| Up-conversion materials are special optical function materials convertinglow-energy photons to high-energy photons. Converting visible light to UV-light is ofgreat significance to the utilization of sunlight. At present, TiO2which is mostly used inthe photocatalysis field is non-toxic, harmless, and environmentally friendly. The energygap of TiO2is3.2eV, so it is difficult to respond stimulation of visible light and can notmake full use of solar energy. Therefore, implementation of up-conversion materials inTiO2and its modified system has important theoretical significances and practicalvalues on improving photocatalytic performances.Preparation of up-conversion materials and their application in TiO2/ZnO compoundphotocatalytic system were researched, with Er （a rare earth element） as up-conversionexcitant and oxide TiO2and fluoride CaF2as base materials, with the use of sol-gelmethod.1.The absorption strength of TiO2/ZnO compound powder to visible light andUV-light was higher than that of TiO2powder and ZnO powder.2.As for the up-conversion material TiO2(Er3+) gained through mixing Er3+andTiO2, the mix of Er3+didn’t influence the structure of TiO2. TiO2(Er3+) may presentedtwo ultraviolet emission peaks, namely349nm and363nm, when exposed under thevisible light of482nm, which indicates that such material can converted low-energyphotons to high-energy photons.3.As for the up-conversion material TiO2(Er3+) gained through mixing Er3+andCaF2, there were two stronger UV-light emission peaks （332nm and377nm） under thestimulation of visible light, which indicates that common alkaline-earth metal fluorideswere also good base materials of up-conversion materials. 4.Compound up-conversion materials gained through mixing (Er3+) into CaF2andTiO2had emission peaks of TiO2(Er3+) and CaF2(Er3+), but light intensity was reduced.5.The results for photocatalytic degradation formaldehyde with the use ofup-conversion material-TiO2/ZnO composite film test and verify that such material wasbetter than TiO2, ZnO, and TiO2/ZnO system in photocatalytic performances. TiO2/ZnOcomposite oxide and calcium fluoride system mixed with Er possesUp-conversion performances, which can convert low-energy photons to high-energyphotons, improve utilization efficiency of visible light, and enhance photocatalyticperformances of photocatalyst. |
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