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

Auo-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 Auo-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, N2 adsorption, 29Si and 27Al MAS-NMR and UV–visible spectroscopic analyses were carried out to characterize the solid porous materials before and after Auo-nanoparticle loading. N2 adsorption data revealed specific surface areas (BET) of 327–579 m2/g, large specific pore volumes of ∼ 0.7 cm3/g, and pore diameters of 0–10 nm. TEM, FESEM and X-ray mapping images revealed Auo-nanoparticles of 0–10 nm evenly distributed on the support. The Auo-nanocrystal composites exhibited the cubic face-centered (fcc) lattice with a preferential growth direction along the (111) plane.