A New Approach to the Preparation of Nitrogen-Doped Titania Visible Light Photocatalyst

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• 作者：Anna Kachina ; Eric Puzenat ; Samy Ould-Chikh ; Christophe Geantet ; Pierre Delichere ; Pavel Afanasiev
• 刊名：Chemistry of Materials
• 出版年：2012
• 出版时间：February 28, 2012
• 年：2012
• 卷：24
• 期：4
• 页码：636-642
• 全文大小：308K
• 年卷期：v.24,no.4(February 28, 2012)
• ISSN：1520-5002

文摘

A new simple method is described, allowing introduction of nitrogen into the TiO₂ lattice at low temperatures. The technique is based on the introduction of oxophilic molecules, such as CCl₄, into the reaction mixture. The treatment of titanium dioxide powders by NH₃鈥揅Cl₄ mixtures leads to highly dispersed N-doped TiO₂. As compared to bare TiO₂ or to the same oxide treated with sole NH₃, the solids treated with NH₃鈥揅Cl₄ mixtures showed a stronger red shift in optical absorption and enhanced photocatalytic activity under visible light, as demonstrated for two reactions of formic acid oxidation and photocatalytic production of hydrogen from methanol. The nitridation temperature can be significantly decreased by introducing CCl₄, because of a favorable change of the reaction thermodynamics. Not only can higher specific surface area of materials be obtained as a result of avoiding sintering but a higher amount of nitrogen is introduced in a position beneficial for the enhanced catalytic activity. The X-ray photoelectron spectroscopy study demonstrated increased surface concentration of nitrogen having N 1s binding energy near 399 eV. As established by ESR, the nature of paramagnetic species generated by treatments is strongly dependent on the titania polymorph variety and crystallinity as well as on the treatment conditions, but in all cases the major part of introduced nitrogen remains ESR-silent.

Keywords:

titania; N-doped; photocatalyst; formic acid oxidation; hydrogen production