Template synthesis of nanoparticle arrays of gold, platinum and palladium in mesoporous silica films and powders

Abstract

Mesoporous silica films were prepared on glass plates by a dip coating method, and the film/plate samples were used as a support for Au, Pt and Pd nanoparticles. By H 2 -or photo-reduction of metal precursors impregnated on the films, metal nanoparticles are formed with an ordered array structure in the mesopores. The nanoparticles are isolated by dissolving the silica film with a dilute HF solution, and the particles are stabilized with ligands such as 1-dodecanethiol and triphenylphosphine. The diameter of the separated nanoparticles is 2.5 nm with narrow distributions, showing that uniform particles are formed in the mesopores. Selective formation of metal nanoparticles rather than nanowires suggests that a 3D-hexagonal structure is involved in the 2D-hexagonal mesoporous silica films. To study the formation of nanoparticles in a 3D-hexagonal structure, HMM-2 powder was used as a support, and in fact Au and Pt nanoparticles are formed in the HMM-2 powders. The XRD study suggests that the Au nanoparticles in the film/plate have an anisotropic orientation in the mesoporous channels. The Au/film/plate sample gives a weak plasmon peak at 570-580 nm using diffuse-reflectance UV-visible spectroscopy, which is shifted to high wavelength by 50-60 nm compared with larger Au particles.

Synthesis of Gold Catalysts Supported on Mesoporous Silica Materials: Recent Developments

“…Au/HMM-2 (Au 2%wt) was prepared by DP of HAuCl 4 aqueous solution in alkaline conditions (pH 11.7) and the resulting solid sample was reduced under H 2 at 200 °C for 2 h [176]. The obtained purple powder with homogeneously dispersed AuNPs (mean diameter of 3.2 ± 0.5 nm) retained the 3D-hexagonal structure of the HMM-2 after gold loading.…”

“…AuNPs (2.5 ± 0.3 nm) closely packed in the mesopores of MCM-41-type mesoporous silica films were prepared by impregnation with HAuCl 4 by Fukuoka et al [176,183]. The silica materials were immersed in aqueous solution of HAuCl 4 .…”

Synthesis and electronic property of platinum nanowire and nanoparticle in mesoporous silica template

“…Therefore, the mesoporous silicas provide great opportunities as a template of nanostructured materials. 2 In our study of the ship-in-bottle synthesis of metal clusters in microporous zeolites [7,13], we extended this chemistry from zeolites to mesoporous silicas and found the formation of metal nanowires in the mesopores [14][15][16][17][18][19][20][21][22][23][24]. Here we report selective synthesis of metal nanowires and nanoparticles in FSM-16 and HMM-1.…”

“…Similar results were obtained using MCM-41, SBA-15, and HMM-1 as supports. We have so far synthesized nanowires of Rh, Pd, Pt, Au and bimetallic Pt-Rh, Pt-Pd by the photoreduction method [14][15][16][17][18][19][20][21][22][23][24].…”

Effect of reduction–oxidation treatment on structure and catalytic properties of ordered mesoporous Cu–Mg–Al composite oxides

“…Ordered mesoporous alumina, like other mesoporous materials [9,10], has been considered as promising support or catalyst for various catalytic applications, because of its large surface area, narrow pore size distribution, highly uniform channels, and tunable pore sizes over a considerably wide range [11][12][13][14]. The development of strategies for synthesizing these mesoporous materials, such as traditional precipitation [15], nanocasting [16], solgel process [17], and cation-anion double hydrolysis [18], was therefore widely stimulated during the last decades.…”