Synthesis and Characterization of Noble Metal (Pd, Pt, Au, Ag) Nanostructured Materials Confined in the Channels of Mesoporous SBA-15

Highly dispersed metal (Pd, Pt) nanoparticles and uniformly distributed metal (Au, Ag) nanowires have been synthesized in ordered mesoporous silica SBA-15 via conventional incipient wetness impregnation followed by novel glow discharge plasma reduction. N2 adsorption−desorption isotherms and the low-angle X-ray diffraction (XRD) patterns indicate that the parent ordered mesoporous structure was well-maintained during the synthesis process. The wide-angle XRD patterns and transmission electron microscope images demonstrate that spherical Pd and Pt nanoparticles as well as rodlike Au and Ag nanowires were fabricated within the channels of SBA-15. The diameters of the metal nanoparticles and the metal nanowires were effectively controlled by the mesopores of the SBA-15 host. The population of the metal nanoparticles and the length of the metal nanowires can be tuned by the metal loading amount. In particular, the novel plasma reduction at ambient temperature is green, economical, and non-time-consuming, showing great advantages over the traditional hydrogen reduction at elevated temperature. This very simple synthesis method with the use of plasma reduction will be very promising as a general technique for the preparation of metal nanostructured materials confined in the host architectures.