TiO_2纳米粒子制备方法对其光催化活性的影响

Influence of Preparation Method on the Photocatalytic Activity of TiO_2 Nanoparticles

分别用胶溶法、金属醇盐水解法和低温水解法制备了 Ti O2 纳米粒子 ;采用 XRD和 BET技术 ,测试了Ti O2 粒子的粒径、晶型及表面积 .以庚烷的气相光催化氧化为探针反应 ,考察了不同方法、不同温度处理的 Ti O2粒子的光催化活性 .结果表明 ,以胶溶法和金属醇盐水解法制备的 Ti O2 粒子 ,随焙烧温度的增加 Ti O2 粒子长大 ,晶型由锐钛矿向金红石型转变 ,光催化活性降低 .用低温水解法 ,可在低温下制得金红石型 Ti O2 粒子 ,但其催化活性很低 .说明由原料和制备方法所决定的 Ti O2 粒子的物理化学性质 ,影响其光催化行为 .锐钛矿型 Ti O2 粒子催化活性较金红石型 Ti O2 好 .这是由于前者的表面羟基含量较高且带隙能较大的缘故 .

TiO-2 nanoparticles were prepared by three methods: colloid chemical method, alkoxide hydrolysis method, and low-temperature hydrolysis method. The particle size, crystal structure, and surface area were characterized by means of XRD and BET techniques. The photocatalytic oxidation of heptane was used as the model reaction to measure the photocatalytic activity of TiO-2 particles prepared by different methods. For TiO-2 particles prepared by the same method, with the increase of calcining temperature the crystal structure changes from anatase to rutile, and the particle size increases and the photocatalytic activity decreases. The photocatalytic behavior is affected by the physicochemical properties, depended on the origin and preparation method. The photocatalytic activity of anatase is higher than that of rutile because the former has a larger band gap and a higher concentration of surface hydroxyl groups.