Scalable and super-stable exfoliation of graphitic carbon nitride in biomass-derived γ-valerolactone: Enhanced catalytic activity for the alcoholysis and cycloaddition of epoxides with CO2

Article abstract of DOI:10.1039/c7gc02583a

Biomass-derived γ-valerolactone (GVL) could exfoliate bulk g-C₃N₄ to form a super-stable dispersion of few-layer g-C₃N₄ nanosheets with a high concentration of up to 0.8 mg mL^-1 due to the polarity and the appropriate surface energy of GVL. The exfoliation process can be easily extended to a 200 ml scale and should be extended further. The formed g-C₃N₄ nanosheets showed enhanced activity for the alcoholysis of epoxides and the cycloaddition of epoxides with CO₂ owing to their higher specific surface areas and more exposed active centers than the bulk g-C₃N₄. This affords a green, facile and scalable method to form few-layer g-C₃N₄ nanosheets and further expand the application of g-C₃N₄ materials to the field of non-photocatalysis.

Full text of DOI:10.1039/c7gc02583a

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April 2016 Pages 1821–2242
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CRITICAL REVIEW
G. Chatel et al.
Heterogeneous catalytic oxidation for lignin valorization into valuable
chemicals: what results? What limitations? What trends?
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Page 1 of 5
Green Chemistry
View Article Online
DOI: 10.1039/C7GC02583A
JournalꢀNameꢀ
COMMUNICATIONꢀ
ꢀ
Scalableꢀandꢀsuper-stableꢀexfoliationꢀofꢀgraphiticꢀcarbonꢀnitrideꢀinꢀ
biomass-derivedꢀ γ-valerolactone:ꢀ Enhancedꢀ catalyticꢀ activityꢀ forꢀ
alcoholysisꢀandꢀcycloadditionꢀofꢀepoxidesꢀwithꢀCO2ꢀ
Receivedꢀ00thꢀJanuaryꢀ20xx,ꢀ
Acceptedꢀ00thꢀJanuaryꢀ20xxꢀ
a
b
b
b
b
ZhiminꢀXue,* ꢀFeijieꢀLiu, ꢀJingyunꢀJiang, ꢀJinfangꢀWang, ꢀandꢀTianchengꢀMu*
DOI:ꢀ10.1039/x0xx00000xꢀ
www.rsc.org/ꢀ
14-16
Biomass-derivedꢀγ-valerolactoneꢀ(GVL)ꢀcouldꢀexfoliateꢀbulkꢀg-C
3
N
4
ꢀ
andꢀ blackꢀ phosphorus),
ꢀ exfoliationꢀ hasꢀ greatꢀ potentialꢀ forꢀ
toꢀformꢀaꢀsuper-stableꢀdispersionꢀofꢀfew-layerꢀg-C
3
N
4
ꢀnanosheetsꢀ effectiveꢀpreparationꢀofꢀfew-layerꢀg-C
3
N
4
ꢀnanosheetsꢀfromꢀtheꢀbulkꢀ
-1
17
withꢀaꢀhighꢀconcentrationꢀofꢀupꢀtoꢀ0.8ꢀmgꢀmL ꢀdueꢀtoꢀtheꢀpolarityꢀ g-C
andꢀtheꢀappropriateꢀsurfaceꢀenergyꢀofꢀGVL.ꢀTheꢀexfoliationꢀprocessꢀ ofꢀ bulkꢀ g-C
3 4
N . ꢀSeveralꢀmethodsꢀhaveꢀbeenꢀdevelopedꢀforꢀtheꢀexfoliationꢀ
1
8,19
20,21
3
N
4
,ꢀ includingꢀ chemical,
ꢀ micromechanical,
ꢀ
2
2
23-25
26
canꢀ beꢀ easilyꢀ extendedꢀ toꢀ 200ꢀ mlꢀ scaleꢀ andꢀ shouldꢀ beꢀ extendedꢀ thermal, ꢀ andꢀ liquid-phase
further.ꢀTheꢀformedꢀg-C ꢀnanosheetsꢀshowedꢀenhancedꢀactivityꢀ phaseꢀexfoliationꢀhasꢀgainedꢀmoreꢀattentionꢀowingꢀtoꢀtheꢀeaseꢀtoꢀ
forꢀalcoholysisꢀofꢀepoxidesꢀandꢀcycloadditionꢀofꢀepoxidesꢀwithꢀCO getꢀ few-layerꢀ g-C ꢀ nanosheetsꢀ inꢀ largeꢀ quantitiesꢀ underꢀ relativeꢀ
owingꢀtoꢀitsꢀhigherꢀspecificꢀsurfaceꢀareaꢀandꢀmoreꢀexposedꢀactiveꢀ mildꢀ conditions.ꢀ Toꢀ dates,ꢀ severalꢀ organicꢀ solventsꢀ (e.g.,ꢀ
ꢀ methods.ꢀ Amongꢀ them, ꢀ liquid-
3 4
N
2
ꢀ
3 4
N
2
3
25
23
centersꢀ thanꢀ theꢀ bulkꢀ g-C
3 4
N .ꢀ Thisꢀ affordsꢀ aꢀ green,ꢀ facileꢀ andꢀ isopropanol, ꢀ 1,3-butanediol, ꢀ N-methyl-pyrrolidone )ꢀ andꢀ someꢀ
2
4,27
scalableꢀmethodꢀtoꢀformꢀfew-layerꢀg-C
3
N
4
ꢀnanosheetsꢀandꢀfurtherꢀ mixedꢀsolvents
ꢀmaterialsꢀtoꢀnon-photocatalysisꢀ .ꢀ However,ꢀ theseꢀ solventsꢀ areꢀ usuallyꢀ notꢀ soꢀ environmentallyꢀ
benign.ꢀ Meanwhile,ꢀ theꢀ obtainedꢀ suspensionsꢀ ofꢀ few-layerꢀ g-C N ꢀ
ꢀhaveꢀbeenꢀappliedꢀinꢀtheꢀexfoliationꢀofꢀbulkꢀg-
expandꢀtheꢀapplicationꢀofꢀg-C
field.ꢀꢀ
3
N
4
3 4
C N
3
4
nanosheetsꢀ areꢀ stillꢀ atꢀ relativelyꢀ lowꢀ concentrations,ꢀ andꢀ areꢀ notꢀ
stableꢀwithꢀprecipitationꢀorꢀaggregationꢀgeneratedꢀinꢀaꢀrelativeꢀshortꢀ
time.ꢀ Therefore,ꢀ furtherꢀ explorationꢀ ofꢀ environmental-friendlyꢀ
Two-dimensionalꢀ(2D)ꢀlayeredꢀmaterialsꢀhaveꢀattractedꢀtremendousꢀ
1
-5
attentionꢀdueꢀtoꢀtheirꢀuniqueꢀpropertiesꢀandꢀdiverseꢀapplications.
