀ toꢀ
polarizeꢀ becauseꢀ ofꢀ theꢀ electron‐donatingꢀ effectꢀ ofꢀ theꢀ –OHꢀ
groupꢀ atꢀ theꢀ metaꢀ position,ꢀ whichꢀ leadsꢀ toꢀ aꢀ longerꢀ reactionꢀ
time.ꢀInꢀconclusion,ꢀthisꢀcatalystꢀshowsꢀhighꢀactivityꢀandꢀselec‐
tivityꢀ forꢀ hydrogenationꢀ ofꢀ challengingꢀ substrates,ꢀ suggestingꢀ
4.ꢀ ꢀ Conclusionsꢀ ꢀ
Weꢀ haveꢀ designedꢀ aꢀ heterogeneousꢀ synergeticꢀ catalystꢀ forꢀ
highlyꢀactiveꢀandꢀselectiveꢀroom‐temperatureꢀhydrogenationꢀofꢀ
nitroarenes.ꢀ Theꢀ excellentꢀ catalyticꢀ performanceꢀ canꢀ beꢀ at‐
tributedꢀtoꢀtheꢀsynergisticꢀeffectꢀofꢀN‐dopedꢀcarbonꢀforꢀprefer‐
entialꢀadsorptionꢀofꢀtheꢀnitroꢀgroupꢀandꢀCoꢀnanoparticlesꢀforꢀ
activationꢀofꢀH
.ꢀElectronꢀtransferꢀfromꢀtheꢀCoꢀnanoparticlesꢀtoꢀ
2
theꢀ N‐dopedꢀ carbonꢀ atomsꢀ atꢀ theꢀ interfaceꢀ resultsꢀ inꢀ elec‐
tron‐richꢀN‐dopedꢀcarbonꢀandꢀelectron‐deficientꢀCoꢀnanoparti‐
cles,ꢀwhichꢀfurtherꢀenhancesꢀtheꢀactivityꢀofꢀN‐dopedꢀcarbonꢀforꢀ
Tableꢀ3ꢀ
Co@NC‐1ꢀcatalyzedꢀhydrogenationꢀofꢀsubstitutedꢀnitroarenes.ꢀ
nitroꢀgroupꢀadsorptionꢀandꢀCoꢀforꢀH
2
ꢀactivation.ꢀTheꢀoptimizedꢀ
catalystꢀ (Co@NC‐1)ꢀ exhibitsꢀ excellentꢀ catalyticꢀ performanceꢀ
Entryꢀ
Substrateꢀ
Productꢀ Timeꢀ(h)ꢀ
Con./Sel.ꢀ(%)ꢀ
−1
withꢀ aꢀ TOFꢀ ofꢀ 12.3ꢀ h ꢀ andꢀ selectivityꢀ forꢀ aminophenolꢀ ofꢀ
