Encapsulated Ni-Co alloy nanoparticles as efficient catalyst for hydrodeoxygenation of biomass derivatives in water

Article abstract of DOI:10.1016/S1872-2067(21)63828-7

Catalytic hydrodeoxygenation (HDO) is one of the most promising strategies to transform oxygen-rich biomass derivatives into high value-added chemicals and fuels, but highly challenging due to the lack of highly efficient nonprecious metal catalysts. Herein, we report for the first time of a facile synthetic approach to controllably fabricate well-defined Ni-Co alloy NPs confined on the tip of N-CNTs as HDO catalyst. The resultant Ni-Co alloy catalyst possesses outstanding HDO performance towards biomass-derived vanillin into 2-methoxy-4-methylphenol in water with 100% conversion efficiency and selectivity under mild reaction conditions, surpassing the reported high performance nonprecious HDO catalysts. Impressively, our experimental results also unveil that the Ni-Co alloy catalyst can be generically applied to catalyze HDO of vanillin derivatives and other aromatic aldehydes in water with 100% conversion efficiency and over 90% selectivity. Importantly, our DFT calculations and experimental results confirm that the achieved outstanding HDO catalytic performance is due to the greatly promoted selective adsorption and activation of C=O, and desorption of the activated hydrogen species by the synergism of the alloyed Ni-Co NPs. The findings of this work affords a new strategy to design and develop efficient transition metal-based catalysts for HDO reactions in water.

Full text of DOI:10.1016/S1872-2067(21)63828-7

ChineseꢀJournalꢀofꢀCatalysisꢀ42ꢀ(2021)ꢀ2027–2037
ꢀ
ꢀ ꢀ ꢀ
ꢀ ꢀ ꢀ ꢀ
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
ꢀ
journal homepage: www.sciencedirect.com/journal/chinese‐journal‐of‐catalysis
ꢀ
ꢀ
Article
EncapsulatedꢀNi‐Coꢀalloyꢀnanoparticlesꢀasꢀefficientꢀcatalystꢀforꢀ ꢀ
hydrodeoxygenationꢀofꢀbiomassꢀderivativesꢀinꢀwaterꢀ
$
a,b
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a,b
c,
a
DongdongꢀWangꢀ ,ꢀWanbingꢀGongꢀ ,ꢀJifangꢀZhangꢀ ,ꢀMiaomiaoꢀHanꢀ ,ꢀChunꢀChenꢀ ,ꢀ ꢀ
a
a
a
a,d,
YunxiaꢀZhangꢀ ,ꢀGuozhongꢀWangꢀ ,ꢀHaiminꢀZhangꢀ ,ꢀHuijunꢀZhaoꢀ *
ꢀ
aꢀKeyꢀLaboratoryꢀofꢀMaterialsꢀPhysics,ꢀCentreꢀforꢀEnvironmentalꢀandꢀEnergyꢀNanomaterials,ꢀAnhuiꢀKeyꢀLaboratoryꢀofꢀNanomaterialsꢀandꢀNanotechnolo‐
gy,ꢀCASꢀCentreꢀforꢀExcellenceꢀinꢀNanoscience,ꢀInstituteꢀofꢀSolidꢀStateꢀPhysics,ꢀHefeiꢀInstitutesꢀofꢀPhysicalꢀScience,ꢀChineseꢀAcademyꢀofꢀSciences,ꢀHefeiꢀ
230031,ꢀAnhui,ꢀChinaꢀ
bꢀUniversityꢀofꢀScienceꢀandꢀTechnologyꢀofꢀChina,ꢀHefeiꢀ230026,ꢀAnhui,ꢀChinaꢀ
cꢀSchoolꢀofꢀScience,ꢀHuzhouꢀUniversity,ꢀHuzhouꢀ313000,ꢀZhejiang,ꢀChinaꢀ
dꢀCentreꢀforꢀCleanꢀEnvironmentꢀandꢀEnergy,ꢀGoldꢀCoastꢀCampus,ꢀGriffithꢀUniversity,ꢀQueenslandꢀ4222,ꢀAustraliaꢀ
A R T I C L E ꢀ I N F O ꢀ
A B S T R A C T ꢀ
Articleꢀhistory:ꢀ
Catalyticꢀ hydrodeoxygenationꢀ (HDO)ꢀ isꢀ oneꢀ ofꢀ theꢀ mostꢀ promisingꢀ strategiesꢀ toꢀ transformꢀ oxy‐
gen‐richꢀbiomassꢀderivativesꢀintoꢀhighꢀvalue‐addedꢀchemicalsꢀandꢀfuels,ꢀbutꢀhighlyꢀchallengingꢀdueꢀ
toꢀtheꢀlackꢀofꢀhighlyꢀefficientꢀnonpreciousꢀmetalꢀcatalysts.ꢀHerein,ꢀweꢀreportꢀforꢀtheꢀfirstꢀtimeꢀofꢀaꢀ
facileꢀsyntheticꢀapproachꢀtoꢀcontrollablyꢀfabricateꢀwell‐definedꢀNi‐CoꢀalloyꢀNPsꢀconfinedꢀonꢀtheꢀtipꢀ
ofꢀN‐CNTsꢀasꢀHDOꢀcatalyst.ꢀTheꢀresultantꢀNi‐CoꢀalloyꢀcatalystꢀpossessesꢀoutstandingꢀHDOꢀperfor‐
manceꢀtowardsꢀbiomass‐derivedꢀvanillinꢀintoꢀ2‐methoxy‐4‐methylphenolꢀinꢀwaterꢀwithꢀ100%ꢀcon‐
versionꢀefficiencyꢀandꢀselectivityꢀunderꢀmildꢀreactionꢀconditions,ꢀsurpassingꢀtheꢀreportedꢀhighꢀper‐
formanceꢀnonpreciousꢀHDOꢀcatalysts.ꢀImpressively,ꢀourꢀexperimentalꢀresultsꢀalsoꢀunveilꢀthatꢀtheꢀ
Ni‐Coꢀ alloyꢀ catalystꢀ canꢀ beꢀ genericallyꢀ appliedꢀ toꢀ catalyzeꢀ HDOꢀ ofꢀ vanillinꢀ derivativesꢀ andꢀ otherꢀ
aromaticꢀaldehydesꢀinꢀwaterꢀwithꢀ100%ꢀconversionꢀefficiencyꢀandꢀoverꢀ90%ꢀselectivity.ꢀImportant‐
ly,ꢀourꢀDFTꢀcalculationsꢀandꢀexperimentalꢀresultsꢀconfirmꢀthatꢀtheꢀachievedꢀoutstandingꢀHDOꢀcata‐
lyticꢀperformanceꢀisꢀdueꢀtoꢀtheꢀgreatlyꢀpromotedꢀselectiveꢀadsorptionꢀandꢀactivationꢀofꢀC=O,ꢀandꢀ
desorptionꢀofꢀtheꢀactivatedꢀhydrogenꢀspeciesꢀbyꢀtheꢀsynergismꢀofꢀtheꢀalloyedꢀNi‐CoꢀNPs.ꢀTheꢀfind‐
ingsꢀofꢀthisꢀworkꢀaffordsꢀaꢀnewꢀstrategyꢀtoꢀdesignꢀandꢀdevelopꢀefficientꢀtransitionꢀmetal‐basedꢀcata‐
lystsꢀforꢀHDOꢀreactionsꢀinꢀwater.ꢀ
Receivedꢀ16ꢀMarchꢀ2021ꢀ
Acceptedꢀ15ꢀAprilꢀ2021ꢀ
Availableꢀonlineꢀ20ꢀAugustꢀ2021ꢀ
Keywords:ꢀ
Ni‐Coꢀalloyꢀnanoparticlesꢀ
Carbonꢀnanotubesꢀ
Hydrodeoxygenationꢀ
Biomassꢀderivativesꢀ
2
H Oꢀsolventꢀ
©ꢀ2021,ꢀDalianꢀInstituteꢀofꢀChemicalꢀPhysics,ꢀChineseꢀAcademyꢀofꢀSciences.
PublishedꢀbyꢀElsevierꢀB.V.ꢀAllꢀrightsꢀreserved.
1
.ꢀ ꢀ Introductionꢀ
celluloseꢀ hasꢀ becomeꢀ aꢀ greenꢀ andꢀ economicꢀ meansꢀ forꢀ massꢀ
productionꢀofꢀbio‐oilsꢀtoꢀsubstituteꢀfossilꢀfuelsꢀ[2–4].ꢀHowever,ꢀ
dueꢀtoꢀtheꢀrichꢀoxygenꢀcontents,ꢀtheꢀobtainedꢀbio‐oilsꢀpossessꢀ
relativelyꢀ lowꢀ energyꢀ densityꢀ andꢀ couldꢀ causeꢀ damageꢀ toꢀ en‐
ginesꢀ[5].ꢀTheꢀcatalyticꢀhydrodeoxygenationꢀ(HDO)ꢀhasꢀthere‐
foreꢀbeenꢀemployedꢀtoꢀupgradeꢀbio‐oilsꢀwithꢀhighꢀenergyꢀden‐
Theꢀconversionꢀofꢀabundantꢀbiomassꢀandꢀtheirꢀderivativesꢀ
intoꢀ highꢀ value‐addedꢀ fuelsꢀ andꢀ chemicalsꢀ isꢀ regardedꢀ asꢀ anꢀ
importantꢀgreenꢀavenueꢀtoꢀreduceꢀourꢀdependenceꢀonꢀconven‐
tionalꢀfossilꢀresourcesꢀ[1].ꢀAmongꢀthem,ꢀtheꢀpyrolysisꢀofꢀligno‐
*
ꢀ
$ꢀ
ꢀCorrespondingꢀauthor.ꢀTel:ꢀ+86‐551‐65591263;ꢀFax:ꢀ+86‐551‐65591434;ꢀE‐mail:ꢀh.zhao@griffith.edu.auꢀ
Correspondingꢀauthor.ꢀTel:ꢀ+86‐551‐65591263;ꢀFax:ꢀ+86‐551‐65591434;ꢀE‐mail:ꢀwbgong@issp.ac.cnꢀ
Correspondingꢀauthor.ꢀTel:ꢀ+86‐551‐65591263;ꢀFax:ꢀ+86‐551‐65591434;ꢀE‐mail:ꢀmmhan@zjhu.edu.cnꢀ
#
ThisꢀworkꢀwasꢀsupportedꢀbyꢀtheꢀNationalꢀNaturalꢀScienceꢀFoundationꢀofꢀChinaꢀ(51902311,ꢀ51871209,ꢀ61804154).ꢀ
DOI:ꢀ10.1016/S1872‐2067(21)63828‐7ꢀ|ꢀhttp://www.sciencedirect.com/journal/chinese‐journal‐of‐catalysisꢀ|ꢀChin.ꢀJ.ꢀCatal.,ꢀVol.ꢀ42,ꢀNo.ꢀ11,ꢀNovemberꢀ2021

