稀土离子掺杂对纳米TiO2光催化制氢活性的影响

采用溶胶-凝胶技术制备了纳米TiO2和一系列稀土离子掺杂的TiO2光催化剂,通过X射线衍射、透射电镜及N2吸附等技术对其进行了表征,考察了样品光催化分解水制氢的性能.结果表明,稀土离子掺杂有效抑制了TiO2粒子的生长,提高了粒子的分散性,增大了催化剂的比表面积,从而大幅度提高了其光催化分解水制氢的性能.其中,Gd3 掺杂的TiO2样品粒径最小,分散性最好,比表面积最大(是未掺杂TiO2的35倍).掺杂离子的电子构型对样品的光催化制氢活性有较大影响,具有全空电子构型的La3 和半充满电子构型的Gd3 掺杂的样品具有较高的光催化制氢活性(分别是未掺杂TiO2的3.69倍和3.72倍).

Effect of Rare Earth Ion Doping on the Photocatalytic Activity of TiO2 for Hydrogen Evolution

TiO2 catalysts doped with different rare earth ions were prepared by the sol-gel method and characterized by X-ray diffraction,transmission electron microscopy,and N2 adsorption. The photocatalytic activity for hydrogen evolution from water decomposition under UV light irradiation was investigated. Doping with rare earth ions restrained the growth of TiO2 particles,improved the particle dispersion,increased the BET surface area,and thus significantly enhanced the photocatalytic activity of TiO2 for H2 evolution. Among the catalysts,Gd3 /TiO2 had the smallest particle size,the best particle dispersion,and the highest BET surface area (35 times higher than that of the undoped TiO2). The gelling time varied with different rare earth ions. The longer the gelling time,the larger the BET surface area. A comparison between La3 /TiO2 and Gd3 /TiO2 indicated that the photocatalytic activity was not linear with the surface area. Moreover,the electronic configuration of rare earth ions had a significant effect on the photocatalytic activity of RE3 /TiO2. TiO2 samples doped with La3 having a full-empty electronic configuration and Gd3 having a half-filled electronic configuration had higher photocatalytic activity for hydrogen evolution (3.69 and 3.72 times higher) than that of the undoped TiO2.