99.9%ꢀatꢀroomꢀtemperature.ꢀThisꢀ catalystꢀ alsoꢀ exhibitsꢀhighꢀ
>
1ꢀ
3ꢀ
97.0/>99.0ꢀ
activityꢀforꢀhydrogenationꢀofꢀnitroarenesꢀwithꢀvariousꢀsubstit‐
uents.ꢀ
ꢀ
ꢀ
2
ꢀ
3ꢀ
99.1/>99.0ꢀ
99.3/>99.0ꢀ
ꢀ
ꢀ
Referencesꢀ
3ꢀ
3ꢀ
[
[
[
1] Y.ꢀG.ꢀSu,ꢀJ.ꢀY.ꢀLang,ꢀL.ꢀP.ꢀLi,ꢀK.ꢀGuan,ꢀC.ꢀF.ꢀDu,ꢀL.ꢀM.ꢀPeng,ꢀD.ꢀHan,ꢀX.ꢀJ.ꢀ
ꢀ
ꢀ
Wang,ꢀJ.ꢀAm.ꢀChem.ꢀSoc.,ꢀ2013,ꢀ135,ꢀ11433–11436.ꢀ
2] D.ꢀGärtner,ꢀA.ꢀWelther,ꢀB.ꢀR.ꢀRad,ꢀR.ꢀWolf,ꢀA.ꢀJ.ꢀWangelin,ꢀAngew.ꢀ
Chem.ꢀInt.ꢀEd.,ꢀ2014,ꢀ53,ꢀ3722–3726.ꢀ
4
ꢀ
4ꢀ
98.4/>99.0ꢀ
99.1/>99.0ꢀ
ꢀ
ꢀ
3] T.ꢀE.ꢀMüller,ꢀK.ꢀC.ꢀHultzsch,ꢀM.ꢀYus,ꢀF.ꢀFoubelo,ꢀM.ꢀTada,ꢀChem.ꢀRev.,ꢀ
5ꢀ
3ꢀ
2008,ꢀ108,ꢀ3795–3892.ꢀ
ꢀ
ꢀ
[4] J.ꢀF.ꢀHartwig,ꢀNature,ꢀ2008,ꢀ455,ꢀ314–322.ꢀ
[
5] F.ꢀ Cárdenas‐Lizana,ꢀ S.ꢀ Gómez‐Quero,ꢀ A.ꢀ Hugon,ꢀ L.ꢀ Delannoy,ꢀ C.ꢀ
6
ꢀ
3ꢀ
99.5/>99.0ꢀ
99.4/>99.0ꢀ
99.2/>99.0ꢀ
Louis,ꢀM.ꢀA.ꢀKeane,ꢀJ.ꢀCatal.,ꢀ2009,ꢀ262,ꢀ235–243.ꢀ
ꢀ
ꢀ
[6] C.ꢀ Kartusch,ꢀ M.ꢀ Makosch,ꢀ J.ꢀ Sá,ꢀ K.ꢀ Hungerbuehler,ꢀ J.ꢀ A.ꢀ vanꢀ
Bokhoven,ꢀChemCatChem,ꢀ2012,ꢀ4,ꢀ236–242.ꢀ
7ꢀ
4ꢀ
[7] H.ꢀS.ꢀWei,ꢀX.ꢀY.ꢀLiu,ꢀA.ꢀQ.ꢀWang,ꢀL.ꢀL.ꢀZhang,ꢀB.ꢀT.ꢀQiao,ꢀX.ꢀT.ꢀYang,ꢀY.ꢀ
Q.ꢀHuang,ꢀS.ꢀMiao,ꢀJ.ꢀY.ꢀLiu,ꢀT.ꢀZhang,ꢀNat.ꢀCommun.,ꢀ2014,ꢀ5,ꢀ5634.ꢀ
[8] S.ꢀZhang,ꢀC.ꢀR.ꢀChang,ꢀZ.ꢀQ.ꢀHuang,ꢀJ.ꢀLi,ꢀZ.ꢀM.ꢀWu,ꢀY.ꢀY.ꢀMa,ꢀZ.ꢀY.ꢀ
Zhang,ꢀY.ꢀWang,ꢀY.ꢀQ.ꢀQu,ꢀJ.ꢀAm.ꢀChem.ꢀSoc.,ꢀ2016,ꢀ138,ꢀ2629–2637.ꢀ
