FeTiO3/TiO2纳米异质结的制备和可见光催化性能

采用水热法和溶胶凝胶法制备了新型FeTiO3/TiO2纳米异质结复合材料,并明确了最优的掺杂比例(0.5%).随后利用X射线衍射能谱(XRD)、紫外-可见漫反射光谱(UV-Vis DRS)、扫描电镜(SEM)和透射电镜(TEM)等手段对该复合材料进行表征,证实了其结晶度、吸光度随掺杂量的规律性变化.电镜照片显示,该复合材料具有蓬松多孔的微观结构,且晶格条纹清晰、分散度高,有利于光电子的传导.对苯的降解实验表明,相比于纯TiO2,该催化剂的气相可见光催化能力大幅提高,降解率提升了3倍,达到40%,而CO2生成量提升了5倍,超过300 ppm.同时,电化学测试和电子顺磁共振谱(ESR)等均证实,FeTiO3的窄能带能够提高TiO2的光响应,实现可见光激发;而二者的能带相互匹配,有助于转移光生载流子,实现电子-空穴的高效分离,进而其光生电子和自由基生成能力大幅增强,因此,表现出了较强、较稳定的光催化活性.

Preparation and photocatalysis of FeTiO3/TiO2 heterojunction

The FeTiO₃/TiO₂ heterojunction was prepared by hydrothermal and sol-gel method and the optimal proportion (0.5%) was confirmed.The photocatalysts were then characterized by X-ray diffraction (XRD) and UV-Vis diffuse reflectance spectra (UV-Vis DRS),and the influence of FeTiO₃ ratio on crystallinity and light response were confirmed.By scanning electron microscopy(SEM)and transmission electron microscopy(TEM),the compound seemed fluffy and porous and their lattice fringe dispersed well.The photocatalytic degradation towards benzene under visible light irradiation grew threefold (up to 40%) comparing to bare TiO₂ and the amount of produced CO₂ significantly increased from 60 ppm to 300 ppm.Furthermore,the electro-chemistry and electron spin-resonance spectroscopy(ESR)provided evidence that the narrow band gap of FeTiO₃wound extend the optical absorption range of TiO₂ to visible region.Besides, the improved performance was attributed to the matching energy band which can transfer charge carriers efficiently and enhance generation of photo-electron and free radicals.