N掺杂对钛酸铋复合TiO_2催化剂的形貌和性能的影响

Effect of N doping on morphology and property of bismuth titanate TiO_2 composite catalyst

以钛酸四丁酯、硝酸铋及尿素为前驱体,利用溶剂热法制备氮掺杂BixTiOy-TiO2复合催化剂,利用X射线衍射(XRD)、紫外-可见漫反射(UV-Vis)、场发射扫描电镜(FE-SEM)、X射线光电子能谱(XPS)和低温氮气吸附(BET)等手段对样品进行表征,以亚甲蓝为模型化合物,考察各催化剂在模拟太阳光下的光催化活性。结果表明:由于一定量的氮掺杂可增强催化剂中Bi12TiO20的含量,氮掺杂的复合催化剂在440～520nm处出现了较大的吸收;氮掺杂使催化剂从圆球形变为花瓣形,增大了催化剂的比表面积和羟基自由基的含量。氮掺杂量为0.15%(质量分数)的BNT2催化剂在250 W金卤灯模拟太阳光下照射3 h后,对20 mg/L的亚甲基蓝溶液的去除率为93.86%,比相同条件下BT和NT催化剂的去除效率分别提高了32%和37.31%。

N-doped BixTiOy-TiO2 composite catalysts were prepared by solvothermal synthesis using tetrabutyl titanate, bismuth nitrate and urea as precursors. The particles were characterized by X-ray diffractometry （XRD）, ultraviolet-visible diffuse reflectance spectroscopy （UV-Vis）, field emission scanning electron microscopy （FE-SEM）, X-ray photoelectron spectroscopy （XPS） and Bnmaner-Emmett-Teller （BET）. The photocatalytic activity of the catalysts was investigated via photodegradation of methylene blue under simulated sunlight irradiation. The results show that the content of Bi12TiO20 increases due to nitrogen doping. A significant absorption at 440-520 nm for N-doped BixTiOy-TiO2 composite catalysts appears, the catalysts turn from spherical into a petal shape which can be ascribed to nitrogen doping resulting in the increase of surface area as well as content of hydroxyl radicals. The best removal rate of methylene blue solution （20 rag/L） reaches 93.86% under Haloid lamp of 250 W after 3 h with the nitrogen dosage of 0.15% （mass fraction）, increase by 32% and 37.31% separately compared with Bi-doped TiO2 and N-doped TiO2 under the same conditions.