| 硼、氮共掺杂纳米晶氧化钛可见光催化性能的研究 | |
| Alternative Title | Investigation of Visible Light Photocatalytic Activity of B, N-co-doped Nanocrystalline TiO2 |
| 赵燕宁 | |
| Subtype | 硕士 |
| Thesis Advisor | 成会明 |
| 2007-06-02 | |
| Degree Grantor | 中国科学院金属研究所 |
| Place of Conferral | 金属研究所 |
| Degree Discipline | 材料学 |
| Keyword | 纳米晶氧化钛 硼 氮共掺杂 可见光催化性能 掺杂状态 |
| Abstract | 为了提高氧化钛对太阳光的利用率，改善可见光催化活性，制备具有良好可见光催化活性的氧化钛具有重要意义。掺杂作为一种调节半导体带隙的方法已广泛运用于氧化钛电子结构的改性，希望通过掺杂过程得到具有较高可见光催化活性的氧化钛光催化剂。本论文综合分析了当前非金属元素掺杂的研究现状，在硼掺杂氧化钛体系的研究基础上，提出了提高氧化钛可见光催化活性的硼、氮两种非金属元素共掺杂思路，并且得到了具有较高可见光催化活性的硼、氮共掺杂的纳米晶氧化钛，并对氧化钛中硼、氮掺杂元素化学状态、可见光吸收性能、可见光催化活性以及三者联系进行了较为系统的研究。 通过两步水热过程加氮化处理制备了硼、氮共掺杂中孔纳米晶氧化钛。采用TG-DSC、XRD、透射电镜、XPS、FTIR、拉曼光谱、紫外-可见吸收光谱等分析手段进行了表征并测定了可见光催化活性，结果表明： （1）硼的掺杂状态与可见光吸收性能密切相关，是硼、氮共掺杂协同作用的基础。随着硼含量增加及氮化过程的进行，硼化学状态在氧化钛基体中变化规律为： 形成氧化硼和氮化硼，但未与TiO2形成化学健,到不仅形成氧化硼和氮化硼而且出现B-Ti-O、N-B-Ti-O掺杂态,到形成大量氧化硼和氮化硼。 （2）氧化钛表面形成B-Ti-O、N-B-Ti-O掺杂态能够改变氧化钛的能带结构，使其产生可见光吸收。 （3）建立了B-Ti-O及N-B-Ti-O掺杂状态模型并进行了第一原理计算，发现这些结构可以在氧化钛表面上存在。综合计算和实验研究结果发现，由于表面硼、氮掺杂原子的引入使氧化钛费米能级附近出现许多局域化能级而引起可见光吸收。同时N-B-Ti-O结构对应的某些局域化能级延长了光生载流子的寿命，从而明显改善了氧化钛的可见光催化活性。 通过本研究提出了实现既具有可见光吸收又具有较高可见光催化活性的硼、氮二元掺杂氧化钛的制备新方法，系统研究了硼、氮掺杂得到的B-Ti-O及N-B-Ti-O结构对于氧化钛能带结构的影响，拓展了非金属元素掺杂氧化钛的认识和理解，所得结果对非金属掺杂氧化钛的应用及研究具有一定参考价值。 |
| Other Abstract | In order to increase the solar light utility and improve the photocatalytic activity in visible light, it is significant to synthesize TiO2 photocatalyst with good performance in visible light photoactivity. As an effective method to modify the band structure of semiconductors, doping is also widely adopted for the band structure modification of TiO2. In this thesis, a novel method of B and N co-doping for the photoactivity enhancement of TiO2 in visible light region was developed. The doping states of the dopants, the visible light absorption, the photocatalytic activity under visible light irradiation and the relationships among them in this B, N-co-doped TiO2 system were also explored. B, N-co-doped nanocrystalline TiO2 powders were synthesized through two-step hydrothermal process and nitridation treatment, and were characterized by TG-DSC, XRD, HRTEM, XPS, FTIR, Raman spectroscopy, UV-Vis absorption spectroscopy, and their photoactivity was evaluated under visible light irradiation. The results obtained are as follows: (1) The doping state of boron is essential for visible light adsorption and for the synergistic effects of B, N-co-doping. The chemical states of B atoms changed as the increase of B concentration and the nitridation treatment, from the formation of B2O3/BN without bonding with TiO2 to the formation of B2O3/BN and surface B-Ti-O, N-B-Ti-O states, and to the enrichment of B2O3/BN; (2) The B-Ti-O and N-B-Ti-O bonds on the TiO2 surface can change the band structure of TiO2, which causes the enhancement of visible light absorption; (3) The theoretical models of B-Ti-O and N-B-Ti-O structures on TiO2 surface were developed and calculated by first principle method, which shows that these structures can stably exist on the surface of TiO2. The DOS of the doped TiO2 reveals that the localized states around Fermi level is the physical basis for visible light absorption performance of the doped TiO2. Meanwhile, some of the localized states of the N-B-Ti-O structure may extend the lifetime of excitons, effectively enhancingthe visible light photocatalytic activity of the doped TiO2. In general, we developed a novel method to obtain B, N binary doped TiO2 for the enhancement of both visible light absorption and visible light photoactivity. The results obtained enrich the understanding of non-metal doped TiO2 and are helpful for the further development and the applications of non-metal doped TiO2. |
| Pages | 101 |
| Language | 中文 |
| Document Type | 学位论文 |
| Identifier | http://ir.imr.ac.cn/handle/321006/17104 |
| Collection | 中国科学院金属研究所 |
| Recommended Citation GB/T 7714 | 赵燕宁. 硼、氮共掺杂纳米晶氧化钛可见光催化性能的研究[D]. 金属研究所. 中国科学院金属研究所,2007. |
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