Mechanistic Insight into the Hydrodeoxygenation of Hydroquinone over Au a ‑ TiO 2 Catalyst Published as part of The Journal of Physic

《Mechanistic Insight into the Hydrodeoxygenation of Hydroquinone over Au a ‑ TiO 2 Catalyst Published as part of The Journal of Physic》由会员上传分享，免费在线阅读，更多相关内容在学术论文-天天文库。

pubs.acs.org/JPCCArticleMechanisticInsightintotheHydrodeoxygenationofHydroquinoneoverAu/a‑TiO2CatalystPublishedaspartofTheJournalofPhysicalChemistryvirtualspecialissue“EnergyandCatalysisinChina”.,##XiaowaNie,*WenjiaWan,ZeshiZhang,YonggangChen,MichaelJ.Janik,ChunshanSong,*andXinwenGuo*CiteThis:J.Phys.Chem.C2021,125,6660−6672ReadOnlineACCESSMetrics&MoreArticleRecommendations*sıSupportingInformationABSTRACT:Themechanismandkineticfeaturesofhydro-deoxygenationofhydroquinoneovertheoxygen-defectiveanatase(a-TiO2)supportedgold(Au)catalystwerestudiedbydensityfunctionaltheorycalculations.TheinvestigationofreactionpathwaysandenergeticsidentifiedthattheconversionofhydroquinoneoverAu10/a-TiO2(001)wentthroughseveralkeyreactionintermediatesincludingbenzoquinone,1,4-cyclohexane-diol,andcyclohexanol.ThedehydrogenationofhydroquinonetobenzoquinoneintermediateoccurredviaH-transferonboththeTiO2surfaceandAucluster.SubsequenthydrogenationoftheCCbondsofbenzoquinonemainlyoccursfromH*−Ausites,whichhasrelativelylowbarriers,indicatingthefacileformationofring-saturatedspecies.The“1,4-cyclohexanediol”pathwaydominatestheoverallreactioninhydroquinoneconversionwithfavorablekineticfeatureduetolowbarriers,leadingtoalargeamountofcyclohexaneintheproduct.Thepresenceofoxygenvacanciesonthea-TiO2(001)surfaceiscriticallyimportantasactivesitestofacilitatethecleavageofC−Obondofintermediatespecies.TheinterfaceofAu−TiO2alsoplaysanimportantroleinstabilizingreactionintermediatesandpromotingtheHtransferbetweenAuclusterandtheadsorbedspeciesontheTiO2surface.1.INTRODUCTIONhydrogenconsumption,andthereductionoftheatomeconomy.Therefore,itisimperativetodevelopefficientcatalystsforTheenvironmentalproblemscausedbytheextensiveselectiveHDOofbiomassanditsderivativestohydrocarbonproductionandconsumptionoffossilenergycreatedanproducts.increasinglyurgentneedtodevelopcleanandrenewableenergyDownloadedviaUNIVOFCONNECTICUTonMay15,2021at21:02:22(UTC).1Asnaturalmacromolecules,ligninshaveverycomplexsystems.Unlikecoal,oil,naturalgas,andotherfossilresources,structures,whicharemainlycomposedofthreemonomericwind,solar,andbiomassenergycanprovidesustainableenergyunitsofphenolicstructuresincludingp-hydroxyphenylpropaneSeehttps://pubs.acs.org/sharingguidelinesforoptionsonhowtolegitimatelysharepublishedarticles.forhumansocieties;hence,theexploitationofrenewableenergy(p-coumarylalcohol),guaiacylpropane(coniferylalcohol),andisanimportantwaytoaddresstheenergycrisisandsyringylpropane(sinapylalcohol).Becauseofthediversityofenvironmentalproblems.Biomasshasgreatpotentialforfurtherligninstructure,thecatalyticHDOstudiesmainlyfocusondevelopmentduetoitsabundantresource,itsabilitytobeligninmodelcompoundssuchasphenol,alkylphenol,hydroxyconvertedintohydrocarbonssimilartopetroleumproducts,and7−122phenol,andmethoxyphenol.Fordifferentphenolicitsrenewablenature.Biomass(includingcellulose,hemi-substances,theHDOmechanismisdifferentduetovariationcellulose,lignin,andfats)mainlycontainsC,H,andOelements,offunctionalgroups,andthereactionpathwaysarealsobutithasthedisadvantageofhighoxygencontentandlowimpactedbyreactionconditionsandtypesofcatalystsused.calorificvalue.Inordertorealizeeffectiveutilization,itisTheHDOmechanismofphenolicsubstancesgenerallyinvolvesnecessarytoreducetheoxygencontentinbiomassderivativesasmuchaspossible.Oneoftheeffectivemethodsiscatalytichydrodeoxygenation(HDO)3−6i.e.,removingoxygenbytheReceived:January15,2021hydrogenolysisofcarbon−oxygenbonds(COorC−O)inRevised:March2,2021biomass.TheHDOnetworkofbiomassderivativesiscomplex,Published:March22,2021andmultiplehydrogenationreactionscanoccurconcurrentlyduringthehydrogenolysisofcarbon−oxygenbonds,leadingtothedecreaseoftargetproductselectivity,theincreaseof©2021AmericanChemicalSocietyhttps://doi.org/10.1021/acs.jpcc.1c003916660J.Phys.Chem.C2021,125,6660−6672

1TheJournalofPhysicalChemistryCpubs.acs.org/JPCCArticle13−15threepaths,including(1)directdeoxygenation(DDO),(Au/a-TiO2)catalystwasusedfortheHDOofhydroquinone,wheretheCAr-Obondiscleavedviahydrogenolysiswithoutaromaticringsaturationoccurredextensively,resultinginalarge57aromaticringsaturation;(2)hydrogenationfollowedbyamountofcyclohexaneintheproduct.Incomparisontodeoxygenation(hydrogenation−deoxygenation,HYD),where,hydroquinone,resorcinoldidnotreactatallontheAu/a-TiO2incontrasttotheDDOpath,hydrogenationofthearomaticringcatalystwhilephenolwasthemajorproductfromtheHDOof57occursbeforeCAr−Obondcleavage;and(3)ketoneformationcatechol.ItappearsthatintheHDOofhydroquinone,theAufromisomerizationfollowedbyhydrogenationanddeoxygena-andTiO2componentsplaymultiplerolesinpromotingdifferenttion(tautomerization-HYD).Amongthesepathways,mostelementaryreactionswiththeformationofdifferentinter-57studiesindicatethatDDOandHYDarethemainreactionpathsmediatesunderthesameconditions.Theseexperimental16,17studiesindicatethatthemolecularstructureandthefunctionalfortheconversionofphenoliccompounds,whichdetermine57theselectivityofaromaticproducts(e.g.,benzene,toluene,andgroupimpacttheHDOreactivityofphenoliccompounds.xylene)relativetoringhydrogenationproducts(e.g.,cyclo-Moreimportantly,thecatalyticsitesonAu/a-TiO2shouldbehexanol,cyclohexane,andalkylcycloalkanes,etc.).differentfortheelementarystepsofdehydrogenation,hydro-ThecatalystsusedinHDOincludeconventionalhydro-genation,deoxygenationanddehydrationincludedinHDO.Indesulfurization(HDS)catalysts(e.g.,CoMoandNiMoordertoclarifytheseunsolvedquestions,densityfunctional3,6,18theory(DFT)calculationswereperformedtoidentifytheactivesulfides),hydrogenationcatalysts(e.g.,Ptseriesprecious6,12,19−2627−2930−33sitesoftheAu/a-TiOcatalystandtodeterminethemetalsandNi-based),zeolites,metaloxides,234,35energeticallyfavorablepathwaysofhydroquinoneHDOandmetalphosphates,etc.Theoperatingconditionsvarywiththetypesofcatalysts.Intheearlystage,conventionalHDSinvolvingmultiplesiteswithdifferentfunctionsontheAu/a-catalysts,suchassulfidedCoMo/Al2O3orNiMo/Al2O3,wereTiO2catalyst.Inaddition,thekineticfeatureofhydroquinoneusedforHDO.However,duetothecompetitiveadsorptionHDOwasrevealedbasedontheexaminedreactionpathwaysbetweensulfur-andoxygen-containingcompounds,theandcalculatedenergybarriers,providingrationalexplanationofpresenceofsulfurcompoundshasanegativeeffectonthetheexperimentalresultsandinsightforfuturecatalystdesign.36deoxygenationreactionrate.ThesecatalystsuseanAl2O3support,whichispronetocarbondepositionandunstableinthe2.METHODS3,37presenceoflargeamountsofwater.AnotherdisadvantageofInthiswork,theViennaabinitiosimulationpackage(VASP)thesetraditionalcatalystsisthattheyshowlowactivityforthewasusedtoperformallthecalculationswithintheframeworkofactivationofH2,whichaffectstheHDOperformanceatlowDFT.58,59Theprojectoraugmentedwave(PAW)potentials60temperatures.Preciousmetalcatalystshavestrongerhydro-wereappliedtodescribetheelectron−ioninteractionswhilethegenolysisandhydrogenationactivitythanCoMoandNiMoexchangeandcorrelationenergieswerecomputedbythespin-sulfidecatalysts,andtheycanrealizetheHDOofphenolicpolarizedgeneralizedgradientapproximation(GGA)approachcompoundsundermildconditions.Inaddition,usingSiO,38602withthePerdew−Burke−Ernzerhof(PBE)functional.A1239,40ZrO2,orTiO2assupportcanimprovethestabilityandlifecutoffenergyoftheplanewaveexpansionof400eVwassetofthecatalyst.Nonetheless,theactivationanddissociationofH2throughoutthiswork.Toallowacertaindegreeofgeometricoccureasilyonpreciousmetals,leadingtoaromaticringrelaxation,theconvergencecriterionfortheforceonallatomshydrogenationandsaturationaswellasC−Cbondhydro-wassetto0.03eV/Å.ThetraditionalPBEmethodoftengenolysistoformgasphaseproducts,whichisdetrimentaltotheunderestimatestheelectronicbandgapofTiO2andtendstoefficientuseofH2andtheatomeconomyofcarbon.Atthesameexcessivelydelocalizetheelectrondensities.61,62Thus,inthistime,theselectivitytoaromaticproductsislimited.Thehighwork,thePBE+Uapproach(theHubbardparameterwassettocostanddifficultregenerationofcatalystsalsolimittheU−J=3)wasappliedforTitoreducethecomputationalerrorsindustrialapplicationofpreciousmetalscatalysts.Nonpreciousandensuregooddescriptionsofstructuralandelectronicmetalswithrelativelylowprices,suchasFe,belongtooxyphilic63,64propertiesofTiO2.Theoptimizedlatticeparametersofbulkmetals.Althoughtheircatalyticactivityisnotashighaspreciousa-TiO2werecalculatedtobea=b=3.88Åandc=9.67Å,inmetals,theyshowuniqueselectivitytoC−Obondactivation65Argoodagreementwiththeexperimentaldetermination,41−46andcleavage,infavorofformingaromaticproducts.Inindicatingthatthemethodusedinthisworkissuitableforthe3447,48recentyears,phosphate,carbide,nitrideandotherTiO2-involvedsystems.TheclimbingimagenudgedelasticbandnonpreciousmetalcatalystswithsimilarpropertiestoPthave66(CI-NEB)methodwasusedtosearchthetransitionstatealsobeenwidelyexploredintheHDOofphenoliccompounds.associatedwitheachelementarystep,basedonwhichtheInordertoimprovetheselectivityoftargetproductsandtheminimumenergypathways(MEPs)forHDOreactionswerestabilityandeconomyofcatalysts,itisveryimportanttomappedout.AllobtainedtransitionstateswereconfirmedtooptimizethedesignofnewcatalystsfortheHDOreaction.haveasingleimaginaryvibrationalfrequencyalongthereactionTherehavebeenanincreasingnumberofstudiesonthecoordinate.BaderchargecalculationwasperformedtoanalyzeapplicationofAucatalysts,especiallytheselectivereactionsof67thechargepropertiesoftheAu/TiO2systems.smallmolecules,suchasCO,H2O,H2,andO2.ThesupportedInthepreviouswork,wehaveexaminedanataseTiO2(101)AucatalystshavebeenexaminedforvariousreactionsduetoandTiO2(001)facetsintheprocessesofadsorption,49−51theiruniqueselectivity,suchasCOoxidation,C−Hbonddissociation,andspilloverofhydrogenandfoundthatthea-5253−55oxidation,andselectivehydrogenation,etc.TherecentTiO2(001)surfacehasahighercatalyticactivityduetotheexperimentalworkfromourgroupshowedthatAu/anatase−specificlatticestructureanduniquearrangementoftitaniumand315668TiO2andAg/anatase−TiO2catalystsareremarkablyactiveoxygenatomsinthisfacet.ThecomputationalresultsshowandselectivetowardguaiacolhydrodeoxygenationtophenolicthattheadsorptionoflargeAuclustersona-TiO2(001)isproducts.Thearomaticringcanbepreservedwithoutfurtherstrongerthanthatonthea-TiO2(101)surface.Also,asthehydrogenationunderreactionconditionsof300°CandH2numbersofoxygenvacanciesincrease,theenergybarrierofpressureof6.5MPa.Bycontrast,whentheAu/anatase−TiO2hydrogendissociationonthedefectivea-TiO2(001)surface6661https://doi.org/10.1021/acs.jpcc.1c00391J.Phys.Chem.C2021,125,6660−6672

2TheJournalofPhysicalChemistryCpubs.acs.org/JPCCArticleFigure1.TopandsideviewsoftheAu10/a-TiO2(001)catalystmodel.TheAuatomsthattakeupO-vacanciesaremarkedbyblackdashedcircles.O-vacanciesusedforaccommodatingthereactantmoleculearemarkedbyreddashedcircles(gray,Ti;red,O;yellow,Au).Figure2.EnergydiagramforformationofbenzoquinonefromhydroquinonedehydrogenationoverAu10/a-TiO2(001).Optimizedstructuresofallstatesinvolvedareshowninthefigure(gray,Ti;red,O;yellow,Au;blue,H;darkgray,C).decreases,indicatingthatthedefective(001)facethassuperiorclusterinthreeatomiclayersonthedefectivea-TiO2(001)68catalyticactivity.Asreportedintheliterature,theoxygen-surface.Atthesametime,theAu10clusterdoesnotundergodefectiveanataseTiO2(001)surfacehasalsobeendemonstratedlargestructuraldeformationinthisconfigurationcomparingtotobeagoodcatalystforothertypesofreactionssuchasN2Othatingasphase,whichpossessesastableadsorptionenergy.dissociation,methanolconversion,andCO2photocatalyticSubsequentcalculationsalsoconfirmedthatthisadsorbedAu1069−71reduction.Therefore,inthiswork,weselectedtheAu10/a-clustercanmaintainastableconfigurationduringtheHDOTiO2(001)surfaceasthecatalystmodelfora-TiO2-supportedreaction.Thesizeofthisp(4×4)supercellwasdeterminedtoAutostudythemechanismofhydroquinoneHDO,onwhichbe15.53×15.53×17.67Å,containing150atomsandfourTiO2fouroxygenvacancieswerecreatedonthea-TiO2(001)surfacelayers(thebottomtwolayerswerefixedinstructuraltofacilitatetheadsorptionofAu10cluster(illustratedinFigureoptimization).Duetotherelativelylargedimensionofthe1).ThecreationoffourO-vacanciescouldwellstabilizetheAu10supercell,aΓ-pointmeshwasappliedforallcalculations.A12Å6662https://doi.org/10.1021/acs.jpcc.1c00391J.Phys.Chem.C2021,125,6660−6672

3TheJournalofPhysicalChemistryCpubs.acs.org/JPCCArticleFigure3.EnergyprofileforthehydrogenationoftheCCbondsofbenzoquinoneoverAu10/a-TiO2(001).(Therelativeenergyofeachstateisgiveninthefigurebasedonwhichtheactualbarrierandreactionenergyforeachelementarystepcanbecalculated.)vacuumregionanddipolecorrectionswereincludedtoavoidincliningtowardtheAucluster.Therefore,theinterfaceofAu−interactionsfromrepeatingslabsintheverticalzdirection.TheTiO2playsaroleinhydroquinoneadsorption.Thisadsorptioncombinedtheoreticalcalculationswithexperimentalmeasure-configurationwouldfacilitatethetransferofHbetweenthementsbyXiaoetal.havedemonstratedthatthedeoxygenationreactant/intermediateandtheAucluster.TheadsorptionofaceticacidcatalyzedbythereducibleZnOproceededthroughenergyofhydroquinoneiscalculatedtobe−0.88eV,indicating72avacancy-drivenmechanism.TheDFTresultsofthethatthehydroquinonemoleculeisfavorablyadsorbedontheelectronicstructureofzincoxidesurfaceshowedthattheoxygenvacancysiteofa-TiO2(001).Inaddition,theH-bondingpresenceofoxygenvacanciescanstrengthentheadsorptionofinteractionisformedbetweentheHofphenolichydroxylgroupoxygen-containingcompoundsandpromotethecleavageofandthesurfaceO2cofTiO2upontheadsorptionofCObondviaelectrondensityregulationatthevacancyhydroquinone,whichcanstabilizetheadsorptionofreactant72sites.ToconstructtheAu10/a-TiO2(001)modelinthiswork,andfacilitatetheactivationofO−Hbondinhydroquinone,asasimilarstrategywasused,inwhichtwoadditionaloxygenobservedinFigure2a.Then,theHatomofphenolichydroxylvacancieswerecreatedclosetotheAu10cluster(seeFigure1),groupmovestothesurfaceO2csite,resultingintheformationofwhichnotonlycanstrengthentheadsorptionofhydroquinoneasurface−O2cHspeciestogetherwiththeC6H5O2intermediatemoleculeviaoccupyingthevacancysitewithits−OHgroupbut(Figure2b).ThisHtransferstepis−1.31eVexothermicalsocanreducethesterichindranceduringsurfacespecieswithoutabarrier,sothattheHtransferproceedseasilyonthea-adsorption.TiO2(001)surface,whichisbothkineticallyandthermodynami-callyfavorable.Subsequently,undertheinteractionbetweenthe3.RESULTSANDDISCUSSIONHofphenolichydroxylgroupatthepara-positionandtheAu468,73Asevidencedfromthepreviousstudies,theheterolyticatom(refertoFigure1forAuatomicnumber)ofthecluster,dissociationofH2moleculeattheAu−TiO2interfacehasbeenanotherHtransferstepoccursfromtheC6H5O2speciestothefoundtobeenergeticallymorefavorablethanthehomolyticAucluster,generatingthedehydrogenationproductof68dissociationonpureAusites.Ourpreviousworkhasbenzoquinone(C6H4O2,Figure2c).TheadsorptionenergyofdemonstratedthattheheterolyticdissociationofH2moleculebenzoquinoneiscalculatedtobe−1.94eVatthevacancysite.onlyhasabarrierof0.3eVonthestoichiometricAu/a-AccordingtoNEBcalculations,thisdehydrogenationstepneedsTiO2(001)surfaceand0.2eVontheoxygen-defectiveAu/a-toovercomeanenergybarrierof0.86eV,withthereactionbeingTiO2(001)surface,indicatingafacileformationofactiveH*endothermicby0.74eV(Figure2).TheO−Hinteratomicspeciesonthecatalystsurface.Afterthedissociationofdistanceinthetransitionstate(TS)configurationis1.52Å,andmolecularH2,theprotonicH*isbondedtothesurfaceO2cthebondlengthofH−Au4is1.71Å(Figure2d).AsillustratedinatomofTiO2,whilethehydrideH*isadsorbedontheAusite.theenergydiagraminFigure2,theformationofbenzoquinoneThespilloverofH*fromtheAuclustertothea-TiO2(001)68fromhydroquinonedehydrogenationisthermodynamicallysurfacehasbeenexaminedinourpreviousstudy,andabarrierfavorable,withtheoverallreactionbeingexothermicby0.57of0.55eVisobtainedforH2Oformationinthisprocess,eV.Kinetically,thisconversionisnotdifficult,byovercomingaindicatingfacileH*spilloverontheAu/a-TiO2catalyst.barrierof0.86eVofthesecondHtransfersteptoproduce3.1.FormationofBenzoquinonefromDehydrogen-benzoquinone.ationofHydroquinone.Benzoquinone,whichisproducedbythedehydrogenationofhydroquinone,hasbeendetectedasaTheabovecalculationresultsrevealthatboththeTiO2keyintermediateintheHDOexperimentofhydroquinoneoversurfaceandgoldclusterplayimportantrolesinthedehydrogen-theAu/a-TiOcatalyst.57Therefore,wefirstexaminedationprocessesofhydroquinone,andtheHtransferonthea-2benzoquinoneformationfromthedehydrogenationofhydro-TiO2(001)surfaceismorefacilethanthatonthegoldcluster.quinoneoverAu10/a-TiO2(001).AsillustratedinFigure2a,theTheenergydiagramshowsthatthedehydrogenationofhydroquinonereactantisadsorbedontothea-TiO2(001)hydroquinonetobenzoquinoneisacriticalinitialstepinthesurfaceandoccupiesoneoxygenvacancyviaaphenolicconversionofhydroquinoneoverAu/a-TiO2catalyst,consistent57hydroxylgroup(−OH).Inthemeantime,theother−OHwiththeexperimentalobservationsbyMaoetal.Inaddition,groupatthepara-positionpointstotheAuclusterthroughthetheirexperimentalworkalsoidentifiedthatbenzoquinoneisaH−Auinteraction,leadingthehydroquinonemolecularplanekeyreactionintermediateintheconversionofhydroquinone,6663https://doi.org/10.1021/acs.jpcc.1c00391J.Phys.Chem.C2021,125,6660−6672

4TheJournalofPhysicalChemistryCpubs.acs.org/JPCCArticleFigure4.OptimizedstructuresoftransitionstatesgeneratedinthehydrogenationoftheCCbondsofbenzoquinoneoverAu10/a-TiO2(001)(gray,Ti;red,O;yellow,Au;blue,H;darkgray,C).EachstructurecorrespondstothestructurallabelgiveninFigure3.Figure5.Energyprofileforcyclohexanolformationvia1,4-cyclohexanedioloverAu10/a-TiO2(001).(Therelativeenergyofeachstateisgiveninthefigurebasedonwhichtheactualbarrierandreactionenergyforeachelementarystepcanbecalculated.)becausetheproductdistributionsintheHDOofbenzoquinoneconfigurationiscalculatedtobe1.70Å(Figure4,plotTS1).The57andhydroquinonearesimilar.activationbarrierforthishydrogenationstepis0.72eVwitha3.2.HydrogenationofCCBondsofBenzoquinone.reactionenergyof−0.16eV.TheexperimentalresultsofMaoetal.haveshownthatthe1,4-Then,weexaminetheadditionofthesecondhydrogen(2H)cyclohexanediolistheinitialdominantproductintheoftheC−C(orCC)bondinthebenzoquinonestructure.hydroquinoneHDOoverAu/a-TiO2anditsyieldreachesThehydrogenationofthebenzoquinone+1Hintermediateon5775%whenthereactiontimeis20min.SincethebenzoquinonetheC2(oppositesideto1H)andtheC3position(samesidetohasbeenidentifiedtobethekeyintermediateinhydroquinone1H)arecalculatedandcompared.TheactivationbarrierforH-conversion,itshydrogenationto1,4-cyclohexanediolshouldbeadditionontheC2positionis0.43eVwhilethatontheC3crucialforthereactionpathway.Inthefollowingsection,wefirstpositonis0.63eV,indicatingthatitismorefaciletohydrogenateexaminethehydrogenationofCCbondsofthebenzoqui-fromtheoppositesidewhenthesecondhydrogenatomisaddednoneintermediate.tothecarbon−carbonbond.Moreover,theformedbenzoqui-AsillustratedinFigure3,theC-positionofthetwoCCnone+2Hintermediatefromhydrogenationontheoppositebondsinbenzoquinonestructureisnumberedas1to4tosideoftheC2position(C6H6O2,FigureS1b)isalsoindicatetheH-additionpositionsinDFTcalculations.ThethermodynamicallymorestablethanthatviahydrogenationdissociationofH2couldgenerateactiveH*ontheAuclusteronthesamesideofC3position.TheC2−2Hdistanceintheandthebenzoquinoneintermediateisproducedattheinterfacetransitionstateforformingthebenzoquinone+2HofAu−TiO2,thusthehydrogenationreactionsoccurfromH*−intermediateismeasuredtobe1.76Å,asobservedfromFigureAutotheCCbondofbenzoquinone.First,thehydrogen4,plotTS2.atom(1H)isadsorbedontheAu2atom(refertoFigure1forAuNext,weconsidertheH-additionontheC3positiontoatomicnumber),andtheinteratomicdistancebetween1Handproducethebenzoquinone+3Hintermediate(C6H7O2,FiguretheC1atomofCCbondis3.37Åintheinitialstate.Asthe1HS1c).TheAu2atomisselectedtobetheadsorptionsiteofactivegraduallymovestowardtheC1atom,theC1−1HdistanceH*(3H)becauseitshortensthedistancebetweenC3atombecomesshorterandfinallyformsaC−Hbond(bondlengthofsubjacenttothemolecularringandthe3Hatom,anditisableto1.11Å)inthebenzoquinone+1Hintermediate(C6H5O2,asreducethesterichindrance.ThecalculatedactivationbarrierofshowninFigureS1a).TheC1-1Hdistanceinthetransitionstatethishydrogenationstepis0.57eV,withareactionenergyof6664https://doi.org/10.1021/acs.jpcc.1c00391J.Phys.Chem.C2021,125,6660−6672

5TheJournalofPhysicalChemistryCpubs.acs.org/JPCCArticleFigure6.Optimizedstructuresoftransitionstatesgeneratedincyclohexanolformationvia1,4-cyclohexanediolintermediateoverAu10/a-TiO2(001)(gray,Ti;red,O;yellow,Au;blue,H;darkgray,C).EachstructurecorrespondstothestructurallabelgiveninFigure5.−0.63eV.TheC3−3Hdistanceinthetransitionstate(Figure4,hindrance.The1C−HdistanceinthetransitionstateplotTS3)forproducingthebenzoquinone+3Hintermediateisconfigurationiscalculatedtobe2.09Å(Figure6,partTS1).1.92Å.Finally,thelastH-additionontheC4positionleadstoThehydrogenationbarriersoftheotherthreesitesareallhighertheformationofcyclohexanedioneintermediate(C6H8O2,than1eV,especiallyforthatofthe4Oposition,ashighas2.59FigureS1d).ThecalculationresultsshowthattheenergybarriereV.ThevarianceinhydrogenationbarriersatthefoursitesmaytobreaktheAu1−4HbondtoformtheC4−4Hbondis0.69eV,becausedbydifferentelectrondistributionsofadsorbateontheandthedistancebetweentheC4atomand4HinthetransitiondefectedTiO2surface,onwhichtheextranegativechargesstateisdeterminedtobe1.42Å(Figure4,plotTS4).createdbyoxygenvacanciesaretransferredtoproximalatomsofTheinvestigationonthehydrogenationofCCbondsoftheadsorbate,especiallytothe1Csite,makingiteasiertobebenzoquinonerevealsthatthetransferredH*comesfromthehydrogenated.ThefirsthydrogenationstepofcyclohexanedioneAucluster,andthehydrogenationkineticsisimpactedbytheleadstotheformationofaC6H9O2intermediate(FigureS2a).stericeffectoftheformedhydrogenationintermediates.WhenaInthenextstep,thehydrogenationonthe3Ositethroughthehydrogen-saturatedCatomisformedononeside,thenexthydrogentransferfrom−O2cHofTiO2totheC6H9O2hydrogenationtendstooccurontheoppositesideratherthanintermediateisexamined.Theresultsillustratethat,similartoonthesameside.Overall,thehydrogenationbarriersarethefirststepofformingbenzoquinoneintermediatefrommoderate,intherangeof0.4−0.7eV,demonstratingthatthehydroquinone,thehydrogentransferfromtheTiO2surfacetoformationofring-saturatedintermediates/productsisfacileonadsorbateorviceversahasnobarrier.However,theformationoftheAu10/a-TiO2(001)surface,consistentwiththeexperimental4-hydroxycyclohexanone(C6H10O2,FigureS2b)fromthe57observation.hydrogenationofC6H9O2intermediateisendothermicby3.3.FormationofCyclohexanolthroughDifferent1.33eV(seeFigure5).Subsequenthydrogenationonthe2CPaths.3.3.1.CyclohexanolFormationvia1,4-Cyclohexane-and4Ositesarecalculatedonthebasisoftheformed4-diol.AsdiscussedintheIntroduction,therearegenerallythreehydroxycyclohexanoneintermediate.ItisfoundthatiftheroutesfortheHDOofphenoliccompoundsincluding(1)hydrogenationfirstoccursonthe2Csite,theformedC6H11O2DDO,(2)HYD,and(3)tautomerization−HYD.Asthe1,4-structureisunstableandtheH*preferstogobacktotheAucyclohexanediolformationhasbeenevidencedfromtheHDOcluster.Whereasifthehydrogenationfirstoccursonthe4Osite,experimentsofhydroquinoneandbenzoquinoneoverAu/a-thereactionenergyiscalculatedtobe0.54eVandthereisno57TiO2,thehydrogenation−deoxygenationpathwayofsub-barriertoovercome(seeFigure5).Thus,thegenerationofO-sequentconversionofcyclohexanedionetocyclohexanolvia1,4-hydrogenatedintermediate(C6H11O2,FigureS2c)ispreferredcyclohexanediolformationisthenstudiedinthiswork(seepriortotheformationof1,4-cyclohexanediol(FigureS2d).AsschemeinFigure5).illustratedinFigure5,thehydrogenationbarrierofthelast2CInthelastsection,thering-saturatedcyclohexanedioneissiteis0.43eV,andthisstepis1.42eVexothermic,indicatingproducedafterthehydrogenationontheCCbondsofthattheformationof1,4-cyclohexanediol(C6H12O2)isbothbenzoquinone.Inordertogenerate1,4-cyclohexanediol,thekineticallyandthermodynamicallyfavorableontheAu10/a-hydrogenationofCObondsneedstobecompleted,whichTiO2(001)surface,consistentwiththeexperimentalobserva-57canoccuratfourpositions1C,2Cand3O,4Ositesofthetwotion.Inthisstep,theactiveH*comesfromH−Au1soastocarbonylgroupsincyclohexanedione(asillustratedinFigure5).reducethesterichindrance,andthe2C−HinteratomicdistanceForclarity,thesefourpositionsaredesignatedas1C,2Cand3O,inthetransitionstateconfigurationisdeterminedtobe2.02Å4O,inwhichthe1Cand3Ositeslocateovertheoxygenvacancy(Figure6,partTS2).Thecalculatedadsorptionenergyof1,4-siteofTiO2whilethe2Cand4Ositeslocateinthepara-positioncyclohexanediolatthevacancysiteis−0.96eV,indicatingafartherfromtheTiO2surface.BycalculatingthehydrogenationstableadsorptionofthisspeciesontheAu10/a-TiO2(001)barriers,itisfoundthatthe1Csiteisthebestpositionforsurface.hydrogenationsinceitonlyhastoovercomeasmallbarrierofThe1,4-cyclohexanediolhasbeenobservedasaproductin740.27eVwithanexothermicreactionenergyof−0.74eV.Thehydroquinonehydrogenationstudies.AccordingtothestudyactiveH*comesfromtheH−Au1soastoreducethestericbyMaoetal.,theproduced1,4-cyclohexanediolwasfurther6665https://doi.org/10.1021/acs.jpcc.1c00391J.Phys.Chem.C2021,125,6660−6672

6TheJournalofPhysicalChemistryCpubs.acs.org/JPCCArticleFigure7.Twopossiblepathwaysfortheformationofcyclohexanolviacyclohexanoneintermediate.Therednumbersrepresentactivationbarriers(eV)whilethebluenumbersarereactionenergies(eV).Figure8.OptimizedstructuresoftransitionstatesinvolvedincyclohexanolformationviacyclohexanoneintermediatethroughPathwayAandPathwayBoverAu10/a-TiO2(001)(gray,Ti;red,O;yellow,Au;blue,H;darkgray,C).Thestatesassignedasa−hcorrespondtothestructurallabelsgiveninFigure7.6666https://doi.org/10.1021/acs.jpcc.1c00391J.Phys.Chem.C2021,125,6660−6672

7TheJournalofPhysicalChemistryCpubs.acs.org/JPCCArticleconvertedtocyclohexanoloverAu/a-TiO2catalystwithPathwayAinvolvesthe4-hydroxycyclohexanoneasareaction57increasinghydroquinoneconversion.Inordertoformintermediate,andthusthefirsttwoelementarystepsarethecyclohexanol,the1,4-cyclohexanediolneedstobestrippedofsametothoseincludedinthe“1,4-cyclohexanediolpathway”ahydroxylgroup,whichisadeoxygenationstep.Itisnoticeddiscussedinthelastsection(seeFigure5).Afterward,thethataftertheremovalofonehydroxylgroupfrom1,4-formed4-hydroxycyclohexanoneremovesthe−OHgroupcyclohexanediol,theformedC6H11OintermediatecannotbeundertheeffectofsurfaceoxygenvacancyandformsaC6H9OeasilyadsorbedontheAuclusterduetothelargestericintermediate(FigureS3a).Thisstepneedstoovercomeahindrance.Onthecontrary,theoxygenvacancyontheTiO2barrierof0.96eVandisexothermicby1.44eV,wherethesurfaceprovidesassistanceinbreakingtheC−O(H)bond,barriersuggeststhatthedeoxygenationreactionisnotfast.Thewhichinducesthe1CatomoriginallyattachedtohydroxylC−Odistanceinthetransitionstateconfigurationisdeterminedgrouptomovetotheothervacancysiteandconnecttoanearbytobe2.04Å(Figure8,partTS1).Then,thehydrogenationofTi5catom.TheoptimizedconfigurationoftheformedC6H11OformedC6H9OintermediateoccursthroughtheprotontransferintermediateisshowninFigureS2e,andthebondlengthoffromthe−O2cHofTiO2tothelowpositionC1site.Theenergy1C−Ti5cismeasuredtobe2.15Å.Theenergybarrierofthisbarrierforthishydrogenationreactionis0.84eV,withareactiondeoxygenationstepis0.85eV,andthereactionenergyis−1.42energyof−0.91eV.TheC−HdistanceinthetransitionstateeV(seeFigure5),signifyingthattheremovalofonehydroxylstructureis1.83Å(Figure8,partTS2).Thecyclohexanonegroupfrom1,4-cyclohexanediolisnotdifficultinthepresenceof(C6H10O)isproducedafterthishydrogenationreaction.Duetooxygenvacanciesonthea-TiO2(001)surface.The1C−3Othesaturationofthering,theformedcyclohexanoneleavesthedistanceinthetransitionstateconfigurationassociatedwiththisTiO2surfaceandadsorbsinbetweentheAuclusterandTiO2,asdeoxygenationstepismeasuredtobe2.90Å(Figure6,partshowninFigureS3b.Forthesubsequentreactiontoproceed,TS3).theformedcyclohexanoneisadsorbedontothevacancysiteofThefinalstepintheformationofcyclohexanol(C6H12O,a-TiO2(001)viatheOatomofcarbonyl(FigureS3c)byFigureS2f)isthehydrogenationonthe1Csitetosaturatetherotatingthemolecule.Theadsorptionenergyofthiscyclo-carbonsite.Sincethe1CatomisconnectedtotheTi5csiteandishexanoneconfigurationiscalculatedtobe−1.38eV,indicatingafarfromthedissociatedH*onthegoldcluster,the−O2cHstronginteractionofthecarbonylgroupwiththevacancysite.species,whichisformedbyH*spilloverfromAuclusterontoAftertwosequentialhydrogenationstepsofthecarbonylgrouptheTiO2surface,isabetterchoicetooffertheH*speciesforofcyclohexanone,cyclohexanolisformed.Thefirsthydro-hydrogenation.Thisstephasabarrierof1.04eVbutisgenationoccurringontheCsiteofCOiskineticallymorethermodynamicallyfavorablewiththereactionexothermicbyfavorablethanthatontheOsiteandthecalculatedbarrieris0.84eV.The1C−Hdistanceinthetransitionstateisonly0.14eV.Thereactionenergyis−1.55eV,whichisdeterminedtobe1.62Å(Figure6,partTS4),andthethermodynamicallyfavorable(seeFigure7).TheformedcyclohexanolmoleculeiseventuallyproducedabovethevacancyC6H11Ointermediateassociatedwiththishydrogenationsite,asshowninFigureS2f.TheadsorptionenergyofreactionisshowninFigureS3d,andthetransitionstatecyclohexanolisdeterminedtobe−0.09eV.DuethesaturationconfigurationcanbeseeninFigure8,partTS3.ThelastofallCatomsinthemoleculeandthelongdistanceofthe−OHhydrogenationontheOsiteofC6H11OintermediatetoproducegrouprelativetotheTiO2surface,theinteractionbetweenthecyclohexanol(C6H12O,FigureS3e)needstoovercomeabarrierO-vacancysiteandcyclohexanolmoleculeisnotstrong,asof0.78eV,withthereactionbeingendothermicby0.46eV.Theevidencedbytheweakadsorptionenergy.transferredH*ofthisstepcomesfromthe−O2cHofTiO2andBasedonthecalculationresultsdiscussedabove,duringthenotfromtheAuclusterduetothestericeffect.Figure8,partformationofcyclohexanolviathe1,4-cyclohexanediolinter-TS4illustratesthetransitionstateconfigurationofthisHmediate,theenergybarrierofC−Obondcleavageishigherthantransferstep,whichhasanH−Odistanceof1.23Å.thatofthehydrogenationstepsexceptforthefinalhydro-InregardtoPathwayB,thefirststepintheconversionof1,4-genationstepduetoadifferentH*sourcefromthe−O2cHcyclohexanedioneistheH*transferfrom−O2cHofTiO2totheratherthanfromtheAucluster.TheseresultssuggestthatthebottomOofCOtoformaC6H9O2intermediate(FiguredeoxygenationwouldbeaslowstepwhilethehydrogenationS3f),whichisbarrierlesswithareactionenergyof1.30eV.Thewouldproceedfasterinthereaction,consistentwiththefollowingstepisthecleavageofC−O(H)bondunderthe57experimentalprediction.interactionofOvacancy,leadingtotheformationofaC6H8O3.3.2.CyclohexanolFormationviaCyclohexanone.InthespeciesboundattheinterfacebetweenAuandTiO2(Figureexperimentalwork,asmallamountofcyclohexanonewasS3g).ThecalculatedAu1−Cbondlengthis2.07ÅwhiletheTi−observedintheconversionofhydroquinoneandbenzoquinoneCbondlengthis2.13Åinthisconfiguration.ThisoverAu/a-TiO2catalystwhenthereactiontimereached180deoxygenationsteponlyhasabarrierof0.35eVandis57min.However,withthereactionproceededlonger(600min),exothermicby0.68eV,proceedingveryfastwithinthePathwaytheproductdistributionwasdominatedbycyclohexeneandB.ThetransitionstatestructureisprovidedinFigure8,partcyclohexanewithsmallerportionsof1,4-cyclohexanediolandTS5,whichhasaC−Odistanceof1.95Å.Followingtwo57cyclohexanol.Therefore,apartfromtherouteofcyclohexanolsequentialhydrogenationstepsoftheformedC6H8Oformationviathe1,4-cyclohexanediolintermediatediscussedintermediate,thecyclohexanone(FigureS3b)canbeproduced.above,anotherrouteofcyclohexanolformationthatgoesTheactiveH*comesfromtheAucluster,andthehydro-throughthecyclohexanoneintermediateisproposedandgenationbarriersarecalculatedtobe0.64and1.32eV,discussedinthissection.Twopossiblepathwaysareconsideredrespectively,tosaturatethebottomCsiteofC6H8Ospecies.fortheformationofcyclohexanonestartingwiththe1,4-Thesetwohydrogenationstepsareexothermicby−1.24andcyclohexanedionespecies.AsillustratedinFigure7,themajor−1.03eV,respectively.Theintermediatestructure(C6H9O)isdifferencebetweenPathwayAandPathwayBliesinwhetheritillustratedinFigureS3h,andthetwocorrespondingtransitionincludestheformationof4-hydroxycyclohexanone.stateconfigurationsaredisplayedinFigure8,partTS6and6667https://doi.org/10.1021/acs.jpcc.1c00391J.Phys.Chem.C2021,125,6660−6672

8TheJournalofPhysicalChemistryCpubs.acs.org/JPCCArticleFigure8,partTS7.TheC−Hinteratomicdistanceinthetwohexanolproceedsrelativelyfasterduetolowerbarriersandtransitionstatesare2.55and1.89Å,respectively.Therestofthefavorablereactionenergies(seeFigure7),consistentwiththe57stepsleadingtocyclohexanolformationoverlapwiththoseexperimentalresults.involvedinPathwayAasdiscussedabove(seeFigure7).3.3.3.Comparisonof1,4-CyxlohexanediolandCyclo-ComparingthetwopathwaysforproducingcyclohexanoneashexanonePathways.AsillustratedinFigure10,the“1,4-presentedinFigure7,thechemicalenvironmentsaredifferentcyclohexanediol”and“cyclohexanone”pathwaybranchesfromfortheelementarysteps.Theformationofcyclohexanonealongsubsequentconversionof4-hydroxycyclohexanone.ThetwoPathwayAisovertheoxygenvacancysiteofTiO2surface,hydrogenationstepsinvolvedin1,4-cyclohexanediolformationwhereasforPathwayB,cyclohexanoneisproducedatthefrom4-hydroxycyclohexanonearebelow0.5eV.However,interfaceofAu−TiO2.Thesetwotypesofactivesitesresultinsubsequentdeoxygenationandhydrogenationtoproducetheobserveddifferenceintheactivationbarrierofthelastcyclohexanolhavelargerbarriers(0.85and1.04eV,hydrogenationsteptosaturatethebottomCatom.Theoxygenrespectively).Theseresultsindicatethatinthe“1,4-cyclo-vacancysiteismorefavorableforcyclohexanoneformation,andhexanediol”pathway,theformationof1,4-cyclohexanediolthehydrogenationbarrieris∼0.5eVlowerthanthatobtainedatthroughhydrogenationreactionsproceedsfastwhereasthetheAu−TiO2interface.Thechargepropertiesoftheinitialandproductionofcyclohexanolviadeoxygenationof1,4-cyclo-transitionstatesassociatedwiththetwocases(a→bandh→bhexanediolfollowedbyhydrogenationisrelativelyslow.InasshowninFigure7)forcyclohexanoneformationarecomparison,inthe“cyclohexanone”pathway,theconversionofillustratedinFigure9,whichindicatethattheinitialstateis4-hydroxycyclohexanonetocyclohexanonethroughdeoxygena-tionfollowedbyhydrogenationneedstoovercomehighbarriersof0.96and0.84eV,respectively;however,subsequentconversionofcyclohexanonetocyclohexanolthroughsequen-tialhydrogenationreactionsproceedsfast,asillustratedinFigure10.Thecalculationresultsonreactionpathwaysandkineticbarriersrevealthatthe“1,4-cyclohexanediol”pathwaygoesthroughaprocessofbeingfastthenslowwhereasthe“cyclohexanone”pathwaygoesinanoppositefashion,withinitialstepsslowthenlatestepsfastontheAu/a-TiO2catalyst.Theratedifferencebetweenthe“1,4-cyclohexanediol”and“cyclohexanone”pathwayimpliesthatatthebeginningofthereaction,theformedcyclohexadioneintermediateismorelikelytoconvertto1,4-cyclohexanediol,leadingtoasmallamountofcyclohexanoneformation.Althoughcyclohexanoneisconvertedtocyclohexanolatafasterrateinthelatestageofthereaction,sincethetotalamountofcyclohexanoneissmall,the“1,4-cyclohexanediol”pathwaystilldominatestheoverallreactioninFigure9.Chargepropertiesofinitialandtransitionstatesassociatedhydroquinoneconversion.TheseresultsprovidemechanisticwithcyclohexanoneformationthroughthehydrogenationofC6H9OexplanationsoftheobservedexperimentalphenomenonbyMaointermediatethroughPathwayA(a→b)andPathwayB(h→b)over57etal.Au10/a-TiO2(001)(gray,Ti;red,O;yellow,Au;white,H;black,C).Theisosurfacecorrespondsto0.0063|e|/Å3.YellowandcyanInaddition,the“1,4-cyclohexanediol”and“cyclohexanone”isosurfacesinthe3Dchargefigurerepresentthechargeaccumulationpathwaysshowsomecommonfeatures.Forexample,oncetheanddepletioninthesystem,respectively.RedandblueregionsinthebottomCsiteoftheintermediatespeciesissaturatedby2DelectrondensitydifferencemaprepresenttheelectrondensitybondingtotwoCatoms,one−OHgroup,andoneHatom,theincreaseanddecreaseinthesystem,respectively.newintermediategeneratedafterdehydroxylationisunstableontheAuclusterduetothesterichindrance,neitherbeingmoreactivatedandthetransitionstateismorestabilizedwhenhydrogenatedbytheactiveH*onAucluster.Inthiscase,thethehydrogenationoccurswiththeprotonfrom−O2cHofTiO2presenceofoxygenvacancyonTiO2facilitatesthestabilizationtotheC6H9Ointermediateadsorbedattheoxygenvacancysiteoftheintermediateformedafterdehydroxylationthroughsincethesestatesaremorepositivelycharged.Incontrast,oncebondingtotheTi5catom,butthedeoxygenationbarriersarethehydrogenationoccurswiththeH*fromAuclustertothealwayshigh(e