Toward Monodispersed Silver Nanoparticles with Unusual Thermal Stability

详细信息    查看全文

• 作者：Junming Sun ; Ding Ma ; He Zhang ; Xiumei Liu ; Xiuwen Han ; Xinhe Bao ; Gisela Weinberg ; Norbert Pfä ; nder ; Dangsheng Su
• 刊名：Journal of the American Chemical Society
• 出版年：2006
• 出版时间：December 13, 2006
• 年：2006
• 卷：128
• 期：49
• 页码：15756 - 15764
• 全文大小：1747K
• 年卷期：v.128,no.49(December 13, 2006)
• ISSN：1520-5126

文摘

A novel in situ autoreduction route has been developed, by which monodispersed silvernanoparticles with tunable sizes could be easily fabricated on silica-based materials, especially inside thechannels of mesoporous silica (MPS). ¹³C CP/MAS NMR spectroscopy was employed to monitor the wholeassembly process. It was demonstrated that the amino groups of APTS (aminopropyltriethoxyl silane)-modified MPS can be used to anchor formaldehyde to form novel reducing species (NHCH₂OH), on whichAg(NH₃)₂NO₃ could be in situ reduced. Monodispersed silver nanoparticles were thus obtained. In situXRD and in situ TEM experiments were used to investigate and compare the thermal stabilities of silvernanoparticles on the external surface of silica gels (unconfined) and those located inside the channels ofSBA-15 (confined). It was observed that unconfined silver nanoparticles tended to agglomerate at lowtemperatures (i.e., lower than 773 K). The aggregation of silver nanoparticles became more serious at 773K. However, for those confined silver nanoparticles, no coarsening process was observed at 773 K, muchhigher than its Tammann temperature (i.e., 617 K). Only when the treating temperature was higher than873 K could the agglomeration of those confined silver nanoparticles happen with time-varying via theOstwald ripening process. The confinement of mesopores played a key role in improving the thermalstabilities of silver nanoparticles (stable up to 773 K without any observable coarsening), which is essentialto the further investigations on their chemical (e.g., catalytic) properties.