贵金属修饰型TiO2 的催化活性及Fermi能级对其光催化性能的影响

采用自制纳米TiO2粉末，以磷酸铝为粘结剂，制备了负载型TiO2光催化剂。将Ag，Pt或Pd3种金属的盐溶液滴涂在负载TiO2的表面，从而得到修饰型负载光催化剂(M／TiO2)。通过甲基橙溶液降解实验研究了贵金属的掺杂种类和含量对TiO2光催化性能的影响。实验结果表明：适量掺杂Ag，Pt或Pd3种金属粒子均可提高TiO2的光催化活性，且3种金属粒子的最佳掺杂质量分数分别为0．5％，1．0％和1．0％。在最佳掺杂量时，Ag／TiO2w(Ag)=0．5％]的光催化活性要高于Pt／TiO2w(Pt)=1．0％]或Pd／TiO2w(Pd)=1．0％]。另外，通过金属-半导体接触理论阐述了M／TiO2的光催化机理，并通过Ag，Pt，Pd金属的Fermi能级的不同，解释了Ag／TiO2，Pt／TiO2和Pd／TiO23种光催化剂催化性能的差别。

PHOTOCATALYTIC ACTIVITY OF TiO2 PHOTOCATALYST MODIFIED WITH NOBLE METAL AND EFFECT OF FERMI LEVEL ON ITS PHOTOCATALYTIC PROPERTIES

Supported TiO_2 photoeatalysts were prepared with aluminum phosphate as bonding agent. Photocatalysts modified with noble metal (M/TiO_2) were obtained by dropping salt solution of Ag, Pt or Pd on the surface of supported TiO_2. The effects of doping agent and doping concentration on photocatalytic properties were investigated by photocatalytic degradation of methyl orange solution. The results show that the photocatalytic activities can be improved by doping Ag, Pt or Pd. As every dopant has optimal doping concentration the photocatalytic properties of Ag/TiO_2 w(Ag)= 0.5%, mass fraction, the same below] are better than those of Pt/TiO_2 w (Pt) = 1.0%] or Pd/TiO_2 w (Pd) = 1.0%]. The photocatalytie mechanism of M/TiO_2 is explained by the theory of metal - semiconductor contacts and the difference in photocatalytic properties of Ag/TiO_2, Pt/TiO_2 and Pd/TiO_2 is analyzed by accounting and comparing their Fermi level.