.g.0.85eVinthe“1,4-cyclohexanediol”pathwayC6H9OintermediateadsorbedattheAu−TiO2interface,theand0.96eVinthe“cyclohexanone”pathway).Ingeneral,thechargetransferbetweentheadsorbateandcatalystandthedeoxygenationreactionsoccuronO-vacancysiteonTiO2,andchargeaccumulationinthetransitionstatearelessascomparedtheH*speciesforthehydrogenationcomesfromeithertheAutotheformercase.Thechargepropertyanalysisagreeswiththeclusterorthe−O2cHsiteofTiO2,dependingonthestructure,trendinbarriercalculation.TheseresultsrevealthatPathwayAstability,andstericeffectoftheintermediatespecies.DFTisdominant,andthe4-hydroxycyclohexanoneisareactionresultsrevealthattheinterfaceofAu−TiO2andO-vacancysitesintermediatewithintheconversionpath.Thisresultisbothplayimportantrolesintheconversionofhydroquinone,consistentwiththestudyofLietal.,identifyingtheformationexhibitingasynergisticeffectinpromotingtheHDOreaction.of4-hydroxycyclohexanoneintermediateintheHDOexperi-3.4.FormationofHydrocarbons.Oncecyclohexanolis75mentofhydroquinone.WithinPathwayA,thedeoxygenationproducedatthecatalystsurface,itsfurtherconversionleadstoof4-hydroxycyclohexanoneandsubsequenthydrogenationtheformationofcyclohexaneorcyclohexenethroughtwostepshavehigherbarriers(0.96and0.84eV,respectively),elementarysteps,respectively,asillustratedinFigure10.Theandthustheformationofcyclohexanoneproceedsslowly.Indehydroxylationofcyclohexanoloccursundertheactionofcontrast,subsequentconversionofcyclohexanonetocyclo-oxygenvacancywhichneedstoovercomeabarrierof0.74eV,6668https://doi.org/10.1021/acs.jpcc.1c00391J.Phys.Chem.C2021,125,6660−6672

9TheJournalofPhysicalChemistryCpubs.acs.org/JPCCArticleFigure10.Conversionofhydroquinonethroughdifferentpathways.Therednumbersrepresentactivationbarriers(eV)whilethebluenumbersarereactionenergies(eV).withareactionenergyof0.12eV.ThetransitionstateconfigurationisshowninFigureS4-TS1,inwhichtheC−Ointeratomicdistanceis2.12Å.TheformedC6H11intermediate(FigureS4a)isadsorbedontheAuclusterwiththeC−Aubondlengthof2.14Å.Inonecase,theformedC6H11intermediatecanbehydrogenatedontheunsaturatedCatomtogeneratethecyclohexaneproduct(FigureS4b,FigureS4-TS2).Theadsorptionenergyofcyclohexaneiscalculatedtobe−0.10eV.Intheothercase,theC6H11intermediatecantakeoneHoffofthe−O2cHspeciesofTiO2,producingthecyclohexeneproduct(FigureS4c,FigureS4-TS3)andH2Ocorrespondingly.ThedesorptionofH2OfromtheTiO2surfaceresultsintheregenerationoftheoxygenvacancyasanactivesitefornextcatalyticcycle.Thecalculatedadsorptionenergyofcyclohexeneis−0.66eV.AsillustratedinFigure10,theformationofcyclohexaneproductisquitefacile,withasmallbarrierof0.18eVandareactionenergyof−1.77eV.Incontrast,theFigure11.ChargepropertiesofinitialandtransitionstatesassociatedcyclohexeneformationfromdehydrogenationofC6H11needstowithcyclohexanoneandcyclohexeneformationthroughthehydro-overcomealargebarrierof1.32eV,andthereactionisgenationanddehydrogenationofC6H11OintermediateoverAu10/a-TiO2(001)(gray,Ti;red,O;yellow,Au;white,H;black:C).Theendothermicby0.52eV.Asillustratedinthechargeproperties3isosurfacecorrespondsto0.0063|e|/Å.YellowandcyanisosurfacesininFigure11,althoughtheBaderchargecalculatedfortheinitialthe3Dchargefigurerepresentthechargeaccumulationanddepletionstateassociatedwithcyclohexaneandcyclohexeneformationisinthesystem,respectively.Redandblueregionsinthe2Delectronsimilar(1.01evs1.00e),thetransitionstateforproducingdensitydifferencemaprepresenttheelectrondensityincreaseandcyclohexaneismorepositivelycharged(1.89evs1.60e),decreaseinthesystem,respectively.indicatingstrongerelectronicinteractionbetweenthecatalystandtheadsorbatethanthatofcyclohexeneformation.Thus,the1Thekeyreactionintermediatesincludingbenzoquinone,transitionstateismorestable,resultinginalowerbarrierforthe1,4-cyclohexanediol,andcyclohexanolhavebeenidenti-hydrogenationofC6H11intermediatetocyclohexaneproduct.fiedbyinvestigatingreactionpathwaysandpotentialThesecalculationresultsrevealthattheproductionofenergysurfaces.Thedehydrogenationofhydroquinonecyclohexaneproductisbothkineticallyandthermodynamicallytobenzoquinoneintermediateisacrucialinitialstepinmorefavorable,agreeingwiththeexperimentalresultsthathydroquinoneconversion,andboththeTiO2surfaceandcyclohexaneisthedominantproductintheHDOof57Auclusterplayimportantroles.TheH*transferonthea-hydroquinoneoverAu/a-TiO2catalysts.TiO2(001)surfaceismorefacilethanthatontheAuclusterinthisprocess.4.CONCLUSIONS2SubsequenthydrogenationoftheCCbondsofThereactionmechanismandkineticfeatureofhydroquinonebenzoquinoneisaffectedbythestericeffectofthehydrodeoxygenationtohydrocarbonproductscatalyzedbytheformedhydrogenationintermediates.Overall,thehydro-defectiveAu/a-TiO2catalysthavebeensystematicallyde-genationbarriersaremoderate,intherangeof0.4−0.7lineatedbyDFTcalculations.ThemainconclusionsareeV,demonstratingthattheformationofring-saturatedsummarizedbelow:6669https://doi.org/10.1021/acs.jpcc.1c00391J.Phys.Chem.C2021,125,6660−6672

10TheJournalofPhysicalChemistryCpubs.acs.org/JPCCArticleintermediates/productsarefacileontheAu10/a-Engineering,DalianUniversityofTechnology,Dalian116024,TiO2(001)surface.P.R.China;orcid.org/0000-0002-6597-4979;3Intheprocessofcyclohexanolformation,thecalculationEmail:guoxw@dlut.edu.cnresultsrevealthatthe“1,4-cyclohexanediol”pathwaygoesAuthorsthroughareactionprocessoffirstbeingfastthenslowwhereasthe“cyclohexanone”pathwayproceedsinanWenjiaWan−StateKeyLaboratoryofFineChemicals,PSU-oppositefashion,firstslowthenfast.The“1,4-cyclo-DUTJointCenterforEnergyResearch,SchoolofChemicalhexanediol”pathwaydominatestheoverallreactioninEngineering,DalianUniversityofTechnology,Dalian116024,hydroquinoneconversion.P.R.ChinaZeshiZhang−StateKeyLaboratoryofFineChemicals,PSU-4Intheformationofhydrocarbonproducts,thecyclo-DUTJointCenterforEnergyResearch,SchoolofChemicalhexaneformationisbothkineticallyandthermodynami-Engineering,DalianUniversityofTechnology,Dalian116024,callypreferredovertheformationofcyclohexene,leadingP.R.ChinatoalargeamountofcyclohexaneintheproductovertheYonggangChen−NetworkandInformationizationCenter,Au/a-TiO2catalyst.DalianUniversityofTechnology,Dalian116024,P.R.China5Thepresenceofoxygenvacanciesona-TiO2isimportantMichaelJ.Janik−EMSEnergyInstitute,PSU-DUTJointasactivesitestofacilitatetheC−ObondcleavageofCenterforEnergyResearch,andDepartmentofChemicalintermediatespeciesfordeoxygenationreactions.TheEngineering,ThePennsylvaniaStateUniversity,UniversityinterfaceofAu−TiO2alsoplaysacrucialroleinstabilizingPark,Pennsylvania16802,UnitedStatesreactionintermediates,promotingHtransferbetweenAuclusterandtheadsorbedspeciesonTiO2.Completecontactinformationisavailableat:6Thiscomputationalworkprovidesimportantnewinsighthttps://pubs.acs.org/10.1021/acs.jpcc.1c00391intothecomplexreactionmechanismofhydroquinoneHDOontheAu/a-TiO2catalystandrationalizestheAuthorContributions#experimentallyobservedproductdistributionandkineticX.N.andW.W.contributedequallytothisworkfeatureofthisreaction.NotesThesynergisticeffectbetweenO-vacancysiteandAu−TiO2Theauthorsdeclarenocompetingfinancialinterest.interfaceiscrucialinpromotingthehydrodeoxygenationofhydroquinonetohydrocarbonproducts;therefore,future■ACKNOWLEDGMENTScatalystdesignshouldfocusonthecreationofO-vacancysitesThisworkissupportedbytheNationalNaturalSciencetopromotetheadsorptionanddeoxygenationofsurfacespeciesFoundationofChina(No.21872012).WeacknowledgetheandalsopayattentiontoincreasingperimetersitesofAu/TiO2SupercomputingCenterofDalianUniversityofTechnologyforcatalysttoexertthepromotionalroleofinterfaceontheprovidingthecomputationalresourcesforthiswork.stabilizationofreactionintermediatesandfacilitatingthehydrogenationreactions.