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用X射线衍射、透射电镜、紫外-可见光漫反射光谱等表征手段研究了纳米TiO2/C光催化剂的晶体结构和性能。结果表明:碳黑改性促使TiO2在较低温度(<500℃)发生由锐钛矿相向金红石相转变,并有效抑制了纳米TiO2晶粒长大,经400℃热处理后,TiO2晶粒尺寸为7.3nm。由于纳米碳黑弥散分布于纳米TiO2颗粒中,提高了该催化剂对亚甲基蓝分子的吸附性能。通过碳黑粒子的光敏化作用提高纳米TiO2的可见光光催化性能,加入5%(质量分数)纳米碳黑的TiO2/C光催化剂在400℃热处理后对亚甲基蓝降解率可达到93%。过多的碳黑会因其阻碍纳米TiO2与有机物接触而降低其降解效果,而过少的碳黑则会降低纳米碳黑对催化剂的敏化作用而降低其催化活性。
The crystal structure and properties of nano-TiO2 / C photocatalysts were characterized by X-ray diffraction, transmission electron microscopy and UV-Vis diffuse reflectance spectroscopy. The results show that the modification of carbon black causes the transformation of anatase phase to rutile phase at a relatively low temperature (<500 ℃) and effectively inhibits the growth of nano-sized TiO2. After heat treatment at 400 ℃, the grain size of TiO2 is 7.3 nm. Due to the dispersion of nano-carbon black in the nano-TiO2 particles, the adsorption of the methylene blue molecule by the catalyst is improved. The photocatalytic activity of nano-TiO2 was enhanced by the photosensitization of carbon black particles. The degradation rate of methylene blue after 93% heat treatment with TiO2 / C photocatalyst with 5% (mass fraction) nano-carbon black reached the maximum at 93 ℃. Too much carbon black will reduce its degradation effect because it hinders the contact of the nano-TiO2 with the organic matter, and too little carbon black will reduce the sensitization of the nano-carbon black to the catalyst and reduce its catalytic activity.