氮掺杂TiO_2/SiO_2核壳型复合微球的制备及其可见光催化性能

Preparation of Nitrogen-Doped TiO_2/SiO_2 Microspheres with Core-Shell Structure and Their Photocatalytic Activity under Visible Light

以单分散性良好的SiO2微球为模板,以钛酸四丁酯为钛源,利用化学吸附和原位水解方法制备了TiO2/SiO2核壳结构复合微球,并在氨气气氛下进行了氮掺杂.以罗丹明B水溶液的光催化降解为模型反应,评价了所制试样在可见光照射下的光催化活性,并借助透射电镜、高分辨透射电镜、X射线衍射、紫外-可见漫反射光谱、红外光谱和X射线光电子能谱等测试手段对其结构、形貌和光谱性质进行了表征.结果表明,氮掺杂TiO2/SiO2为核壳结构,TiO2包覆层厚约10nm.由于SiO2核与TiO2壳间形成了Ti-O-Si键,TiO2的热稳定性增强.掺杂的氮形成了Ti-O-N键.600℃下氮化1h得到的试样的可见光活性最佳.由于结合了SiO2核优良的吸附性能及氮掺杂TiO2壳的可见光响应性能,该复合微球在整体上表现出比P25更优的光催化活性.

TiO2/SiO2 microspheres with core-shell structure were synthesized by chemical adsorption and in situ hydrolysis using well-dispersed SiO2 microspheres as the template and tetrabutyl titanate as the precursor. The samples were calcined in a tube furnace under ammonia atmosphere at various temperatures to dope with nitrogen. The structure and morphology of the obtained samples were characterized by transmission electron microscopy, high-resolution transmission electron microscopy, X-ray diffraction, ultraviolet-visible diffuse reflectance spectroscopy, infrared spectroscopy, and X-ray photoelectron spectroscopy. The photocatalytic activity was evaluated by the degradation of rhodamine B solution under visible light irradiation. TiO2/SiO2 was of coreshell structure, and the TiO2 shell was about 10 nm in thickness. The phase transition of TiO2 at high temperature was inhibited by the formation of the Ti-O-Si bond. TiO2/SiO2 was modified by N doping in the form of the Ti-O-N bond. The effects of calcination temperature on the photocatalytic activity were investigated. The highest activity was obtained with TiO2/SiO2 calcined at 600 ℃ for 1 h under ammonia atmosphere. The SiO2 core resulted in better adsorption property, and the N-doped TiO2 shell resulted in visible light sensitization. N- doped TiO2/SiO2 benefited from both of the effects.