Inꢀ theꢀ contextꢀ ofꢀ 2Dꢀ materials,ꢀ metal-freeꢀ andꢀ nontoxicꢀ graphiticꢀ
carbonꢀnitrideꢀ(g-C )ꢀwithꢀhighꢀthermalꢀandꢀchemicalꢀstabilityꢀcanꢀ
ꢀ
3 4
solventsꢀ forꢀ large-scaleꢀ exfoliationꢀ ofꢀ bulkꢀ g-C N ꢀ toꢀ formꢀ super-
3 4
N
stableꢀ suspensionsꢀisꢀ stillꢀ highlyꢀdesirableꢀ inꢀorderꢀ toꢀ improveꢀ theꢀ
exfoliationꢀ efficiencyꢀ andꢀ fulfillꢀ theꢀ versatileꢀ applicationsꢀ ofꢀ few-
beꢀeasilyꢀsynthesizedꢀusingꢀlow-costꢀandꢀabundantꢀnitrogen-richꢀrawꢀ
6
materialsꢀthroughꢀaꢀsimpleꢀcalcinationꢀprocess, ꢀandꢀhasꢀemergedꢀasꢀ
layerꢀg-C
3 4
N ꢀnanosheets.ꢀꢀ
aꢀ veryꢀ attractiveꢀ 2Dꢀ layeredꢀ materialꢀ inꢀ solarꢀ energyꢀ conversion,ꢀ
Nowadays,ꢀ utilizationꢀ ofꢀ biomass-derivedꢀ compoundsꢀ asꢀ
7-12
2
8
electrocatalysis,ꢀ andꢀ especiallyꢀ inꢀ photocatalysis. ꢀ However,ꢀ theꢀ
solventsꢀhasꢀbecomeꢀaꢀhotꢀfield. ꢀInꢀthisꢀregard,ꢀincreasingꢀinterestꢀ
hasꢀbeenꢀpaidꢀonꢀγ-valerolactoneꢀ(GVL),ꢀwhichꢀcanꢀbeꢀproducedꢀinꢀaꢀ
largeꢀ scaleꢀ fromꢀ cellulose.ꢀ GVLꢀ hasꢀ beenꢀ consideredꢀ asꢀ anꢀ
alternativeꢀdipolarꢀaproticꢀsolventꢀforꢀcommonꢀorganicꢀsolventsꢀdueꢀ
13
applicationsꢀ ofꢀ g-C
Explorationꢀ ofꢀ newꢀ non-photocatalysisꢀ applicationsꢀ forꢀ g-C
beenꢀattractedꢀmoreꢀattention,ꢀwhichꢀcanꢀsignificantlyꢀexpandꢀtheꢀ
3
N
4
ꢀ inꢀ non-photocatalysisꢀ areꢀ veryꢀ limited. ꢀ
3 4
N ꢀ hasꢀ
2
9-31
applicatedꢀfieldꢀofꢀg-C
3
N
4
ꢀtoꢀmakeꢀfullꢀuseꢀofꢀthisꢀuniqueꢀmetal-freeꢀ
toꢀitsꢀpropertiesꢀofꢀbiocompatibleꢀandꢀbiodegradability.
ꢀAsꢀwell-
material.ꢀꢀ
known,ꢀ solventsꢀ possessingꢀ properꢀ polarity,ꢀ surfaceꢀ tension,ꢀ andꢀ
3 4
Generally,ꢀ ultrathinꢀ g-C N
ꢀ withꢀ fewꢀ layersꢀ possessesꢀ betterꢀ
electronꢀ donationꢀ ability,ꢀ etc.,ꢀ areꢀ theꢀ mostꢀ efficientꢀ solventsꢀ forꢀ
17,25
performancesꢀ inꢀ theꢀ applicationꢀ ofꢀ catalysisꢀ dueꢀ toꢀ theꢀ higherꢀ
specificꢀ surfaceꢀ areaꢀ andꢀ theꢀ easy-contactꢀ ofꢀ activeꢀ centersꢀ
comparedꢀ withꢀ theꢀ bulkꢀ one.ꢀ Therefore,ꢀ greatꢀ effortsꢀ haveꢀ beenꢀ
exfoliationꢀofꢀbulkꢀg-C
3
N
4
.
ꢀTherefore,ꢀconsideringꢀitsꢀpolarityꢀandꢀ
surfaceꢀ tension,ꢀ GVLꢀ asꢀ aꢀ biomass-derivedꢀ solventꢀ hasꢀ greatꢀ
3 4
potentialꢀ forꢀ theꢀ formationꢀ ofꢀ few-layerꢀ g-C N ꢀ nanosheetsꢀ byꢀ
devotedꢀinꢀtheꢀsynthesisꢀofꢀfew-layerꢀg-C
3
N
4
ꢀnanosheets.ꢀInspiredꢀbyꢀ
,ꢀ
liquid-phaseꢀexfoliation.ꢀꢀ
theꢀstrategiesꢀforꢀotherꢀ2Dꢀlayeredꢀmaterialsꢀ(e.g.,ꢀgraphene,ꢀMoS
2
Herein,ꢀweꢀconductedꢀtheꢀfirstꢀworkꢀonꢀutilizationꢀofꢀbiomass-
derivedꢀ GVLꢀ toꢀ exfoliateꢀ bulkꢀ g-C .ꢀ Thisꢀ greenꢀ processꢀ hadꢀhighꢀ
efficiency.ꢀAꢀdispersionꢀofꢀfew-layerꢀg-C ꢀnanosheetsꢀwithꢀaꢀhighꢀ
3 4
N
3 4
N
-
1
concentrationꢀofꢀ0.8ꢀmgꢀmL ꢀcouldꢀbeꢀgeneratedꢀinꢀGVL,ꢀwhichꢀwasꢀ
stableꢀforꢀtwelveꢀmonthsꢀatꢀambientꢀtemperatureꢀwithoutꢀobviousꢀ
precipitationꢀ orꢀ aggregation.ꢀ Surprisingly,ꢀ theꢀ formedꢀ few-layerꢀ g-
C
3
N
4
ꢀ nanosheetsꢀ showedꢀ enhancedꢀ activityꢀ forꢀ alcoholysisꢀ ofꢀ
epoxidesꢀ (aꢀ newꢀ reactionꢀ catalyzedꢀ overꢀ g-C ꢀ nanosheets)ꢀ andꢀ
3 4
N
Thisꢀjournalꢀisꢀ©ꢀTheꢀRoyalꢀSocietyꢀofꢀChemistryꢀ20xxꢀ
J.ꢀName.,ꢀ2013,ꢀ00,ꢀ1-3ꢀ|ꢀ1ꢀꢀ

Green Chemistry
Page 2 of 5
COMMUNICATIONꢀ
JournalꢀNameꢀ
cycloadditionꢀofꢀepoxidesꢀwithꢀCO
2
,ꢀcomparedꢀwithꢀtheꢀbulkꢀg-C
3
N
4
ꢀ
wasꢀmadeꢀofꢀmonolayersꢀorꢀfewꢀatomicꢀlayers.ꢀTheꢀstVriuewctAurrtieclꢀeoOfꢀntlhineeꢀ
DOI: 10.1039/C7GC02583A
(
Fig.ꢀ1).ꢀꢀ
3 4
as-preparedꢀfew-layerꢀg-C N ꢀnanosheetsꢀwasꢀalsoꢀcharacterizedꢀbyꢀ
Similarꢀwithꢀsomeꢀreportedꢀexfoliationꢀprocessesꢀforꢀotherꢀ2Dꢀ atomicꢀforceꢀmicroscopyꢀ(AFM)ꢀmethod.ꢀTheꢀresultsꢀofꢀAFMꢀinꢀFigs.ꢀ
layeredꢀ materials,ꢀ asꢀ describedꢀ inꢀ Fig.ꢀ 1,ꢀ bulkꢀ g-C ꢀ wasꢀ initiallyꢀ 2cꢀ andꢀ 2dꢀ showedꢀ thatꢀ theꢀ averageꢀ thicknessꢀ ofꢀ theꢀ few-layerꢀ g-
suspendedꢀ inꢀ GVLꢀ withꢀ aꢀ concentrationꢀ ofꢀ 3ꢀ mgꢀ mL ,ꢀ andꢀ thenꢀ
sonicatedꢀ(100ꢀW)ꢀwithꢀaꢀfrequencyꢀofꢀ40ꢀkHzꢀatꢀroomꢀtemperatureꢀ wasꢀconsistedꢀofꢀaboutꢀ6ꢀlayers.
