Mechanism of Nitrogen-Concentration Dependence on pH Value: Experimental and Theoretical Studies on Nitrogen-Doped TiO2

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• 作者：Hongqi Sun ; Yuan Bai ; Huijing Liu ; Wanqin Jin ; Nanping Xu ; Guojun Chen ; Bingqian Xu
• 刊名：Journal of Physical Chemistry C
• 出版年：2008
• 出版时间：August 28, 2008
• 年：2008
• 卷：112
• 期：34
• 页码：13304-13309
• 全文大小：254K
• 年卷期：v.112,no.34(August 28, 2008)
• ISSN：1932-7455

文摘

Experiments and density functional theory (DFT) calculations were combined in an attempt to investigate the origin of the differences in nitrogen concentration incorporated by N-doped TiO₂. X-ray photoelectron spectroscopy (XPS), UV−vis diffusive reflectance spectra (UV−vis), and photodegradation experiments were conducted to set some premises for DFT calculations. Fourier transform infrared (FT-IR) spectroscopy was applied to investigate the NH_x-containing species in the dried precipitate from the hydrolysis. [Ti(H₂O)_a(NH₃)_b(OH)_cCl_d]^(4−c−d) (a + b + c + d = 6) is defined as the Ti complex produced by the hydrolysis process, and its pH-dependent character was further determined by Gibbs energy calculations for the reaction based on those of related equations. Adsorption energies of NO on TiO₂ surfaces were calculated to study the ability of NO_x to be incorporated into the TiO₂ matrix under different pH conditions. Finally, we propose three processes as being responsible for the dependence of the nitrogen concentration on the pH value.