金属离子掺杂与贵金属沉积对TiO2光催化性能的影响

采用溶胶-凝胶-浸渍法制备了掺杂La^3＋并沉积Pt的TiO2粉体光催化剂，考察了它对直接耐晒蓝的降解效果。结果表明，以TiO2干凝胶为母体，依次浸渍La^3＋、Pt^4＋所制备的粉体光催化剂La^3＋／Pt／TiO2降解效果比纯TiO2高80％，比相应的La^3＋/TiO2高36％，比Pt／TiO2高10．9％。X射线衍射分析表明，该法制备的TiO2粉体中锐钛矿相占95％以上，没有镧的氧化物形式，Pt以纳米级原子簇的形式沉积在La^3＋／TiO2表面，平均晶粒粒径为7nm，小于TiO2的平均粒径10nm；红外吸收光谱分析表明，无论是纯TiO2还是经过掺杂金属离子、掺杂与沉积贵金属共用后的TiO2，红外吸收光谱图相似，说明掺杂和沉积贵金属并没有极大地改变TiO2的化学结构，光催化性能的提高取决于杂质能级的电子捕获陷阱作用和光生载流子的重新分布。沉积贵金属有利于分离电子-空穴对，但沉积量不宜过大。

Effect of metal-ion doping and noble metal deposition on photocatalytic activity of TiO2

TiO_2 photocatalyst which was doped with La~(3+) and deposited Pt was prepared by using sol-gel-immersion method. Its degradation effect on direct fast blue was investigated. The results demonstrated that degradation effect of La~(3+)/Pt/TiO_2 with TiO_2 dry gel as motherbody, after La~(3+),Pt~(4+) was in turn immersed, was 80% higher than that of TiO_2, 36% higher than that of La~(3+)/TiO and 10.9% higher than that of Pt/TiO_2. XRD analysis indicated that anatase phase in TiO_2 was more than 95%, no oxidation phase of La~(3+), Pt was deposited on the surface of La~(3+)/TiO_2, which was namometer-order atom. The mean crystal diameter was 7nm. FTIR analysis indicated that metal-ion doping and noble metal depositon could not greatly change the chemical structure of TiO_2. Photocatalytic activity was promoted because of electron -tractor effect of La~(3+) and redistribution of photogenerated carriers. The deposition of noble metal was favorate to separate electron-hole pairs, but the effect of degradation was worse for higher deposition.