2028ꢀ
DongdongꢀWangꢀetꢀal.ꢀ/ꢀChineseꢀJournalꢀofꢀCatalysisꢀ42ꢀ(2021)ꢀ2027–2037ꢀ
sityꢀbyꢀselectivelyꢀremovingꢀoxygenꢀcontentsꢀ[6–8].ꢀAsꢀaꢀdirectꢀ
lignocelluloseꢀ pyrolysisꢀ product,ꢀ vanillinꢀ canꢀ beꢀ upgradedꢀ toꢀ
Ni‐basedꢀ catalysts,ꢀ allyingꢀ Niꢀ withꢀ otherꢀ 3d‐TMsꢀhasꢀbeenꢀin‐
vestigated.ꢀLiuꢀetꢀal.ꢀ[35]ꢀtheoreticallyꢀunveiledꢀthatꢀtheꢀactiva‐
tionꢀofꢀC–Oꢀbondꢀofꢀm‐cresolꢀandꢀphenolicꢀintermediatesꢀcanꢀbeꢀ
markedlyꢀpromotedꢀbyꢀNi‐Feꢀalloy.ꢀInꢀfact,ꢀChen’sꢀgroupꢀ[36]ꢀ
demonstratedꢀthatꢀalloyingꢀtheꢀgroupꢀVIIIꢀnobleꢀmetalsꢀsuchꢀasꢀ
Ptꢀ(111)ꢀwithꢀ3d‐TMsꢀ(e.g.,ꢀCu,ꢀNi,ꢀFeꢀandꢀCo)ꢀcanꢀpromoteꢀtheꢀ
selectiveꢀ cleavingꢀ C=Oꢀ bondꢀ toꢀ enhanceꢀ HDOꢀ activity.ꢀ Theseꢀ
researchꢀfindingsꢀinspireꢀusꢀtoꢀexploreꢀ3d‐TMsꢀalloysꢀwithꢀsu‐
periorꢀ catalyticꢀ performanceꢀ towardꢀ HDOꢀ ofꢀ vanillinꢀ andꢀ itsꢀ
derivativesꢀinꢀaqueousꢀmediaꢀunderꢀmildꢀreactionꢀconditions.ꢀ
Here,ꢀweꢀforꢀtheꢀfirstꢀtimeꢀreportꢀtheꢀcontrollableꢀsynthesisꢀ
ofꢀ well‐definedꢀ Ni‐Coꢀ alloyꢀ NPsꢀ confinedꢀ byꢀ N‐dopedꢀ carbonꢀ
nanotubesꢀ (N‐CNTs)ꢀ graftedꢀ onꢀ carbonizedꢀ Melamineꢀ Foamꢀ
(CMF)ꢀ andꢀ theirꢀ applicationꢀ asꢀ anꢀ efficientꢀ HDOꢀ catalystꢀ toꢀ
transformꢀvanillin,ꢀitsꢀderivativesꢀandꢀotherꢀaromaticꢀaldehydesꢀ
toꢀ theꢀ correspondingꢀ MMPsꢀ andꢀ deoxygenatedꢀ products.ꢀ Ourꢀ
experimentalꢀ resultsꢀ demonstrateꢀ thatꢀ theꢀ as‐synthesizedꢀ
Ni‐CoꢀalloyꢀNPsꢀcatalystꢀ(NiCo@N‐CNTs/CMF)ꢀcanꢀcompletelyꢀ
convertꢀ vanillinꢀ toꢀ MMPꢀ withꢀ aꢀ 100%ꢀ selectivityꢀ withinꢀ 6ꢀ hꢀ
2‐methoxy‐4‐methylphenolꢀ(MMP)ꢀ viaꢀHDOꢀ[9].ꢀTheꢀobtainedꢀ
MMPꢀhasꢀwideꢀapplicationsꢀnotꢀonlyꢀasꢀaꢀhighꢀenergyꢀdensityꢀ
fuelꢀbutꢀalsoꢀasꢀanꢀimportantꢀintermediateꢀtoꢀsynthesizeꢀdrugsꢀ
andꢀfragrancesꢀ[10].ꢀOverꢀtheꢀpastꢀdecade,ꢀmanyꢀefficientꢀcata‐
lystsꢀ haveꢀ beenꢀ designedꢀ andꢀ synthesizedꢀ forꢀ HDOꢀ reactions.ꢀ
Dueꢀtoꢀtheirꢀhighꢀactivities,ꢀtheꢀpreciousꢀmetalꢀcatalystsꢀsuchꢀasꢀ
Pt,ꢀPd,ꢀRuꢀandꢀAu‐basedꢀcatalystsꢀhaveꢀbeenꢀextensivelyꢀstudiedꢀ
[7,11–14].ꢀNonetheless,ꢀtheꢀundesirableꢀsideꢀreactionsꢀresultedꢀ
fromꢀpoorꢀselectivityꢀaddingꢀtoꢀtheꢀhighꢀcostꢀandꢀlowꢀreserveꢀ
seriouslyꢀlimitꢀtheꢀwidespreadꢀuseꢀofꢀpreciousꢀmetalsꢀ[15].ꢀRe‐
cently,ꢀ theꢀ transitionꢀ metalsꢀ (TMs)ꢀ suchꢀ asꢀ Fe,ꢀ Co,ꢀ Niꢀ andꢀ Cuꢀ
basedꢀ catalyticꢀ materialsꢀ haveꢀ demonstratedꢀ toꢀ possessꢀ cata‐
lyticꢀactivitiesꢀtowardꢀHDOꢀofꢀvanillinꢀtoꢀMMPꢀ[16–22].ꢀHowev‐
er,ꢀdueꢀtoꢀtheꢀsuperiorꢀsolubilityꢀofꢀH2ꢀandꢀreactantsꢀinꢀorganicꢀ
solvents,ꢀtheꢀmajorityꢀofꢀtheꢀreportedꢀHDOꢀreactionsꢀareꢀper‐
formedꢀinꢀorganicꢀsolventsꢀsuchꢀasꢀmethanolꢀandꢀisopropanolꢀ
[18,19,21–24],ꢀ whichꢀisꢀundesirableꢀ fromꢀ economicꢀandꢀ envi‐
ronmentalꢀ viewpointsꢀ [13].ꢀ Therefore,ꢀ developingꢀ efficientꢀ
nonpreciousꢀmetalꢀcatalystsꢀcapableꢀofꢀselectivelyꢀHDOꢀofꢀvan‐
illinꢀtoꢀMMPꢀinꢀwaterꢀisꢀrequired.ꢀInꢀthisꢀregard,ꢀRanawareꢀetꢀal.ꢀ
underꢀ2ꢀMPaꢀH
2
ꢀandꢀ120ꢀ°C.ꢀUnderꢀmildꢀreactionꢀconditions,ꢀtheꢀ
catalystꢀexhibitsꢀexcellentꢀHDOꢀcatalyticꢀperformanceꢀtowardꢀaꢀ
wideꢀspectrumꢀofꢀvanillinꢀderivativesꢀandꢀotherꢀaromaticꢀalde‐
hydesꢀ withꢀ 100%ꢀ conversionꢀ efficiencyꢀ andꢀ highꢀ selectivityꢀ
(91.5%ꢀtoꢀ100%).ꢀTheꢀexperimentalꢀresultsꢀandꢀdensityꢀfunc‐
tionalꢀtheoryꢀcalculationsꢀunveilꢀthatꢀtheꢀexcellentꢀHDOꢀcatalyt‐
icꢀperformanceꢀofꢀNiCo@N‐CNTs/CMFꢀcanꢀbeꢀattributedꢀtoꢀtheꢀ
greatlyꢀ promotedꢀ selectiveꢀ adsorptionꢀ andꢀ activationꢀ ofꢀ C=O,ꢀ
andꢀ desorptionꢀ ofꢀ theꢀ activatedꢀ hydrogenꢀ speciesꢀ onꢀ theꢀ al‐
loyedꢀNi‐CoꢀNPsꢀsurface.ꢀ
[20]ꢀ recentlyꢀ demonstratedꢀ aꢀ magnetically‐separableꢀ
ZnO/Co@N‐CNTsꢀcatalystꢀtoꢀachieveꢀcompleteꢀvanillinꢀconver‐
sionꢀ withꢀ aꢀ 100%ꢀ MMPꢀ selectivity,ꢀ however,ꢀ requiresꢀ aꢀ rela‐
tivelyꢀ highꢀ reactionꢀ temperatureꢀ ofꢀ 150ꢀ °C.ꢀ Weꢀ recentlyꢀ re‐
portedꢀ aꢀ highlyꢀ dispersedꢀ Ni‐basedꢀ HDOꢀ catalystꢀ toꢀ achieveꢀ
completeꢀ vanillinꢀ conversionꢀ withꢀ 100%ꢀ MMPꢀ selectivityꢀ inꢀ
ꢀ
waterꢀatꢀ130 °Cꢀoverꢀaꢀ10ꢀhꢀreactionꢀperiodꢀ[25].ꢀItꢀisꢀknownꢀ
thatꢀaꢀhighꢀreactionꢀtemperatureꢀcouldꢀaccelerateꢀcatalystꢀde‐
activationꢀ dueꢀ toꢀ theꢀ acceleratedꢀ leachingꢀ andꢀ formationꢀ ofꢀ
cokeꢀ[26,27].ꢀToꢀthisꢀend,ꢀtheꢀdesignꢀofꢀnonpreciousꢀcatalystsꢀ
capableꢀofꢀefficientlyꢀconvertingꢀvanillinꢀtoꢀMMPꢀinꢀwaterꢀunderꢀ
mildꢀconditionsꢀstillꢀremainsꢀasꢀaꢀchallenge.ꢀ ꢀ
2.ꢀ ꢀ Experimentalꢀ
2.1.ꢀ ꢀ Materialsꢀ ꢀ
Recently,ꢀtheꢀsynergeticꢀeffectꢀofꢀtheꢀalloyedꢀnanoparticlesꢀ
NPs)ꢀbasedꢀcatalystsꢀhasꢀbeenꢀadvantageouslyꢀutilizedꢀtoꢀdra‐
AllꢀchemicalꢀreagentsꢀwereꢀofꢀARꢀpurityꢀandꢀusedꢀwithoutꢀ
furtherꢀ purification.ꢀ Melamineꢀ Foamꢀ (MF)ꢀ wasꢀ providedꢀ byꢀ
(
maticallyꢀenhanceꢀtheꢀcatalystꢀperformanceꢀforꢀupgradingꢀbio‐
massꢀ andꢀ biomass‐derivativesꢀ toꢀ highꢀ valuedꢀ chemicalsꢀ andꢀ
fuelsꢀ [28–32].ꢀ Miyazakiandꢀ andꢀ co‐workersꢀ employedꢀ aꢀ SiO2ꢀ
Puyangꢀ Greenꢀ Foamꢀ Co.ꢀ Ltd.ꢀ Co(NO
3
)
2
∙6H
2
O,ꢀ Ni(NO
3
)
2
∙6H Oꢀ
2
andꢀmelamineꢀwereꢀpurchasedꢀfromꢀSinopharmꢀChemicalꢀRea‐
gentꢀ Co.ꢀ Ltd.ꢀ Vanillin,ꢀ 4‐hydroxymethyl‐2‐methoxyphenol,ꢀ
2‐methoxy‐4‐methylphenol,ꢀ ethylꢀ vanillin,ꢀ syringaldehyde,ꢀ
para‐hydroxyꢀ benzaldehyde,ꢀ ortho‐methylꢀ benzaldehyde,ꢀ pa‐
ra‐methylꢀ benzaldehyde,ꢀ isovanillin,ꢀ n‐octanolꢀ andꢀ ethylꢀ ace‐
tateꢀwereꢀpurchasedꢀfromꢀAladdinꢀReagentꢀCompany.ꢀ
supportedꢀRh‐BiꢀalloyꢀNPsꢀ(RhBi/SiO )ꢀtoꢀefficientlyꢀhydrogen‐
2
ateꢀtrans‐1,4‐hexadieneꢀtoꢀtrans‐2‐hexeneꢀ[30].ꢀTheyꢀattributedꢀ
theꢀexcellentꢀ catalyticꢀperformanceꢀtoꢀtheꢀ synergismꢀofꢀRh‐Biꢀ
NPsꢀ inducedꢀ regioselectivityꢀ forꢀ theꢀ terminalꢀ C=Cꢀ bondꢀ andꢀ
chemoselectivityꢀtoꢀformꢀtrans‐2‐hexene.ꢀWeꢀrecentlyꢀdemon‐
stratedꢀtheꢀuseꢀofꢀtheꢀsynergismꢀofꢀFe‐CoꢀalloyꢀNPsꢀbasedꢀhy‐
drogenationꢀ catalystꢀ toꢀ concurrentlyꢀ andꢀ efficientlyꢀ convertꢀ
cinnamaldehydeꢀ toꢀ cinnamylꢀ alcoholꢀ inꢀ waterꢀ withꢀ highꢀ con‐
versionꢀefficiencyꢀ(95.1%)ꢀandꢀselectivityꢀ(91.7%)ꢀ[31].ꢀHow‐
ever,ꢀtoꢀtheꢀbestꢀofꢀourꢀknowledge,ꢀtheꢀusingꢀ3d‐TMsꢀalloyꢀNPsꢀ
basedꢀcatalystꢀforꢀHDOꢀofꢀvanillinꢀandꢀitsꢀderivativesꢀhasꢀrarelyꢀ
beenꢀreported.ꢀ ꢀ
Inꢀgenerally,ꢀtheꢀgroupꢀVIIIꢀmetalsꢀ(Ni,ꢀRu,ꢀRh,ꢀPd,ꢀPt)ꢀpos‐
sessꢀhighꢀcatalyticꢀactivitiesꢀforꢀhydrogenationꢀofꢀunsaturatedꢀ
C=CꢀbondsꢀandꢀC=Oꢀbondsꢀ[33].ꢀForꢀthisꢀreason,ꢀNi‐basedꢀcata‐
lystsꢀhaveꢀbeenꢀwidelyꢀemployedꢀtoꢀcatalyzeꢀHDOꢀreactions,ꢀbutꢀ
exhibitingꢀlimitedꢀselectivityꢀtowardꢀoxygen‐freeꢀproductsꢀ[34].ꢀ
Toꢀ enhanceꢀ theꢀ deoxygenationꢀ activityꢀ andꢀ selectivityꢀ ofꢀ
2.2.ꢀ ꢀ Synthesisꢀofꢀcatalystsꢀ ꢀ
3
Aꢀpieceꢀ(4.5ꢀꢀ3ꢀꢀ3ꢀcm )ꢀofꢀcleanꢀMFꢀwasꢀtreatedꢀinꢀaꢀtubularꢀ
furnaceꢀunderꢀArꢀatmosphereꢀatꢀ800ꢀ°Cꢀforꢀ2ꢀhꢀtoꢀobtainꢀtheꢀ
carbonizedꢀMFꢀ(CMF).ꢀTheꢀresultantꢀCMFꢀ(2.5ꢀꢀ1.5ꢀꢀ1ꢀcm3)ꢀ
wasꢀfurtherꢀtreatedꢀwithꢀ3ꢀMꢀHNO ꢀinꢀaꢀTeflon‐linedꢀstainlessꢀ
3
steelꢀautoclaveꢀatꢀ120ꢀ°Cꢀforꢀ1ꢀh.ꢀTheꢀtreatedꢀCMFꢀwasꢀrinsedꢀ
withꢀdeionizedꢀwaterꢀandꢀdriedꢀatꢀ60ꢀ°C.ꢀ
TheꢀobtainedꢀCMFꢀwasꢀusedꢀasꢀtheꢀporousꢀsupportꢀtoꢀsyn‐
thesizeꢀ NiCo@N‐CNTs/CMF.ꢀ Inꢀ aꢀ typicalꢀ syntheticꢀ process,ꢀ aꢀ
pieceꢀofꢀCMFꢀwasꢀfirstlyꢀimmersedꢀinꢀ50ꢀmLꢀaqueousꢀsolutionꢀ
3 2 2
containingꢀ 5ꢀ mmolꢀ Ni(NO ) ∙6H Oꢀ andꢀ Co(NO
3 2
)
∙6H Oꢀ underꢀ
2
constantꢀstirringꢀforꢀ12ꢀh,ꢀthenꢀdriedꢀatꢀ60ꢀ°Cꢀovernight.ꢀTheꢀ

