Interface Engineering of Monolayer MoS2／GaN Hybrid Heterostructure：Modified Band Alignment for Photocatalytic Water Splitting Ap.docx

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1、InterfaceEngineeringofMonolayerM0S2/GaNHybridHeterostructure：ModifiedBandAlignmentforPhotocatalyticWaterSplittingApplicationbyNitridationTreatmentZhaofuZhang,+flQingkaiQian,”BaikuiLi/andKevinJ.Chen*,+DepartmentofElectronicandComputerEngineering,TheHongKongUniversityofScienceandTechnology,ClearWaterB

2、ay,Kowloon,HongKongtCollegeofOptoelectronicandComputerEngineering,ShenzhenUniversity,Shenzhen51806(),China*SupportingInformationABSTRACT:Interfaceengineeringisakeystrategytodealwiththetwo-dimensional(2D)/three-dimensional(3D)hybridhctcrostructurc,sincethepropertiesofthisatomiclaycr-thick2Dmaterialca

3、neasilybeimpactedbythesubstrateenvironment.Inthiswork,thestructural,electronic,andopticalpropertiesofthe2D/3DheterostructureofmonolayerM0S2onwurtziteGaNsurfacewithoutandwithnitridationinterfaciallayeraresystematicallyinvestigatedbyfirstprinciplescalculationandexperimentalanalysis.Thenitridationinter

4、faciallayercanbeintroducedintothe2D/3DhctcrostructurcbyremoteN2plasmatreatmenttoGaNsamplesurfacepriortostackingmonolayerM0S2ontop.Thecalculationresultsrevealthatthe2D/3Dintegratedheterostructureisenergeticallyfavorablewithanegativeformationenergy.Bothinterfacesdemonstrateindirectbandgap,whichisabene

5、fitfbrlongerlifetimeofthephotocxcitcdcarriers.Meanwhile,theconductionbandedgeandvalencebandedgeoftheMoSisideincreasesafternitridationtreatment.ThemodificationtobandalignmentisthenverifiedbyX-rayphotoelectronspectroscopymeasurementonMoS/GaNhctcrostructurcsconstructedbyamodifiedwet-transfertechnique,w

6、hichindicatesthattheMoSz/GaNheterostructurewithoutnitridationshowsatype-TIalignmentwithaconductionbandoffset(CBO)ofonly0.07eV.However,bythedeploymentofinterfacenitridation,thebandedgesofM0S2moveupwardfbr00.5eVasaresultofthenitridizedsubstrateproperty.ThesignificantlyincreasedCBOcouldleadtobetterelec

7、tronaccumulationcapabilityattheGaNside.Thenitridized2D/3Dheterostructurewitheffectiveinterfacetreatmentexhibitsacleanbandgapandsubstantialopticalabsorptionabilityandcouldbepotentiallyusedaspracticalphotocatalystfbrhydrogengenerationbywatersplittingusingsolarenergy.KEYWORDS:nitridationeffects,GaNsurf

8、ace,monolayerM0S2,heterostructurephotocatalyst,bandalignmentholescanbeeffectivelyseparatedinatype-IIalignmenthctcrostructurcwithreasonablebandoffsetvalues,leadingtoseparatedhydrogenandoxygengenerationattheoppositesideoftheheterostructure.Suchanapproachcaneffectivelyimprovethewatersplittingefficiency

9、.energy generation, since H2 could be produced directly fromwater by exposing to sunlight.1 2 * For high-efficiencyWurtziteGaNisawidebandgapsemiconductorofconsiderableinterestfbrradiofrequency(RF)poweramplifiersandpowerswitchingapplicationsphotocatalysts in solar energy conversion application,severa

10、l critical requirements should be satisfied, such assuitable band gap value and reasonable positions of theconduction band minimum (CBM) and valence bandmaximum (VBM) with respect to the water redoxpotentials?-4 * To reasonably design material fbr feasibleapplications, one of the practicable strateg

11、ies is to constructheterostructure photocatalysts that possess electronic andoptical properties beyond those offered by the individualconstituent parts/ since the band gap width and band gappositions could be effectively modulated once thehctcrostructurc is formed. Meanwhile, the photocxcitcdelectro

12、ns andaswellasoptoelectronicdevices/Inthepastdecades,therehavebeenseveralattemptstodeployGaNfbrphotocatalyticwatersplittingapplicationsconsideringGaNsexcellentchemicalandthermalstabilitiesaswellashighthermalconductivity.10Besides,thetunablebandgapofgroupIII-nitridccompoundsemiconductorsspansnearlyth

13、eentiresolarspectrumandhasabandedgepotentialthatstraddlesbetweenredoxpotentialofReceived:January23,2018Accepted:April30,2018Published:April30,2018ACSPublications2018AmericanChemicalSocietyACS ADolied Materials & InterfacesResearch Article?，9SSJ。1/52SousuacEnergy(eV)17420 DOI: 10.1021/acsami.9b01286A

14、CS AppL Mater. Interfaces 2018r 10,17419-17426Figure1.(a,d)Atomicstructures,(b,c)bandstructures,and(c,f)densityofstatesofmonolayerM0S2(top)andwurtziteGaNsurface(bottom).Yellow,purple,green,andgrayballsrepresentS,Mo.Ga,andNatoms,respectively.ThesurfacestatesinGaNsurfacearchighlightedinredcurves.water

15、.111Nevertheless,therelativelargebandgapwidthconstraintsthefiuitfiilimplementationinthevisiblelightenvironment.Tobetterutilizethevisiblelightwavelengthrange,severalgroupsreportedconstnictingGaNheterostructureswithlow-dimensionalmaterials,suchasM0S2andWSe2,1416motivatedbythesmalllatticemismatchandexcellentabsorptioncapabilityofthetwo-dimensional(2D)materials.17However,thereportedGaN/2Dheterostructuresallemploythegraphene-likeCiaNinthe2Dphase,whichisnotpracticalfbrnear-termapplicationdespitealreadyexperimentallysynthesized.IsInGaNdevicecommu