Study On The Synthesis Of 2,4,6-tris (1-imidazolyl)-1,3,5-triazine-based Polyoxometalate Hybrid Compounds And Its Photodegradation Properties

Polyoxometalates(POMs)as an effective green photocatalysts for the reduction of environmental pollution haveattracted immense interest during the last few decades due to their excellent photochemical nature.However,there are several drawbacks thatrestrict their use as efficient photocatalysts in multi-electron reactionsdegradation of recalcitrant organicpollutants.First,POMs are very soluble in water and polar solvents.Second,Keggin-type tungsten-based POM,can only utilize ultraviolet light in sunlight.The introduction of organic photosensitizers,reacting with POMs to form an organic and inorganic hybrid,has been shown to be a promisingapproach to stabilize,also to achieve increase its catalytic activity in the visible light.Therefore,looking for a suitable photosensitizer attracts people's attention.In this paper,yellow organics 2,4,6-tris(1-imidazolyl)-1,3,5-triazine(TIT)was selected as the photosensitizer.reacting with the Keggin type phosphotungstic acid and silicon tungsten acidunder the conventional solution conditions and under simple coprecipitationrespectively.Twohybrids based on Keggin-type polyoxometalate have been successfully obtained:TITH-PW12 ? TITH-SiW12.In this communication,the activity of twohybrids under visible light was evaluated usingthe photocatalytic transformation of methyl orange solution(MO)in aqueousmedia withoutoxygen.In addition,their catalytic degradation mechanism was also discussed.The experimental results show that,POMswas intact during the precipitation process.At the same time,the hybridspresentadditionalabsorption bands in the visible region.Under the irradiation of visible light,the hybrids could completely degrade the methyl orange(MO)solution without any oxygen.Thecatalyst can be easily separated from the reaction system and has good stability for reuse.The kinetics of the photodecomposition follow the first-order reaction.It was also found that the catalytic activity of the formed complex did not change significantly when the same photosensitizer was used and the Keggin type POM was different.Therefore,the choice ofphotosensitizer plays an important role in degrading dyes.