Acta Phys. -Chim. Sin. ›› 2014, Vol. 30 ›› Issue (7): 1384-1390.doi: 10.3866/PKU.WHXB201405122

• PHYSICAL CHEMISTRY OF MATERIALS • Previous Articles     Next Articles

Preparation and Characterization of Ag Nanoparticles Embedded in Hierarchically Porous Monolithic Silica

YU Huan, YANG Hui, YAO Rui, GUO Xing-Zhong   

  1. Department of Materials Science and Engineering, Zhejiang University, Hangzhou 310027, P. R. China
  • Received:2014-03-24 Revised:2014-05-12 Published:2014-06-30
  • Contact: GUO Xing-Zhong E-mail:msewj01@zju.edu.cn
  • Supported by:

    The project was supported by the National Natural Science Foundation of China (51372225) and Natural Science Foundation of Zhejiang Province, China (LY13B010001).

Abstract:

Ag nanoparticles (NPs) were uniformly immobilized in hierarchically porous monolithic silica using γ-(aminopropyl)triethoxysilane (APTES) as a modifier and ethanol as a reductant, where the silica monolith was pre-prepared via the sol-gel accompanied by phase separation. Ag NPs embedded in the hierarchically porous silica monoliths were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), mercury porosimetry, nitrogen adsorption/desorption analysis, and X-ray photoelectron spectroscopy (XPS). The mechanism of the modification by APTES, the reduction using ethanol, and pore structure changes of the silica monolith after immobilization of Ag NPs are discussed. The results show that APTES modifies the monolith by incorporating amino groups onto the surface of the meso-macroporous skeletons, and then amino groups react with silver ions to form a silver-amine complex. Ethanol used as an effective reductant is adopted to promote the reduction process of the silver-amine complex. Ag NPs with an average size of approximately 16 nm were homogeneously supported on both the macroporous skeletons and in the mesopores of the silica monolith with good dispersion. The embedding of Ag NPs did not spoil the macroporous skeleton of the monolithic silica, and the surface area decreased from 418 to 254 m2 ·g-1 after introducing Ag NPs into its macromesopores. It was also found that the loading amount of Ag NPs increased with repeated modification and reduction treatments.

Key words: Sol-gel, Phase separation, Hierarchically porous monolithic silica, Ag nanoparticle, Ethanol

MSC2000: 

  • O647