forꢀtheꢀgradualꢀexfoliationꢀofꢀtheꢀbulkꢀg-C ꢀtoꢀformꢀfew-layerꢀg-
ꢀnanosheets.ꢀAfterꢀaꢀsonicationꢀtimeꢀofꢀ24ꢀh,ꢀtheꢀdispersionꢀwasꢀ
centrifugedꢀ atꢀ 4000ꢀ rpmꢀ forꢀ 30ꢀ minꢀ toꢀ removeꢀ aggregations,ꢀ
obtainingꢀ aꢀ homogeneousꢀ dispersionꢀ ofꢀ few-layerꢀ g-C
3 4
N
-1
3 4 3 4
C N ꢀnanosheetsꢀwasꢀaboutꢀ2ꢀnm,ꢀsuggestingꢀtheꢀachievedꢀg-C N ꢀ
2
4,35
ꢀ
3
N
4
ꢀ
3 4
C N
3 4
N ꢀ
-
1
nanosheetsꢀwithꢀaꢀconcentrationꢀofꢀupꢀtoꢀ0.8ꢀmgꢀmL ,ꢀwhichꢀwasꢀ
32
calculatedꢀ accordingꢀ toꢀ theꢀ Lambert-Beerꢀ lawꢀ (Fig.ꢀ S1), ꢀ andꢀ wasꢀ
consistentꢀ withꢀ theꢀ resultsꢀ obtainedꢀ byꢀ weighing.ꢀ Theꢀ obtainedꢀ
25
dispersionꢀ showedꢀ anꢀ obviousꢀ Tyndallꢀ effectꢀ (Fig.ꢀ 1), ꢀ andꢀ wasꢀ
stableꢀafterꢀbeingꢀstoredꢀforꢀtwelveꢀmonthsꢀwithꢀnoꢀprecipitationꢀorꢀ
aggregationꢀ(Fig.ꢀS2).ꢀMeanwhile,ꢀtheꢀconcentrationꢀofꢀfew-layerꢀg-
3 4
C N ꢀnanosheetsꢀinꢀGVLꢀafterꢀ12-monthꢀstorageꢀwasꢀstillꢀaboutꢀ0.8ꢀ
-1
mgꢀ mL ꢀ accordingꢀ toꢀ theꢀ Lambert-Beerꢀ lawꢀ (Fig.ꢀ S1),ꢀ furtherꢀ
indicatingꢀtheꢀsuperꢀstabilityꢀofꢀtheꢀg-C ꢀnanosheetsꢀdispersionꢀinꢀ
GVL,ꢀ andꢀ FT-IRꢀ spectraꢀ ofꢀ theꢀ few-layerꢀ g-C ꢀ nanosheetsꢀ afterꢀ
3 4
N
Fig.ꢀ2.ꢀTEMꢀimageꢀ(a),ꢀHR-TEMꢀimageꢀ(b),ꢀAFMꢀimageꢀ(c),ꢀandꢀcorrespondingꢀ
3 4
N
thicknessꢀanalysisꢀ(d)ꢀtakenꢀaroundꢀtheꢀblueꢀlineꢀinꢀ(c)ꢀforꢀtheꢀobtainedꢀfew-
storedꢀinꢀGVLꢀforꢀtwelveꢀmonthsꢀwasꢀsimilarꢀwithꢀtheꢀbulkꢀoneꢀ(Fig.ꢀ
S3),ꢀsuggestingꢀnoꢀchangeꢀofꢀtheꢀchemicalꢀstructureꢀafterꢀstoredꢀforꢀ
aꢀlongꢀperiodꢀ(12ꢀmonths).ꢀAdditionally,ꢀtheꢀcolorꢀofꢀtheꢀexfoliatedꢀ
3 4
layerꢀg-C N ꢀnanosheets.ꢀ
ꢀ
3 4
Theꢀ crystalꢀ structureꢀ ofꢀ theꢀ few-layerꢀg-C N ꢀ nanosheetsꢀ wasꢀ
few-layerꢀ g-C
Fig.ꢀ S4).ꢀ Furthermore,ꢀ thisꢀ methodꢀ wasꢀ stillꢀ effectiveꢀ whenꢀ theꢀ
scaleꢀ wasꢀ expandedꢀ toꢀ 200ꢀ mLꢀ (Fig.ꢀ S5).ꢀ Thereꢀ wereꢀ twoꢀ mainꢀ
reasonsꢀ forꢀ theꢀ highꢀ efficiencyꢀ ofꢀ GVLꢀ toꢀ exfoliateꢀ bulkꢀ g-C .ꢀ
Firstly,ꢀasꢀaꢀdipolarꢀaproticꢀsolvent,ꢀGVLꢀcouldꢀformꢀhydrogenꢀbondsꢀ
3 4 3 4
N ꢀ nanosheetsꢀ becameꢀ lighterꢀ thanꢀ theꢀ bulkꢀ g-C N ꢀ
examinedꢀthroughꢀX-rayꢀdiffractionꢀ(XRD)ꢀmethodꢀ(Fig.ꢀ3a).ꢀAꢀstrongꢀ
(
o
peakꢀ forꢀ theꢀ (002)ꢀ planeꢀ atꢀ 27.7 ꢀ wasꢀ found,ꢀ whichꢀ wasꢀ theꢀ
characteristicꢀ interlayerꢀ stackingꢀ reflectionꢀ ofꢀ conjugatedꢀ aromaticꢀ
3 4
N
25
systems. ꢀHowever,ꢀtheꢀintensityꢀofꢀthisꢀpeakꢀforꢀtheꢀfew-layerꢀg-
ꢀnanosheetsꢀsignificantlyꢀdecreasedꢀcomparedꢀwithꢀthatꢀforꢀtheꢀ
bulkꢀ g-C ,ꢀ indicatingꢀ theꢀ bulkꢀ g-C ꢀ hadꢀ beenꢀ successfulꢀ
2
4,25
3 4
C N
withꢀtheꢀdanglingꢀhydrogensꢀonꢀtheꢀlayersꢀofꢀbulkꢀg-C
thusꢀ bulkꢀ g-C ꢀ wasꢀ expandedꢀ andꢀ exfoliatedꢀ inꢀ GVLꢀ assistedꢀ byꢀ
weakꢀsonication.ꢀSecondly,ꢀGVLꢀhasꢀappropriateꢀsurfaceꢀenergyꢀ(~60ꢀ
3
N
4
,
ꢀandꢀ
3
N
4
3 4
N
3 4
N
exfoliatedꢀ asꢀ weꢀ desired,ꢀ whichꢀ wasꢀ consistentꢀ withꢀ theꢀ resultsꢀ
obtainedꢀ fromꢀ TEMꢀ andꢀ AFMꢀ (Fig.ꢀ 2).ꢀ Furthermore,ꢀ X-rayꢀ
photoelectronꢀ spectroscopyꢀ (XPS)ꢀ techniqueꢀ wasꢀ conductedꢀ toꢀ
-2 33
mJꢀm ), ꢀwhichꢀwasꢀmatchedꢀwithꢀꢀvanꢀderꢀWaalsꢀbondedꢀsurfacesꢀ
-
2 23,34
(
~70ꢀ mJꢀ m ),
ꢀ therefore,ꢀ GVLꢀ showedꢀ remarkableꢀ performanceꢀ
3 4
