【作者】 陈旭；

【导师】 付贤智； 李旦振；

【作者基本信息】 福州大学 ， 工业催化， 2005， 硕士

【摘要】 以TiO₂为代表的半导体光催化氧化技术能在常温下利用光能氧化分解污染物,是具有广阔应用前景的治理环境污染的新技术。但TiO₂禁带宽度大（3.2eV）,只能利用太阳光中的紫外线部分（仅占太阳光能3⁴%）。这使TiO₂作为光催化剂在实际应用中难以大规模推广。采用非金属元素氮对TiO₂ 进行掺杂改性,是拓展TiO₂ 光谱响应范围的有效途径。本文以氨为氮源,分别采用溶胶-凝胶法结合浸渍法以及水解沉淀法制备氮掺杂TiO₂光催化剂。以乙烯为模型反应物,分别考察了不同制备条件、不同方法制备的催化剂在可见光和紫外光照射下的气相光催化性能,并采用XRD、BET、TEM、DRS、EFISPS 及XPS 等表征手段,研究这些催化剂的结构和光电性质,讨论了氮掺杂影响TiO₂光催化性能的机理。此外,本文还探索了以肼为氮源制备氮掺杂TiO₂的新方法。研究结果表明:（1）采用溶胶-凝胶法结合浸渍法制备氮掺杂TiO₂时,400℃焙烧的样品可见光活性最高,主要原因是样品中少量金红石相的存在可以有效提高光生载流子的分离效率。氮的掺杂可以提高TiO₂对可见光和紫外光的吸收,但对TiO2的结构影响很小。氮掺杂在TiO₂禁带中引入了杂质能级,使TiO₂在可见光激发下也可以产生光生载流子,提高了催化剂的可见光催化性能,然而这些杂质能级同时成为了载流子的复合中心,从而降低了催化剂的紫外光催化性能。（2）通过比较溶胶-凝胶法结合浸渍法与水解沉淀法制备的氮掺杂TiO₂的光催化性能、结构及光吸收性质,发现由溶胶-凝胶法结合浸渍法所得到的催化剂结构明显改善,光催化性能也得到提高。（3）以肼为氮源,利用其可燃性,制备出了晶粒小、比表面积大、具有多孔结构的氮掺杂TiO₂。该氮掺杂TiO₂的可见光催化性能较好。本课题的创新之处:（1）采用改进的溶胶-凝胶法结合浸渍法制备了性能优良的氮掺杂TiO₂光催化剂;（2）首次采用电场诱导表面光电压谱研究了氮掺杂TiO₂光催化剂的光电性质,探讨了氮掺杂影响TiO₂光催化性能的机理;（3）首次利用肼的可燃性,以肼为氮源,在短时间高温条件下制备了氮掺杂TiO₂光催化剂。更多还原

【Abstract】 TiO2-based semiconductor photocatalysis technology has been shown to be potentially advantageous for environmental remediation as it may lead to complete mineralization of pollutants at ambient conditions with the use of ultraviolet light as the energy source. However, The large scale application of titanium dioxide as mutual photocatalyst is hampered by the fact that it absorbs only the very small ultraviolet part （3⁴%） of solar light due to its wide band-gap of 3.2eV. An effective approach to shifting the optical response of TiO₂ from the ultraviolet to the visible spectral range is the doping of TiO₂ with nonmetal nitrogen. In this paper, by using ammonia as nitrogen source, nitrogen-doped TiO₂ samples were prepared by the sol-gel and impregnation method or hydrolysis-precipitation method. The photocatalytic degradation of ethylene was used as model reaction to evaluate the visible light and ultraviolet light activity of nitrogen-doped TiO₂ samples prepared under different conditions or by various methods. The structural and photoelectric properties of such photocatalysts were characterized by XRD, BET, DRS, XPS, TEM and EFISPS. The mechanism of the influence induced by nitrogen doping on photocatalytic performance was discussed. Moreover, we invented a new method of preparing nitrogen-doped TiO₂ by using hydrazine as nitrogen source. The results showed: （1）The nitrogen-doped TiO₂（prepared by the sol-gel and impregnation method） calcined at 400℃showed the highest photocatalytic activity under visible light irradiation mainly because a small amount of rutile facilitated the separation of photogenerated charge. Nitrogen doping enhanced the absorption of TiO₂ towards visible light and ultraviolet light, and had little influence on the structure of TiO₂. Nitrogen doping produced impurity midgap levels, involving the enhancement of visible light activity of TiO₂. However, such midgap levels became recombination centers of photogenerated charge, and leaded to the decline of ultraviolet light activity of TiO₂. （2）Compared with that prepared by hydrolysis-precipitation method, nitrogen-doped TiO₂ prepared by the sol-gel and impregnation method demonstrated higher photocatalytic activity due to better structural properties. （3）The nitrogen-doped TiO₂ photocatalyst was prepared by using hydrazine as nitrogen source together with its ignitability. The photocatalyst had small crystalline size, large specific surface area and micropore structure, and showed good photocatalytic performance under visible light. The innovations of this work included: （1） preparing nitrogen-doped TiO2 with high photocatalytic activity by the sol-gel and impregnation method, （2） investigating the photoelectric properties of nitrogen-doped TiO2 by EFISPS, and discussing the mechanism of the influence induced by nitrogen doping on photocatalytic performance, （3）preparing nitrogen-doped TiO2 under short-time high temperature condition using hydrazine as nitrogen source.更多还原