Surface structural, morphological, and catalytic studies of homogeneously dispersed anisotropic Ag nanostructures within mesoporous silica

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• 作者：Shweta Sareen ; Vishal Mutreja ; Bonamali Pal…
• 关键词：Mesoporous silica ; Post modification ; Ag nanoparticles ; Ag nanoparticles dispersed SBA ; 15 ; Ag/SBA ; 15 nanocomposites ; Nitroaromatic reduction
• 刊名：Journal of Nanoparticle Research
• 出版年：2016
• 出版时间：November 2016
• 年：2016
• 卷：18
• 期：11
• 全文大小：5,058 KB
• 刊物类别：Chemistry and Materials Science
• 刊物主题：Chemistry
  Nanotechnology
  Inorganic Chemistry
  Characterization and Evaluation Materials
  Physical Chemistry
  Applied Optics, Optoelectronics and Optical Devices
  
• 出版者：Springer Netherlands
• ISSN：1572-896X
• 卷排序：18

文摘

Highly dispersed anisotropic Ag nanostructures were synthesized within the channels of 3-aminopropyltrimethoxysilane (APTMS)-modified mesoporous SBA-15 for catalyzing the reduction of p-dinitrobenzene, p-nitrophenol, and p-nitroacetophenone, respectively. A green templating process without involving any reducing agent, by varying the amount (1–10 wt.%) of Ag loading followed by calcination at 350 °C under H₂ led to change in the morphology of Ag nanoparticles from nanospheres (~7–8 nm) to nanorods (aspect ratio ~12–30 nm) without any deformation in mesoporous sieves. In comparison to white bare SBA-15, gray-colored samples were formed with Ag impregnation exhibiting absorption bands at 484 and 840 nm indicating the formation of anisotropic Ag nanostructures within mesoporous matrix. TEM and FE-SEM micrographs confirmed the presence of evenly dispersed Ag nanostructures within as well as on the surface of mesoporous matrix. AFM studies indicated a small decrease in the average roughness of SBA-15 from 20.59 to 19.21 nm for 4 wt.% Ag/m-SBA-15, illustrating the encapsulation of majority of Ag nanoparticles in the siliceous matrix and presence of small amount of Ag nanoparticles on the mesoporous support. Moreover, due to plugging of mesopores with Ag, a significant decrease in surface area from 680 m2/g of SBA-15 to 385 m2/g was observed. The Ag-impregnated SBA-15 catalyst displayed superior catalytic activity than did bare SBA-15 with 4 wt.% Ag-loaded catalyst exhibiting optimum activity for selective reduction of p-nitrophenol to p-aminophenol (100 %), p-nitroacetophenone to p-aminoacetophenone (100 %), and p-dinitrobenzene to p-nitroaniline (87 %), with a small amount of p-phenylenediamine formation.