determineꢀ theꢀ chemicalꢀ statesꢀ ofꢀ theꢀ preparedꢀ few-layerꢀ g-C N ꢀ
3 4 3 4
forꢀ theꢀ exfoliationꢀ ofꢀ bulkꢀ g-C N ꢀ toꢀ formꢀ few-layerꢀ g-C N ꢀ
nanosheetsꢀ andꢀ theꢀ bulkꢀ oneꢀ (Fig.ꢀ 3b).ꢀ Meanwhile,ꢀ inꢀ theꢀ highꢀ
resolutionꢀXPSꢀspectraꢀofꢀCꢀ1sꢀ(Fig.ꢀ3c),ꢀtheꢀpeakꢀappearingꢀatꢀ288.4ꢀ
nanosheets.ꢀ
ꢀ
2
eVꢀoriginatedꢀfromꢀtheꢀsp -bondedꢀcarbonꢀ(N-C-N)ꢀinꢀtheꢀaromaticꢀ
ring,ꢀ whileꢀ theꢀ peakꢀ atꢀ 284.8ꢀ withꢀ lowꢀ intensityꢀ wasꢀ relatedꢀ toꢀ
23
carbonꢀcontamination. ꢀAdditionally,ꢀfromꢀhighꢀresolutionꢀXPSꢀofꢀNꢀ
sꢀ(Fig.ꢀ3d),ꢀtheꢀspectrumꢀwasꢀdividedꢀintoꢀthreeꢀpeaksꢀindicatingꢀ
threeꢀtypesꢀofꢀN-bondingꢀinꢀtheꢀg-C .ꢀTheꢀthreeꢀpeaksꢀofꢀNꢀ1sꢀatꢀ
98.4,ꢀ399.5ꢀandꢀ400.8ꢀeVꢀwereꢀattributedꢀtoꢀsp ꢀNꢀatomsꢀinꢀtriazineꢀ
rings,ꢀtertiaryꢀnitrogenꢀ(N-(C)3)ꢀandꢀterminalꢀaminoꢀfunctionsꢀ(C-N-
1
3 4
N
2
3
24
H), ꢀ respectively.ꢀ Theseꢀ resultsꢀ ofꢀ XPSꢀ examinationsꢀ showedꢀ thatꢀ
thereꢀwasꢀnoꢀobviousꢀchangeꢀforꢀtheꢀchemicalꢀstatesꢀofꢀbothꢀcarbonꢀ
andꢀ nitrogenꢀ inꢀ bothꢀ bulkꢀ g-C
nanosheetsꢀobtainedꢀinꢀGVLꢀ(Figs.ꢀ3b,ꢀ3c,ꢀandꢀS7).ꢀ
Theꢀchemicalꢀstructureꢀofꢀtheꢀfew-layerꢀg-C
furtherꢀ studiedꢀ byꢀ FT-IRꢀ spectraꢀ (Fig.ꢀ 3e).ꢀ Theꢀ broadꢀ peaksꢀ fromꢀ
3 4 3 4
N ꢀ andꢀ theꢀ few-layerꢀ g-C N ꢀ
3 4
Fig.ꢀ1.ꢀSchematicꢀillustrationꢀofꢀGVL-exfoliationꢀprocessꢀfromꢀtheꢀbulkꢀg-C N ꢀtoꢀg-
3 4
N ꢀnanosheetsꢀwasꢀ
C
3
N
4
ꢀnanosheets.ꢀ
-1
ꢀ
3
000ꢀtoꢀ3600ꢀcm ꢀwereꢀresultedꢀfromꢀtheꢀN-Hꢀstretches,ꢀsuggestingꢀ
2
3,24
3 4
Theꢀmorphologyꢀofꢀobtainedꢀfew-layerꢀg-C N ꢀnanosheetsꢀwasꢀ
theꢀexistenceꢀofꢀdanglingꢀhydrogensꢀinꢀtheꢀg-C
3
N
4
ꢀlayers,
ꢀwhichꢀ
determinedꢀ byꢀ transmissionꢀ electronꢀ microscopyꢀ (TEM)ꢀ andꢀ highꢀ
3 4
resolutionꢀ TEMꢀ (HR-TEM).ꢀ Asꢀ shownꢀ inꢀ Fig.ꢀ 2a,ꢀ few-layerꢀ g-C N ꢀ
couldꢀ formꢀ hydrogenꢀ bondꢀ withꢀ GVL,ꢀ andꢀ thusꢀ causingꢀ theꢀ
exfoliationꢀofꢀtheꢀbulkꢀg-C ꢀasꢀdiscussedꢀabove.ꢀTheꢀpeakꢀatꢀ807ꢀ
3 4
N
-
1
23
nanosheetsꢀ wereꢀ indeedꢀ generatedꢀ throughꢀ GVL-exfoliationꢀ
cm ꢀ wasꢀ theꢀ characteristicꢀ breathingꢀ modeꢀ forꢀ s-triazineꢀ ring. ꢀ
OtherꢀpeaksꢀinꢀFT-IRꢀspectraꢀwereꢀdueꢀtoꢀtheꢀstretchingꢀvibrationꢀofꢀ
process,ꢀwhichꢀillustratedꢀanꢀobviousꢀcomparisonꢀwithꢀtheꢀbulkꢀg-
2
5
C
C
3
N
N
4
4
ꢀ (Fig.ꢀ S6).ꢀ HR-TEMꢀ imagesꢀ (Fig.ꢀ 2b)ꢀ showedꢀ theꢀ exfoliatedꢀ g-
3 4
ꢀwasꢀveryꢀthinꢀandꢀtransparent,ꢀindicatingꢀtheꢀobtainedꢀg-C N ꢀ
C=NꢀandꢀC-Nꢀheterocycles. ꢀMeanwhile,ꢀtheꢀspectraꢀforꢀfew-layerꢀg-
ꢀnanosheetsꢀwereꢀsimilarꢀwithꢀthatꢀforꢀbulkꢀg-C ,ꢀindicatingꢀ
3
C
N
3 4
N
3
4
2
ꢀ|ꢀJ.ꢀName.,ꢀ2012,ꢀ00,ꢀ1-3ꢀ
Thisꢀjournalꢀisꢀ©ꢀTheꢀRoyalꢀSocietyꢀofꢀChemistryꢀ20xxꢀ

Page 3 of 5
Green Chemistry
JournalꢀNameꢀ
theꢀ chemicalꢀ structureꢀ wasꢀ unchangedꢀ afterꢀ exfoliationꢀ inꢀ GVL,ꢀ showedꢀ thatꢀ theꢀ reactionꢀ overꢀ few-layerꢀ g-C
ꢀCOMMUNICATIONꢀ
ꢀ nanosheetsꢀ couldꢀ
3 4
N
View Article Online
o
DOI: 10.1039/C7GC02583A
whichꢀwasꢀconsistentꢀwithꢀtheꢀresultsꢀobtainedꢀinꢀXPSꢀexaminations.ꢀ beꢀcompletedꢀinꢀ5ꢀhꢀatꢀ120ꢀ C,ꢀshowingꢀaꢀhigherꢀrateꢀthanꢀthatꢀoverꢀ
Meanwhile,ꢀUV-visꢀdiffuseꢀreflectanceꢀspectroscopyꢀ(Fig.ꢀ3f)ꢀshowedꢀ theꢀ bulkꢀ one,ꢀ whichꢀ neededꢀ aboutꢀ 8ꢀ hꢀ toꢀ fulfillꢀ theꢀ reaction.ꢀ
