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采用化学溶液分解法制备了Aurivillius结构钛酸铋铌化合物Bi_7Ti_4NbO_(21),并对其进酸化处理。X射线衍射(X-ray diffraction,XRD)表征表明,500℃以上的温度进行热处理,可以制得结晶性良好的Bi_7Ti_4NbO_(21)。对Bi_7Ti_4NbO_(21)进行浓硝酸酸化处理,可转化为结晶性良好的焦绿石结构钛酸铋化合物Bi2Ti2O7。采用SEM观察了所合成的Bi_7Ti_4NbO_(21)和Bi_2Ti_2O_7的形貌和尺寸。在紫外光照射下对甲基橙的光催化降解实验表明,所合成的钛酸铋铌化合物Bi_7Ti_4NbO_(21)及其酸化产物钛酸铋Bi2Ti2O7均具有良好的光催化活性。试验结果表明,光催化剂颗粒的结晶性及其尺寸对其光催化活性均具有很大影响。550℃热处理得到的Bi_7Ti_4NbO_(21)具有最高的催化活性,而将钛酸铋铌酸化处理得到的Bi_2Ti_2O_7其光催化性能显著提高,优于标准光催化剂P25。
Aurivillius structure of bismuth titanate niobium compound Bi_7Ti_4NbO_ (21) was prepared by chemical solution decomposition, and its acidification. X-ray diffraction (XRD) characterization indicated that Bi 7 Ti 4 NbO 21 with good crystallinity could be obtained by heat treatment at a temperature above 500 ℃. Bi_7Ti_4NbO_ (21) concentrated nitric acid acidification can be transformed into a good crystal structure of pyrochlore bismuth titanate compounds Bi2Ti2O7. The morphologies and sizes of Bi_7Ti_4NbO_ (21) and Bi_2Ti_2O_7 synthesized by SEM were observed. The photocatalytic degradation of methyl orange under UV irradiation showed that Bi7Ti4NbO_ (21) and Bi2Ti2O7, the bismuth titanate (BiTi2O7) synthesized by the reaction, all have good photocatalytic activity. The experimental results show that the crystallinity of photocatalyst particles and their size have a great influence on their photocatalytic activity. Bi 7Ti 4 NbO 2 (21) obtained by thermal treatment at 550 ℃ has the highest catalytic activity. The photocatalytic activity of Bi 2 Ti 2 O 7 obtained by the bismuth niobate titanate treatment is significantly higher than that of the standard photocatalyst P25.