[9] G.ꢀX.ꢀChen,ꢀC.ꢀF.ꢀXu,ꢀX.ꢀQ.ꢀHuang,ꢀJ.ꢀY.ꢀYe,ꢀL.ꢀGu,ꢀG.ꢀLi,ꢀZ.ꢀC.ꢀTang,ꢀB.ꢀH.ꢀ
Wu,ꢀH.ꢀY.ꢀYang,ꢀZ.ꢀP.ꢀZhao,ꢀZ.ꢀZhou,ꢀG.ꢀFu,ꢀN.ꢀF.ꢀZheng,ꢀNat.ꢀMater.,ꢀ
ꢀ
ꢀ
8ꢀ
3.5ꢀ
ꢀ
ꢀ
Reactionꢀconditions:ꢀ0.5ꢀmmolꢀsubstrate,ꢀ30ꢀmgꢀCo@CN‐1,ꢀ5ꢀmLꢀethanol,
roomꢀtemperature,ꢀandꢀ10ꢀbarꢀH .ꢀ
ꢀ
2
2016,ꢀ15,ꢀ546–569.ꢀ

ꢀ
RuijieꢀGaoꢀetꢀal.ꢀ/ꢀChineseꢀJournalꢀofꢀCatalysisꢀ39ꢀ(2018)ꢀ664–672ꢀ
GraphicalꢀAbstractꢀ
671ꢀ
Chin.ꢀJ.ꢀCatal.,ꢀ2018,ꢀ39:ꢀ664–672ꢀ ꢀ ꢀ doi:ꢀ10.1016/S1872‐2067(17)62988‐7
Cobaltꢀnanoparticlesꢀencapsulatedꢀinꢀnitrogen‐dopedꢀcarbonꢀforꢀroom‐temperatureꢀselectiveꢀhydrogenationꢀofꢀnitroarenesꢀ
RuijieꢀGao,ꢀLunꢀPan,ꢀZhengwenꢀLi,ꢀXiangwenꢀZhang,ꢀLiꢀWang,ꢀJi‐JunꢀZouꢀ*ꢀ
TianjinꢀUniversity;ꢀCollaborativeꢀInnovativeꢀCenterꢀofꢀChemicalꢀScienceꢀandꢀEngineeringꢀ(Tianjin)ꢀ
H
H2
e-
N-carbon
Co
ꢀ
Cobaltꢀ nanoparticlesꢀencapsulatedꢀinꢀN‐dopedꢀcarbonꢀactꢀasꢀanꢀefficientꢀcatalystꢀforꢀroom‐temperatureꢀhydrogenationꢀ ofꢀnitroarenesꢀ
owingꢀtoꢀtheꢀsynergeticꢀeffectꢀofꢀH ꢀactivationꢀonꢀtheꢀCoꢀnanoparticlesꢀandꢀnitroꢀgroupꢀadsorptionꢀonꢀN‐dopedꢀcarbon.ꢀ
2
[
10] C.ꢀW.ꢀA.ꢀChan,ꢀ A.ꢀ H.ꢀMahadi,ꢀ M.ꢀM.ꢀJ.ꢀLi,ꢀE.ꢀC.ꢀCorbos,ꢀC.ꢀTang,ꢀ G.ꢀ
Jones,ꢀW.ꢀC.ꢀH.ꢀKuo,ꢀJ.ꢀCookson,ꢀC.ꢀM.ꢀBrown,ꢀP.ꢀT.ꢀBishop,ꢀS.ꢀC.ꢀE.ꢀ
Tsang,ꢀNat.ꢀCommun.,ꢀ2014,ꢀ5,ꢀ5787.ꢀ