theꢀabsorptionꢀspectrumꢀofꢀfew-layerꢀg-C
slightꢀblueꢀshiftꢀinꢀcomparisonꢀwithꢀtheꢀbulkꢀg-C
gapꢀ ofꢀ bulkꢀ g-C ꢀ ofꢀ ∼2.64ꢀ eVꢀ increasedꢀ toꢀ 2.78ꢀ eVꢀ forꢀ theꢀ theꢀexfoliationꢀeffectꢀofꢀmethanolꢀinꢀtheꢀinitialꢀ3ꢀh.ꢀThisꢀinterestingꢀ
obtainedꢀ few-layerꢀ g-C ꢀ nanosheets.ꢀ Additionally,ꢀ fromꢀ Ramanꢀ phenomenonꢀtoꢀsomeꢀextentꢀprovedꢀtheꢀhigherꢀactivityꢀofꢀfew-layerꢀ
spectra,ꢀ theꢀ exfoliatedꢀ g-C ꢀ nanosheetsꢀ showedꢀ nearlyꢀ identicalꢀ g-C ꢀ nanosheets.ꢀ Weꢀ alsoꢀ conductedꢀ alcoholysisꢀ ofꢀ otherꢀ
Ramanꢀ shiftsꢀ ofꢀ bulkꢀ g-C ꢀ (Fig.ꢀ S8a),ꢀ indicatingꢀ theꢀ obtainedꢀ g- epoxidesꢀwithꢀdifferentꢀalcoholsꢀ(Tableꢀ1,ꢀentriesꢀ2-7)ꢀoverꢀfew-layerꢀ
ꢀnanosheetsꢀretainedꢀtheꢀsameꢀcrystalꢀstructureꢀofꢀbulkꢀg-C .ꢀ g-C ꢀ nanosheetsꢀ andꢀ theꢀ bulkꢀ one,ꢀ andꢀ allꢀ theꢀ experimentsꢀ
However,ꢀtheꢀexfoliatedꢀg-C ꢀnanosheetsꢀshowedꢀaꢀblueꢀshiftꢀofꢀ providedꢀ theꢀ sameꢀ tendencyꢀ thatꢀ few-layerꢀ g-C ꢀ nanosheetsꢀ
aboutꢀ 1.7ꢀ cm ꢀ (Fig.ꢀ S8b),ꢀ ascribingꢀ toꢀ theꢀ phononꢀ confinementꢀ possessedꢀhigherꢀactivityꢀthanꢀtheꢀbulkꢀone.ꢀAdditionally,ꢀtheꢀfew-
effectꢀofꢀtheꢀas-exfoliatedꢀ nanosheetsꢀandꢀinferringꢀtheirꢀultrathinꢀ layerꢀ g-C ꢀ nanosheetsꢀ couldꢀ beꢀ reusedꢀ atꢀ leastꢀ fourꢀ timesꢀ forꢀ
alcoholysisꢀ ofꢀ glycidylꢀ phenylꢀ etherꢀ (Fig.ꢀ S10)ꢀ withoutꢀ obviousꢀ
aggregationsꢀ ofꢀ theꢀ C ꢀ layersꢀ (Fig.ꢀ S11)ꢀ dueꢀ toꢀ theꢀ exfoliationꢀ
effectꢀ ofꢀ theꢀ usedꢀ alcoholꢀ toꢀ someꢀ extent. ꢀ Furthermore,ꢀ
3
N
4
ꢀnanosheetsꢀdisplayedꢀaꢀ Meanwhile,ꢀweꢀobservedꢀthatꢀtheꢀreactionꢀrateꢀoverꢀtheꢀbulkꢀg-C
3 4
N ꢀ
3 4
N ,ꢀandꢀtheꢀbandꢀ inꢀ3ꢀhꢀwasꢀlowerꢀthanꢀthatꢀfromꢀ3ꢀhꢀtoꢀ8ꢀh,ꢀwhichꢀmayꢀbeꢀcausedꢀbyꢀ
3 4
N
3 4
N
3
N
4
3 4
N
3 4
N
C
3
N
4
3
N
4
3 4
N
3
N
4
3 4
N
-1
3 4
N
2
4
thickness. ꢀ
ꢀ
3 4
N
23
cycloadditionꢀofꢀepoxidesꢀwithꢀCO
2
,ꢀanꢀimportantꢀreactionꢀforꢀCO
2
4
4
ꢀ
ꢀ
ꢀ
36-38
transformation,
ꢀwasꢀalsoꢀexaminedꢀoverꢀbothꢀfew-layerꢀg-C
3
3
N
N
nanosheetsꢀandꢀtheꢀbulkꢀone.ꢀAsꢀshownꢀinꢀTableꢀ2,ꢀfew-layerꢀg-C
nanosheetsꢀ stillꢀ showedꢀ aꢀ higherꢀ activityꢀ thanꢀ theꢀ bulkꢀ oneꢀ forꢀ
o
cycloadditionꢀofꢀallꢀtheꢀexaminedꢀepoxidesꢀandꢀCO
CO ꢀpressureꢀofꢀ3ꢀMPa.ꢀInꢀaddition,ꢀtheꢀfew-layerꢀg-C
couldꢀalsoꢀbeꢀreusedꢀatꢀleastꢀfourꢀtimesꢀforꢀcycloadditionꢀofꢀglycidylꢀ
3 4
phenylꢀ etherꢀ withꢀ CO ꢀ (Tableꢀ S1)ꢀ withoutꢀ obviousꢀ g-C N ꢀ
2
ꢀatꢀ120ꢀ Cꢀwithꢀaꢀ
2
3 4
N ꢀnanosheetsꢀ
2
nanosheetsꢀaggregationsꢀ(Fig.ꢀS12)ꢀdueꢀtoꢀtheꢀexfoliationꢀeffectꢀofꢀ
theꢀin-situꢀformedꢀcyclicꢀcarbonates.ꢀTheseꢀaboveꢀresultsꢀprovedꢀtheꢀ
3 4
superiorityꢀ ofꢀ theꢀ exfoliatedꢀ few-layerꢀ g-C N ꢀ nanosheetsꢀ asꢀ
efficientꢀcatalystsꢀcomparedꢀwithꢀtheꢀbulkꢀone.ꢀ
ꢀ
Fig.ꢀ 3.ꢀ XRDꢀ patternꢀ (a),ꢀ XPSꢀ surveyꢀ spectraꢀ (b),ꢀ high-resolutionꢀ Nꢀ 1sꢀ XPSꢀ
spectraꢀ(c),ꢀhigh-resolutionꢀ Nꢀ 1sꢀ XPSꢀ spectraꢀ (d)ꢀ FT-IRꢀspectraꢀ(e)ꢀandꢀUV-
3 4 3 4
visibleꢀabsorptionꢀspectraꢀ(f)ꢀforꢀtheꢀg-C N ꢀnanosheetsꢀandꢀtheꢀbulkꢀg-C N .ꢀ
Fig.ꢀ 4.ꢀ Kineticꢀ experimentsꢀ forꢀ alcoholysisꢀ ofꢀ glycidylꢀ phenylꢀ etherꢀ overꢀ g-
ꢀ
C
1
3
N
4