ꢀ
DongdongꢀWangꢀetꢀal.ꢀ/ꢀChineseꢀJournalꢀofꢀCatalysisꢀ42ꢀ(2021)ꢀ2027–2037ꢀ
2029ꢀ
resultantꢀ CMFꢀ withꢀ adsorbedꢀ Ni2+ꢀ andꢀ Co ꢀ (Ni ‐Co /CMF)ꢀ
wasꢀ transferredꢀ toꢀ aꢀ ceramicꢀ boatꢀ andꢀ placedꢀ atꢀ theꢀ down‐
streamꢀofꢀtheꢀquartzꢀtubeꢀinꢀtheꢀtubularꢀfurnace.ꢀAꢀceramicꢀboatꢀ
loadedꢀwithꢀ500ꢀmgꢀmelamineꢀwasꢀplacedꢀatꢀtheꢀupstreamꢀofꢀ
2+
2+
2+
placedꢀintoꢀtheꢀautoclave,ꢀpurgedꢀthreeꢀtimesꢀwithꢀN2ꢀtoꢀremoveꢀ
theꢀair,ꢀpressurizedꢀwithꢀH ꢀtoꢀaꢀdesiredꢀlevelꢀandꢀheatedꢀtoꢀaꢀ
2
pre‐determinedꢀtemperatureꢀunderꢀaꢀconstantꢀstirringꢀrateꢀofꢀ
600ꢀrpm.ꢀOnceꢀtheꢀdesiredꢀreactionꢀtimeꢀwasꢀreached,ꢀtheꢀau‐
toclaveꢀ wasꢀ quicklyꢀ cooledꢀ downꢀ toꢀ roomꢀ temperature.ꢀ Theꢀ
catalystꢀ andꢀ productsꢀwereꢀthenꢀ separatedꢀ fromꢀ theꢀ reactionꢀ
solutionꢀbyꢀcentrifugationꢀandꢀethylꢀacetateꢀextraction,ꢀrespec‐
tively.ꢀ Forꢀ catalystꢀ reusabilityꢀ tests,ꢀ theꢀ centrifugationꢀ recov‐
eredꢀcatalystꢀwasꢀwashedꢀwithꢀwaterꢀandꢀethanolꢀseveralꢀtimesꢀ
andꢀdriedꢀunderꢀvacuumꢀovenꢀatꢀ60ꢀ°C.ꢀ
TheꢀobtainedꢀliquidꢀproductꢀafterꢀHDOꢀreactionꢀwasꢀidenti‐
fiedꢀ byꢀ gasꢀ chromatography‐massꢀ spectrometryꢀ (GC‐MS,ꢀ
Thermoꢀ Fisherꢀ Scientific‐TXQꢀ Quntumꢀ XLS,ꢀ col‐
umn‐TG‐WAXMS)ꢀandꢀquantitativelyꢀanalyzedꢀbyꢀGCꢀ(Shimad‐
zu,ꢀ GC‐2010ꢀ Plus),ꢀ equippedꢀ withꢀ aꢀ flameꢀ ionizationꢀ detectorꢀ
andꢀaꢀKB‐WAXꢀcapillaryꢀcolumnꢀ(30ꢀmꢀꢀ0.25ꢀmmꢀꢀ0.25ꢀµm,ꢀ
KromatꢀCorporation,ꢀUSA).ꢀTheꢀcarbonꢀbalanceꢀwasꢀcheckedꢀinꢀ
everyꢀrunꢀandꢀitꢀwasꢀfoundꢀtoꢀbeꢀhigherꢀthanꢀ95%.ꢀ
–1ꢀ
theꢀquartzꢀtube.ꢀUnderꢀaꢀ50ꢀmLꢀmin flowꢀrateꢀofꢀH /Arꢀgas,ꢀtheꢀ
furnaceꢀ wasꢀheatedꢀ withꢀ aꢀ rampꢀofꢀ 2ꢀ °Cꢀmin ꢀtoꢀ600ꢀ°Cꢀandꢀ
maintainedꢀforꢀ2ꢀhꢀtoꢀobtainꢀNiCo@N‐CNTs/CMF.ꢀ ꢀ
Forꢀ comparisonꢀ experiments,ꢀ Co@N‐CNTs/CMFꢀ andꢀ
Ni@N‐CNTs/CMFꢀ catalystsꢀ wereꢀ fabricatedꢀ usingꢀ theꢀ sameꢀ
syntheticꢀprocedureꢀasꢀthatꢀofꢀNiCo@N‐CNTs/CMF,ꢀexceptꢀtheꢀ
adsorptionꢀ stepꢀ whereꢀ theꢀ adsorptionꢀ solutionꢀ containsꢀ 5ꢀ
2
–1
mmolꢀ ofꢀ Ni(NO
usedꢀtoꢀobtainꢀNi /CMFꢀandꢀCo /CMF.ꢀ ꢀ
3
)
2
∙6H
2
Oꢀ orꢀ Co(NO
3
)
2
∙6H Oꢀ wasꢀ respectivelyꢀ
2
2
+
2+
2.3.ꢀ ꢀ Catalystsꢀcharacterizationꢀ
Scanningꢀelectronꢀmicroscopyꢀ(SEM)ꢀimagesꢀwereꢀobtainedꢀ
fromꢀHITACHIꢀUHRꢀFE‐SEMꢀ(SU8020)ꢀunderꢀaꢀ5.0ꢀkVꢀacceler‐
atingꢀ voltage.ꢀ Transmissionꢀ electronꢀ microscopyꢀ (TEM)ꢀ andꢀ
highꢀ resolutionꢀ TEMꢀ imagesꢀ wereꢀ gainedꢀ respectivelyꢀ fromꢀ
JEOL‐2010ꢀwithꢀanꢀaccelerationꢀvoltageꢀofꢀ200ꢀkV,ꢀandꢀPhilipsꢀ
TecnaiG2ꢀ F20ꢀ withꢀ anꢀ accelerationꢀ voltageꢀ ofꢀ 200ꢀ kV.ꢀ Philipsꢀ
X‐Pertꢀ Proꢀ wasꢀ employedꢀ toꢀ recordꢀ X‐rayꢀ diffractionꢀ (XRD)ꢀ
Theꢀ reactantꢀ conversionꢀ andꢀ theꢀ productꢀ selectivityꢀ wereꢀ
calculatedꢀaccordingꢀtoꢀEq.ꢀ(1)ꢀandꢀEq.ꢀ(2),ꢀrespectively.ꢀ
ꢃꢄꢅ ꢄꢆ ꢇꢈꢉꢊꢋꢉꢌꢋꢀꢉꢆꢋꢈꢇꢀꢇꢈꢉꢊꢋꢍꢄꢌ
Conversionꢀ(%)ꢀ=ꢀ ꢁ1 ꢂ
ꢏ ꢐ 100% ꢀ (1)ꢀ
ꢃꢄꢅ ꢄꢆ ꢇꢈꢉꢊꢋꢉꢌꢋꢀꢎꢈꢆꢄꢇꢈꢀꢇꢈꢉꢊꢋꢍꢄꢌ
ꢃꢄꢅꢀꢄꢆꢀꢋꢉꢇꢑꢈꢋꢈꢒꢀꢓꢇꢄꢒꢔꢊꢋ
Selectivityꢀ(%)ꢀ=ꢀ
ꢐ 100% ꢀ ꢀ (2)ꢀ
ꢃꢄꢅꢀꢄꢆꢀꢉꢅꢅꢀꢓꢇꢄꢒꢔꢊꢋꢕ
α
patternsꢀusingꢀaꢀNi‐filteredꢀmonochromaticꢀCuꢀK ꢀradiationꢀ(λꢀ=ꢀ
1.5418ꢀÅ)ꢀatꢀ40ꢀkeVꢀandꢀ40ꢀmA.ꢀTheꢀspecificꢀsurfaceꢀareaꢀandꢀ
2.5.ꢀ ꢀ Computationalꢀmethodsꢀ
poreꢀsizeꢀdistributionꢀwereꢀtestedꢀatꢀ77ꢀKꢀusingꢀaꢀSurfaceꢀAreaꢀ
andꢀ Porosityꢀ Analyzerꢀ (Autosorbꢀ iQꢀ Stationꢀ 2).ꢀ Theꢀ valenceꢀ
statesꢀ wereꢀ analyzedꢀ byꢀ ESCALABꢀ 250ꢀ XPSꢀ (Thermo,ꢀ USA)ꢀ
equippedꢀwithꢀAlꢀKα1,2ꢀmonochromatizedꢀradiationꢀatꢀ1486.6ꢀeVꢀ
X‐rayꢀsource.ꢀRamanꢀspectraꢀwereꢀobtainedꢀbyꢀLabRAMꢀHR800ꢀ
confocalꢀmicroscopeꢀRamanꢀsystemꢀ(HoribaꢀJobinꢀYvon)ꢀusingꢀ
anꢀ Arꢀ ionꢀ laserꢀ operatingꢀ atꢀ 532ꢀ nm.ꢀ Theꢀ metalꢀ loadingsꢀ andꢀ
alloyꢀcontentsꢀwereꢀtestedꢀbyꢀinductivelyꢀcoupledꢀplasmaꢀ(ICPꢀ
Allꢀtheꢀcalculationsꢀhaveꢀbeenꢀperformedꢀwithinꢀtheꢀframe‐
workꢀ ofꢀ densityꢀ functionꢀ theoryꢀ (DFT),ꢀ usingꢀ theꢀ Viennaꢀ Abꢀ
initioꢀ Simulationꢀ Packageꢀ (VASP)ꢀ withꢀ Perdew‐Burke‐Ernzer‐ꢀ
hofꢀgeneralizedꢀgradientꢀapproximationꢀ(PBE‐GGA)ꢀfunctional.ꢀ
Theꢀprojectorꢀaugmentedꢀwaveꢀ(PAW)ꢀmethodꢀhasꢀbeenꢀusedꢀ
toꢀdescribeꢀtheꢀinertꢀcoreꢀelectrons.ꢀWeꢀrelaxedꢀtheꢀstructuresꢀ
–4
untilꢀtheꢀtotalꢀenergyꢀchangesꢀwithinꢀ1ꢀ×ꢀ10 ꢀeVꢀperꢀatomꢀandꢀ
6
H
300,ꢀThermoꢀFisherꢀScientific)ꢀafterꢀmicrowaveꢀdigestion.ꢀTheꢀ
ꢀ temperature‐programmedꢀ desorptionꢀ (H ‐TPD)ꢀ profilesꢀ
wereꢀobtainedꢀbyꢀaꢀMicromeriticsꢀAutoChemꢀIIꢀ2920ꢀequippedꢀ
withꢀaꢀthermalꢀconductivityꢀdetectorꢀ(TCD).ꢀInꢀaꢀtypicalꢀH ‐TPDꢀ
theꢀHellmann‐Feynmanꢀforceꢀonꢀeachꢀatomicꢀsiteꢀwasꢀlessꢀthanꢀ
2
2
0.05ꢀeV/Å,ꢀwithꢀaꢀ400ꢀeVꢀcutoffꢀenergy.ꢀTheꢀfccꢀCoꢀandꢀNiꢀwereꢀ
usedꢀforꢀtheꢀbulk,ꢀNi‐Coꢀalloyꢀwasꢀconstructedꢀbyꢀreplacingꢀtwoꢀ
CoꢀatomsꢀbyꢀtwoꢀNiꢀatomꢀinꢀCo.ꢀCoꢀ(111),ꢀNiꢀ(111)ꢀandꢀNi‐Coꢀ
2
measurementꢀprocess,ꢀtheꢀsampleꢀ(30ꢀmg)ꢀwasꢀfirstꢀsealedꢀandꢀ
purgedꢀinꢀtheꢀreactorꢀunderꢀHeꢀatmosphereꢀatꢀ250ꢀ°Cꢀforꢀ1ꢀh.ꢀ
Theꢀ reactorꢀ wasꢀ subsequentlyꢀ cooledꢀ downꢀ toꢀ 50ꢀ °Cꢀ andꢀ
(
111)ꢀslabꢀmodelsꢀwereꢀconstructedꢀwithꢀthreeꢀatomicꢀlayersꢀ
andꢀaꢀvacuumꢀspaceꢀlargerꢀthanꢀ20ꢀÅ.ꢀTheꢀΓ‐centeredꢀ2ꢀꢀ2ꢀꢀ1ꢀ
Monkhorst‐Packꢀsamplingꢀwasꢀusedꢀforꢀthoseꢀsurfaces.ꢀClimb‐
ingꢀ imageꢀ nudgedꢀ elasticꢀ bandꢀ (CINEB)ꢀ methodꢀ wasꢀ usedꢀ toꢀ
calculateꢀ theꢀ transitionꢀ state.ꢀ Theꢀ perpendicularꢀ adsorptionꢀ
configurationꢀ ofꢀ vanillinꢀ andꢀ HMPꢀ areꢀ chosenꢀ forꢀ qualitativeꢀ
analysis.ꢀInꢀallꢀtheꢀcalculations,ꢀtheꢀtopꢀtwoꢀatomicꢀlayersꢀofꢀtheꢀ
surfacesꢀwereꢀallowedꢀtoꢀrelaxꢀtogetherꢀwithꢀtheꢀmoleculeꢀad‐
sorbate,ꢀwhileꢀtheꢀbottomꢀoneꢀlayerꢀwasꢀkeepꢀfixedꢀtoꢀpresentꢀ
theꢀbulkꢀproperties.ꢀTheꢀbindingꢀenergyꢀofꢀmoleculeꢀwithꢀsur‐
faceꢀwasꢀcalculatedꢀaccordingꢀtoꢀEq.ꢀ(3).ꢀ
purgedꢀwithꢀaꢀgasꢀmixtureꢀofꢀH
adsorptionꢀofꢀH ꢀtoꢀtheꢀsample.ꢀTheꢀdesorptionꢀofꢀH
measuredꢀbyꢀraisingꢀtheꢀtemperatureꢀfromꢀ50ꢀtoꢀ450ꢀ°Cꢀatꢀaꢀ
2
ꢀandꢀHeꢀ(1:9,ꢀv/v)ꢀforꢀ2ꢀhꢀforꢀ
2
2
ꢀwasꢀthenꢀ
–1
–1
heatingꢀrateꢀofꢀ10ꢀ°C·min ꢀunderꢀaꢀHeꢀflowꢀrateꢀofꢀ30ꢀmLꢀmin .ꢀ
Theꢀsurfaceꢀwettabilityꢀwasꢀmeasuredꢀbyꢀaꢀcontactꢀangleꢀtesterꢀ
(SolonꢀTech.ꢀ(Shanghai)ꢀCo.,ꢀLtd).ꢀFT‐IRꢀspectraꢀwereꢀobtainedꢀ
fromꢀaꢀThermoꢀNicoletꢀNEXUSꢀFI‐IRꢀspectrophotometerꢀusingꢀaꢀ
–1
KBrꢀpelletꢀmethodꢀinꢀtheꢀspectralꢀrangeꢀofꢀ400–4000ꢀcm .ꢀ
E
ꢀ=ꢀEslab/adsꢀ–ꢀEmoleculeꢀ–ꢀEslabꢀ ꢀ ꢀ ꢀ ꢀ ꢀ ꢀ ꢀ ꢀ ꢀ ꢀ ꢀ ꢀ ꢀ ꢀ ꢀ ꢀ ꢀ ꢀ ꢀ ꢀ ꢀ (3)ꢀ
b
2
.4.ꢀ ꢀ Catalystꢀperformanceꢀevaluationꢀandꢀproductꢀanalysisꢀ
Where,ꢀEslab/adsꢀisꢀtheꢀtotalꢀenergyꢀofꢀtheꢀcatalystꢀsurfaceꢀwithꢀ
adsorbedꢀorganicꢀmolecules,ꢀEmoleculeꢀisꢀtheꢀenergyꢀofꢀmoleculesꢀ
inꢀ theirꢀ freeꢀ state,ꢀ andꢀ Eslabꢀ isꢀ theꢀ energyꢀ ofꢀ employedꢀ metalꢀ
surfaceꢀslabꢀmodel.ꢀTheꢀadsorptionꢀenergyꢀofꢀH*ꢀwasꢀcalculatedꢀ
Allꢀcatalystꢀperformanceꢀevaluationꢀexperimentsꢀwereꢀcon‐
ductedꢀinꢀaꢀ25ꢀmLꢀstainlessꢀsteelꢀautoclaveꢀ(AnhuiꢀKemiꢀMa‐
chineryꢀTechnologyꢀCo.,ꢀLtd)ꢀwithꢀaꢀpressureꢀgauge,ꢀaꢀmechan‐
icalꢀstirrerꢀandꢀanꢀautomaticꢀtemperatureꢀcontrolꢀapparatus.ꢀInꢀ
aꢀtypicalꢀexperiment,ꢀaꢀTeflonꢀvesselꢀloadedꢀwithꢀaꢀmixtureꢀofꢀ
takingꢀH
2
ꢀasꢀtheꢀreferenceꢀstate.ꢀ ꢀ
3
.ꢀ ꢀ Resultsꢀandꢀdiscussionꢀ
reactantsꢀ (0.5ꢀ mmol),ꢀ catalystꢀ (30ꢀ mg)ꢀ andꢀ H Oꢀ (10ꢀ ml)ꢀ wasꢀ
2

