梯型多孔gC3N4Zn02Cd08SDETA复合材料的合成及其高效稳定光催化产氢性能

梯型多孔梯型多孔gC3N4Zn02Cd08SDETAgC3N4Zn02Cd08SDETA复合材料的合成及其高效稳复合材料的合成及其高效稳 定光催化产氢性能定光催化产氢性能 Chinese Journalof Catalysis41 2020 41 49催化学报2020年第41卷第1期 cjcatal availableat sciencedirect journalhomepage elsevier locate chnjc Article Special Issueon Photocatalytic H2Production andCO2Reduction Step scheme porous g C3N4 Zn0 2Cd0 8S DETA positesfor efficientand stablephotocatalytic H2production Feifei Mei a Zhen Lia Kai Daia Jinfeng Zhanga Changhao Liangb a College of Physics and ElectronicInformation Anhui Key Laboratory of Energetic Materials Huaibei NormalUniversity Huaibei235000 Anhui China bKeyLaboratory of MaterialsPhysics andAnhui KeyLaboratoryofNanomaterials and Nanotechnology Institute ofSolid StatePhysics Hefei Institutesof PhysicalScience Chinese Academyof Sciences Hefei230031 Anhui China AR TI CL EI NF OA BS TR AC TArticle history Received8April2019Aepted1May2019Published5January20 20In recentyears environmental pollutionand energycrisis havebee increasinglyserious issuesowing to the burning of fossil fuels Among themany technologies deposition ofwater topro duce hydrogenhas attractedmuch attentionbecause ofits sustainabilityand non polluting charac teristic However highly efficientdeposition ofwater thatis drivenby visible light isstill achal lenge Herein we reportthe large scale preparationof step scheme porousgraphite carbonni tride Zn0 2Cd0 8S diethyleriamine Pg C3N4 Zn0 2Cd0 8S DETA posite by a facilesolvothermal method It wasfound byUV vis spectroscopythat15 Pg C3N4 Zn0 2Cd0 8S DETA exhibitedsuitable visibleabsorption edgeand band gap forwater deposition The hydrogen production rateof15 Pg C3N4 Zn0 2Cd0 8S DETA posite was6 69mmol g 1h 1 which was16 73 1 61 and1 44times greaterthan those of Pg C3N4 CdS DETA and Zn0 2Cd0 8S DETA respectively In addition 15 Pg C3N4 Zn0 2Cd0 8S DETA positedisplayed excellentphotocatalytic stability which wasmaintained forseven cycles of photocatalyticwater splittingtest We believethat15 Pg C3N4 Zn0 2Cd0 8S DETA positecan bea valuableguide for the developmentof solarhy drogenproductionapplications in the nearfure 2020 Dalian Instituteof ChemicalPhysics Chinese Academyof Sciences Published by Elsevier B V All rightsreserved Keywords Pg C3N4Zn0 2Cd0 8S DiethyleriaminePhotocatalysis Step scheme porousposite1 Introduction Nowadays a greenand cleanenergy source is urgentlysought owing to insufficientfossilfuelreserves andpollution problems 1 4 Hydrogen H2 is anextremely cleanenergy source and theonly substancethat burnsin airis watervapor Furthermore solar energyis an inexhaustible sourceof energy Therefore photocatalytic H2evolution is a potentialresearch field 5 9 To date many semiconductorssuch asmetal selenides 10 14 metal sulfides 15 19 carbon nitrides 20 21 and metaloxides 22 26 have beenreported forpho tocatalytic H2production It isworth notingthat CdSis widelystudied owing to its suitable band gap about2 4eV and bandedge which resultin thematerial exhibitinggood performanc es under visible light irradiation However a singlelayer of CdS displaysa highcarrier rebinationrate underlightirradia tion 27 which resultsin seriousphoto corrosion In orderto solvethis problemof CdS many methodshave been developed rrg Fax 86 561 3803256 E mail daikai940 chnu Corresponding author ail jfzhang chnu Corresponding author E mail chliang issp ac Thiswork wassupported bythe NationalNatural SciceFoundation of China 51572103 51502106 the DistinguishedYoung Scholarof Anhui Province 1808085J14 the Foundationfor YoungTalents inCollegeofAnhui Province gxyqZDxx051 the KeyFoundation ofEducational