ꢀnanosheetsꢀandꢀbulkꢀg-C
3
N
4
.ꢀReactionꢀconditions:ꢀglycidylꢀphenylꢀether,ꢀ
Generallyꢀ speaking,ꢀ few-layerꢀ g-C
betterꢀ performanceꢀ thanꢀ theꢀ bulkꢀ g-C
catalystꢀ becauseꢀ theꢀ few-layerꢀ g-C
3
N
4
ꢀ nanosheetsꢀ possessꢀ
ꢀ whenꢀ itꢀ isꢀ usedꢀ asꢀ aꢀ
3 4
N ꢀ nanosheetsꢀ haveꢀ higherꢀ
o
ꢀmmol;ꢀmethanol,ꢀ4ꢀg;ꢀcatalyst,ꢀ0.1ꢀg;ꢀreactionꢀtemperature,ꢀ120ꢀ C.ꢀ
3 4
N
ꢀ
Tableꢀ 1.ꢀ Catalyticꢀ activityꢀ ofꢀ g-C
3
N
4
ꢀ nanosheetsꢀ andꢀ bulkꢀ g-C
3
N
4
ꢀ forꢀ
specificꢀ surfaceꢀ areaꢀ andꢀ moreꢀ activeꢀ centersꢀ exposedꢀ comparedꢀ
withꢀ theꢀ bulkꢀ one,ꢀ whichꢀ makesꢀ theꢀ reactantꢀ toꢀ beꢀ moreꢀ easilyꢀ
a
alcoholysisꢀofꢀepoxides. ꢀ
Timeꢀ Yieldꢀ
contactedꢀwithꢀtheꢀcatalyticꢀcenters.ꢀHerein,ꢀweꢀattemptedꢀtoꢀutilizeꢀ Entryꢀ
g-C ꢀmaterialsꢀ(few-layerꢀnanosheetsꢀorꢀtheꢀbulkꢀone)ꢀasꢀefficientꢀ
catalystsꢀinꢀnon-opticalꢀreactionsꢀinꢀorderꢀtoꢀexpandꢀtheꢀapplicationꢀ
fieldꢀofꢀg-C ꢀmaterials.ꢀWeꢀconductedꢀalcoholysisꢀofꢀepoxidesꢀ(aꢀ
newꢀreactionꢀcatalyzedꢀoverꢀg-C ꢀnanosheets)ꢀandꢀcycloadditionꢀ
ofꢀ epoxidesꢀ withꢀ CO ꢀ (Schemeꢀ S1)ꢀ toꢀ examineꢀ theꢀ differenceꢀ ofꢀ
catalyticꢀactivityꢀbetweenꢀtheꢀobtainedꢀfew-layerꢀg-C ꢀnanosheetsꢀ
andꢀ theꢀ bulkꢀ g-C ꢀ (Tableꢀ 1ꢀ andꢀ 2).ꢀ Initially,ꢀ controlꢀ experimentsꢀ
indicatedꢀthatꢀ120ꢀ Cꢀwasꢀaꢀsuitableꢀreactionꢀtemperatureꢀforꢀtheꢀ
alcoholysisꢀ ofꢀ glycidylꢀ phenylꢀ etherꢀ overꢀ few-layerꢀ g-C
Epoxideꢀ
Alcoholꢀ
Productꢀ
b
(
h)ꢀ
(%) ꢀ
98.7ꢀ
3 4
N
OH
O
O
O
OCH3
1
ꢀ
Methanolꢀ
Methanolꢀ
Methanolꢀ
Methanolꢀ
5ꢀ
3 4
N
ꢀ
ꢀ
(89.6)ꢀ
97.9ꢀ
3 4
N
OH
O
OCH3
2
2ꢀ
6ꢀ
5ꢀ
8ꢀ
ꢀ
ꢀ
ꢀ
(82.3)ꢀ
3 4
N
9
9.4ꢀ
(86.5)ꢀ
6.8ꢀ
(82.3)ꢀ
3 4
N
O
Cl
OCH3
3
ꢀ
Cl
o
OH
ꢀ
3 4
N ꢀ
OCH3
9
O
nanosheetsꢀ underꢀ ourꢀ reactionꢀ conditionsꢀ (Fig.ꢀ S9).ꢀ Subsequently,ꢀ
kineticꢀexperimentsꢀforꢀalcoholysisꢀofꢀglycidylꢀphenylꢀetherꢀ(Fig.ꢀ4)ꢀ
4ꢀ
ꢀ
OH
ꢀ
Thisꢀjournalꢀisꢀ©ꢀTheꢀRoyalꢀSocietyꢀofꢀChemistryꢀ20xxꢀ
J.ꢀName.,ꢀ2013,ꢀ00,ꢀ1-3ꢀ|ꢀ3ꢀ

Green Chemistry
Page 4 of 5
COMMUNICATIONꢀ
JournalꢀNameꢀ
9
7.1ꢀ
exposedꢀofꢀtheꢀfew-layerꢀg-C
3
N
4
ꢀnanosheets.ꢀThisꢀworkꢀexpandsꢀtheꢀ
O
OCH3
View Article Online
5
6
7
ꢀ
ꢀ
ꢀ
Methanolꢀ
Ethanolꢀ
6ꢀ
8ꢀ
ꢀ
OH
ꢀ
DOI: 10.1039/C7GC02583A
(
85.6)ꢀ applicationsꢀofꢀfew-layerꢀg-C N ꢀnanosheetsꢀexceptꢀforꢀitsꢀutilizationꢀ
3 4
OH
inꢀphotocatalysisꢀandꢀprovidesꢀaꢀhelpfulꢀexampleꢀthatꢀfew-layerꢀg-
C N ꢀnanosheetsꢀhaveꢀcatalyticꢀactivityꢀthanꢀbulkꢀg-C N .ꢀWeꢀbelieveꢀ
O
O
94.9ꢀ
O
O
O
2 3
OCH CH
3
4
3 4
ꢀ
ꢀ
ꢀ
(79.3)ꢀ
87.7ꢀ
thatꢀ GVLꢀ hasꢀ greatꢀ potentialꢀ toꢀ exfoliateꢀ variousꢀ 2Dꢀ materialsꢀ
OH
1-
O
OCH CH CH
3
2
2
efficientlyꢀforꢀvariousꢀapplications.ꢀ
10ꢀ
Propanolꢀ
ꢀ
(78.3)ꢀ
a
o
Reactionꢀconditions:ꢀepoxide,ꢀ1ꢀmmol;ꢀalcohol,ꢀ4ꢀg;ꢀtemperature,ꢀ120ꢀ C;ꢀg-
b
Conflictsꢀofꢀinterestꢀ
Thereꢀareꢀnoꢀconflictsꢀtoꢀdeclare.ꢀ
C
3
N
4
,ꢀ0.ꢀ1ꢀg.ꢀ TheꢀyieldsꢀwereꢀdeterminedꢀbyꢀGCꢀusingꢀanisoleꢀasꢀtheꢀinternalꢀ
standard.ꢀTheꢀvaluesꢀinꢀparenthesesꢀwereꢀtheꢀreactionsꢀconductedꢀoverꢀbulkꢀ
g-C N .ꢀꢀ
3 4
ꢀ
Tableꢀ 2.ꢀ Catalyticꢀ activityꢀ ofꢀ g-C
3
N
4
ꢀ nanosheetsꢀ andꢀ bulkꢀ g-C
3
N
4
ꢀ forꢀ
Acknowledgementsꢀ
a
cycloadditionꢀofꢀepoxidesꢀwithꢀCO
2
.
