热处理对活性炭负载纳米TiO_2光催化剂晶体结构及光活性的影响

Effect of Thermal Treatment on Crystal Structure and Photocatalytic Act ivity of Activated Carbon Loaded Nano-TiO_2 Photocatalyst

用改性溶胶 凝胶法合成了活性炭负载纳米TiO2 光催化剂粉末 ,通过X射线衍射 (XRD)、拉曼光谱 (Raman)、透射电子显微镜 (TEM)等研究光催化剂的晶体结构和表面形貌。不同气氛下煅烧对TiO2 的晶体转变的影响研究表明 :氮气下TiO2 晶体转变温度明显低于空气下晶体转变温度 ,但是活性炭负载量对晶体结构的影响不大。光催化活性实验表明 :活性炭负载纳米TiO2 光催化剂对亚甲基蓝的降解作用要优于纯TiO2 的降解作用。不同气氛下煅烧实验研究发现 ,在低于 4 0 0℃时 ,空气中煅烧的光催化剂的光催化活性明显要优于在氮气中煅烧的 ;但在 4 0 0℃时氮气中煅烧后的光催化剂对亚甲基蓝的降解作用达到了最佳 ,且高于同温度下在空气中煅烧的样品。而高于 4 0 0℃后其降解效果逐渐下降。在空气中煅烧后的光催化剂在 5 5 0℃煅烧后才对亚甲基蓝的降解活性达到了最佳状态。

Activated carbon loaded nano-TiO2 photocatalysts were prepared by the modified sol-gel method. The powders were characterized by XRD, Raman, TEM for examing their crystal structure and surface morphology. The influence factors of crystal transformation of TiO2 calcined in different atmospheres were investigated. The results show that the transformation temperature of TiO2 crystal calcined in nitrogen is obviously lower than that calcined in the air. The effect of amount of activated carbon on the crystal transformation is not observed. The experiment of photocatalytic activity reveals that the activated carbon loaded nano-TiO2 photocatalysts possess better degradation rate on Methylene blue calcined in the air than in nitrogen at the temperature below 400°C. However, the photocatalysis activity of activated carbon loaded TiO2 shows the highest degradation rate calcined in nitrogen at 400°C, but the photocatalyst calcined in the air does not reach the highest activity until 550°C.