Com mission ofAnhuiProvince KJxxSD53 and InnovationTeam ofDesign andApplication ofAdvanced EnergeticMaterials KJxxTD003 DOI S1872 2067 19 63389 9 sciencedirect science journal 18722067 Chin J Catal Vo l 41 No 1 January202042Feifei Meiet al Chinese Journalof Catalysis41 2020 41 49including theconstruction ofheterojunctions with other semi conductors 28 30 formation ofsolid solutions 31 32 and depositionof preciousmetals 33 35 Many isomorphouscrystals producehomogeneous andvariable positionsolid solutions When a wide band gap semiconductorand anarrow bandgap semiconductorform asolid solution 36 37 a novelphotocatalyst with a continuous ly varyingbandgapcan beprepared In recentyears solid so lutions have been extensivelystudied because of theirexcellent performancesundervisible light irradiation 38 40 Zinc sul fide ZnS exhibits goodphotocatalytic activityand stabilityowing toits highconduction bandenergy position 41 42 However ZnS has awidebandgap of about3 5eV and canonly beexcited withultraviolet light Therefore introduction of Zn ionsinto CdSto formZn1 x Cdx Ssolid solutionscan bihe photostability of ZnS and the photocatalytic activity of CdS More importantly the bandstructure can be adjustedby changing the molarratio of Zn to Cd In recentyears organic inorganic hybridmaterials haveplayed ahuge rolein photocatalysis As asmall organicmole cule diethyleriamine DETA can beprotonated bysol vothermal reactionwith waterunder highpressures toform positivelycharged amine ions 43 The protonatedamineionsform anorganic inorganic hybridmaterial bycoordination with anions Our grouphas synthesizedZn1 x Cdx S DETA withdifferent band gaps bya simpleone step solvothermal method 44 The organic inorganic hybridmaterial can not onlyadjust themorphology but alsoimprove theirphotocatalytic perfor mance Therefore solid solutionshavgreat research prospects inphotocatalysis Although thesingle solidsolution improvedthe photocatalytic performance its stabilitydecreased afterrepeated cycles of experiments In orderto overethis shorting some researcershave previouslyconstructed heterojunctions withother semiconductors such asCdSe Zn xCd1 x S 45 Fe2O3 Zn0 4Cd0 6S 46 and ZnCdS CdS 47 Graphite carbonnitride g C3N4 asatwo dimensional ma terial is widelystudied becauseit ischeap non toxic and dis plays goodphotostability 48 50 Metal free g C3N4can beexcited withvisiblelightbecauseofitssuitablebandgap about2 83eV an d itsconduction bandposition issufficiently nega tive 1 28eV 51 54 Based on the abovepoints g C3N4has greatresearchprospectsin thefield of photocatalytic H2pro duction 55 56 The shortingis that the photogeneratedcarriers of single g C3N4can easilyrebine which hindersits practicalapplication Some strategiessuch asdoping other elements 57 58 loading cocatalysts 59 61 tuning themor phology and formingheterojunctionswithothersemiconduc tors havebeendevelopedto addressthis issue 62 66 We obtainedporousg C3N4 Pg C3N4 by thermaldeposition ofthiourea andurea Compared withthat ofg C3N4 Pg C3N4 with aporous structure exhibits a larger specificsurface area In addition these poresprovide internalchannels thataelerate thecarrier migration This offersthe possibilityof practicalapplication of Pg C3N4 In ourwork we suessfullydeveloped aheterojunction between Pg C3N4and Zn0 2Cd0 8S DETA byan in situ sol vothermalmethod The H2evolution activityof Pg C3N4 Zn0 2Cd0 8S DETA positewas alsostudied The resultsshow that the Pg C3N4 Zn0 2Cd0 8S DETA positesdisplay en hanced H2production activitiesand stabilities pared to thoseofother catalysts Among them 15 Pg C3N4 Zn0 2Cd0 8S DETA shows