2030ꢀ
DongdongꢀWangꢀetꢀal.ꢀ/ꢀChineseꢀJournalꢀofꢀCatalysisꢀ42ꢀ(2021)ꢀ2027–2037ꢀ
3.1.ꢀ ꢀ Catalystsꢀcharacterizationꢀ
distributionꢀofꢀNꢀspecies,ꢀsuggestingꢀtheꢀexistenceꢀofꢀNꢀinꢀbothꢀ
carbonꢀskeletonꢀandꢀCNTs.ꢀTheꢀhighꢀmagnificationꢀTEMꢀimageꢀ
(Fig.ꢀ1(e))ꢀunveilsꢀthatꢀtheꢀobtainedꢀCNTsꢀareꢀofꢀmultiwallꢀCNTsꢀ
withꢀaꢀconfinedꢀmetalꢀNPꢀonꢀtheirꢀtip.ꢀInꢀfact,ꢀtheꢀtippedꢀmetalꢀ
NPsꢀ serveꢀ asꢀ theꢀ catalystꢀ forꢀ theꢀ growthꢀ ofꢀ CNTsꢀ [38].ꢀ Theꢀ
high‐resolutionꢀTEMꢀ(HRTEM)ꢀimagesꢀ(Fig.ꢀ1(f))ꢀshowꢀtheꢀlat‐
ticeꢀspacingsꢀofꢀ0.215ꢀandꢀ0.340ꢀnmꢀcorrespondꢀtoꢀtheꢀ(111)ꢀ
facetꢀofꢀNi‐Coꢀalloyꢀandꢀ(002)ꢀfacetꢀofꢀgraphiticꢀcarbon,ꢀrespec‐
tively,ꢀwhichꢀcanꢀbeꢀfurtherꢀconfirmedꢀbyꢀtheꢀcontrastꢀlineꢀpro‐
filesꢀ(Figs.ꢀ1(g),ꢀ(h))ꢀ[39].ꢀInꢀaddition,ꢀtheꢀlineꢀprofileꢀobtainedꢀ
fromꢀaꢀrepresentativeꢀmetalꢀNPꢀ(Fig.ꢀ1(i))ꢀshowsꢀtheꢀhomoge‐
neouslyꢀ distributedꢀ Ni,ꢀ Coꢀ andꢀ Cꢀ species.ꢀ Furthermore,ꢀ theꢀ
high‐angleꢀ annularꢀ dark‐fieldꢀ scanningꢀ transmissionꢀ electronꢀ
microscopyꢀ(HAADF‐STEM)ꢀimageꢀandꢀtheꢀcorrespondingꢀele‐
mentꢀmappingꢀimagesꢀ(Fig.ꢀ1(j))ꢀalsoꢀconfirmꢀtheꢀhomogene‐
ouslyꢀdistributedꢀCꢀandꢀNꢀinꢀCNTsꢀandꢀNiꢀandꢀCoꢀinꢀtheꢀtippedꢀ
metalꢀNPs.ꢀTheꢀNiꢀandꢀCoꢀcontentsꢀwereꢀtestedꢀusingꢀtheꢀinduc‐
tivelyꢀcoupledꢀplasmaꢀ(ICP)ꢀtoꢀbeꢀofꢀ12.82ꢀwt%ꢀandꢀ12.79ꢀwt%,ꢀ
respectivelyꢀ (Tableꢀ S1),ꢀ equivalentꢀ toꢀ aꢀ Ni/Coꢀ atomicꢀ ratioꢀ ofꢀ
~1.ꢀ
Typicalꢀ fabricationꢀ procedureꢀ ofꢀ NiCo@N‐CNTs/CMFꢀ isꢀ
schematicallyꢀillustratedꢀinꢀFig.ꢀ1(a).ꢀInꢀbrief,ꢀaꢀpieceꢀofꢀcom‐
mercialꢀ Melamineꢀ Foamꢀ (MF,ꢀ Fig.ꢀ S1)ꢀ wasꢀ thermallyꢀ treatedꢀ
underꢀ Arꢀ atmosphereꢀ toꢀ obtainꢀ theꢀ CMF,ꢀ whichꢀ wasꢀ furtherꢀ
treatedꢀ withꢀ 3ꢀ Mꢀ HNO ꢀ toꢀ improveꢀ itsꢀ hydrophilicityꢀ andꢀ in‐
3
creaseꢀ oxygen‐containingꢀ functionalꢀ groups.ꢀ Althoughꢀ theꢀ
overallꢀsizeꢀofꢀtheꢀobtainedꢀCMFꢀwasꢀnoticeablyꢀreducedꢀ(Fig.ꢀ
S2(a)),ꢀtheꢀ3DꢀcarbonꢀnetworkꢀstructuresꢀofꢀMFꢀwereꢀwellꢀre‐
tainedꢀbyꢀCMFꢀ(Fig.ꢀS2(b)).ꢀTheꢀXRDꢀpatternꢀofꢀCMFꢀ(Fig.ꢀS2(c))ꢀ
displaysꢀtwoꢀbroadꢀdiffractionꢀpeaksꢀatꢀ25.4°ꢀandꢀ43.2°,ꢀcorre‐
spondingꢀ toꢀ theꢀ characteristicꢀ peaksꢀ ofꢀ amorphousꢀ carbonsꢀ
[
37].ꢀTheꢀacidꢀtreatedꢀCMFꢀwasꢀthenꢀimpregnatedꢀwithꢀdesira‐
2
+
2+
2+
2+
bleꢀamountsꢀofꢀ Ni ꢀandꢀCo ꢀ(Ni ‐Co /CMF)ꢀviaꢀadsorption.ꢀ
2+
2+
Theꢀ driedꢀ Ni ‐Co /CMFꢀ wasꢀ subsequentlyꢀ calcinedꢀ inꢀ theꢀ
presenceꢀ ofꢀ melamineꢀ asꢀ additionalꢀ Cꢀ andꢀ Nꢀ sourcesꢀ underꢀ
H /ArꢀatmosphereꢀtoꢀgrowꢀN‐CNTsꢀonꢀtheꢀsurfaceꢀofꢀCMFꢀ(de‐
2
notedꢀ asꢀ NiCo@N‐CNTs/CMF).ꢀ Theꢀ well‐retainedꢀ 3Dꢀ carbonꢀ
networkꢀstructuresꢀwithꢀdenselyꢀpopulatedꢀCNTsꢀonꢀtheꢀcarbonꢀ
skeletonꢀ surfaceꢀ areꢀ unveiledꢀ byꢀ theꢀ FESEMꢀ imagesꢀ ofꢀ Ni‐
Co@N‐CNTs/CMFꢀ(Figs.ꢀ1(b),ꢀ(c)ꢀandꢀS3).ꢀTheꢀTEMꢀimageꢀ(Fig.ꢀ
(d))ꢀ confirmsꢀ thatꢀ aꢀ layerꢀ ofꢀ CNTsꢀ (~400ꢀ nm)ꢀ isꢀ uniformlyꢀ
wrappedꢀ onꢀ theꢀ carbonꢀ skeletonꢀ surfaceꢀ ofꢀ CMF.ꢀ Theꢀ corre‐
spondingꢀ TEMꢀ elementꢀ mappingsꢀ (Fig.ꢀ S4)ꢀ showsꢀ aꢀ uniformꢀ
TheꢀXRDꢀpatternꢀofꢀNiCo@N‐CNTs/CMFꢀ(Figs.ꢀ2(a),ꢀ(b))ꢀun‐
veilꢀaꢀgroupꢀofꢀdiffractionꢀpeaksꢀcenteredꢀatꢀ26.4°,ꢀ44.3°,ꢀ51.6°ꢀ
andꢀ76.2°,ꢀwhichꢀcanꢀbeꢀrespectivelyꢀindexedꢀtoꢀgraphiticꢀcar‐
bonꢀ andꢀ Ni‐Coꢀ alloyꢀ [28].ꢀ Theꢀ surfaceꢀ chemicalꢀ statesꢀ ofꢀ Ni‐
Co@N‐CNTs/CMFꢀ wereꢀ investigatedꢀ byꢀ X‐rayꢀ photoelectronꢀ
1
Fig.ꢀ1.ꢀ(a)ꢀSchematicꢀdiagramꢀillustratingꢀtheꢀsyntheticꢀprocedureꢀofꢀNiCo@N‐CNTs/CMF;ꢀLowꢀandꢀhighꢀmagnificationꢀSEMꢀimagesꢀ(b,c),ꢀlowꢀandꢀhighꢀ
magnificationꢀTEMꢀimagesꢀ(d,e)ꢀandꢀHRTEMꢀimagesꢀ(f)ꢀofꢀNiCo@N‐CNTs/CMF;ꢀ(g,h)ꢀContrastꢀintensityꢀprofilesꢀindicatingꢀtheꢀlatticeꢀparameterꢀof
NiCoꢀalloyꢀandꢀC,ꢀrespectively;ꢀ(i)ꢀLineꢀprofileꢀofꢀaꢀrepresentativeꢀNiCoꢀNP;ꢀ(j)ꢀHAADF‐STEMꢀimageꢀandꢀcorrespondingꢀelementꢀmappingꢀimages.ꢀ

ꢀ
DongdongꢀWangꢀetꢀal.ꢀ/ꢀChineseꢀJournalꢀofꢀCatalysisꢀ42ꢀ(2021)ꢀ2027–2037ꢀ
2031ꢀ
(a)
(b)
C
PDF No. 00-001-0640
Ni PDF No. 01-087-0712
Co PDF No. 00-015-0806
Ni@N-CNTs/CMF
NiCo@N-CNTs/CMF
Co@N-CNTs/CMF
Ni@N-CNTs/CMF
NiCo@N-CNTs/CMF
Co@N-CNTs/CMF
20
30
40
50
60
70
80
42.5 43.0 43.5 44.0 44.5 45.0 45.5 46.0 46.5
o
o
2

