Nanostructured SnO2鈥揨nO Heterojunction Photocatalysts Showing Enhanced Photocatalytic Activity for the Degradation of Organic Dyes

详细信息    查看全文

• 作者：Md. Tamez Uddin ; Yohann Nicolas ; C茅line Olivier ; Thierry Toupance ; Laurent Servant ; Mathis M. M眉ller ; Hans-Joachim Kleebe ; J眉rgen Ziegler ; Wolfram Jaegermann
• 刊名：Inorganic Chemistry
• 出版年：2012
• 出版时间：July 16, 2012
• 年：2012
• 卷：51
• 期：14
• 页码：7764-7773
• 全文大小：613K
• 年卷期：v.51,no.14(July 16, 2012)
• ISSN：1520-510X

文摘

Nanoporous SnO₂鈥揨nO heterojunction nanocatalyst was prepared by a straightforward two-step procedure involving, first, the synthesis of nanosized SnO₂ particles by homogeneous precipitation combined with a hydrothermal treatment and, second, the reaction of the as-prepared SnO₂ particles with zinc acetate followed by calcination at 500 掳C. The resulting nanocatalysts were characterized by X-ray diffraction (XRD), FTIR, Raman, X-ray photoelectron spectroscopy (XPS), nitrogen adsorption鈥揹esorption analyses, transmission electron microscopy (TEM), and UV鈥搗is diffuse reflectance spectroscopy. The SnO₂鈥揨nO photocatalyst was made of a mesoporous network of aggregated wurtzite ZnO and cassiterite SnO₂ nanocrystallites, the size of which was estimated to be 27 and 4.5 nm, respectively, after calcination. According to UV鈥搗isible diffuse reflectance spectroscopy, the evident energy band gap value of the SnO₂鈥揨nO photocatalyst was estimated to be 3.23 eV to be compared with those of pure SnO₂, that is, 3.7 eV, and ZnO, that is, 3.2 eV, analogues. The energy band diagram of the SnO₂鈥揨nO heterostructure was directly determined by combining XPS and the energy band gap values. The valence band and conduction band offsets were calculated to be 0.70 卤 0.05 eV and 0.20 卤 0.05 eV, respectively, which revealed a type-II band alignment. Moreover, the heterostructure SnO₂鈥揨nO photocatalyst showed much higher photocatalytic activities for the degradation of methylene blue than those of individual SnO₂ and ZnO nanomaterials. This behavior was rationalized in terms of better charge separation and the suppression of charge recombination in the SnO₂鈥揨nO photocatalyst because of the energy difference between the conduction band edges of SnO₂ and ZnO as evidenced by the band alignment determination. Finally, this mesoporous SnO₂鈥揨nO heterojunction nanocatalyst was stable and could be easily recycled several times opening new avenues for potential industrial applications.