西北師大光催化二氧化鈦課件

報(bào)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(diǎn)實(shí)驗(yàn)室日期：2012年11月17日文獻(xiàn)閱讀匯報(bào)

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(jiàn)光TiO2會(huì)分解染料(eqn10).(2)在染料同時(shí)生成的有機(jī)自由基和活性氧會(huì)吸引其他共存的有機(jī)污染物，并將他們分解(eqn11).(3)通過(guò)染料改性的催化劑可以在可見(jiàn)光下分解無(wú)色的有機(jī)污染物同時(shí)自身的有顏色的有機(jī)集團(tuán)在反映后不會(huì)發(fā)生分解和變色(eqn12).(4)有機(jī)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(jī)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(lái)；f:反向轉(zhuǎn)移到被氧化的有機(jī)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(gè)羥基與氧原子形成二配位的螯合共價(jià)鍵。3.1.2PerformanceofthedegradationofdyepollutantsbySMPD.Rateofdecolorization

ExtentofmineralizationtoCO2,H2OandotherinorganicspeciesFormationofintermediatesandproductsThedegradationprocessofthedyescanbecharacterizedbyseveralparameters

3.3Effec