Controlled nanopore formation and stabilization of gold nanocrystals in acid-activated montmorillonite

Au-o-nanoparticles of 0-10 nm were generated in situ by the reduction of [AuCl4](-) impregnated on acid-activated montmorillonites with maximum pore diameters of about 3, 4, 6, and 8 nm. The size of the Au-o-nanoparticles depended on the pore diameter of the micro- and mesopores of the support. The montmorillonite was activated with HCl under control conditions for generating different pore sizes. Powder X-ray diffraction (XRD), FTIR, FESEM-EDX, HRTEM, N-2 adsorption, Si-29 and Al-27 MAS-NMR and UV-visible spectroscopic analyses were carried out to characterize the solid porous materials before and after Au-o-nanoparticle loading. N-2 adsorption data revealed specific surface areas (BET) of 327-579 m(2)/g, large specific pore volumes of similar to 0.7 cm(3)/g, and pore diameters of 0-10 nm. TEM, FESEM and X-ray mapping images revealed Au-o-nanoparticles of 0-10 nm evenly distributed on the support. The Au-o-nanocrystal composites exhibited the cubic face-centered (fcc) lattice with a preferential growth direction along the (111) plane. (C) 2010 Elsevier B.V. All rights reserved.