ꢀ
ThisꢀworkꢀwasꢀsupportedꢀbyꢀtheꢀFundamentalꢀResearchꢀFundsꢀ
forꢀ theꢀ Centralꢀ Universitiesꢀ (2017ZY40)ꢀ andꢀ theꢀ Nationalꢀ
NaturalꢀScienceꢀFoundationꢀofꢀChinaꢀ(21503016,ꢀ21773307)ꢀforꢀ
financialꢀsupport.ꢀ
Pressureꢀ
Timeꢀ
(h)ꢀ
Yieldꢀ
Entryꢀ
Epoxideꢀ
Productꢀ
b
(
MPa)ꢀ
(%) ꢀ
O
O
O
O
O
O
O
53.6ꢀ
O
O
O
1
2
3
4
ꢀ
ꢀ
ꢀ
ꢀ
0.5ꢀ
4ꢀ
4ꢀ
4ꢀ
4ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
(36.1)ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
O
O
Notesꢀandꢀreferencesꢀ
O
O
82.7ꢀ
O
O
O
O
1ꢀ
2ꢀ
3ꢀ
1
2
.
.
M.ꢀXu,ꢀT.ꢀLiang,ꢀM.ꢀShiꢀandꢀH.ꢀChen,ꢀChem.ꢀRev.,ꢀ2013,ꢀ113,ꢀ3766-3798.ꢀ
C.ꢀCheng,ꢀS.ꢀLi,ꢀA.ꢀThomas,ꢀN.ꢀA.ꢀKotovꢀandꢀR.ꢀHaag,ꢀChem.ꢀRev.,ꢀ2017,ꢀ
(50.2)ꢀ
O
O
1
17,ꢀ1826-1914.ꢀꢀ
O
O
93.2ꢀ
3. Q.ꢀH.ꢀWang,ꢀK.ꢀKalantar-Zadeh,ꢀA.ꢀKis,ꢀJ.ꢀN.ꢀColemanꢀandꢀM.ꢀS.ꢀStrano,ꢀ
(68.4)ꢀ
NatureꢀNanotechnol.,ꢀ2012,ꢀ7,ꢀ699-712.ꢀꢀ
4
5
.
.
M.ꢀChhowalla,ꢀH.ꢀS.ꢀShin,ꢀG.ꢀEda,ꢀL.-J.ꢀLi,ꢀK.ꢀP.ꢀLohꢀandꢀH.ꢀZhang,ꢀNatureꢀ
Chem.,ꢀ2013,ꢀ5,ꢀ263-275.ꢀꢀ
L.ꢀLi,ꢀY.ꢀYu,ꢀG.ꢀJ.ꢀYe,ꢀQ.ꢀGe,ꢀX.ꢀOu,ꢀH.ꢀWu,ꢀD.ꢀFeng,ꢀX.ꢀH.ꢀChenꢀandꢀY.ꢀZhang,ꢀ
NatureꢀNanotechnol.,ꢀ2014,ꢀ9,ꢀ372-377.ꢀꢀ
O
O
O
O
99.2ꢀ
(73.3)ꢀ
O
O
6. J.ꢀZhu,ꢀP.ꢀXiao,ꢀH.ꢀLiꢀandꢀS.ꢀA.ꢀC.ꢀCarabineiro,ꢀACSꢀAppl.ꢀMater.ꢀInterfaces,ꢀ
2014,ꢀ6,ꢀ16449-16465.ꢀꢀ
O
O
88.3ꢀ
c
5
ꢀ
3ꢀ
3ꢀ
3ꢀ
3ꢀ
4ꢀ
4ꢀ
(59.1)ꢀ
7
8
.
.