(
)
2
(
)
Ni 2p
Co 2p
(c)
(d)
NiCo@N-CNTs/CMF
NiCo@N-CNTs/CMF
0
.2 eV
0
.2 eV
Oxidized Co
Oxidized Ni
Sat.
2p3/2
2p1/2
2p3/2
Sat.
2p1/2
Sat.
Sat.
Ni@N-CNTs/CMF
Co@N-CNTs/CMF
0
Ni
0
Co
885
880
875
870
865
860
855
810
805
800
795
790
785
780
Binding energy (eV)
Binding energy (eV)
Fig.ꢀ2.ꢀ(a,b)ꢀXRDꢀpatternsꢀofꢀNi@N‐CNTs/CMF,ꢀCo@N‐CNTs/CMFꢀandꢀNiCo@N‐CNTs/CMF,ꢀrespectively;ꢀ(c)ꢀNiꢀ2pꢀXPSꢀspectraꢀofꢀNi@N‐CNTs/CMFꢀ
andꢀNiCo@N‐CNTs/CMF;ꢀ(d)ꢀCoꢀ2pꢀXPSꢀspectraꢀofꢀCo@N‐CNTs/CMFꢀandꢀNiCo@N‐CNTs/CMF.ꢀ
spectroscopyꢀ (XPS)ꢀ analysis.ꢀ Theꢀ XPSꢀ surveyꢀ spectrumꢀ (Fig.ꢀ
S5(a))ꢀ confirmsꢀ theꢀ presenceꢀ ofꢀ C,ꢀ N,ꢀ O,ꢀ Niꢀ andꢀ Co.ꢀ Theꢀ highꢀ
resolutionꢀ Cꢀ 1sꢀ XPSꢀ spectrumꢀ (Fig.ꢀ S5(b))ꢀ canꢀ beꢀ fittedꢀ intoꢀ
threeꢀpeaksꢀcentredꢀatꢀ284.8,ꢀ285.8ꢀandꢀ287.5ꢀeV,ꢀcorrespond‐
ingꢀ toꢀ C–C,ꢀ C=Nꢀ andꢀ C–Nꢀ bonds,ꢀ respectivelyꢀ [40].ꢀ Theꢀ highꢀ
resolutionꢀNꢀ1sꢀXPSꢀspectrumꢀ(Fig.ꢀS5(c))ꢀshowsꢀtheꢀexistenceꢀ
ofꢀpyridinic‐Nꢀ(398.8ꢀeV),ꢀpyrrolic‐Nꢀ(400.6ꢀeV),ꢀquaternary‐Nꢀ
Co@N‐CNTs/CMFꢀ (Fig.ꢀ S6)ꢀ showsꢀDꢀ andꢀGꢀbandsꢀcenteredꢀ atꢀ
–1
1340ꢀandꢀ1580ꢀcm ,ꢀconfirmingꢀtheꢀformationꢀofꢀgraphitizedꢀ
CNTs.ꢀAꢀrelativelyꢀhighꢀI /I ꢀratioꢀofꢀ1.00ꢀimpliesꢀaꢀdegreeꢀofꢀ
disorderedꢀgraphiticꢀcarbonꢀstructureꢀofꢀtheꢀobtainedꢀN‐CNTs.ꢀ
Theꢀ N ꢀ adsorption‐desorptionꢀ isothermꢀ revealsꢀ aꢀ typicalꢀ
D
G
2
type‐IVꢀhysteresisꢀbehaviorꢀ(Fig.ꢀS7).ꢀTheꢀdeterminedꢀBrunau‐
er‐Emmett‐Tellerꢀsurfaceꢀareaꢀ(SBET)ꢀandꢀporeꢀvolumeꢀ(Vpore)ꢀofꢀ
2
–1
3
–1
(401.5ꢀeV)ꢀandꢀoxide‐Nꢀ(404.8ꢀeV),ꢀsuggestingꢀthatꢀtheꢀobtainedꢀ
NiCo@N‐CNTs/CMFꢀ areꢀ 157.6ꢀ m ꢀ g ꢀ andꢀ 0.391ꢀ cm ꢀ g ,ꢀ re‐
spectivelyꢀ(TableꢀS2).ꢀTheꢀmeasuredꢀstaticꢀwaterꢀcontactꢀangleꢀ
ofꢀ25.2°ꢀdemonstratesꢀaꢀhydrophilicꢀnatureꢀofꢀNiCo@N‐CNTs/ꢀ
CMFꢀ (Fig.ꢀS8),ꢀ whichꢀisꢀ aꢀ favorableꢀ propertyꢀ forꢀ aꢀ catalystꢀtoꢀ
workꢀinꢀwaterꢀmedium.ꢀ
CNTsꢀareꢀofꢀN‐dopedꢀCNTsꢀ[41].ꢀSuchꢀCNTsꢀwithꢀdopedꢀNꢀandꢀ
concomitantꢀ disorderꢀ carbonꢀ structureꢀ shouldꢀ possessꢀ im‐
provedꢀ hydrophilicityꢀ andꢀ affordꢀ additionalꢀ catalyticꢀ activeꢀ
sites,ꢀ favorableꢀ forꢀ aqueousꢀ phaseꢀ catalysisꢀ applicationsꢀ
[
38,42].ꢀTheꢀhighꢀresolutionꢀNiꢀ2pꢀXPSꢀspectrumꢀcanꢀbeꢀfittedꢀ
Forꢀcomparativeꢀpurpose,ꢀtheꢀmonometallicꢀCoꢀandꢀNiꢀNPsꢀ
basedꢀ N‐CNTs/CMFꢀ counterpartsꢀ withꢀ equivalentꢀ metalꢀ load‐
ingsꢀ wereꢀ synthesizedꢀ (Figs.ꢀ S9,ꢀ 10).ꢀ Asꢀ canꢀ beꢀ seen,ꢀ bothꢀ
Co@N‐CNTs/CMFꢀ andꢀ Ni@N‐CNTs/CMFꢀ possessꢀ veryꢀ similarꢀ
morphologicalꢀ andꢀ structuralꢀ characteristicsꢀ asꢀ thatꢀ ofꢀ Ni‐
Co@N‐CNTs/CMF.ꢀTheꢀXRDꢀpatternꢀofꢀCo@N‐CNTs/CMFꢀ(Fig.ꢀ
2(a))ꢀdisplayꢀaꢀsetꢀofꢀdiffractionꢀpeaksꢀatꢀ44.2°,ꢀ51.5°ꢀandꢀ75.9°ꢀ
assignableꢀrespectivelyꢀtoꢀ(111),ꢀ(200)ꢀandꢀ(220)ꢀcrystalꢀplanesꢀ
ofꢀ metallicꢀ Coꢀ (PDFꢀ No.00‐015‐0806),ꢀ whileꢀ theꢀ diffractionꢀ
peaksꢀofꢀ44.5°,ꢀ51.9°ꢀandꢀ76.4°ꢀunveiledꢀbyꢀtheꢀXRDꢀpatternꢀofꢀ
Ni@N‐CNTs/CMFꢀcanꢀbeꢀindexedꢀrespectivelyꢀtoꢀ(111),ꢀ(200)ꢀ
andꢀ(220)ꢀcrystalꢀplanesꢀofꢀmetallicꢀNiꢀ(PDFꢀNo.ꢀ01‐087‐0712).ꢀ
TheꢀlocallyꢀamplifiedꢀXRDꢀpatternsꢀaroundꢀ44ꢀ±ꢀ1.5°ꢀ(Fig.ꢀ2(b))ꢀ
showꢀ thatꢀ comparingꢀ withꢀ NiCo@N‐CNTs/CMF,ꢀ theꢀ obtainedꢀ
(111)ꢀ planesꢀ diffractionꢀ peakꢀ fromꢀ Co@N‐CNTs/CMFꢀ andꢀ
Ni@N‐CNTs/CMFꢀareꢀnegativelyꢀandꢀpositivelyꢀshifted,ꢀrespec‐
tively,ꢀconfirmingꢀtheꢀformationꢀofꢀtheꢀalloyedꢀNi‐CoꢀNPs.ꢀTheꢀ
tippedꢀ Coꢀandꢀ NiꢀNPsꢀ showꢀtheꢀlatticeꢀ spacingsꢀ ofꢀ 0.205ꢀ andꢀ
0.203ꢀnm,ꢀcorrespondingꢀrespectivelyꢀtoꢀtheꢀ(111)ꢀfacetꢀofꢀCoꢀ
andꢀ (111)ꢀ facetꢀ ofꢀ Niꢀ [46,47].ꢀ Theꢀ characteristicsꢀ ofꢀ Ramanꢀ
spectraꢀobtainedꢀfromꢀCo@N‐CNTs/CMFꢀandꢀNi@N‐CNTs/CMFꢀ
(Fig.ꢀ S6)ꢀ areꢀ veryꢀ similarꢀ toꢀ thatꢀ obtainedꢀ fromꢀ Ni‐
Co@N‐CNTs/CMF,ꢀ confirmingꢀ theꢀ formationꢀ ofꢀ graphitizedꢀ
CNTsꢀ withꢀ aꢀdegreeꢀofꢀdisorderedꢀ graphiticꢀ carbonꢀ structure.ꢀ
intoꢀtwoꢀspin‐orbitꢀdoubletsꢀandꢀtwoꢀsatellitesꢀ(Fig.ꢀ2(c)).ꢀTheꢀ
peaksꢀ centeredꢀ atꢀ 855.0ꢀ andꢀ 873.6ꢀ eVꢀ canꢀ beꢀ assignedꢀ toꢀ Niꢀ
2
atꢀ 853.8ꢀ eVꢀ confirmsꢀ theꢀ presenceꢀ ofꢀ Ni ,ꢀ whileꢀ theꢀ peaksꢀ atꢀ
8
species.ꢀ Theꢀ existenceꢀ ofꢀ oxidizedꢀ stateꢀ isꢀ aꢀ resultꢀ ofꢀ theꢀ at‐
mosphereꢀexposureꢀofꢀtheꢀsampleꢀbeforeꢀXPSꢀtestꢀthatꢀpartiallyꢀ
oxidizesꢀtheꢀouterꢀsurfaceꢀofꢀNi‐CoꢀNPs.ꢀImportantly,ꢀcomparingꢀ
toꢀtheꢀmonometallicꢀNi,ꢀ~0.2ꢀeVꢀpositivelyꢀshiftedꢀNiꢀ2p1/2ꢀandꢀ
p
3/2ꢀandꢀNiꢀ2p1/2,ꢀrespectivelyꢀ[43].ꢀTheꢀfittingꢀpeakꢀofꢀNiꢀ2p3/2
ꢀ
0
54.9ꢀ andꢀ 856.4ꢀ eVꢀ indicateꢀ theꢀ co‐existenceꢀ ofꢀ oxidizedꢀ Niꢀ
2
p
3/2ꢀpeaksofꢀNiCo@N‐CNTs/CMFꢀindicateꢀtheꢀdecreasedꢀelec‐
ꢀ
tronꢀ cloudꢀ densityꢀ ofꢀ Ni,ꢀ confirmingꢀ theꢀ formationꢀ ofꢀ theꢀ al‐
loyedꢀ Niꢀ [44].ꢀ Theꢀ Coꢀ 2pꢀ spectrumꢀ (Fig.ꢀ 2(d))ꢀ confirmsꢀ theꢀ
presenceꢀofꢀCo ꢀ(778.4ꢀeV)ꢀandꢀtheꢀoxidizedꢀformsꢀofꢀCoꢀspeciesꢀ
(
alloyedꢀ Coꢀ 2p1/2ꢀ andꢀ 2p3/2ꢀ peaksꢀ ofꢀ NiCo@N‐CNTs/CMFꢀ areꢀ
negativelyꢀ shiftedꢀ ~0.2ꢀ eV,ꢀ indicatingꢀ anꢀ increasedꢀ electronꢀ
cloudꢀdensityꢀofꢀCoꢀdrawnꢀfromꢀtheꢀneighboringꢀNiꢀatomsꢀ[44].ꢀ
TheseꢀobservedꢀshiftsꢀinꢀtheꢀalloyedꢀNiꢀandꢀCoꢀbindingꢀenergiesꢀ
confirmꢀtheꢀstrongꢀelectronicꢀinteractionꢀamongꢀtheꢀneighbor‐
ingꢀNiꢀandꢀCoꢀspecies,ꢀwhichꢀisꢀaꢀlikelyꢀoriginꢀofꢀtheꢀsynergeticꢀ
effectꢀofꢀbimetallicꢀNi‐Coꢀalloyꢀ[28].ꢀ
0
780.5/781.7ꢀ eV)ꢀ [45].ꢀ Comparingꢀ withꢀ monometallicꢀ Co,ꢀ theꢀ
Otherꢀ physiochemicalꢀ propertiesꢀ ofꢀ NiCo@N‐CNTs/CMFꢀ
wereꢀ alsoꢀ characterized.ꢀ Ramanꢀ spectrumꢀ ofꢀ Ni‐

