Synthesis and Characterization of Gold Nanoparticle‐Functionalized Ordered Mesoporous Materials

Abstract

We report the synthesis and characterization of three different ordered mesoporous materials, labeled MCM‐48, SBA‐155, and SBA‐16 type materials, which were functionalized with gold nanoparticles using three different strategies. The functionalization strategies can be categorized as (i) in situ growth of gold nanoparticles, (ii) template loading, and (iii) diffusion loading of prefabricated gold nanoparticles. Two different particle sizes were employed in the latter two strategies, 5 nm and 10 nm. For all mesoporous structures, functionalization strategies, and particle sizes attempted, the materials retained their long‐range order upon incorporation of nanoparticles. From the adsorption isotherms, incorporation of gold nanoparticles altered the pore structure of the mesoporous support of some of the SBA‐15 and SBA‐16 type materials, with the effect on incorporation on the pore structure being particle size dependent in most cases. The majority of gold nanoparticles were found to reside on the external surface of the materials regardless of substrate and functionalization strategy; however, for the in situ synthesis and the template loading strategies, a significant fraction of the particles was determined to reside within the pore system of the material. In situ growth resulted in the highest content of gold nanoparticles in the solid phase. The relative effectiveness in retaining gold nanoparticles in the solid phase for each functionalization strategy was determined to be, in descending order, in situ synthesis, template loading, and diffusion loading.

Keywords:

• Mesoporous molecular sieves
• gold nanoparticles
• silica
• SBA‐15
• catalyst
• TEM
• diffuse‐reflectance UV‐vis
• adsorption isotherms

Acknowledgments

The authors sincerely thank Professor Vicente Rives and Ms. Patricia Benito at the Department of Inorganic Chemistry, Universidad de Salamanca, Spain, for collecting the diffuse‐reflectance UV‐vis spectra. We also thank the Research Council of Norway (NFR) for financial support.