[26] L.ꢀ P.ꢀ Zhang,ꢀ J.ꢀ B.ꢀ Niu,ꢀ L.ꢀ M.ꢀ Dai,ꢀ Z.ꢀ H.ꢀ Xia,ꢀ Langmuir,ꢀ 2012,ꢀ 28,ꢀ
7542–7550.ꢀ
[27] M.ꢀM.ꢀTrandafir,ꢀM.ꢀFlorea,ꢀF.ꢀNeatu,ꢀA.ꢀPrimo,ꢀV.ꢀI.ꢀParvulescu,ꢀH.ꢀ
García,ꢀChemSusChem,ꢀ2016,ꢀ9,ꢀ1565–1569.ꢀ
[28] R.ꢀJ.ꢀGao,ꢀL.ꢀPan,ꢀJ.ꢀH.ꢀLu,ꢀJ.ꢀS.ꢀXu,ꢀX.ꢀW.ꢀZhang,ꢀL.ꢀWang,ꢀJ.ꢀJ.ꢀZou,ꢀ
ChemCatChem,ꢀ2017,ꢀ9,ꢀ4287–4294.ꢀ
[29] B.ꢀ V.ꢀ Jagadeesh,ꢀ H.ꢀ Junge,ꢀ M.ꢀ M.ꢀ Pohl,ꢀ J.ꢀ Radnik,ꢀ A.ꢀ Brückner,ꢀ M.ꢀ
Beller,ꢀJ.ꢀAm.ꢀChem.ꢀSoc.,ꢀ2013,ꢀ135,ꢀ10776–10782.ꢀ
[30] H.ꢀSu,ꢀK.ꢀX.ꢀZhang,ꢀB.ꢀZhang,ꢀH.ꢀH.ꢀWang,ꢀQ.ꢀY.ꢀYu,ꢀX.ꢀH.ꢀLi,ꢀM.ꢀAnto‐
niett,ꢀJ.ꢀS.ꢀChen,ꢀJ.ꢀAm.ꢀChem.ꢀSoc.,ꢀ2017,ꢀ139,ꢀ811–818.ꢀ ꢀ
[31] Y.ꢀJ.ꢀGao,ꢀD.ꢀMa,ꢀG.ꢀHu,ꢀP.ꢀZhai,ꢀX.ꢀH.ꢀBao,ꢀB.ꢀZhu,ꢀB.ꢀS.ꢀZhang,ꢀD.ꢀS.ꢀSu,ꢀ
Angew.ꢀChem.ꢀInt.ꢀEd.,ꢀ2011,ꢀ50,ꢀ10236–10240.ꢀ
[32] R.ꢀLiu,ꢀS.ꢀM.ꢀMahurin,ꢀC.ꢀLi,ꢀR.ꢀR.ꢀUnocic,ꢀJ.ꢀC.ꢀIdrobo,ꢀH.ꢀJ.ꢀGao,ꢀS.ꢀJ.ꢀ
Pennycook,ꢀS.ꢀDai,ꢀAngew.ꢀChem.ꢀInt.ꢀEd.,ꢀ2011,ꢀ50,ꢀ6799–6802.ꢀ
[33] X.ꢀF.ꢀYu,ꢀL.ꢀB.ꢀMao,ꢀJ.ꢀGe,ꢀZ.ꢀL.ꢀYu,ꢀJ.ꢀW.ꢀLiu,ꢀS.ꢀH.ꢀYu,ꢀSci.ꢀBull.,ꢀ2016,ꢀ
61,ꢀ700–705.ꢀ
[
[
[
11] A.ꢀS.ꢀCrampton,ꢀM.ꢀD.ꢀRötzer,ꢀC.ꢀJ.ꢀRidge,ꢀF.ꢀF.ꢀSchweinberger,ꢀU.ꢀ
Heiz,ꢀB.ꢀYoon,ꢀU.ꢀLandman,ꢀNat.ꢀCommun.,ꢀ2016,ꢀ7,ꢀ10389.ꢀ
12] G.ꢀKennedy,ꢀG.ꢀMelaet,ꢀH.ꢀL.ꢀHan,ꢀW.ꢀT.ꢀRalston,ꢀG.ꢀA.ꢀSomorjai,ꢀACSꢀ
Catal.,ꢀ2016,ꢀ6,ꢀ7140–7147.ꢀ
