西北師大光催化二氧化鈦課件

報告人：安寧單位：生態(tài)環(huán)境相關(guān)高分子材料教育部重點實驗室日期：2012年11月17日文獻閱讀匯報

Semiconductor-mediatedphotodegradationof

pollutantsundervisible-lightirradiation

Chem.Soc.Rev.,2010,39,4206–4219Theadsorbeddyeorothercolorspeciescanabsorbvisiblelighttobeexcited.Theexcitedspeciescaninjectelectronsintotheconductionbandofthesemiconductor,formingconductionbandelectrons(ecb-)andtheoxidizedantennamoleculestorealizethechargeseparation(2)and(3).1.IntroductionTheabsorptionofaphotonwithenergylargerthanthebandgapofthesemiconductorcanexciteanelectronfromthevalencebandtotheconductionband.Thisband–bandexcitationproducesthereductiveconductionbandelectrons(ecb-)andoxidativevalencebandholes(hvb+).超氧自由基負(fù)離子能壘很小的反應(yīng)(1)itpossessessuitableredoxpotentialsofconductionbandandvalencebandtoensurethesimultaneousreductionofO2andoxidationoftheH2Oororganiccompounds;(2)Italsohasmanydesirablepropertiesasenvironmentalphotocatalysts,suchashighefficiency,readyavailability,non-toxicity,andhighchemicalstability.TiO2：(1)在有氧氣的環(huán)境下，當(dāng)照射可見光TiO2會分解染料(eqn10).(2)在染料同時生成的有機自由基和活性氧會吸引其他共存的有機污染物，并將他們分解(eqn11).(3)通過染料改性的催化劑可以在可見光下分解無色的有機污染物同時自身的有顏色的有機集團在反映后不會發(fā)生分解和變色(eqn12).(4)有機鹵化物可以被注入的電子還原發(fā)生脫鹵素反應(yīng)(eqn13).

2.3MechanisticcharacteristicsofSMPD

PhotogeneratedHoles

2.4RoleofthesemiconductorinSMPD

b:從有機染料注入的電子轉(zhuǎn)向半導(dǎo)體表面；c:電子被捕獲；d:電子與電子受體發(fā)生反應(yīng)；e:電子克服能壘從捕獲陷阱中出來；f:反向轉(zhuǎn)移到被氧化的有機染料上(A)TiO2

表面的羥基與染料的羧基發(fā)生酯化作用。(B)鄰位的兩個羥基與氧原子形成二配位的螯合共價鍵。3.1.2PerformanceofthedegradationofdyepollutantsbySMPD.Rateofdecolorization

ExtentofmineralizationtoCO2,H2OandotherinorganicspeciesFormationofintermediatesandproductsThedegradationprocessofthedyescanbecharacterizedbyseveralparameters

3.3Effec