Fabrication and Photocatalytic Activity of Highly Crystalline Nitrogen Doped Mesoporous TiO2

Highly crystalline nitrogen doped mesoporous TiO2 photocatalysts were fabricated by the sol-gel method using tetrabutyl titanate as the Ti source, urea as the N source, and polyacrylamide (PAM) and polyethylene glycol (PEG) as the templates, and then by calcining in nitrogen and air. The photocatalysts were characterized by X-ray diffraction, transmission electron microscopy, N2 adsorption, X-ray photoelectron spectroscopy, and UV-Vis spectroscopy. When the mass ratio of PAM and PEG was 1:4, the sample prepared by calcining at 600 °C in nitrogen and 500 °C in air had the anatase phase and a mesoporous structure and high crystallinity. The average pore size, crystallite size, and specific surface area were 5.11 nm, 12.5 nm, and 110.8 m2/g, respectively. Nitrogen atoms were incorporated into the TiO2 lattice mainly as substitutional N and molecularly chemisorbed γ-N2, and a small amount of interstitial N. Nitrogen doping narrowed the band gap and allowed light absorption in the visible light region. Compared with undoped mesoporous TiO2, the absorption band edge of nitrogen doped samples exhibited a red shift and the light absorption intensity was increased. Photocatalytic degradation of methyl orange showed that the nitrogen doped mesoporous TiO2 had a higher photocatalytic activity than undoped mesoporous TiO2 under visible light.

摘要以钛酸丁酯为钛源, 尿素为氮源, 聚丙烯酰胺 (PAM) 和聚乙二醇 (PEG) 为复合模板剂, 采用溶胶-凝胶法, 在氮气和空气气氛中分段煅烧, 制得高结晶度氮掺杂介孔 TiO2 光催化剂. 利用 X 射线衍射 透射电镜 N2 吸附-脱附 X 射线光电子能谱和紫外-可见漫反射光谱等技术对其进行了表征. 结果表明, 当 PAM 和 PEG 的质量比为 1:4 时, 先在氮气中 600 丰C 煅烧, 后在空气中 500 丰C 煅烧所得样品是锐钛矿相, 具有良好的孔隙结构和较高的结晶度, 平均孔径为 5.11 nm, 晶粒尺寸为 12.5 nm, 比表面积 110.8 m2/g. 掺杂介孔 TiO2 的氮主要以取代氮和化学吸附分子 吵-N2 的形式存在, 少量以间隙氮形式存在. 氮掺杂使 TiO2 的能带变窄, 吸收带边明显红移, 且使光吸收强度显著增大. 光催化降解甲基橙实验结果表明, 与未掺杂样品相比, 氮掺杂介孔 TiO2 在可见光作用下表现出较高的催化活性.

Nitrogen doped mesoporous TiO2 photocatalysts with high crystallinity were fabricated by the sol-gel method using polyacrylamide and polyethylene glycol as templates, and then calcining in nitrogen and air.Figure optionsDownload as PowerPoint slide