锐钛矿型TiO_(2)纳米粒子的形态对其光催化性能的影响

Effect of morphology of anatase TiO_(2)nanoparticles on their photocatalytic performance

以异丙醇钛为钛源、三乙醇胺为稳定剂,采用凝胶-溶胶法通过改变体系的pH值合成了从颗粒状到棒状形态径向比逐渐增大的锐钛矿型TiO_(2)纳米粒子。通过不同形态的TiO_(2)在紫外灯下光催化降解阳离子型染料亚甲基蓝(MB)、孔雀石绿(MG)、罗丹明B(RB)与阴离子型染料甲基橙(MO)、刚果红(CR),探究TiO_(2)的形态对其光催化性能的影响。研究结果表明:随着棒状二氧化钛纳米粒子的径向比的增加,其对碱性阳离子染料的光催化活性随之升高,而对酸性阴离子染料的光催化活性则随之降低。在阳离子染料中对MG的降解率最为显著,紫外光照2 h内降解率可达100.0%;而在阴离子染料中对CR的效果最好,紫外光下照射2 h后的降解率可达68.0%。通过对比二氧化钛的形态,可见二氧化钛纳米粒子的各个晶面中c面所占比例大小决定了TiO_(2)纳米粒子的选择性吸附,从而影响其光催化性能,而其中同种类型染料的降解速率的不同与染料自身结构有关。

Anatase TiO_(2)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 TiO_(2)nanoparticles with different morphologies under excitation of a UV lamp,the influence of the morphology of TiO_(2)on its photocatalytic performance was investigated.The results showed that with the increase of the aspect ratio of TiO_(2)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 TiO_(2)catalysts,it can be concluded that the ratio of c-plane in each crystal surface of TiO_(2)nanoparticles determines the selective adsorption of dyes on TiO_(2)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.