2032ꢀ
DongdongꢀWangꢀetꢀal.ꢀ/ꢀChineseꢀJournalꢀofꢀCatalysisꢀ42ꢀ(2021)ꢀ2027–2037ꢀ
Typicalꢀ type‐IVꢀ hysteresisꢀ behaviorꢀ ofꢀ Co@N‐CNTs/CMFꢀ andꢀ
Ni@N‐CNTs/CMFꢀ areꢀ unveiledꢀ byꢀ theirꢀ adsorp‐
tion‐desorptionꢀisothermsꢀ(Fig.ꢀS7).ꢀTheꢀSBETꢀandꢀVporeꢀareꢀ114.2ꢀ
°Cꢀwithꢀaꢀgivenꢀreactionꢀtimeꢀofꢀ6ꢀhꢀ(Fig.ꢀ3(b)).ꢀWhenꢀtheꢀH
pressureꢀisꢀincreasedꢀfromꢀ0.5ꢀtoꢀ2.0ꢀMPa,ꢀbothꢀvanillinꢀconver‐
sionꢀefficiencyꢀandꢀMMPꢀselectivityꢀareꢀincreasedꢀtoꢀ100%ꢀdueꢀ
toꢀ theꢀ promotedꢀ hydrogenolysisꢀ reactionꢀ byꢀ theꢀ elevatedꢀ H
pressure.ꢀUnderꢀaꢀfixedꢀtemperatureꢀofꢀ120ꢀ°CꢀandꢀaꢀH ꢀpres‐
sureꢀofꢀ2ꢀMPa,ꢀwhenꢀtheꢀreactionꢀtimeꢀisꢀincreasedꢀfromꢀ1ꢀtoꢀ6ꢀ
h,ꢀ aꢀ completeꢀ vanillinꢀ conversionꢀ andꢀ 100%ꢀ MMPꢀ selectivityꢀ
canꢀbeꢀachievedꢀ(Fig.ꢀ3(c)).ꢀThisꢀindicatesꢀthatꢀtheꢀhydrogena‐
tionꢀofꢀtheꢀbranchedꢀcarbonylꢀgroupꢀ(C=O)ꢀinꢀvanillinꢀtoꢀformꢀ
HMPꢀisꢀtheꢀfirstꢀreactionꢀstepꢀofꢀtheꢀHDOꢀreactionꢀandꢀMMPꢀisꢀ
formedꢀ viaꢀ theꢀ cleavedꢀ C–Oꢀ bondꢀ inꢀ HMPꢀ byꢀ hydrogenolysisꢀ
[14,48].ꢀ
2
ꢀ
2
N ꢀ
2
–1
3
–1
2
–1
m ꢀg ꢀandꢀ0.364ꢀcm ꢀg ꢀforꢀCo@N‐CNTs/CMFꢀandꢀ219.3ꢀm ꢀg ꢀ
2
ꢀ
3
–1
andꢀ 0.416ꢀ cm ꢀ g ꢀ forꢀ Ni@N‐CNTs/CMF,ꢀ respectivelyꢀ (Tableꢀ
S2).ꢀTheꢀdeterminedꢀNiꢀandꢀCoꢀ contentsꢀ inꢀ Co@N‐CNTs/CMFꢀ
andꢀNi@N‐CNTs/CMFꢀbyꢀICPꢀareꢀfoundꢀtoꢀbeꢀ25.87ꢀwt%ꢀandꢀ
2
26.11ꢀ wt%,ꢀ respectively,ꢀ whichꢀ areꢀ veryꢀ closeꢀ toꢀ theꢀ totalꢀ Niꢀ
andꢀCoꢀcontentꢀinꢀNiCo@N‐CNTs/CMFꢀ(TableꢀS1).ꢀ
3.2.ꢀ ꢀ Performanceꢀofꢀhydrodeoxyenationꢀofꢀbiomass‐derivedꢀ
vanillinꢀ
Theꢀcatalystꢀstabilityꢀandꢀreusabilityꢀareꢀcriticallyꢀimportantꢀ
forꢀpracticalꢀapplicationsꢀandꢀwereꢀthereforeꢀinvestigatedꢀ(Fig.ꢀ
3(d)).ꢀ Gratifyingly,ꢀ theꢀ well‐retainedꢀ vanillinꢀ conversionꢀ effi‐
ciencyꢀandꢀMMPꢀselectivityꢀoverꢀtheꢀfiveꢀconsecutiveꢀreactionꢀ
cyclesꢀsignifyꢀtheꢀsuperiorꢀcatalyticꢀstabilityꢀandꢀreusabilityꢀofꢀ
NiCo@N‐CNTs/CMF.ꢀ Theꢀ well‐retainedꢀ catalyticꢀ performanceꢀ
canꢀ beꢀ attributedꢀ toꢀ theꢀ superiorꢀ structuralꢀ stabilityꢀ ofꢀ Ni‐
Co@N‐CNTs/CMF.ꢀAsꢀunveiledꢀinꢀFigs.ꢀS11,ꢀS12ꢀandꢀTableꢀS1,ꢀ
noꢀ noticeableꢀ structuralꢀ decayꢀ andꢀ chemicalꢀ compositionꢀ
changeꢀcanꢀbeꢀobservedꢀfromꢀNiCo@N‐CNTs/CMFꢀafterꢀ5ꢀcon‐
secutiveꢀreactionꢀcycles.ꢀToꢀtheꢀbestꢀofꢀourꢀknowledge,ꢀtheꢀvan‐
illinꢀHDOꢀperformanceꢀbyꢀNiCo@N‐CNTs/CMFꢀunderꢀtheꢀmildꢀ
Theꢀ catalyticꢀ performanceꢀ ofꢀ NiCo@N‐CNTs/CMFꢀ forꢀ HDOꢀ
ofꢀvanillinꢀtoꢀMMPꢀwasꢀthenꢀinvestigatedꢀinꢀwaterꢀsolvent.ꢀTheꢀ
reactionꢀ temperatureꢀ affectingꢀ theꢀ conversionꢀ efficiencyꢀ andꢀ
2
selectivityꢀwasꢀfirstlyꢀexaminedꢀunderꢀaꢀfixedꢀH ꢀpressureꢀofꢀ2ꢀ
MPaꢀwithꢀ aꢀgivenꢀreactionꢀtimeꢀofꢀ6ꢀhꢀ(Fig.ꢀ3(a)).ꢀ Atꢀ60ꢀ °C,ꢀaꢀ
5.2%ꢀ ofꢀ vanillinꢀ isꢀ reactedꢀ butꢀ withꢀ 0%ꢀ MMPꢀ selectivityꢀ asꢀ
‐hydroxymethyl‐2‐methoxyphenolꢀ(HMP)ꢀresultingꢀfromꢀvan‐
2
4
illinꢀ hydrogenationꢀ reactionꢀ isꢀ theꢀ soleꢀ product.ꢀ Theꢀ vanillinꢀ
conversionꢀisꢀincreasedꢀfromꢀ25.2%ꢀtoꢀ100%,ꢀwhichꢀaccompa‐
niesꢀanꢀincreaseꢀinꢀMMPꢀselectivityꢀfromꢀ0ꢀtoꢀ56.8%ꢀdueꢀtoꢀtheꢀ
proportionallyꢀdecreasedꢀHMP.ꢀFurtherꢀincreasingꢀtemperatureꢀ
toꢀ120ꢀ°CꢀleadsꢀtoꢀanꢀincreasedꢀMMPꢀselectivityꢀtoꢀ100%ꢀthatꢀ
accompaniesꢀ aꢀ decreasedꢀ HMPꢀ selectivityꢀ toꢀ 0%.ꢀ Theseꢀ ob‐
servedꢀ resultsꢀ suggestꢀ thatꢀ lowerꢀ temperaturesꢀ areꢀ favorableꢀ
forꢀvanillinꢀhydrogenationꢀreaction,ꢀwhileꢀrelativelyꢀhighꢀtem‐
peraturesꢀ areꢀ requiredꢀ forꢀ efficientꢀ hydrogenolysisꢀ toꢀ realizeꢀ
theꢀHDOꢀreaction,ꢀbecauseꢀofꢀtheꢀfacilitatedꢀtheꢀactivationꢀandꢀ
breakageꢀ ofꢀ C‐Oꢀ bondꢀ byꢀ theꢀ elevatedꢀ temperatureꢀ [7].ꢀ Theꢀ
reactionꢀconditionsꢀ(120ꢀ°C,ꢀ2ꢀMPaꢀH
ꢀandꢀ6ꢀh)ꢀsurpassesꢀtheꢀ
2
reportedꢀnonpreciousꢀmetalꢀcatalystsꢀ(TableꢀS3).ꢀ
Asꢀexperimentallyꢀconfirmedꢀabove,ꢀbothꢀNi@N‐CNTs/CMFꢀ
andꢀ Co@N‐CNTs/CMFꢀ possessꢀ similarꢀ morphologicalꢀ andꢀ
structuralꢀ characteristics,ꢀ andꢀ totalꢀ metalꢀ contentꢀ asꢀ thatꢀ ofꢀ
NiCo@N‐CNTs@CMF.ꢀTheirꢀcatalyticꢀperformancesꢀforꢀHDOꢀofꢀ
vanillinꢀtoꢀMMPꢀinꢀwaterꢀwereꢀthereforeꢀcarriedꢀoutꢀtoꢀascer‐
tainꢀ theꢀ presenceꢀ ofꢀ theꢀ alloyedꢀ Ni‐Coꢀ NPsꢀ inꢀ Ni‐
Co@N‐CNTs/CMFꢀisꢀresponsibleꢀforꢀtheꢀsuperiorꢀHDOꢀcatalyticꢀ
effectꢀofꢀH
2
ꢀpressureꢀonꢀtheꢀconversionꢀefficiencyꢀandꢀselectivi‐
tyꢀwasꢀthenꢀinvestigatedꢀatꢀaꢀfixedꢀreactionꢀtemperatureꢀofꢀ120ꢀ
(
a) 100
100 (b) 100
100
80
60
40
20
0
80
60
40
20
0
80
60
40
20
0
80
60
40
20
0
Conversion
Selectivity of HMP
Selectivity of MMP
Conversion
Selectivity of HMP
Selectivity of MMP
60
70
80
90
100
o
110
120
0.5
1.0
1.5
2.0
2.5
Temperature ( C)
H pressure (MPa)
2
1
00
100
80
60
40
20
0
(
c) 100
100 (d)
8
0
80
60
40
20
0
80
60
40
20
0
Conversion
Selectivity of HMP
Selectivity of MMP
60
40
20
0
Conversion
Selectivity of HMP
Selectivity of MMP
1
2
3
4
5
6
1
2
3
4
5
Time (h)
Cycles
2 2
Fig.ꢀ3.ꢀCatalyticꢀHDOꢀofꢀvanillinꢀinꢀwaterꢀbyꢀNiCo@N‐CNTs/CMF;ꢀ(a)ꢀEffectꢀofꢀreactionꢀtemperatureꢀ(2ꢀMPaꢀH ,ꢀ6ꢀh);ꢀ(b)ꢀEffectꢀofꢀH ꢀpressureꢀ(120ꢀ°C,ꢀ6ꢀ
h);ꢀ(c)ꢀEffectꢀofꢀreactionꢀtimeꢀ(120ꢀ°C,ꢀ2ꢀMPaꢀH
andꢀ0.5ꢀmmolꢀvanillin.ꢀ
2
);ꢀ(d)ꢀCyclicꢀstabilityꢀtestꢀ(120ꢀ°C,ꢀ2ꢀMPaꢀH
2
,ꢀ1ꢀh).ꢀReactionꢀsolution:ꢀ10ꢀmLꢀH Oꢀcontainsꢀ30ꢀmgꢀcatalystꢀ
2

ꢀ
DongdongꢀWangꢀetꢀal.ꢀ/ꢀChineseꢀJournalꢀofꢀCatalysisꢀ42ꢀ(2021)ꢀ2027–2037ꢀ
2033ꢀ
1
00
100
80
60
40
20
0
(
a) 100
Conversion
Selectivity of HMP
Selectivity of MMP
100 (b)
Conversion
Selectivity of HMP
Selectivity of HMP
80
80
60
40
20
0
80
60
40
20
0
6
0
0
4
20
0
1
2
3
4
5
6
1
2
3
4
5
6
Time (h)
Time (h)
(c)
(d)
0.79
NiCo@N-CNTs/CMF
Ni@N-CNTs/CMF
Co@N-CNTs/CMF
0.8
4
3
2
1
0
0.6
0.4
0.2
0.0
0.17
0.08
0
1
2
3
4
5
6
Time (h)
Fig.ꢀ4.ꢀCatalyticꢀHDOꢀofꢀvanillinꢀinꢀwaterꢀunderꢀ120ꢀ°Cꢀandꢀ2ꢀMPaꢀH
againstꢀreactionꢀtimeꢀ(c)ꢀandꢀtheꢀcorrespondingꢀreactionꢀrateꢀconstantsꢀ(d)ꢀforꢀNi@N‐CNTs/CMF,ꢀCo@N‐CNTs/CMFꢀandꢀNiCo@N‐CNTs/CMF.ꢀReac‐
tionꢀsolution:ꢀ10ꢀmLꢀH Oꢀcontainsꢀ30ꢀmgꢀcatalystꢀandꢀ0.5ꢀmmolꢀvanillin.ꢀ
2
ꢀpressureꢀbyꢀNi@N‐CNTs/CMFꢀ(a)ꢀandꢀCo@N‐CNTs/CMFꢀ(b);ꢀPlotꢀofꢀ‐ln(C/C )ꢀ
0
2
performance.ꢀTheꢀsameꢀsetꢀofꢀexperimentalꢀconditionsꢀusedꢀforꢀ
Fig.ꢀ3(c)ꢀwasꢀemployed.ꢀAsꢀcanꢀbeꢀseenꢀfromꢀFigs.ꢀ4(a),ꢀ(b),ꢀforꢀ
bothꢀcatalysts,ꢀanꢀincreaseꢀinꢀreactionꢀtimeꢀleadsꢀtoꢀincreasesꢀinꢀ
vanillinꢀ conversionꢀ efficiencyꢀ andꢀ MMPꢀ selectivity.ꢀ However,ꢀ
underꢀtheꢀexperimentalꢀconditions,ꢀtheꢀhighestꢀvanillinꢀconver‐
sionꢀ efficiencyꢀ andꢀ MMPꢀ selectivityꢀ achievedꢀ byꢀ
Ni@N‐CNTs/CMFꢀ areꢀ 65.3%ꢀ andꢀ 36.8%,ꢀ respectively,ꢀ andꢀ forꢀ
Co@N‐CNTs/CMF,ꢀ onlyꢀ aꢀ 37.4%ꢀ vanillinꢀ conversionꢀ withꢀ aꢀ
slightlyꢀhigherꢀMMPꢀselectivityꢀofꢀ57.1%ꢀareꢀachieved.ꢀThatꢀis,ꢀ
theꢀ vanillinꢀ conversionꢀ efficiencyꢀ followsꢀ aꢀ trendꢀ ofꢀ Ni‐
Co@N‐CNTs/CMFꢀ (100%)ꢀ >ꢀ Ni@N‐CNTs/CMFꢀ (65.3%)ꢀ >ꢀ
Co@N‐CNTs/CMFꢀ (37.4%),ꢀ whileꢀ theꢀ MMPꢀ selectivityꢀ isꢀ or‐
deredꢀ asꢀ NiCo@N‐CNTs/CMFꢀ (100%)ꢀ >ꢀ Co@N‐CNTs/CMFꢀ
vanillin,ꢀleadingꢀtoꢀtheꢀenhancedꢀcatalyticꢀactivityꢀandꢀselectiv‐
ityꢀ[49].ꢀ ꢀ
3.3.ꢀ ꢀ Theoreticalꢀstudiesꢀ ꢀ
TheꢀDFTꢀcalculationsꢀwereꢀperformedꢀtoꢀfurtherꢀconfirmꢀtheꢀ
promotionalꢀeffectꢀofꢀtheꢀalloyedꢀNi‐CoꢀforꢀHDOꢀofꢀvanillinꢀtoꢀ
MMP.ꢀ Basedꢀ onꢀ theꢀ experimentallyꢀ determinedꢀ structuralꢀ
characteristicsꢀ ofꢀ NiCo@N‐CNTs/CMFꢀ andꢀ theꢀ correspondingꢀ
monometallicꢀ catalysts,ꢀ theꢀ (111)ꢀ planeꢀ ofꢀ Ni,ꢀ Coꢀ andꢀ Ni‐Coꢀ
alloyꢀwereꢀchosenꢀforꢀtheꢀDFTꢀcalculations.ꢀFig.ꢀ5(a)ꢀshowsꢀtheꢀ
mostꢀstableꢀvanillinꢀadsorptionꢀconfigurationsꢀ viaꢀC=Oꢀonꢀtheꢀ
(111)ꢀplaneꢀofꢀNi,ꢀCoꢀandꢀNi‐Coꢀalloy,ꢀrespectively.ꢀTheꢀcalcu‐
latedꢀadsorptionꢀenergyꢀ(Ead)ꢀforꢀNiꢀ(111),ꢀCoꢀ(111)ꢀandꢀNi‐Coꢀ
(111)ꢀareꢀ–0.36,ꢀ–0.36ꢀandꢀ–0.48ꢀeV,ꢀrespectively,ꢀindicatingꢀanꢀ
alloyꢀ inducedꢀ enhancementꢀ forꢀ vanillinꢀ adsorption.ꢀ Fig.ꢀ S13ꢀ
showsꢀ theꢀ Fourierꢀ transformꢀ infraredꢀ (FT‐IR)ꢀ spectraꢀ ofꢀ theꢀ
adsorbedꢀ vanillinꢀ onꢀ theꢀ alloyedꢀ andꢀ monometallicꢀ catalysts.ꢀ
Theꢀhighestꢀrelativeꢀintensityꢀspectrumꢀobtainedꢀfromꢀtheꢀad‐
sorbedꢀvanillinꢀonꢀNiCo@N‐CNTs/CMFꢀconfirmsꢀitsꢀadsorptionꢀ
superiorityꢀoverꢀNi@N‐CNTs/CMFꢀandꢀCo@N‐CNTs/CMF.ꢀTheꢀ
strongꢀadsorptionꢀofꢀvanillinꢀonꢀNi‐Coꢀalloyꢀisꢀsupportedꢀbyꢀtheꢀ
(
57.1%)ꢀ >ꢀ Ni@N‐CNTs/CMFꢀ (36.8%).ꢀ Furthermore,ꢀ theꢀ
ln(C/C
)ꢀvaluesꢀwereꢀderivedꢀfromꢀFigs.ꢀ3(c)ꢀandꢀ4(a),ꢀ(b),ꢀandꢀ
plottedꢀ againstꢀ theꢀreactionꢀtimeꢀ(Fig.ꢀ4(c)).ꢀ Theꢀ well‐definedꢀ
linearꢀ−ln(C/C )ꢀ–ꢀtꢀrelationshipsꢀobtainedꢀfromꢀallꢀcasesꢀinves‐
−
0
0
tigatedꢀconfirmꢀthatꢀHDOꢀofꢀvanillinꢀcatalyzedꢀbyꢀtheseꢀcatalystsꢀ
followꢀtheꢀpseudoꢀfirst‐orderꢀkinetics.ꢀAsꢀshownꢀinꢀFig.ꢀ4(d),ꢀtheꢀ
rateꢀ constantsꢀ derivedꢀ fromꢀ theꢀ slopeꢀ ofꢀ theꢀ correspondingꢀ
−
ln(C/C )ꢀ –ꢀ tꢀ curveꢀ followsꢀ anꢀ orderꢀ ofꢀ NiCo@N‐CNTs/CMFꢀ
0
–1
–1
(0.79ꢀ h )ꢀ >ꢀ Ni@N‐CNTs/CMFꢀ (0.17ꢀ h )ꢀ >ꢀ Co@N‐CNTs/CMFꢀ

