原位红外光谱法研究La/TiO2对有机污染物的光催化降解

本工作采用改进的溶胶-凝胶法和浸渍法制备了TiO₂掺杂稀土离子La³⁺的La/TiO₂光催化剂，运用XRD、N₂吸附脱附、紫外可见漫反射光谱(DRS)、表面光电压谱(SPS)等手段进行表征，同时利用原位红外技术考察了La/TiO₂样品光催化降解乙烯、丙酮、苯的气-固相光催化氧化反应，对其光催化降解有机污染物的过程进行了研究。结果表明，TiO₂经适量La³⁺掺杂后，锐钛矿晶型的含量增加，晶粒度减小，比表面积增大，禁带宽度增加，表面光电压信号增强，光生电子-空穴对有效分离；La/TiO₂样品对乙烯、丙酮、苯的光催化性能与纯TiO₂相比均有不同程度的改善，乙烯可以被光催化氧化完全矿化生成CO₂，而丙酮被光催化氧化可能生成中间产物丙酸，苯被光催化氧化可能生成中间产物苯酚和苯醌。

In Situ FTIR Study on Photocatalytic Degradation of Organic Contaminants over La3+-doped TiO2

The La³⁺-doped TiO₂ photocatalyst was prepared by the improved sol-gel and impregnation method. XRD, N₂ adsorption, UV-Vis diffuse reflection spectroscopy and surface photovoltage spectroscopy (SPS) were applied to study the effect of La³⁺ doping. At the same time, the photocatalytic process of TiO₂ and La³⁺-doped TiO₂ catalysts for degradation of ethylene, acetone, benzene were further studied by means of in situ FTIR. The result indicated that La³⁺ doping could enhance the photocatalytic activities of ethylene, acetone, benzene to some extend as compared with pure TiO₂. The increase in photoactivity is probably due to higher content of anatase, smaller particle size , higher specific surface area and lager band gap. In addition, the higher photocatalytic activity of La³⁺-doped TiO₂ may be attributed to the stronger photovoltage signal and the effective separation of photo-generated electron-hole pairs. The result also showed that ethylene could be photocatalytically oxidized to CO₂. The acetone and benzene may be photocatalytically oxidized to propionic acid and phenol, quinone, respectively.