the bestphotocatalytic activityand stability Specifically it maintainsits excellentactivity after seven cycles The improvementin the photocatalytic activityis attributed to theformation ofa step scheme heterojunctionbetween Pg C3N4and Zn0 2Cd0 8S DETA 2 Experimental2 1 Materials Urea zinc chloride ZnCl2 sulfourea sodium sulfide Na2S sublimed sulfur S chloroplatinic acid H2PtCl6 and DETA were obtainedfrom Sinopharm P R China Absolute ethylalcohol sodium sulfate Na2SO4 polyethylene glycol cadmium chloride CdCl2 2 5H2O Nafion and sodiumsulfite Na2SO3 were providedby ShanghaiChemical ReagentCo Ltd P R China Deionized water DW 18 25M was usedin theex periments 2 2 Preparation of Pg C3N4First urea andthiourea weremixed inmortar atthe ratioof3 1and continuouslyground Thereafter the mixture was placed in amuffle furnace and heatedto550 C for2h Then the samplewas naturallycooled toroom temperature and finally Pg C3N4was obtained 2 3 Preparation ofX Pg C3N4 Zn0 2Cd0 8S DETA positesX Pg C3N4 Zn0 2Cd0 8S DETA X 5 10 and15 posites weresynthesized byanin situ growthmethod First different gradesof Pg C3N4were addedto thereactor followed bythe addition of0 0489g ZnCl2 0 328g CdCl2 24mL DETA and12mL DW Thereafter 0 256g Swas addedto themixed liquidd stirredwell for3h then the reactionkettle wasplaced inan ovenand heatedat80 C for48h After cooling the po sitewaswashed severaltimes withDW and the Pg C3N4 Zn0 2Cd0 8S DETA system was obtainedby freezedry ing 2 4 Characterization Thecrystal structures of Pg C3N4 Pg C3N4 Zn0 2Cd0 8S DETA system and Zn0 2Cd0 8S DETA wereinvestigated byXRD Rigaku D MAX24000 TEM JEM 2100electron microscope was usedto determihe particlesizes andstructuresof the samples The chemicalpositions of the sampleswere de teined byXPS Thermo ESCALAB250 and Fouriertrans form infraredspectroscopy FT IR NICOLET6700 Moreover UV vis diffusereflectance spectroscopy DRS measurement wereperformed byusing aPerkinElmer Lambda950UV vis spectrophotometer The PLspectra of Pg C3N4 15 Pg C3N4 Feifei Meiet al Chinese Journalof Catalysis41 2020 41 4943Zn0 2Cd0 8S DETA and Zn0 2Cd0 8S DETAwereacquired byFLS920bined fluorescencelife timemeasurements The photoelectrochemicalmeasurements wereperformed ona ShanghaiChenhua CHI 660D electrochemicalsystem The elec trolyte solution was1 0mol L Na2SO4 In addition 0 05gof the catalystsamples wasmixed with50 L5 Nafion and0 5mL ethylalcohol toform aslurry The slurrywas injectedinto a1 cm2ITO conductiveglass electrodeand driedfor30min at60 C 2 5 Evaluation of the photocatalytic activity The photocatalytic H2production experimentwas carriedout ina250mL flask with three necks First 50mg ofa sample 100mL of0 25mol L Na2SO3 and asolution mixedwith0 35mol L Na2Sand300 L H2PtCl6 0 6wt were placed in theflaskwiththreenecks Then the mixture was dispersedby ultrasoundfor30min andstirred foranother30min The sys temwasbubbled withnitrogen for30min underdark condi tions Finally a300W Xe lamp witha420nm cut off filterwas usedfortheirradiation The distancebetween theXelampand thereactor was5cm The amount of H2produced byillumina tionwasmeasured bygas chromatography GC 7900 3 Results anddiscussion Fig 1shows thesynthetic processof15 Pg C3N4 Zn0 2Cd0 8S DETA First a certainamount ofurea andthiourea weremixed inmortar forgrinding The groundmixturewasplacedina crucible which wasthen transferredthe mufflefurnaceandannealed at550 C fortwo hoursto producePg C3N4 Thereafter a certainamount of Pg C3N4was addedto polytetrafluoroethylenelinerspecific amountsof DETA sublimed S cadmium chloride and zinhloride wereadded After themixturewasstirred ina