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

Abstract

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. N 2 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.

Ligand-assisted preparation of highly active and stable nanometric Pd confined catalysts for deep catalytic oxidation of toluene

“…2(A), we can observe that all diffraction peaks of Pd confined samples shift slightly to lower angles, corresponding to a tiny increase of d 1 0 0 and a 0 , as listed in Table 1. This shift suggests that the frameworks of the silica host are slightly enlarged during the synthesis process [13]. The wide-angle XRD (WA-XRD) and EDS (insert) patterns of all Pdsupported catalysts are shown in Fig.…”

“…Therefore, the exploration of new preparation methods is still very urgent. Liu and co-workers [13] synthesized the monodispersed Pd nanoparticles in the interior surface of SBA-15 channels via a glow discharge plasma reduction approach, but the average Pd particle size was still unsatisfactory (ca. 8.2 nm).…”

Nanometric palladium confined in mesoporous silica as efficient catalysts for toluene oxidation at low temperature

“…Besides, the (1 0 0), (1 1 0) and (2 0 0) reflection becomes more intense and prominent with the decreasing of Al content, indicating that the hexagonal order is decreased to some extent with the introduction of Al species. Besides, it can be noticed that all diffraction peaks of Pd/SC-x samples shift slightly to lower angles (i.e., d 100 and a 0 are slightly enlarged [22]) compared with the Pd/SBA-15 and Pd/SBA-15-T materials, suggesting that Al atoms are introduced into the frameworks of the SC-x host as the Al-O bond length is longer than that of Si-O bond. Fig.…”

“…On the other hand, recent work suggested that noble metal confined catalysts possess high catalytic activity and stability as the pore channels of supports have the potential ability to inhibit active particles growth and aggregation during reactions [22]. Various strategies were developed for incorporating metal nanoparticles into mesoporous silica, such as chemical vapor deposition [23], wet impregnation [7,16,24,25] and ion exchange [26].…”

Preparation and Characterization of Nanomaterials for Sustainable Energy Production

“…For example, nonequilibrium cold plasma preparations with high electron temperatures (as high as 10 4 K) and very low gas temperatures (as low as room temperature) can generate materials similar to the virus template. 50 With such high electron temperatures, nucleation and growth kinetics vary substantially from that of the conventional thermal method. Moreover, the development of new characterization techniques for nanomaterials is extremely important.…”