13] S.ꢀIqbal,ꢀS.ꢀA.ꢀKondrat,ꢀD.ꢀR.ꢀJones,ꢀD.ꢀSchoenmakers,ꢀJ.ꢀK.ꢀEdwards,ꢀ
L.ꢀLu,ꢀB.ꢀR.ꢀYeo,ꢀP.ꢀP.ꢀWells,ꢀE.ꢀK.ꢀGibson,ꢀD.ꢀJ.ꢀMorgan,ꢀC.ꢀJ.ꢀKiely,ꢀG.ꢀJ.ꢀ
Hutchings,ꢀACSꢀCatal.,ꢀ2015,ꢀ5,ꢀ5047–5059.ꢀ
[
14] F.ꢀA.ꢀWesterhaus,ꢀR.ꢀV.ꢀJagadeesh,ꢀG.ꢀP.ꢀWienhöfer,ꢀM.ꢀM.ꢀPohl,ꢀJ.ꢀ
Radnik,ꢀA.ꢀE.ꢀSurkus,ꢀJ.ꢀRabeah,ꢀK.ꢀJunge,ꢀH.ꢀJunge,ꢀM.ꢀNielsen,ꢀA.ꢀ
Brückner,ꢀM.ꢀBeller,ꢀNat.ꢀChem.,ꢀ2013,ꢀ5,ꢀ537–543.ꢀ
[15] R.ꢀ V.ꢀ Jagadeesh,ꢀ A.ꢀ E.ꢀ Surkus,ꢀ H.ꢀ Junge,ꢀ M.ꢀ M.ꢀ Pohl,ꢀ J.ꢀ Radnik,ꢀ J.ꢀ
Rabeah,ꢀH.ꢀHuan,ꢀV.ꢀSchünemann,ꢀA.ꢀBrückner,ꢀM.ꢀBeller,ꢀScience,ꢀ
2013,ꢀ342,ꢀ1073–1076.ꢀ
[
[
[
[
[
[
[
16] J.ꢀJꢀSong,ꢀZ.ꢀF.ꢀHuang,ꢀL.ꢀPan,ꢀJ.ꢀJ.ꢀZou,ꢀX.ꢀW.ꢀZhang,ꢀL.ꢀWang,ꢀACSꢀ
[34] M.ꢀ Latorre‐Sánchez,ꢀ A.ꢀ Primo,ꢀ H.ꢀ García,ꢀ Angew.ꢀ Chem.ꢀ Int.ꢀ Ed.,ꢀ
2013,ꢀ52,ꢀ11813–11816.ꢀ
Catal.,ꢀ2015,ꢀ5,ꢀ6594–6599.ꢀ
17] H.ꢀL.ꢀNiu,ꢀJ.ꢀH.ꢀLu,ꢀJ.ꢀJ.ꢀSong,ꢀL.ꢀPan,ꢀX.ꢀW.ꢀZhang,ꢀL.ꢀWang,ꢀJ.ꢀJ.ꢀZou,ꢀ
Ind.ꢀEng.ꢀChem.ꢀRes.,ꢀ2016,ꢀ55,ꢀ8527–8533.ꢀ
18] J.ꢀH.ꢀLu,ꢀJ.ꢀJ.ꢀSong,ꢀH.ꢀL.ꢀNiu,ꢀL.ꢀPan,ꢀX.ꢀW.ꢀZhang,ꢀL.ꢀWang,ꢀJ.ꢀJ.ꢀZou,ꢀ
Appl.ꢀSurf.ꢀSci.,ꢀ2016,ꢀ371,ꢀ61–66.ꢀ
19] Y.ꢀC.ꢀZhang,ꢀL.ꢀPan,ꢀJ.ꢀH.ꢀLu,ꢀJ.ꢀJ.ꢀSong,ꢀZ.ꢀLi,ꢀX.ꢀW.ꢀZhang,ꢀL.ꢀWang,ꢀJ.ꢀJ.ꢀ
Zou,ꢀAppl.ꢀSurf.ꢀSci.,ꢀ2017,ꢀ401,ꢀ241–247.ꢀ
20] Z.ꢀZ.ꢀWei,ꢀJ.ꢀWang,ꢀS.ꢀJ.ꢀMao,ꢀD.ꢀF.ꢀSu,ꢀH.ꢀY.ꢀJin,ꢀY.ꢀH.ꢀWang,ꢀF.ꢀXu,ꢀH.ꢀR.ꢀ
