硫/铜共掺杂纳米TiO_2的制备、表征及其光催化性能

以钛酸丁酯为钛源,采用溶胶凝胶法制备了硫/铜共掺杂的锐钛矿型TiO2粉体(S/Cu-TiO2),并通过X射线衍射(XRD)、扫描电镜(SEM)、傅里叶变换红外光谱(FT-IR)和N2吸附等手段对其进行了表征;以中性红为模型物考察了其光催化活性。结果表明:在450℃下焙烧2 h得到摩尔分数0.2%S/Cu-TiO2为单一锐钛矿相纳米颗粒,平均粒径为40—70 nm,而于550℃和650℃下焙烧得到的样品中含有部分金红石相,因此,掺杂离子可有效抑制TiO2晶粒的生长,温度高于450℃不利于制备锐钛矿相TiO2;在最优的实验条件下,即在紫外光下达吸附平衡的200 mL质量浓度为20 mg/L的中性红溶液加入0.15 g 0.2%S/Cu-TiO2,紫外光催化降解120 min,此时中性红的降解率达近100%;该催化剂降解中性红的动力学结果显示该过程可由Langmuir-Hinshelwood(L-H)拟一级动力学模型来描述。

Preparation and characterization of S/Cu co-doped nano-TiO_2 and its photocatalytic property

By using tetrabutyl titanate as the precursor,S/Cu co-doped anatase TiO2 photocatalysts(S/Cu-TiO2) were prepared by the sol-gel method,which were characterized by XRD,SEM,FT-IR and N2 adsorption.The photocatalytic activities of the catalysts were investigated with neutral red as the model compound.The results show that the co-doped nano-catalysts with 0.2%(mole fraction) S/Cu-TiO2 calcined at 450 ℃ for 2 h have only anatase phase with the average particle size of 40-70 nm which is smaller than that of the pure TiO2,while the samples calcined at 550 ℃ and 650 ℃ contain rutile phase.Therefore,the doping of ions can restrain the growth of particles,and the temperature higher than 450 ℃ is not suitable to prepare the pure anatase TiO2.The best conditions for degradation of neutral red were obtained by single factor experiments,i.e.under ultraviolet irradiation,addition of 0.15 g 0.2% S/Cu-TiO2 in the 200 mL neutral red solution with a mass concentration of 20 mg/L,photocatalytic time of 120 min,the degradation rate of neutral red can reach about 100%.The kinetic study shows that the photocatalytic process coincides with the Langmuir-Hinshelwood(L-H) pseudo-first-order kinetic model.