Z.ꢀZhao,ꢀY.ꢀSunꢀandꢀF.ꢀDong,ꢀNanoscale,ꢀ2015,ꢀ7,ꢀ15-37.ꢀꢀ
Y.ꢀGong,ꢀM.ꢀLi,ꢀH.ꢀLiꢀandꢀY.ꢀWang,ꢀGreenꢀChem.,ꢀ2015,ꢀ17,ꢀ715-736.ꢀꢀ
O
O
98.9ꢀ
9. Q.ꢀ Han,ꢀ B.ꢀ Wang,ꢀ J.ꢀ Gaoꢀ andꢀ L.ꢀ Qu,ꢀ Angew.ꢀ Chem.ꢀ Int.ꢀ Ed.,ꢀ 2016,ꢀ 55,ꢀ
O
6
7
8
ꢀ
ꢀ
ꢀ
Cl
ꢀ
ꢀ
Cl
O
10849-10853.ꢀꢀ
ꢀ
(81.9)ꢀ
1
0. W.-J.ꢀOng,ꢀL.-L.ꢀTan,ꢀY.ꢀH.ꢀNg,ꢀS.-T.ꢀyongꢀandꢀS.-P.ꢀChai,ꢀChem.ꢀRev.,ꢀ2016,ꢀ
116,ꢀ7159-7329.ꢀ
O
O
96.3ꢀ
O
O
8ꢀ
11. M.ꢀBaarꢀandꢀS.ꢀBlechert,ꢀChem.ꢀEur.ꢀJ.,ꢀ2015,ꢀ21,ꢀ526-530.ꢀ
2. W.ꢀZhang,ꢀA.ꢀBariotaki,ꢀI.ꢀSmonouꢀandꢀF.ꢀHollmann,ꢀGreenꢀChem.,ꢀ2017,ꢀ
9,ꢀ2096-2100.ꢀ
(77.6)ꢀ
1
ꢀ
1
O
97.2ꢀ
O
13. Y.ꢀWang,ꢀX.ꢀWangꢀandꢀM.ꢀAntonietti,ꢀAngew.ꢀChem.ꢀInt.ꢀEd.,ꢀ2012,ꢀ51,ꢀ
O
20ꢀ
ꢀ
O
ꢀ
(87.4)ꢀ
68-89.ꢀ
a
14. J.ꢀN.ꢀColeman,ꢀM.ꢀLotya,ꢀA.ꢀO’Neill,ꢀS.ꢀD.ꢀBerginꢀandꢀP.ꢀJ.ꢀKing,ꢀScience,ꢀ
2011,ꢀ331,ꢀ568-571.ꢀ
3 4 2
Reactionꢀ conditions:ꢀ epoxide,ꢀ 10ꢀ mmol;ꢀ g-C N ,ꢀ 50ꢀ mg;ꢀ CO ,ꢀ 3ꢀ MPa;ꢀ
o
b
temperature,ꢀ120ꢀ C.ꢀ TheꢀyieldsꢀwereꢀdeterminedꢀbyꢀGCꢀusingꢀn-butanolꢀasꢀ
theꢀ internalꢀ standard.ꢀ Theꢀ valuesꢀ inꢀ parenthesesꢀ wereꢀ theꢀ reactionsꢀ
1
1
1
1
1
5. W.ꢀZhao,ꢀX.ꢀTan,ꢀJ.ꢀJiang,ꢀF.ꢀLiuꢀandꢀT.ꢀMu,ꢀChem.ꢀAnꢀAsianꢀJ.,ꢀ2017,ꢀ12,ꢀ
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6. W.ꢀZhao,ꢀZ.ꢀXue,ꢀJ.ꢀWang,ꢀJ.ꢀJiang,ꢀX.ꢀZhaoꢀandꢀT.ꢀMu,ꢀACSꢀAppl.ꢀMater.ꢀ
Interfaces,ꢀ2015,ꢀ7,ꢀ27608-27612.ꢀ
7. H.ꢀTao,ꢀY.ꢀZhang,ꢀY.ꢀGao,ꢀZ.ꢀSun,ꢀC.ꢀYanꢀandꢀJ.ꢀTexter,ꢀPhys.ꢀChem.ꢀChem.ꢀ
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8. J.ꢀ Xu,ꢀ L.ꢀ Zhang,ꢀ R.ꢀ Shiꢀ andꢀ Y.ꢀ Zhu,ꢀ J.ꢀ Mater.ꢀ Chem.ꢀ A,ꢀ 2013,ꢀ 1,ꢀ 14766-
c
o
3 4
conductedꢀoverꢀbulkꢀg-C N .ꢀ Theꢀreactionꢀwasꢀconductedꢀatꢀ110ꢀ C.ꢀꢀ
Conclusionsꢀ
Inꢀsummary,ꢀbiomass-derivedꢀGVLꢀhadꢀbeenꢀsuccessfullyꢀusedꢀasꢀanꢀ
efficientꢀ solventꢀ toꢀ exfoliateꢀ bulkꢀ g-C ꢀ toꢀ generateꢀ few-layerꢀ g-
ꢀ nanosheets.ꢀ Aꢀ stableꢀ dispersionꢀ ofꢀ few-layerꢀ g-C
1
4772.ꢀ
3 4
N
9. L.ꢀMa,ꢀH.ꢀFan,ꢀM.ꢀLi,ꢀH.ꢀTian,ꢀJ.ꢀFangꢀandꢀG.ꢀDong,ꢀJ.ꢀMater.ꢀChem.ꢀA,ꢀ
2015,ꢀ3,ꢀ22404-22412.ꢀ
C
3
N
4
3 4
N ꢀ
-1
nanosheetsꢀwithꢀaꢀhighꢀconcentrationꢀofꢀupꢀtoꢀ0.8ꢀmgꢀmL ꢀcouldꢀbeꢀ 20. T.ꢀN.ꢀYan,ꢀE.ꢀH.ꢀLiu,ꢀZ.ꢀY.ꢀChuꢀandꢀX.ꢀD.ꢀLi,ꢀJ.ꢀNanoꢀRes.,ꢀ2017,ꢀ45,ꢀ49-54.ꢀ
2
1. K.ꢀZhu,ꢀW.ꢀWang,ꢀA.ꢀMeng,ꢀM.ꢀZhao,ꢀJ.ꢀWang,ꢀM.ꢀZhao,ꢀD.ꢀZhang,ꢀY.ꢀJia,ꢀC.ꢀ
obtainedꢀdueꢀtoꢀtheꢀpolarityꢀandꢀtheꢀappropriateꢀsurfaceꢀenergyꢀofꢀ
GVL,ꢀandꢀnoꢀobviousꢀprecipitationꢀorꢀaggregationꢀwasꢀfoundꢀafterꢀ
storedꢀ forꢀ twelveꢀ monthsꢀ atꢀ ambientꢀ temperature.ꢀ Moreꢀ
XuꢀandꢀZ.ꢀLi,ꢀRSCꢀAdv.,ꢀ2015,ꢀ5,ꢀ56239-56243.ꢀ
2
2. P.ꢀQiu,ꢀH.ꢀChen,ꢀC.ꢀXu,ꢀN.ꢀZhou,ꢀF.ꢀJiang,ꢀX.ꢀWangꢀandꢀY.ꢀFu,ꢀJ.ꢀMater.ꢀ
Chem.ꢀA,ꢀ2015,ꢀ3,ꢀ24237-24244.ꢀ
importantly,ꢀ theꢀ formedꢀ few-layerꢀ g-C
enhancedꢀ activityꢀ forꢀ alcoholysisꢀ ofꢀ epoxidesꢀ andꢀ cycloadditionꢀ ofꢀ
epoxidesꢀ withꢀ CO ꢀ comparedꢀ withꢀ theꢀ bulkꢀ g-C ,ꢀ whichꢀ wasꢀ
causedꢀbyꢀtheꢀhigherꢀspecificꢀsurfaceꢀareaꢀandꢀmoreꢀactiveꢀcentersꢀ
3 4
N ꢀ nanosheetsꢀ showedꢀ 23. S.ꢀYang,ꢀY.ꢀGong,ꢀJ.ꢀZhang,ꢀL.ꢀZhan,ꢀL.ꢀMa,ꢀZ.ꢀFang,ꢀR.ꢀVajtai,ꢀX.ꢀWangꢀandꢀ
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3 4
N
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5. X.ꢀShe,ꢀH.ꢀXu,ꢀY.ꢀXu,ꢀJ.ꢀYan,ꢀJ.ꢀXia,ꢀL.ꢀXu,ꢀY.ꢀSong,ꢀY.ꢀJiang,ꢀQ.ꢀZhangꢀandꢀH.ꢀ
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