磁性二氧化钛纳米粒子的制备及其光催化性能

Preparation of Magnetic Titanium Dioxide Nanoparticles and Its Photocatalytic Activity

以硫酸钛和Fe3O4为原料,采用共沉淀法制备了掺杂不同量Fe3O4的磁性纳米TiO2(Fey-TiO2+x),通过X-射线衍射(XRD)、热重-差示扫描量热(TG-DSC)、紫外-可见吸收光谱(UV-Vis)和荧光光谱等分析手段对样品的晶体类型、光谱吸收特征和磁响应性等进行了表征;以太阳光为光源,考察其对甲基橙的光催化降解活性.结果表明,Fey-TiO2+x纳米粒子主要以锐钛矿相存在,粒子的粒径约为12 nm;在8 mT外加磁场作用下,粒子悬浮液的吸光度在12 min内减少70%,而无外加磁场时仅减少25%,说明Fey-TiO2+x纳米粒子具有良好的磁响应性.Fe2+和Fe3+离子掺入TiO2后,使TiO2晶格形成缺陷,使吸收带边由380 nm红移到460 nm,从而提高了TiO2对可见光的吸收效率.Fe的最佳掺杂量为Ti的0.05%(摩尔比),该催化剂在240 min内对甲基橙的降解率接近100%;加入少量H2O2能显著提高Fe0.05-TiO2的光催化性能,在20 min内对甲基橙的降解率即接近100%.

Fey-TiO2 ＋ x nanoparticles were prepared by co-precipitation method from Ti （SO4 ）2 and Fe3O4. The crystal types, the property of absorption spectrum and magnetic response of Fey-TiO2＋X were examined by XRD, TGDSC, UV-Vis and fluorescence spectra. Using the photocatalytic degradation of methyl orange as a model reaction, activity of prepared photocatalysts was investigated in TiO2 and Fey-TiO2 ＋x nanoparticles suspension irradiated by sun. The results indicate that the diameter of Fey-TiO2＋X particles are 12 nm, the mainly crystal phase is anatase. The absorbency of the particles aqueous suspension under 8 mT magnetic field can decrease 70% for 12 min, contrast to that of 25% under natural deposition. It is concluded that the particles are responsive to the magnetic field. The doped Fe^2 ＋ and Fe^3＋ ions could mainly substitute the Ti^4＋ ions of TiO2, which increasing the visible light absorption of TiO2. The original absorption edge （about 380 nm） of TiO2 moves to the longer wave （about 460 nm）. The optimum doping amount of Fe is 0.05% of Ti （ molar ratio）, the degradation efficiency of methyl orange is access to 100% for 240 min. The addition of H202 can notably enhanced the photocatalytic activity of Fe0.05-TiO2, the degradation efficiency of methyl orange is access to 100% for 20 min.