Li,ꢀY.ꢀWang,ꢀACSꢀCatal.,ꢀ2015,ꢀ5,ꢀ4783–4789.ꢀ
21] H.ꢀFan,ꢀX.ꢀHuang,ꢀL.ꢀShang,ꢀY.ꢀT.ꢀCao,ꢀY.ꢀF.ꢀZhao,ꢀL.ꢀZ.ꢀWu,ꢀC.ꢀH.ꢀTung,ꢀ
Y.ꢀD.ꢀYin,ꢀT.ꢀR.ꢀZhang,ꢀAngew.ꢀChem.ꢀInt.ꢀEd.,ꢀ2016,ꢀ55,ꢀ2167–2170.ꢀ
22] L.ꢀShang,ꢀY.ꢀH.ꢀLiang,ꢀM.ꢀZ.ꢀLi,ꢀG.ꢀI.ꢀN.ꢀWaterhouse,ꢀP.ꢀTang,ꢀD.ꢀMa,ꢀL.ꢀ
Z.ꢀ Wu,ꢀ C.ꢀ H.ꢀ Tung,ꢀ T.ꢀ R.ꢀ Zhang,ꢀ Adv.ꢀ Func.ꢀ Mater.,ꢀ 2017,ꢀ 27,ꢀ
[35] C.ꢀ Tang,ꢀ H.ꢀ F.ꢀ Wang,ꢀ X.ꢀ Chen,ꢀ B.ꢀ Q.ꢀ Li,ꢀ T.ꢀ Z.ꢀ Hou,ꢀ B.ꢀ S.ꢀ Zhang,ꢀ Q.ꢀ
Zhang,ꢀM.ꢀM.ꢀTitirici,ꢀF.ꢀWei,ꢀAdv.ꢀMater.,ꢀ2016,ꢀ28,ꢀ6845–6851.ꢀ
[36] Y.ꢀJ.ꢀGao,ꢀG.ꢀHu,ꢀJ.ꢀZhong,ꢀZ.ꢀJ.ꢀShi,ꢀY.ꢀS.ꢀZhu,ꢀD.ꢀS.ꢀSu,ꢀJ.ꢀG.ꢀWang,ꢀX.ꢀH.ꢀ
Bao,ꢀD.ꢀMa,ꢀAngew.ꢀChem.ꢀInt.ꢀEd.,ꢀ2013,ꢀ52,ꢀ2109–2113.ꢀ
[37] X.ꢀK.ꢀKong,ꢀZ.ꢀY.ꢀSun,ꢀM.ꢀChen,ꢀC.ꢀL.ꢀChen,ꢀQ.ꢀW.ꢀChen,ꢀEnergyꢀEnvi‐
ron.ꢀSci.,ꢀ2013,ꢀ6,ꢀ3260–3266.ꢀ
[38] Y.ꢀY.ꢀCai,ꢀX.ꢀH.ꢀLi,ꢀY.ꢀN.ꢀZhang,ꢀX.ꢀWei,ꢀK.ꢀX.ꢀWang,ꢀJ.ꢀS.ꢀChen,ꢀAngew.ꢀ
Chem.ꢀInt.ꢀEd.,ꢀ2013,ꢀ52,ꢀ11822–11825.ꢀ
[39] L.ꢀ H.ꢀ Gong,ꢀY.ꢀY.ꢀ Cai,ꢀX.ꢀH.ꢀ Li,ꢀY.ꢀN.ꢀZhang,ꢀJ.ꢀ Su,ꢀJ.ꢀS.ꢀChen,ꢀGreenꢀ
Chem.,ꢀ2014,ꢀ16,ꢀ3736–3751.ꢀ
[40] X.ꢀH.ꢀLi,ꢀM.ꢀAntonietti,ꢀChem.ꢀSoc.ꢀRev.,ꢀ2013,ꢀ42,ꢀ6593–6604.ꢀ
[41] Y.ꢀZ.ꢀChen,ꢀC.ꢀM.ꢀWang,ꢀZ.ꢀY.ꢀWu,ꢀY.ꢀJ.ꢀXiong,ꢀQ.ꢀXu,ꢀS.ꢀH.ꢀYu,ꢀH.ꢀL.ꢀ
Jiang,ꢀAdv.ꢀMater.,ꢀ2015,ꢀ27,ꢀ5010–5016.ꢀ
1606215.ꢀ
[
[
[