Teflonliner for3h the linerwas transferred to astainless steelreactor andplacedinan ovenfor48h ata temperatureof80 C and finally 15 Pg C3N4 Zn0 2Cd0 8S DETA wasobtained In orderto furtherinvestigate the phases of the synthesizedphotocatalysts we performedXRD onall the photocatalysts The XRD patterns of Pg C3N4and X Pg C3N4 Zn0 2Cd0 8S DETA are shown in Fig 2 Furthermore thephasesof Zn0 2Cd0 8S DETA and Pg C3N4havebeenidentified byprevious work and areshown in Fig 2 It iseasy tosee that5 Pg C3N4 Zn0 2Cd0 8S DETA 15 Pg C3N4 Zn0 2Cd0 8S DETA and25 Pg C3N4 Zn0 2Cd0 8S DETA allexhibit the peaks of Zn0 2Cd0 8S DETA which indicatethat allthe positescontain Zn0 2Cd0 8S DETA In addition the main 002 peak ofX Pg C3N4 Zn0 2Cd0 8S DETA graduallygrows andresembl of Pg C3N4with theincrease inX value which indicatesthat Pg C3N4is presentin the posite From this it canbe concluded that X Pg C3N4 Zn0 2Cd0 8S DETA containsboth Pg C3N4and Zn0 2Cd0 8S DETA To furtherexplore themicromorphology ofeach photocata lyst we alsoinvestigatethe samplesby meansof TEM HRTEM EDS mapping and SEM As canbe seenclearly in Fig 3a Pg C3N4is an ultrathin porousnanosheet witha holeof20 50nm In Fig 3b Zn0 2Cd0 8S DETA exhibitsa nanoflowerstructure witha sizeof about300nm and thepetals of the nanoflowersexist inanultrathinstate It canbe clearlyseen from Fig 3c that the surfaceof theultrathin andporous Pg C3N4is filledwith Zn0 2Cd0 8S DETA nanoflowers It canalso be seen fromFig 3dthat the spacingsof Pg C3N4and Zn0 2Cd0 8S DETA are0 33and0 35nm respectively Addition ally in Fig 3d the redcurve on the leftside clearlyshowstheheterojunction formedbetweenPg C3N4and Zn0 2Cd0 8S DETA This indicatesthat the15 Pg C3N4 Zn0 2Cd0 8S DETA materialwe synthesized isaresult of the binationof Pg C3N4and Zn0 2Cd0 8S DETA and not a mixtureof twopure substances Fig 3e isa SEM image of15 Pg C3N4 Zn0 2Cd0 8S DETA Fig 3f showsthe EDS pattern of15 Pg C3N4 Zn0 2Cd0 8S DETA The EDSpattern showsthat theposites wesynthesized containonly C N O Zn Cd and S elements and noother impurities The elementalmaps areshown in Fig 3g 3l It isobvious that the15 Pg C3N4 Zn0 2Cd0 8S DETA positecontains C N O Zn Cd and Selementsand that the elementsare evenlydistrib uted The XPSpatterns areshown in Fig 4 Fig 4a reveals the measured spectra of Zn0 2Cd0 8S DETA Pg C3N4 and15 Pg C3N4 Zn0 2Cd0 8S DETA Zn0 2Cd0 8S DETA showsthe presence ofC1s O1s N1s Zn2p Cd3d and S2p elementswithout other impurities Pg C3N4revealsthe presenceofC1s N1s and O1s elements and nootherelementswere detected Among them the Oelement foundin Pg C3N4may haveorigi Fig 1 Schematic diagramof theformation of15 Pg C3N4 Zn0 2Cd0 8S DETA posite 1020304050607080 2Theta degree Intensity a u Pg C3N4Zn0 2Cd0 8S DETA25 Pg C3N4 Zn0 2Cd0 8S DETA15 Pg C3N4 Zn0 2Cd0 8S DETA5 Pg C3N4 Zn0 2Cd0 8S DETA Fig 2 XRD patterns of Pg C3N4 Zn0 2Cd0 8S DETA Zn0 2Cd0 8S DETA and Pg C3N4 44Feifei Meiet al Chinese Journalof Catalysis41 2020 41 49nated from the oxygenin theair 15 Pg C3N4 Zn0 2Cd0 8S DETA showsthe presenceofC1s O1s N1s Zn2p Cd3d and S2p elements and nootherimpuritieswere de tected which indicatethe purityof thesubstance High resolution XPSC1s patternsareshown in Fig 4b 15 Pg C3N4 Zn0 2Cd0 8S DETA displaystwo main peaks which ardue to theinclusion of Pg C3N4 67 However the peak onthe right sideis larger which is attributed tothe highcontent of Zn0 2Cd0 8S DETA Moreover the mainpeak of15 Pg C3N4 Zn0 2Cd0 8S DETA wasshifted relativeto that of Pg C3N4 Fig 4c showsthe high resolution XPSN1s spectra Among them 15 Pg C3N4 Zn0 2Cd0 8S DETA exhibitsa largerpeak onthe leftside anda