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以紫外可见漫反射光谱(UV-VIS-DRS)和X射线光电子能谱(XPS)分析和研究了四种方法制备的N掺杂TiO2光催化剂的结构,即水解法(N/TiO2-H)、氨热还原法(N/TiO2-A)、机械化学法(N/TiO2-M)和尿素热处理法(N/TiO2-T)等.结果表明,N/TiO2-H和N/TiO2-T两种催化剂在490 nm处有吸收带边,可见光激发途径是掺杂的N以填隙方式形成的杂质能级吸收电子发生的跃迁引起的;而N/TiO2-A和N/TiO2-M两种催化剂在整个可见光区域内具有可见光吸收,其对可见光的激发途径是掺杂N和氧空缺共同作用的结果.理论计算的N杂质能级位于价带上0.75 eV,与实验观察到的吸收带边结果十分吻合.XPS结果表明,几种催化剂的N1 s结合能位置都在399 eV附近,显示为填隙掺杂的N原子.填隙掺杂的N/TiO2,其Ti原子的2p结合能与未掺杂的TiO2相比增加了+0.3-+0.6 eV,而O1s电子的结合能增加了+0.2-+0.5eV,这是因为填隙的N原子夺取Ti和O的电子,Ti和O原子周围的电子密度降低了.电子能谱和吸光特性的研究都表明,掺杂的机理是在TiO2晶格内形成N原子的填隙.
The structures of N-doped TiO2 photocatalyst prepared by four methods were analyzed and studied by UV-VIS-DRS and XPS. That is to say, the hydrolysis method (N / TiO2-H) , N / TiO2-A, N / TiO2-M, N / TiO2-T and so on.The results showed that N / TiO2-H and N / TiO2- The two catalysts have absorption band edges at 490 nm, and the visible light excitation is caused by the transition of the impurity level of the doped N formed by interstitial absorption of electrons. The ratio of N / TiO2-A and N / TiO2-M Species of catalysts have visible light absorption in the whole visible region, and the excitation of visible light is the result of the interaction between doped N and oxygen vacancies.The theoretically calculated N impurity level is 0.75 eV on the valence band, which is in agreement with the experimentally observed absorption band XPS results show that the N1s binding energies of several catalysts are near 399 eV and are shown as interstitial-doped N atoms. The interstitial-doped N / TiO2 has a 2p binding energy of Ti atoms +0.3- +0.6 eV increased compared to undoped TiO2, whereas the binding energy of O1s increased by +0.2- + 0.5eV because the interstitial N atoms captured Ti and O electrons, Ti and The electron density around the O atom decreases.Electron energy spectra and absorption properties show that the mechanism of doping is to form interstitials of N atoms in the TiO2 lattice.