–1
(0.08ꢀh ).ꢀTheseꢀresultsꢀdemonstrateꢀthatꢀtheꢀsuperiorꢀperfor‐
Baderꢀchargeꢀanalysis,ꢀwhereꢀNi‐Coꢀsurfaceꢀcanꢀdonateꢀ0.08ꢀe ꢀ
manceꢀinꢀtermsꢀofꢀvanillinꢀconversionꢀefficiencyꢀandꢀMMPꢀse‐
lectivityꢀ achievedꢀ byꢀ NiCo@N‐CNTs/CMFꢀ couldꢀ beꢀ dueꢀ toꢀ theꢀ
presenceꢀofꢀtheꢀalloyedꢀNi‐Co.ꢀAsꢀunveiledꢀbyꢀtheꢀXPSꢀspectraꢀ
moreꢀthanꢀthatꢀofꢀCoꢀorꢀNiꢀsurfaceꢀtoꢀOꢀatomꢀinꢀC=Oꢀofꢀvanillin.ꢀ
Theꢀ deformationꢀ chargeꢀ densityꢀ ofꢀ theꢀ absorbedꢀ vanillinꢀ onꢀ
Ni‐Coꢀsurfaceꢀwasꢀthenꢀcalculatedꢀ(Fig.ꢀS14).ꢀItꢀrevealsꢀthatꢀtheꢀ
CoꢀatomꢀinꢀNi‐CoꢀalloyꢀdirectlyꢀconnectedꢀtoꢀOꢀatomꢀinꢀC=Oꢀofꢀ
vanillinꢀcontributesꢀtheꢀmostꢀtoꢀtheꢀelectronꢀtransfer,ꢀandꢀtheꢀ
adsorptionꢀinducedꢀelectronꢀlossꢀinꢀC=Oꢀleadsꢀtoꢀtheꢀactivationꢀ
ofꢀC=O,ꢀwhichꢀcanꢀbeꢀfurtherꢀevidencedꢀbyꢀtheꢀelongatedꢀbondꢀ
lengthꢀ fromꢀ 1.229ꢀ Åꢀ (free‐state)ꢀ toꢀ 1.260ꢀ Åꢀ (theꢀ ad‐
sorbed‐state).ꢀ ꢀ
(Figs.ꢀ 2(c),ꢀ (d)),ꢀ theꢀ Coꢀ atomꢀ inꢀ Ni‐Coꢀ Alloyꢀ inꢀ Ni‐
Co@N‐CNTs/CMFꢀ canꢀ drawꢀ theꢀ d‐electronsꢀ fromꢀ theꢀ neigh‐
boringꢀNiꢀatoms,ꢀleadingꢀtoꢀanꢀelectronꢀcloudꢀdensityꢀincreaseꢀ
forꢀCoꢀandꢀdecreaseꢀforꢀNi.ꢀSuchꢀsynergisticallyꢀchangedꢀelec‐
tronꢀdistributionsꢀincreaseꢀtheꢀoxophilicityꢀofꢀtheꢀalloyedꢀcata‐
lystꢀtoꢀpromoteꢀtheꢀadsorptionꢀandꢀactivationꢀofꢀC=Oꢀbondꢀinꢀ

2034ꢀ
DongdongꢀWangꢀetꢀal.ꢀ/ꢀChineseꢀJournalꢀofꢀCatalysisꢀ42ꢀ(2021)ꢀ2027–2037ꢀ
alloyedꢀNi‐Coꢀ[51].ꢀ ꢀ
-
-
-
-
0.6
0.5
0.4
0.3
(
a)
3.4.ꢀ ꢀ Substrateꢀscopeꢀ
-
0.48 eV
Theꢀ catalyticꢀ HDOꢀ ofꢀ vanillinꢀ derivativesꢀ andꢀ variousꢀ un‐
-
0.36 eV
-0.36 eV
saturatedꢀ aromaticꢀ aldehydesꢀ containingꢀ differentꢀ functionalꢀ
groupsꢀwereꢀperformedꢀtoꢀdemonstrateꢀtheꢀversatileꢀcatalyticꢀ
capabilitiesꢀ ofꢀ NiCo@N‐CNTs/CMFꢀ (Tableꢀ 1).ꢀ Theꢀ completeꢀ
conversionꢀcanꢀbeꢀachievedꢀforꢀallꢀsubstratesꢀinvestigatedꢀun‐
Ni (111)
Co (111)
NiCo (111)
241 o
C
(
b)
(c)
derꢀmildꢀreactionꢀconditionsꢀ(120ꢀ°Cꢀandꢀ2ꢀMPaꢀH
2
),ꢀconfirmingꢀ
364 o
C
-0.7
-0.6
-0.5
-0.69
theꢀsuperiorꢀHDOꢀcatalyticꢀactivityꢀofꢀtheꢀalloyedꢀcatalyst.ꢀForꢀ
vanillinꢀ derivatives,ꢀ theꢀ ethylꢀ vanillinꢀ canꢀ beꢀ convertedꢀ toꢀ itsꢀ
correspondingꢀ deoxygenatedꢀ productꢀ ofꢀ 2‐ethoxy‐4‐ꢀ
methylphenolꢀwithꢀ98.7%ꢀselectivityꢀ(entryꢀ2,ꢀTableꢀ1),ꢀwhileꢀ
forꢀsyringaldehyde,ꢀaꢀ100%ꢀselectivityꢀtowardꢀitsꢀcorrespond‐
ingꢀ deoxygenatedꢀ productꢀ ofꢀ 2,6‐dimethoxy‐4‐methylphenolꢀ
canꢀbeꢀreadilyꢀachievedꢀ(entryꢀ3,ꢀTableꢀ1).ꢀThisꢀindicatesꢀthatꢀ
theꢀ methoxyꢀ groupꢀ atꢀ theꢀ meta‐positionꢀ inꢀ theꢀ aromaticꢀ ringꢀ
doesꢀnotꢀhinderꢀHDOꢀactivityꢀofꢀaldehyde.ꢀFurthermore,ꢀwhenꢀ
isovanillinꢀ isꢀ usedꢀ asꢀ aꢀ substrate,ꢀ theꢀ HDOꢀ productꢀ ofꢀ
-
0.65
9
2 o
C
-
0.60
1
)
111)
(111)
Co
(
11
o (
50
100 150 200 250 300 350 400
Ni
C
Ni
o
Temperature ( C)
Fig.ꢀ5.ꢀ(a)ꢀOptimizedꢀgeometryꢀforꢀtheꢀconfigurationꢀofꢀvanillinꢀadsorp‐
tionꢀonꢀNiꢀ(111),ꢀCoꢀ(111)ꢀandꢀNiCoꢀ(111)ꢀsurfaces.ꢀGrey,ꢀblue,ꢀbrown,
red,ꢀ andꢀ pinkꢀ spheresꢀ representꢀ Ni,ꢀ Co,ꢀ C,ꢀ Oꢀ andꢀ H,ꢀ respectively;ꢀ (b)ꢀ
AdsorptionꢀenergyꢀofꢀhydrogenꢀonꢀNiꢀ(111),ꢀCoꢀ(111)ꢀandꢀNiCoꢀ(111)
surfaces;ꢀ (c)ꢀ H ‐TPDꢀ profilesꢀ ofꢀ Ni@N‐CNTs/CMF,ꢀ Co@N‐CNTs/CMFꢀ
andꢀNiCo@N‐CNTs/CMF.ꢀ
Tableꢀ1ꢀ
2
a
HDOꢀofꢀvariousꢀsubstratesꢀcatalyzedꢀbyꢀNiCo@N‐CNTs/CMFꢀcatalystꢀ .ꢀ
Timeꢀ Conv.ꢀ Sel.ꢀ
Entryꢀ
Substrateꢀ
Productꢀ
(h)ꢀ
(%)ꢀ (%)
Itꢀisꢀwell‐knownꢀthat,ꢀforꢀaꢀhydrogenationꢀreaction,ꢀinꢀaddi‐
tionꢀtoꢀtheꢀadsorptionꢀcapability,ꢀtheꢀcatalyst’sꢀabilityꢀtoꢀactiveꢀ
1ꢀ
6ꢀ
100ꢀ 100
H
2
ꢀmoleculeꢀandꢀdissociateꢀitꢀintoꢀH*ꢀisꢀalsoꢀcriticallyꢀimportantꢀ
inꢀdeterminingꢀcatalyst’sꢀperformanceꢀ[22,50].ꢀAsꢀshownꢀinꢀFig.ꢀ
S15,ꢀtheꢀH ꢀmoleculeꢀwillꢀspontaneouslyꢀdissociateꢀtoꢀtwoꢀacti‐
ꢀ
2
vatedꢀ H*ꢀ onꢀ metalꢀ surface.ꢀ Interestingly,ꢀ theꢀ dissociatedꢀ 2H*ꢀ
possessesꢀaꢀsmallerꢀEadꢀ(–0.60ꢀeV)ꢀonꢀNi‐Coꢀalloyꢀsurfaceꢀthanꢀ
thatꢀofꢀtheꢀmonometallicꢀNiꢀ(–0.65ꢀeV)ꢀandꢀCoꢀ(–0.69ꢀeV)ꢀsur‐
facesꢀ(Fig.ꢀ5(b)),ꢀindictingꢀanꢀeasierꢀdesorptionꢀprocessꢀatꢀNi‐Coꢀ
alloyꢀactiveꢀsites.ꢀConsequently,ꢀtheꢀactivatedꢀH*ꢀcanꢀbeꢀmoreꢀ
easilyꢀ participatingꢀ inꢀ theꢀ hydrogenationꢀ ofꢀ C=O.ꢀ Toꢀ experi‐
2ꢀ
6ꢀ
4ꢀ
100ꢀ 98.7
100ꢀ 100
ꢀ
3ꢀ
mentallyꢀtestifyꢀtheꢀDFTꢀresults,ꢀH
alloyꢀandꢀmonometallicꢀNiꢀandꢀCoꢀcatalystsꢀwereꢀobtainedꢀ(Fig.ꢀ
(c)).ꢀ Theꢀ desorptionꢀ peaksꢀ appearedꢀ inꢀ theꢀ temperatureꢀ
2
‐TPDꢀprofilesꢀofꢀtheꢀNi‐Coꢀ
ꢀ
5
rangesꢀ ofꢀ 60–125ꢀ °Cꢀ andꢀ 190–280ꢀ °Cꢀ canꢀ beꢀ assignedꢀ toꢀ theꢀ
adsorbedꢀhydrogenꢀonꢀN‐CNTsꢀ[51]ꢀandꢀtheꢀchemisorbedꢀhy‐
drogenꢀ onꢀ metalꢀ surface,ꢀ respectivelyꢀ [52],ꢀ whileꢀ theꢀ desorp‐
tionꢀpeakꢀatꢀtheꢀhighꢀtemperatureꢀrangeꢀ(340–410ꢀ°C)ꢀmightꢀbeꢀ
attributedꢀtoꢀtheꢀspilloverꢀhydrogenꢀonꢀtheꢀCNTsꢀ[53].ꢀTheꢀhy‐
drogenꢀadsorptionꢀcapabilityꢀcalculatedꢀbasedꢀonꢀtheꢀintegrat‐
4
ꢀ
6ꢀ
6ꢀ
100ꢀ 92.4
100ꢀ 98.1
HO
O
ꢀ
5ꢀ
edꢀ areasꢀ ofꢀ theꢀ correspondingꢀ H
‐TPDꢀ profilesꢀ areꢀ 4.14,ꢀ 5.74ꢀ
2
–
1
ꢀ
ꢀ
andꢀ6.96ꢀmmolꢀg ꢀforꢀCo@N‐CNTs/CMF,ꢀNi@N‐CNTs/CMFꢀandꢀ
NiCo@N‐CNTs/CMF,ꢀrespectivelyꢀ(TableꢀS2),ꢀinꢀaꢀgoodꢀagree‐
mentꢀ withꢀ theꢀ DFTꢀ predictedꢀ superiorꢀ hydrogenꢀ adsorptionꢀ
capabilityꢀ ofꢀ Ni‐Coꢀ alloyꢀ overꢀ theꢀ monometallicꢀ Niꢀ andꢀ Co.ꢀ Inꢀ
addition,ꢀitꢀcanꢀbeꢀnotedꢀfromꢀFig.ꢀ5(c)ꢀthatꢀcomparingꢀtoꢀtheꢀ
monometallicꢀ Co@N‐CNTs/CMFꢀ andꢀ Ni@N‐CNTs/CMF,ꢀ theꢀ
correspondingꢀhydrogenꢀdesorptionꢀpeakꢀtemperaturesꢀofꢀNi‐
Co@N‐CNTs/CMFꢀareꢀobviouslyꢀshiftedꢀtoꢀlowerꢀtemperatures.ꢀ
Theseꢀ resultsꢀ validateꢀ theꢀ easierꢀ desorptionꢀ processꢀ atꢀ Ni‐Coꢀ
alloyꢀactiveꢀsitesꢀpredictedꢀbyꢀDFTꢀcalculations,ꢀconfirmingꢀtheꢀ
promotedꢀhydrogenꢀdesorptionꢀbyꢀtheꢀsynergeticꢀeffectꢀofꢀtheꢀ
6
ꢀ
10ꢀ
10ꢀ
100ꢀ 93.2
100ꢀ 91.5
7ꢀ
ꢀ
aꢀReactionꢀconditions:ꢀ30ꢀmgꢀcatalyst,ꢀ0.5ꢀmmolꢀsubstrates,ꢀ10ꢀmLꢀH
120ꢀ°C,ꢀ2ꢀMPaꢀH ꢀpressure.ꢀ
2
O,ꢀ
2