23] Y.ꢀM.ꢀLin,ꢀS.ꢀC.ꢀWu,ꢀW.ꢀShi,ꢀB.ꢀS.ꢀZhang,ꢀJ.ꢀWang,ꢀY.ꢀA.ꢀKin,ꢀM.ꢀEndo,ꢀD.ꢀ
[42] G.ꢀ Kennedy,ꢀ L.ꢀ R.ꢀ Baker,ꢀ G.ꢀ A.ꢀ Sormorjai,ꢀ Angew.ꢀ Chem.ꢀ Int.ꢀ Ed.,ꢀ
2014,ꢀ53,ꢀ3405–3408.ꢀ
[43] H.ꢀJ.ꢀYu,ꢀL.ꢀShang,ꢀT.ꢀBian,ꢀR.ꢀShi,ꢀG.ꢀI.ꢀN.ꢀWaterhouse,ꢀY.ꢀF.ꢀZhao,ꢀC.ꢀ
Zhou,ꢀ L.ꢀ Z.ꢀ Wu,ꢀ C.ꢀ H.ꢀ Tung,ꢀ T.ꢀ R.ꢀ Zhang,ꢀ Adv.ꢀ Mater.,ꢀ 2016,ꢀ 28,ꢀ
5080–5086.ꢀ
S.ꢀSu,ꢀChem.ꢀCommun.,ꢀ2015,ꢀ51,ꢀ13086–13089.ꢀ
24] S.ꢀC.ꢀWu,ꢀG.ꢀD.ꢀWen,ꢀJ.ꢀWang,ꢀJ.ꢀF.ꢀRong,ꢀB.ꢀN.ꢀZong,ꢀR.ꢀSchlögl,ꢀD.ꢀS.ꢀ
Su,ꢀCatal.ꢀSci.ꢀTechnol.,ꢀ2014,ꢀ4,ꢀ4183–4187.ꢀ
25] Y.ꢀ J.ꢀ Gao,ꢀ D,ꢀ Ma,ꢀ C.ꢀ L.ꢀ Wang,ꢀ J.ꢀ Guan,ꢀ X.ꢀ H.ꢀ Bao,ꢀ Chem.ꢀ Commun.,ꢀ
2011,ꢀ47,ꢀ2432–2434.ꢀ
[44] R.ꢀN.ꢀButler,ꢀA.ꢀG.ꢀCoyne,ꢀChem.ꢀRev.,ꢀ2010,ꢀ110,ꢀ6302–6337.ꢀ

672ꢀ
RuijieꢀGaoꢀetꢀal.ꢀ/ꢀChineseꢀJournalꢀofꢀCatalysisꢀ39ꢀ(2018)ꢀ664–672ꢀ
[
[
[
45] S.ꢀZhang,ꢀC.ꢀR.ꢀChang,ꢀZ.ꢀQ.ꢀHuang,ꢀJ.ꢀLi,ꢀZ.ꢀM.ꢀWu,ꢀY.ꢀY.ꢀMa,ꢀZ.ꢀY.ꢀ
Zhang,ꢀY.ꢀWang,ꢀY.ꢀQ.ꢀQu,ꢀJ.ꢀAm.ꢀSoc.ꢀChem.,ꢀ2016,ꢀ138,ꢀ2629–2637.ꢀ
46] P.ꢀMaity,ꢀS.ꢀBasu,ꢀS.ꢀBhaduri,ꢀG.ꢀK.ꢀLahiri,ꢀAdv.ꢀSynth.ꢀCatal.,ꢀ2007,ꢀ
Chem.,ꢀ2011,ꢀ13,ꢀ570–572.ꢀ
[48] E.ꢀ A.ꢀ Gelder,ꢀ S.ꢀ D.ꢀ Jackson,ꢀ C.ꢀ M.ꢀ Lok,ꢀ Catal.ꢀ Lett.,ꢀ 2002,ꢀ 84,ꢀ
205–208.ꢀ
[49] Z.ꢀZ.ꢀWei,ꢀJ.ꢀWang,ꢀS.ꢀJ.ꢀMao,ꢀD.ꢀF.ꢀSu,ꢀH.ꢀY.ꢀJin,ꢀY.ꢀH.ꢀWang,ꢀF.ꢀXu,ꢀH.ꢀR.ꢀ
Li,ꢀY.ꢀWang,ꢀACSꢀCatal.,ꢀ2015,ꢀ5,ꢀ4783–4789.
