Nanocomposite of montmorillonite and silver nanoparticles: Characterization and application in catalytic reduction of 4-nitrophenol

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• 作者：Petr Praus^a ; ^{petr.praus@vsb.cz} ; Martina Turicová ; ^a ; Martina Karl&iacute ; ková ; ^b ; Libor Kv&iacute ; tek^b ; Richard Dvorský ; ^c
• 关键词：A. Microporous materials ; A. Nanostructures ; A. Metals ; A. Composite materials ; D. Surface properties ; D. Optical properties
• 刊名：Materials Chemistry and Physics
• 出版年：2013
• 出版时间：15 July, 2013
• 年：2013
• 卷：140
• 期：2-3
• 页码：493-498
• 全文大小：1255 K

文摘

Silver ions previously intercalated into a montmorillonite (MMT) interlayer were reduced by sodium borohydride forming a nanocomposite of MMT and silver nanoparticles (Ag-MMT) with no other stabilizing additives. Within 360?min no coagulation of an aqueous Ag-MMT dispersion was observed. However, after 24?h the coagulation was indicated by a red shift of absorption maximum from 408?nm to 434?nm and by broadening of the absorbance band.

The nanocomposite was characterized by transmission electron microscopy (TEM), X-ray powder diffraction (XRD) and measurements of specific surface area (SSA). It contained 4.94?wt. % of silver. Ag nanoparticles with an average size of 6.9?nm were located on the external MMT surface, mostly in its pores.

Ag-MMT was used as a catalyst for reduction of 4-nitrophenol with sodium borohydride forming 4-aminophenol. After 30?s the reaction kinetics changed from zero order to first order, which was explained by means of the Langmuir-Hinshelwood model. The whole reduction was completed after 290?s. During this time min. 95?wt. % of Ag nanoparticles stayed fixed on the MMT support.