■REFERENCES■(1)Wildschut,J.;Arentz,J.;Rasrendra,C.B.;Venderbosch,R.H.;ASSOCIATEDCONTENTHeeres,H.J.CatalyticHydrotreatmentofFastPyrolysisOil:Model*sıSupportingInformationStudiesonReactionPathwaysfortheCarbohydrateFraction.Environ.TheSupportingInformationisavailablefreeofchargeatProg.SustainableEnergy2009,28,450−460.https://pubs.acs.org/doi/10.1021/acs.jpcc.1c00391.(2)Caputo,A.C.;Palumbo,M.;Pelagagge,P.M.;Scacchia,F.OptimizedstructuresassociatedwithdifferentelementaryEconomicsofBiomassEnergyUtilizationinCombustionandGasificationPlants:EffectsofLogisticVariables.BiomassBioenergyreactionsoverAu10/a-TiO2(001)(PDF)2005,28,35−51.(3)Furimsky,E.CatalyticHydrodeoxygenation.Appl.Catal.,A2000,■AUTHORINFORMATION199,147−190.CorrespondingAuthors(4)Saidi,M.;Samimi,F.;Karimipourfard,D.;Nimmanwudipong,T.;XiaowaNie−StateKeyLaboratoryofFineChemicals,PSU-Gates,B.C.;Rahimpour,M.R.UpgradingofLignin-DerivedBio-OilsDUTJointCenterforEnergyResearch,SchoolofChemicalbyCatalyticHydrodeoxygenation.EnergyEnviron.Sci.2014,7,103−129.Engineering,DalianUniversityofTechnology,Dalian116024,(5)Choudhary,T.V.;Phillips,C.B.RenewableFuelsviaCatalyticP.R.China;orcid.org/0000-0002-9937-5456;Hydrodeoxygenation.Appl.Catal.,A2011,397,1−12.Email:niexiaowa@dlut.edu.cn(6)Bu,Q.;Lei,H.;Ren,S.;Wang,L.;Holladay,J.;Zhang,Q.;Tang,J.;ChunshanSong−StateKeyLaboratoryofFineChemicals,Ruan,R.PhenolandPhenolicsfromLignocellulosicBiomassbyPSU-DUTJointCenterforEnergyResearch,SchoolofCatalyticMicrowavePyrolysis.Bioresour.Technol.2011,102,7004−ChemicalEngineering,DalianUniversityofTechnology,7007.Dalian116024,P.R.China;DepartmentofChemistry,(7)Shafaghat,H.;Rezaei,P.S.;MohdWan,A.W.D.EffectiveFacultyofScience,TheChineseUniversityofHongKong,ParametersonSelectiveCatalyticHydrodeoxygenationofPhenolicShatin,NT,HongKong,P.R.China;EMSEnergyInstitute,CompoundsofPyrolysisBio-OiltoHigh-ValueHydrocarbons.RCSPSU-DUTJointCenterforEnergyResearch,andDepartmentAdv.2015,5,103999−104042.(8)Shu,R.;Li,R.;Lin,B.;Wang,C.;Cheng,Z.;Chen,Y.AReviewonofChemicalEngineering,ThePennsylvaniaStateUniversity,theCatalyticHydrodeoxygenationofLignin-DerivedPhenolicUniversityPark,Pennsylvania16802,UnitedStates;CompoundsandtheConversionofRawLignintoHydrocarbonorcid.org/0000-0003-2344-9911;LiquidFuels.BiomassBioenergy2020,132,105432.Email:chunshansong@cuhk.edu.hk(9)Foster,A.J.;Do,P.T.M.;Lobo,R.F.TheSynergyoftheSupportXinwenGuo−StateKeyLaboratoryofFineChemicals,PSU-AcidFunctionandtheMetalFunctionintheCatalyticHydro-DUTJointCenterforEnergyResearch,SchoolofChemicaldeoxygenationofm-Cresol.Top.Catal.2012,55,118−128.6670https://doi.org/10.1021/acs.jpcc.1c00391J.Phys.Chem.C2021,125,6660−6672

11TheJournalofPhysicalChemistryCpubs.acs.org/JPCCArticle(10)Huuska,M.EffectofCatalystCompositionontheHydro-MolybdenumOxideCatalystsfortheHydrodeoxygenation(HDO)ofgenolysisofAnisole.Polyhedron1986,5,233−236.m-Cresol.J.Catal.2015,331,86−97.(11)Boullosa-Eiras,S.;Lødeng,R.;Bergem,H.;Stocker,M.;(31)Mao,J.;Zhou,J.;Xia,Z.;Wang,Z.;Xu,Z.;Xu,W.;Yan,P.;Liu,Hannevold,L.;Blekkan,A.CatalyticHydrodeoxygenation(HDO)ofK.;Guo,X.;Zhang,Z.C.AnataseTiO2ActivatedbyGoldPhenoloverSupportedMolybdenumCarbide,Nitride,PhosphideandNanoparticlesforSelectiveHydrodeoxygenationofGuaiacoltoOxideCatalysts.Catal.Today2014,223,44−53.Phenolics.ACSCatal.2017,7,695−705.(12)Gutierrez,A.;Kaila,R.K.;Honkela,M.L.;Slioor,R.;Krause,A.(32)Teles,C.A.;Rabelo-Neto,R.C.;Duong,N.;Quiroz,J.;O.I.HydrodeoxygenationofGuaiacolonNobleMetalCatalysts.Catal.Camargo,P.H.C.;Jacobs,G.;Resasco,D.E.;Noronha,F.B.RoleofToday2009,147,239−246.theMetal-SupportInterfaceintheHydrodeoxygenationReactionof(13)Liu,D.;Li,G.;Yang,F.;Wang,H.;Han,J.;Zhu,X.;Ge,Q.Phenol.Appl.Catal.,B2020,277,119238.CompetitionandCooperationofHydrogenationandDeoxygenation(33)Chen,T.;Vohs,J.M.DirectHydrodeoxygenationofm-CresoltoReactionsduringHydrodeoxygenationofPhenolonPt(111).J.Phys.TolueneoverBifunctionalNbOx−Pt.J.Phys.Chem.C2020,124,Chem.C2017,121,12249−12260.14253−14261.(14)Yoon,Y.;Rousseau,R.;Weber,R.S.;Mei,D.;Lercher,J.A.First-(34)Moon,J.S.;Kim,E.G.;Lee,Y.K.ActiveSitesofNi2P/SiO2PrinciplesStudyofPhenolHydrogenationonPtandNiCatalystsinCatalystforHydrodeoxygenationofGuaiacol:AJointXAFSandDFTAqueousPhase.J.Am.Chem.Soc.2014,136,10287−10298.Study.J.Catal.2014,311,144−152.(15)deSouza,P.M.;Rabelo-Neto,R.C.;Borges,L.E.P.;Jacobs,G.;(35)Inocencio,C.V.M.;deSouza,P.M.;Rabelo-Neto,R.C.;dâDavis,B.H.;Sooknoi,T.;Resasco,D.E.;Noronha,F.B.RoleofKetoSilva,V.T.;Noronha,F.B.ASystematicStudyoftheSynthesisofIntermediatesintheHydrodeoxygenationofPhenoloverPdonTransitionMetalPhosphidesandTheirActivityforHydrodeoxygena-OxophilicSupports.ACSCatal.2015,5,1318−1329.tionofPhenol.Catal.Today2020,DOI:10.1016/j.cattod.2020.07.077.(16)Zhao,C.;Camaioni,D.M.;Lercher,J.A.SelectiveCatalytic(36)Bredenberg,J.B.;Huuska,M.;Räty,J.;Korpio,M.Hydro-HydroalkylationandDeoxygenationofSubstitutedPhenolstogenolysisandHydrocrackingoftheCarbon-OxygenBond:I.Bicycloalkanes.J.Catal.2012,288,92−103.HydrocrackingofSomeSimpleAromaticO-Compounds.J.Catal.(17)Hong,D.Y.;Miller,S.J.;Agrawal,P.K.;Jones,C.W.1982,77,242−247.HydrodeoxygenationandCouplingofAqueousPhenolicsover(37)Furimsky,E.;Massoth,F.E.DeactivationofHydroprocessingBifunctionalZeolite-SupportedMetalCatalysts.Chem.Commun.Catalysts.Catal.Today1999,52,381−495.2010,46,1038−1040.(38)Lee,C.R.;Yoon,J.S.;Suh,Y.W.;Choi,J.W.;Ha,J.M.;Suh,D.(18)Romero,Y.;Richard,F.;Brunet,S.Hydrodeoxygenationof2-J.;Park,Y.K.CatalyticRolesofMetalsandSupportsonHydro-EthylphenolasaModelCompoundofBio-CrudeoverSulfidedMo-deoxygenationofLigninMonomerGuaiacol.Catal.Commun.2012,17,BasedCatalysts:PromotingEffectandReactionMechanism.Appl.54−58.Catal.,B2010,98,213−223.(39)Omotoso,T.O.;Baek,B.;Grabow,L.C.;Crossley,S.P.(19)Graca,I.;Lopes,J.M.;Cerqueira,H.S.;Ribeiro,M.F.Bio-OilşExperimentalandFirst-PrinciplesEvidenceforInterfacialActivityofUpgradingforSecondGenerationBiofuels.Ind.Eng.Chem.Res.2013,Ru/TiO2fortheDirectConversionofm-CresoltoToluene.52,275−287.ChemCatChem2017,9,2642−2651.(20)Shin,E.J.;Keane,M.A.Gas-PhaseHydrogenation/Hydro-(40)KayLup,A.N.;Abnisa,F.;Daud,W.M.A.W.;Aroua,M.K.genolysisofPhenoloverSupportedNickelCatalysts.Ind.Eng.Chem.SynergisticInteractionofMetal-AcidSitesforPhenolHydro-Res.2000,39,883−892.deoxygenationoverBifunctionalAg/TiO2Nanocatalyst.Chin.J.(21)Rivoira,L.;Martínez,M.L.;Beltramone,A.HydrodeoxygenationChem.Eng.2019,27,349−361.ofGuaiacoloverPt-Ga-MesoporousCatalysts.MicroporousMesoporous(41)Olcese,R.N.;Bettahar,M.;Petitjean,D.;Malaman,B.;Mater.2021,312,110815.Giovanella,F.;Dufour,A.Gas-PhaseHydrodeoxygenationofGuaiacol(22)Raikwar,D.;Majumdar,S.;Shee,D.SynergisticEffectofNi-CooverFe/SiO2Catalyst.Appl.Catal.,B2012,115−116,63−73.AlloyingonHydrodeoxygenationofGuaiacoloverNi-Co/Al2O3(42)Olcese,R.;Bettahar,M.M.;Malaman,B.;Ghanbaja,J.;Catalysts.Mol.Catal.2021,499,111290.Tibavizco,L.;Petitjean,D.;Dufour,A.Gas-PhaseHydrodeoxygenation(23)Silva,N.K.G.;Ferreira,R.A.R.;Ribas,R.M.;Monteiro,R.S.;ofGuaiacoloverIron-BasedCatalysts.EffectofGasesComposition,Barrozo,M.A.S.;Soares,R.R.Gas-PhaseHydrodeoxygenationIronLoadandSupports(SilicaandActivatedCarbon).Appl.Catal.,B(HDO)ofGuaiacoloverPt/Al2O3CatalystPromotedbyNb2O5.Fuel2013,129,528−538.2021,287,119509.