Effect of morphology of anatase TiO2 nanoparticles on their photocatalytic performance
Anatase TiO2 nanoparticles with gradually increasing aspect ratio of granular and rod-shaped morphology were synthesized by a gel-sol method with titanium isopropoxide as titanium source and triethanolamine as stabilizer by adding different pH regulators.Through the photocatalytic degradation of cationic dyes methylene blue(MB),malachite green(MG),Rhodamine B(RB)and anionic dyes methyl orange(MO)and Congo red(CR)by the use of TiO2 nanoparticles with different morphologies under excitation of a UV lamp,the influence of the morphology of TiO2 on its photocatalytic performance was investigated.The results showed that with the increase of the aspect ratio of TiO2 nanoparticles,the photocatalytic efficiency for alkaline cationic dyes increased,while for acid anionic dyes it decreased.Among cationic dyes,the degradation rate of MG is the most significant,reaching as high as 100％within 2 h of irradiation of the ultraviolet light.Among anionic dyes,CR has suffered the strongest influence and the degradation rate of CR reaches 68.0％in the same period.By comparing the morphology of the TiO2 catalysts,it can be concluded that the ratio of c-plane in each crystal surface of TiO2 nanoparticles determines the selective adsorption of dyes on TiO2 nanoparticles,thus affecting its photocatalytic performance.In addition,the difference among the degradation rate of dyes with the same type is probably related to the structure of the dye itself.
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