Bi_7Ti_4NbO_(21)的合成、酸化及光催化性能

Fabrication and acid treatment of Bi_7Ti_4NbO_(21) and their photocatalytic properties

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 compound Bi7Ti4NbO21 was fabricated by a chemical solution decomposition method （CSD） and acid treated. X-ray diffraction （XRD） analysis revealed that well-crystallized Bi7Ti4NbO21 could be prepared with a cal- cination temperature at or above 550 ℃. Well-crystallized Bi2Ti2O7 with uniform particle sizes was obtained by concen- trated nitric acid treatment. Field emission scanning electron microscopy （FESEM） was used to examine the morpholo- gy and particles size of as-prepared Bi7Ti4NbO21 and acid-treated product Bi2Ti2O7. The results showed that both Bi7Tia NbO21 and Bi2Ti2O7 were highly photocatalytic active for the degradation of organic dye methyl orange under UV light irradiation. The crystallinity and particles size of as-prepared photocatalysts were found to strongly influence the photocatalytic activities. The BTN-550 calcined at 550 ℃ showed the highest activity of as-prepared Bi7Ti4NbO21. The Bi2Ti2O7 obtained by acid-treated Bi7Ti4NbO21 exhibited remarkable enhanced photocatalytic activity which was superior to that of P25.