(43)Olcese,R.N.;Lardier,G.;Bettahar,M.;Ghanbaja,J.;Fontana,S.;(24)Chen,C.;Zhou,M.;Liu,P.;Sharma,B.K.;Jiang,J.FlexibleCarré,V.;Aubriet,F.;Petitjean,D.;Dufour,A.AromaticChemicalsbyNiCo-BasedCatalystforDirectHydrodeoxygenationofGuaiacoltoIron-CatalyzedHydrotreatmentofLigninPyrolysisVapor.ChemSu-Cyclohexanol.NewJ.Chem.2020,44,18906−18916.sChem2013,6,1490−1499.(25)Resasco,J.;Yang,F.;Mou,T.;Wang,B.;Christopher,P.;(44)Olcese,R.N.;Francois,J.;Bettahar,M.M.;Petitjean,D.;Dufour,Resasco,D.E.RelationshipbetweenAtomicScaleStructureandA.HydrodeoxygenationofGuaiacol,ASurrogateofLigninPyrolysisReactivityofPtCatalysts:Hydrodeoxygenationofm-CresoloverVapors,OverIronBasedCatalysts:KineticsandModelingoftheLigninIsolatedPtCationsandClusters.ACSCatal.2020,10,595−603.toAromaticsIntegratedProcess.EnergyFuels2013,27,975−984.(26)Saleheen,M.;Verma,A.M.;Mamun,O.;Lu,J.;Heyden,A.(45)Li,C.;Nakagawa,Y.;Tamura,M.;Nakayama,A.;Tomishige,K.InvestigationofSolventEffectsontheHydrodeoxygenationofHydrodeoxygenationofGuaiacoltoPhenoloverCeria-SupportedIronGuaiacoloverRuCatalysts.Catal.Sci.Technol.2019,9,6253−6273.Catalysts.ACSCatal.2020,10,14624−14639.(27)Tran,N.T.T.;Uemura,Y.;Chowdhury,S.;Ramli,A.Vapor-(46)Yang,Y.;Tan,M.;Garcia,A.;Zhang,Z.;Lin,J.;Wan,S.;PhaseHydrodeoxygenationofGuaiacolonAl-MCM-41SupportedNiMcEwen,J.S.;Wang,S.;Wang,Y.ControllingtheOxidationStateofandCoCatalysts.Appl.Catal.,A2016,512,93−100.Fe-BasedCatalyststhroughNitrogenDopingtowardtheHydro-(28)Venkatesan,K.;Krishna,J.V.J.;Anjana,S.;Selvam,P.;Vinu,R.deoxygenationofm-Cresol.ACSCatal.2020,10,7884−7893.HydrodeoxygenationKineticsofSyringol,GuaiacolandPhenolover(47)Engelhardt,J.;Lyu,P.;Nachtigall,P.;Schüth,F.;García,A.M.H-ZSM-5.Catal.Commun.2021,148,106164.TheInfluenceofWateronthePerformanceofMolybdenumCarbide(29)Yan,P.;Li,M.M.J.;Kennedy,E.;Adesina,A.;Zhao,G.;CatalystsinHydrodeoxygenationReactions:ACombinedTheoreticalSetiawan,A.;Stockenhuber,M.TheRoleofAcidandMetalSitesinandExperimentalStudy.ChemCatChem2017,9,1985−1991.HydrodeoxygenationofGuaiacoloverNi/BetaCatalysts.Catal.Sci.(48)Tran,C.C.;Mohan,O.;Banerjee,A.;Mushrif,S.H.;Kaliaguine,Technol.2020,10,810−825.S.ACombinedExperimentalandDFTInvestigationofSelective(30)Shetty,M.;Murugappan,K.;Prasomsri,T.;Green,W.H.;HydrodeoxygenationofGuaiacoloverBimetallicCarbides.EnergyFuelsRomán-Leshkov,Y.ReactivityandStabilityInvestigationofSupported2020,34,16265−16273.6671https://doi.org/10.1021/acs.jpcc.1c00391J.Phys.Chem.C2021,125,6660−6672

12TheJournalofPhysicalChemistryCpubs.acs.org/JPCCArticle(49)Zhao,K.;Tang,H.;Qiao,B.;Li,L.;Wang,J.HighActivityofAu/(69)Sowmiya,M.;Senthilkumar,K.DissociationofN2OonAnataseγ-Fe2O3forCOOxidation:EffectofSupportCrystalPhaseinCatalystTiO2(001)Surface−TheEffectofOxygenVacancyandPresenceofDesign.ACSCatal.2015,5,3528−3539.AgCluster.Appl.Surf.Sci.2016,389,1220−1232.(50)Yang,J.H.;Henao,J.D.;Raphulu,M.C.;Wang,Y.;Caputo,T.;(70)Henderson,M.A.;Lyubinetsky,I.Molecular-LevelInsightsintoGroszek,A.J.;Kung,M.C.;Scurrell,M.S.;Miller,J.T.;Kung,H.H.PhotocatalysisfromScanningProbeMicroscopyStudiesonActivationofAu/TiO2CatalystforCOOxidation.J.Phys.Chem.BTiO2(110).Chem.Rev.2013,113,4428−4455.2005,109,10319−10326.(71)Yu,J.;Low,J.;Xiao,W.;Zhou,P.;Jaroniec,M.Enhanced(51)Cargnello,M.;Gentilini,C.;Montini,T.;Fonda,E.;Mehraeen,PhotocatalyticCO2-ReductionActivityofAnataseTiO2byCoexposedS.;Chi,M.;Herrera-Collado,M.;Browning,N.D.;Polizzi,S.;{001}and{101}Facets.J.Am.Chem.Soc.2014,136,8839−8842.Pasquato,L.;Fornasiero,P.ActiveandStableEmbeddedAu@CeO(72)Xiao,X.;Bergstrom,H.;Saenger,R.;Johnson,B.;Sun,R.;2CatalystsforPreferentialOxidationofCO.Chem.Mater.2010,22,Peterson,A.TheRoleofOxygenVacanciesinBiomassDeoxygenation4335−4345.byReducibleZinc/ZincOxideCatalysts.Catal.Sci.Technol.2018,8,(52)Sharma,M.;Das,B.;Baruah,M.J.;Biswas,S.;Roy,S.;Hazarika,1819−1827.(73)Sun,K.;Kohyama,M.;Tanaka,S.;Takeda,S.AStudyontheA.;Bhargava,S.K.;Bania,K.K.Pd-Au-YasEfficientCatalystforC-CCouplingReactions,BenzylicC-HBondActivation,andOxidationofMechanismforH2DissociationonAu/TiO2Catalysts.J.Phys.Chem.C2014,118,1611−1617.EthanolforSynthesisofCinnamaldehydes.ACSCatal.2019,9,5860−(74)Li,G.;Dong,P.;Ji,D.;Xu,Y.;Li,Y.;Mu,R.EffectofSupport5875.MaterialsonLiquid-PhaseHydrogenationofHydroquinoneover(53)Lu,Z.;Sun,K.;Wang,J.;Zhang,Z.;Liu,C.AHighlyActiveAu/RutheniumCatalysts.SolidStateSci.2013,23,13−16.In2O3-ZrO2CatalystforSelectiveHydrogenationofCO2toMethanol.(75)Li,H.;Ji,D.;Li,Y.;Liang,Y.;Li,G.X.EffectofAlkalineEarthCatalysts2020,10,1360.MetalsontheLiquid-PhaseHydrogenationofHydroquinoneoverRu-(54)Juliusa,M.;Robertsa,S.;Fletchera,J.C.Q.AReviewoftheUseBasedCatalysts.SolidStateSci.2015,50,85−90.ofGoldCatalystsinSelectiveHydrogenationReactions.GoldBull.2010,43,298−306.(55)Ward,T.;Delannoy,L.;Hahn,R.;Kendell,S.;Pursell,C.J.;Louis,C.;Chandler,B.D.EffectsofPdonCatalysisbyAu:COAdsorption,COOxidation,andCyclohexeneHydrogenationbySupportedAuandPd−AuCatalysts.ACSCatal.2013,3,2644−2653.(56)Liu,K.;Yan,P.;Jiang,H.;Xia,Z.;Xu,Z.;Bai,S.;Zhang,Z.C.SilverInitiatedHydrogenSpilloveronAnataseTiO2CreatesActiveSitesforSelectiveHydrodeoxygenationofGuaiacol.J.Catal.2019,369,396−404.(57)Mao,J.;Zhao,B.;Zhou,J.;Zhang,L.;Yang,F.;Guo,X.;Zhang,Z.C.IdentificationandCharacteristicsofCatalyticQuad-FunctionsonAu/AnataseTiO2.ACSCatal.2019,9,7900−7911.(58)Kresse,G.;Furthmüller,J.EfficiencyofAb-InitioTotalEnergyCalculationsforMetalsandSemiconductorsusingaPlane-WaveBasisSet.Comput.Mater.Sci.1996,6,15−50.(59)Kresse,G.;Furthmüller,J.EfficientIterativeSchemesforAbInitioTotal-EnergyCalculationsusingaPlane-WaveBasisSet.Phys.Rev.B:Condens.MatterMater.Phys.1996,54,11169−11186.(60)Blöchl,P.E.ProjectorAugmented-WaveMethod.Phys.Rev.B:Condens.MatterMater.Phys.1994,50,17953−17979.(61)deP.R.Moreira,I.;Illas,F.;Martin,R.L.EffectofFockExchangeontheElectronicStructureandMagneticCouplinginNiO.Phys.Rev.B:Condens.MatterMater.Phys.2002,65,155102.(62)Dagotto,E.CorrelatedElectronsinHigh-TemperatureSuper-conductors.Rev.Mod.Phys.1994,66,763−840.(63)Schlexer,P.;RuizPuigdollers,A.;Pacchioni,G.TuningtheChargeStateofAgandAuAtomsandClustersDepositedonOxideSurfacesbyDoping:ADFTStudyoftheAdsorptionPropertiesofNitrogen-andNiobium-DopedTiO2andZrO2.Phys.Chem.Chem.Phys.2015,17,22342−22360.(64)Puigdollers,A.R.;Schlexer,P.;Pacchioni,G.GoldandSilverClustersonTiO2andZrO2(101)Surfaces:RoleofDispersionForces.J.Phys.Chem.C2015,119,15381−15389.(65)Djerdj,I.;Tonejc,A.M.;Tonejc,A.StructuralRefinementofNanocrystallineTiO2Samples.ElectronCrystallography2006,211,497−501.(66)Henkelman,G.;Jónsson,H.ImprovedTangentEstimateintheNudgedElasticBandMethodforFindingMinimumEnergyPathsandSaddlePoints.J.Chem.Phys.2000,113,9978−9985.(67)Henkelman,G.;Arnaldsson,A.;Jónsson,H.AFastandRobustAlgorithmforBaderDecompositionofChargeDensity.Comput.Mater.Sci.2006,36,354−360.(68)Wan,W.;Nie,X.;Janik,M.J.;Song,C.;Guo,X.Adsorption,Dissociation,andSpilloverofHydrogenoverAu/TiO2Catalysts:TheEffectsofClusterSizeandMetal-SupportInteractionfromDFT.J.Phys.Chem.C2018,122,17895−17916.6672https://doi.org/10.1021/acs.jpcc.1c00391J.Phys.Chem.C2021,125,6660−6672