纳米LaFeO_3的制备和表征及其气相光催化性能

Preparation and characterization of perovskite-type LaFeO_3 nanoparticles and their gas phase photocatalytic activity

以硝酸镧和硝酸铁为原料,柠檬酸为络合剂,利用溶胶凝胶法制备了钙钛矿结构的纳米LaFeO3,并用TG-DTA、XRD、BET、SPS等方法对样品进行了表征．重点考察了热处理温度对光催化降解气相正戊炕活性的影响,探讨了表面光电压信号与光催化活性的关系．结果表明：热处理温度为500℃时,钙钛矿结构的纳米LaFeO3开始生成,随着焙烧温度升高,结晶度变高．在光催化实验中,500℃焙烧的纳米LaFeO3表现出较高的光催化活性,且焙烧温度升高,光催化活性下降,与表征结果一致．说明热处理温度越低,LaFeO3纳米晶尺寸越小,SPS信号越弱,光催化活性越高．

The perovskite LaFeO3 nanoparticles were prepared by a sol-gel method with citric acid （HOOCCH2 C （OH） （COOH） CH2 COOH） as complexing reagent, using La （ NO3 ）3 · 6H2 O and Fe （ NO3 ）3 · 9H2 O as raw materials, which were characterized by TG - DTA, XRD, BET, SPS testing techniques. The influences of calcination temperature on the photocatalytic activity for degrading gas phase n-Pentane were further investigated, and the relationships between the surface photovoltage spectrum and photocatalytic activity were discussed in detail. Results indicated that LaFeO3 nanoparticles could be formed when calcined at 500 ℃. As the calcinaton temperature increased, the crystallinity became more perfect. Moreover, in the experiment of photocatalytic degradation gas phase n-Pentane, LaFeO3 nanoparticles calcined at 500 ℃ exhibited a higher photocatalytic activity and the photocatalytic activity declined as the caclinaton temperature increased, which was coincident with the results of the characterization. It was sugguested that the higher the calcination temperature was, the larger the LaFeO3 nanoparticle size, the stronger the SPS signal, and the lower the photocatalytic activity would be.