smallerpeakonthe rightside which isdue tothe highercontent of Zn0 2Cd0 8S DETA However thepeakintensity ontherightside of15 Pg C3N4 Zn0 2Cd0 8S DETA ishigher thanthat of Zn0 2Cd0 8S DETA which isascribed tothe smallamount ofPg C3N4in theposite 68 In addition the mainpeak of thepositereveals adifferent degreeof shift Fig 3 TEM images of a Pg C3N4 b Zn0 2Cd0 8S DETA and c 15 Pg C3N4 Zn0 2Cd0 8S DETA d HRTEM imageof15 Pg C3N4 Zn0 2Cd0 8S DETA e SEMimageand f EDSpatternof15 Pg C3N4 Zn0 2Cd0 8S DETA g l Elemental mappingimagesof15 Pg C3N4 Zn0 2Cd0 8S DETA correspondingtoC N O Zn Cd andS 1xx0008006004002000Cd3dN1s N1sCd3dN1s15 Pg C3N4 Zn0 2Cd0 8S DETAPg C3N4aO1sO1sO1sC1sZn2p C1sS2p S2pZn2pC1sZn0 2Cd0 8S DETABinding energy eV Intensity a u 294291288285282Pg C3N4288 39eV284 84eV284 87eVC1sb15 Pg C3N4 Zn0 2Cd0 8S DETABinding energy eV Intensity a u 287 17eV40840640440240039839639439 8 32eV15 Pg C3N4 Zn0 2Cd0 8S DETAPg C3N4404 82eV400 81eV398 95eVN1s cBindingenergy eV Intensity a u 403 63eV104810401032102410 1615 Pg C3N4 Zn0 2Cd0 8S DETA1021 04eV1044 06eV1020 77eV1043 79eVZn0 2Cd0 8S DETAIntensity a u dBinding energy eV Zn2p41641240840415 Pg C3N4 Zn0 2Cd0 8S DETA403 52eV410 25eVCd3dZn0 2Cd0 8S DETA410 31eV403 58eVBinding energy eV Intensity a u e164162160158159 77eV160 94eVS2p15 Pg C3N4 Zn0 2Cd0 8S DETAZn0 2Cd0 8S DETAIntensity a u 159 99eV161 16eVBinding energy eV f Fig 4 XPS spectraof theas prepared photocatalysts a Overview b C1s c N1s d Zn2p e Cd3d f S2p Feifei Meiet al Chinese Journalof Catalysis41 2020 41 4945pared withthat ofthe mainpeak ofthe puresubstance From echanges in the C1sandN1s bindingenergies it canbe seenthat thecurrent densityofPg C3N4is increased and itis con cluded thatelectrons flowfrom Zn0 2Cd0 8S DETA toPg C3N4 69 Fig 4d showsa high resolution XPSZn2p spectra The two main peaks of15 Pg C3N4 Zn0 2Cd0 8S DETA areshifted byabout0 27eV relativeto thoseof Zn0 2Cd0 8S DETA Fig 4eishigh resolution XPSCd3dspectra The two main peaks of15 Pg C3N4 Zn0 2Cd0 8S DETA areshifted byabout0 06eV relativeto thoseof Zn0 2Cd0 8S DETA As shownin Fig 4f the S2p patterncanbefitted withtwomainpeaks and thetwomainpeaksof15 Pg C3N4 Zn0 2Cd0 8S DETA areshifted byabout0 22eV withrespect tothosof Zn0 2Cd0 8S DETA This furtherproves theconclusion madeabove In Fig 4b 4f the mainpeaksofthe15 Pg C3N4 Zn0 2Cd0 8S DETA positereveal differentdegrees ofshift relativetothoseof purePg C3N4or Zn0 2Cd0 8S DETA which suggestthattheposite wesynthe sizedisnotasimple mixtureof twopure substances In orderto investigatethe light absorptions ofthe pureand positematerials we conductedUV vis DRSstudies As shownin Fig 5a the absorptionedges of Zn0 2Cd0 8S DETA andPg C3N4are about521and449nm respectively A reductionin the lightabsorptionat320 380nm canbe observedin allthe prepared samples The reason is thatthe instrumentis chang ingthelight The correspondingbandgapsare2 45and2 85eV respectively Fig 5b In Fig 5a the absorptionedge of5 Pg C3N4 Zn0 2Cd0 8S DETA issimilar tothat of Zn0 2Cd0 8S DETA This isduetothe lowcontent ofPg C3N4 which willnot signif icantly affectthe opticalabsorption propertiesof Zn0 2Cd0 8S DETA However with theincrease inPg C3N4con tent the absorptionedge ofPg C3N4 Zn0 2Cd0 8S DETA po site shiftsto bluewavelengths which isattributed tothe lowabsorption capacityofPg C3N4 Fig 5b presentslinear trans formations ofthe Pg C3N4and Zn0 2Cd0 8S DETA absorptioncurves As canbe seenfromFig 5b the bandgaps ofPg C3N4and Zn0 2Cd0 8S DETA are2 83and2 48eV respectively Th conductionband CB and valenceband VB energy levelsare givenbyE VB X E c 0 5E g 1E CB EVB E g 2 Here the value