RE/TiO2光催化剂的谱学特性与气相光催化性能的研究

采用改进的sol-gel法和浸渍法制备了TiO₂掺杂稀土离子La³⁺、Y³⁺、Gd³⁺、Er³⁺、Nd³⁺、Pr³⁺的RE/TiO₂光催化剂，运用FTIR、XRD、TEM、低温氮吸附/脱附、TG/DTA、UV-Vis DRS、表面光电压谱(SPS)等进行表征，以气相光催化降解乙烯、溴代甲烷作为探针反应，阐明了RE/TiO₂光催化剂的谱学特性与气相光催化性能的关系。结果显示，稀土离子掺杂后，TiO₂的锐钛矿含量增加，比表面积增大，粒径变小，吸收边发生蓝移，表面光电压的响应阈值增大，此外，Pr³⁺除外的其它稀土离子掺杂的TiO₂的表面光电压信号增强；光催化降解实验表明，与纯TiO₂相比，La³⁺、Y³⁺、Gd³⁺、Er³⁺、Nd³⁺掺杂TiO₂样品上乙烯、溴代甲烷的光催化活性均有不同程度的增强，而且表现出较强的矿化能力。但是，掺杂Pr³⁺的TiO₂的光催化性能降低恰好对应较弱的表面光电压信号。所以，本文认为提高光生电子-空穴对的分离效率是改善光催化性能的关键因素。

Spectroscopic Properties and Gas-phase Photocatalytic Performance of Lanthanide Doped Titanium Dioxide

The Lanthan ide doped TiO₂ photocatalysts were prepared by the sol-gel and impregnation method, denoted as RE/TiO₂(RE=La, Y, Gd, Er, Nd, Pr). FTIR, XRD, TEM, Low temperature adsorption/desorption, TG/DTA, UV-Vis diffuse reflectance spectroscopy(DRS) and surface photovoltage spectroscopy (SPS) were used to characterize TiO₂ and RE/TiO₂. The photocatalytic degradation of C₂H₄ and CH₃Br was used as a probe reaction to evaluate their photocatalytic activities. The relationship of spectroscopic properties and gas-phase photocatalytic performance of TiO₂ and RE/TiO₂ was discussed. The results indicated that RE/TiO₂ catalysts had higher content of anatase, smaller particle sizes , higher specific surface area and lager band gap than those of pure TiO₂. In addition, La³⁺, Y³⁺, Gd³⁺, Er³⁺, Nd³⁺doped TiO₂ had stronger photovoltage signals and higher photocatalytic activities as compared with pure TiO₂. However Pr³⁺doped TiO₂ had lower photocatalytic activity responding to the lower photovoltage signal. The higher photocatalytic activities may be mostly attributed to the effective separation of photo-generated electron-hole pairs.