349,ꢀ1955–1962.ꢀ
47] X.ꢀC.ꢀMeng,ꢀH.ꢀY.ꢀCheng,ꢀS.ꢀFujita,ꢀY.ꢀC.ꢀYu,ꢀF.ꢀY.ꢀZhao,ꢀM.ꢀArai,ꢀGreenꢀ
氮掺杂碳包覆纳米钴颗粒用于硝基芳烃室温选择性加氢
a,b,*
a,b
a,b
a
a,b
a,b
高睿杰 , 潘 伦 , 李正稳 , 张香文 , 王 莅 , 邹吉军
a
天津大学化工学院, 绿色合成与转化教育部重点实验室, 天津300372
b
天津化学化工协同创新中心, 天津300372
摘要: 通过硝基芳烃选择性加氢能高效地制备芳香胺和环胺, 其中芳香胺作为重要的化工中间体应用于多个领域(精细化
工、商业产品和聚合物). 在加氢反应过程中, 硝基的还原伴随着生成一些副产物(如亚硝基和偶氮化合物). 同时对于含还
原性基团的取代硝基苯, 硝基的选择还原也面临着很大的挑战. 金属钴是常用的硝基加氢催化剂活性成分, 但是由于对反
应底物的过度吸附, 导致其选择性不高. 早期研究发现, 氮掺杂碳催化剂能有效吸附硝基基团, 从而在硝基苯加氢中表现
出一定活性, 但对分子氢的活化不足. 因此, 氮掺杂碳作为吸附材料与钴构建复合催化剂, 能够发挥吸附和活化氢的协同
作用, 从而高效催化硝基苯加氢.
基于此, 本课题组发展了一种制备方法, 可将钴颗粒尺寸限制在10 nm左右, 且包覆在氮掺杂碳中, 并应用于对硝基苯
酚的室温选择性加氢反应中, 发现相较于碳负载钴和氮掺杂碳催化剂, 所制催化剂在室温下表现出了很好的活性和选择
性. 在此基础上, 本文采用元素分析、X射线光电子能谱(XPS)和拉曼光谱(Raman)等手段对催化剂形貌和结构进行了研究.
表征结果表明, 保持钴前驱体的量不变, 随着氮化碳加入量的增加, 催化剂中氮掺杂浓度提高; 当氮化碳/钴>1时, 氮掺
杂浓度不变. 红外结果表明, 与普通碳载体相比, 氮掺杂碳对硝基苯有很强的吸附作用, 而氮掺杂碳包覆的钴催化剂也表
现出同样的结果. 通过调节氮的掺杂浓度, 一方面可以修饰碳载体的电子结构, 增加表面缺陷的浓度, 提高与反应底物的
相互作用; 另一方面可以促进电子由钴颗粒转移至与之相连的氮原子上, 因此进一步促进钴颗粒对分子氢的活化作用. 该
复合结构的催化剂实现了底物吸附和氢活化的协同作用, 氮掺杂碳将反应底物吸附在表面, 钴颗粒活化氢, 随后解离的氢
原子与表面吸附物反应, 从而实现硝基苯的高效加氢. 其中Co@NC-1催化活性最高, 并在循环套用10次后, 仍维持较高的
催化活性, 同时对含其它取代基的硝基苯均表现很高的活性和选择性.
关键词: 钴颗粒; 氮掺杂碳; 硝基芳烃; 选择加氢; 氢活化; 多相催化
收稿日期: 2017-11-29. 接受日期: 2017-12-22. 出版日期: 2018-04-05.
*
通讯联系人. 电话/传真: (022)27892340; 电子信箱: jj_zou@tju.edu.cn
基金来源: 国家自然科学基金(U1462119); 天津市自然科学基金(16JCQNJC05200).
本文的电子版全文由Elsevier出版社在ScienceDirect上出版(http://www.sciencedirect.com/science/journal/18722067).