ꢀ
DongdongꢀWangꢀetꢀal.ꢀ/ꢀChineseꢀJournalꢀofꢀCatalysisꢀ42ꢀ(2021)ꢀ2027–2037ꢀ
2035ꢀ
2
‐methoxy‐5‐methylphenolꢀ canꢀ alsoꢀ beꢀ obtainedꢀ withꢀ aꢀ highꢀ
aꢀnewꢀmethodꢀtoꢀdesignꢀandꢀdevelopꢀefficientꢀtransitionꢀmet‐
al‐basedꢀcatalystsꢀforꢀHDOꢀreactionsꢀinꢀwater.ꢀ
selectivityꢀofꢀ92.4%.ꢀ(entryꢀ4,ꢀTableꢀ1).ꢀTheꢀHDOꢀofꢀotherꢀaro‐
maticꢀ aldehydesꢀ areꢀ alsoꢀ foundꢀ toꢀ beꢀ highlyꢀ selective,ꢀ withꢀ aꢀ
98.1%ꢀpara‐methylꢀphenolꢀselectivityꢀforꢀHDOꢀofꢀpara‐hydroxyꢀ
Electronicꢀsupportingꢀinformationꢀ
benzaldehydeꢀ(entryꢀ5,ꢀTableꢀ1),ꢀandꢀ93.2%ꢀandꢀ91.5%ꢀselec‐
tivitiesꢀtowardꢀHDOꢀofꢀortho‐ꢀandꢀpara‐methylꢀbenzaldehydesꢀ
Supportingꢀinformationꢀisꢀavailableꢀinꢀtheꢀonlineꢀversionꢀofꢀ
thisꢀarticle.ꢀ ꢀ
(entriesꢀ6ꢀandꢀ7,ꢀTableꢀ1).ꢀTheseꢀresultsꢀdemonstrateꢀtheꢀge‐
nericꢀ applicabilityꢀ ofꢀ NiCo@N‐CNTs/MFꢀ forꢀ efficientꢀ HDOꢀ ofꢀ
variousꢀunsaturatedꢀaromaticꢀaldehydesꢀinꢀwater.ꢀ ꢀ
Declarationꢀofꢀinterestsꢀ
4
.ꢀ ꢀ Conclusionsꢀ
Theꢀauthorsꢀdeclareꢀthatꢀtheyꢀhaveꢀnoꢀknownꢀcompetingꢀfi‐
nancialꢀinterestsꢀorꢀpersonalꢀrelationshipsꢀthatꢀcouldꢀhaveꢀap‐
pearedꢀtoꢀinfluenceꢀtheꢀworkꢀreportedꢀinꢀthisꢀpaper.ꢀ
Inꢀsummary,ꢀweꢀhaveꢀdemonstratedꢀaꢀcontrollableꢀsyntheticꢀ
approachꢀtoꢀfabricateꢀwell‐definedꢀNi‐CoꢀalloyꢀNPsꢀconfinedꢀonꢀ
theꢀ tipꢀ ofꢀ N‐CNTs.ꢀ Weꢀ haveꢀ alsoꢀ exemplifiedꢀ theꢀ genericꢀ ap‐
plicabilityꢀ ofꢀ theꢀ synthesizedꢀ Ni‐Coꢀ alloyꢀ NPꢀ catalystꢀ towardꢀ
HDOꢀofꢀvanillin,ꢀitsꢀderivativesꢀandꢀotherꢀaromaticꢀaldehydesꢀinꢀ
water,ꢀ underꢀ mildꢀ reactionꢀ conditions.ꢀ Importantly,ꢀ weꢀ haveꢀ
theoreticallyꢀ andꢀ experimentallyꢀ validatedꢀ thatꢀ theꢀ achievedꢀ
outstandingꢀ HDOꢀ catalyticꢀ performanceꢀ isꢀ resultedꢀ fromꢀ theꢀ
greatlyꢀ promotedꢀ selectiveꢀ adsorptionꢀ andꢀ activationꢀ ofꢀ C=O,ꢀ
andꢀdesorptionꢀofꢀtheꢀactivatedꢀhydrogenꢀspeciesꢀbyꢀtheꢀsyner‐
gismꢀofꢀtheꢀalloyedꢀNi‐CoꢀNPs.ꢀTheꢀfindingsꢀofꢀthisꢀworkꢀaffordsꢀ
Referencesꢀ
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[
4
GraphicalꢀAbstractꢀ
Chin.ꢀJ.ꢀCatal.,ꢀ2021,ꢀ42:ꢀ2027–2037ꢀ ꢀ ꢀ doi:ꢀ10.1016/S1872‐2067(21)63828‐7
EncapsulatedꢀNi‐Coꢀalloyꢀnanoparticlesꢀasꢀefficientꢀcatalystꢀforꢀhydrodeoxygenationꢀofꢀbiomassꢀderivativesꢀinꢀwaterꢀ
DongdongꢀWang,ꢀWanbingꢀGongꢀ*,ꢀJifangꢀZhang,ꢀMiaomiaoꢀHanꢀ*,ꢀChunꢀChen,ꢀYunxiaꢀZhang,ꢀGuozhongꢀWang,ꢀHaiminꢀZhang,ꢀ ꢀ
HuijunꢀZhaoꢀ*ꢀ
HefeiꢀInstitutesꢀofꢀPhysicalꢀScience,ꢀChineseꢀAcademyꢀofꢀSciences,ꢀChina;ꢀUniversityꢀofꢀScienceꢀandꢀTechnologyꢀofꢀChina,ꢀChina;ꢀ ꢀ
HuzhouꢀUniversity,ꢀChina;ꢀGriffithꢀUniversity,ꢀAustraliaꢀ
Hydrodeoxygenation of Biomass Derivatives
HMP
H*
Vanillin
MMP
H2
Encapsulated bimetallic Ni-Co alloy catalyst
ꢀ
AnꢀencapsulatedꢀbimetallicꢀNi‐Coꢀalloyingꢀstrategyꢀisꢀinnovativelyꢀdesignedꢀtoꢀenhanceꢀtheꢀhydrodeoxygenationꢀperformanceꢀofꢀbiomassꢀ
derivativesꢀtoꢀtheꢀcorrespondingꢀmethylatedꢀproductsꢀinꢀwater.ꢀ

2036ꢀ
DongdongꢀWangꢀetꢀal.ꢀ/ꢀChineseꢀJournalꢀofꢀCatalysisꢀ42ꢀ(2021)ꢀ2027–2037ꢀ
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限域NiCo合金纳米颗粒高效催化生物质衍生物水相加氢脱氧
a,b
a,#
a,b
c,$
a
a
a
a
a,d,*
汪东东 , 龚万兵 , 张继方 , 韩苗苗 , 陈 春 , 张云霞 , 汪国忠 , 张海民 , 赵惠军
a
中国科学院合肥物质科学研究院固体所, 环境与能源纳米材料中心, 安徽合肥230031, 中国
b
中国科学技术大学, 安徽合肥230026, 中国
c
湖州师范学院, 浙江湖州313000, 中国
d
格里菲斯大学, 清洁环境与能源中心, 昆士兰, 澳大利亚
摘要: 将储量丰富的生物质及其衍生物转化为具有高附加值的燃料和化学品被认为是一种有前景的绿色途径, 可以极大
地减少人们对传统化石资源的依赖. 作为木质纤维素热解的直接产物和生物油升级的模型化合物, 香草醛可以通过加氢
脱氧(HDO)过程选择性地转化为2-甲氧基-4-甲基苯酚(MMP). MMP是一种有价值的化学品, 常用于香料和药物等重要中
间体的合成. 在过去十年里, 大量的金属催化剂被用来催化香草醛HDO转化为MMP. 其中, 贵金属(Pt, Pd, Ru和Au)虽然活

ꢀ
DongdongꢀWangꢀetꢀal.ꢀ/ꢀChineseꢀJournalꢀofꢀCatalysisꢀ42ꢀ(2021)ꢀ2027–2037ꢀ
2037ꢀ
性高, 但是其储量低、价格昂贵, 不利于工业化应用; 而非贵金属(Fe, Co, Ni和Cu)的催化活性普遍较低, 需要苛刻的反应条
件来提高转化效率和选择性. 此外, 这类HDO反应大都在有机溶剂中进行, 容易造成环境污染. 因此, 开发高效、稳定的非
贵金属催化剂用于水相HDO反应是一个巨大的挑战.
一般来说, 合金纳米颗粒(NPs)具有强烈的协同效应, 能产生良好的配位结构和电子环境, 从而显著提升催化活性和选
择性. 基于此, 本文首次采用了一种简单可控的合成方法来制备三聚氰胺海绵负载的氮掺杂碳纳米管(N-CNTs)限域的
2
Ni-Co合金NPs(NiCo@N-CNTs/CMF)催化剂. 该催化剂具有优异的HDO性能, 在2 MPa H , 120 ºC反应6 h条件下, 能在水相
中将生物质衍生的香草醛高效转化为MMP, 转化率和选择性均达到100%. 相比于单金属的Ni@N-CNTs/CMF和
Co@N-CNTs/CMF催化剂, 香草醛转化率和MMP选择性都有大幅度的提高. 而且, 在温和的反应条件下, 该催化剂对香草
醛衍生物和其他芳香醛类化合物同样表现出优异的HDO性能, 拥有100%的转化率以及较高的MMP选择性(91.5%~100%).
XPS结果表明, Ni-Co形成合金后发生了电子结构的偏移, 即Co原子可以从邻近的Ni原子处得到电子, 提高Co电子云密度,
从而促进对香草醛中C=O键的吸附. DFT计算结果表明, 相比于单金属的Ni和Co, Ni-Co合金化后能显著提高对C=O键的选
2
择性吸附和活化. 同时, H 解离后形成的活性H*物种在Ni-Co合金NPs表面更容易脱附并参与催化反应. 因此, Ni-
Co@N-CNTs/CMF催化剂优异的HDO性能主要是由于Ni-Co合金NPs的协同作用大大促进了其对C=O键的选择性吸附和活
化, 以及活化氢物种的脱附. 本文为设计和制备高效的非贵金属催化剂应用于水相的HDO反应提供了一个新策略.
关键词: Ni-Co合金纳米颗粒; 碳纳米管; 加氢脱氧; 生物质衍生物; 水溶剂
收稿日期: 2021-03-16. 接受日期: 2021-04-15. 上网时间: 2021-08-20.
*
通讯联系人. 电话: (0551)65591263; 传真: (0551) 65591434; 电子信箱: h.zhao@griffith.edu.au
#
通讯联系人. 电话: (0551)65591263; 传真: (0551) 65591434; 电子信箱: wbgong@issp.ac.cn
通讯联系人. 电话: (0551)65591263; 传真: (0551) 65591434; 电子信箱: mmhan@zjhu.edu.cn
$
基金来源: 国家自然科学基金(51902311, 51871209, 61804154).
本文的电子版全文由Elsevier出版社在ScienceDirect上出版(http://www.sciencedirect.com/journal/chinese-journal-of-catalysis).