Natural Chrysotile-Based Nanowires Decorated with Monodispersed Ag Nanoparticles as a Highly Active and Reusable Hydrogenation Catalyst

Abstract

Silver nanoparticles/silica nanowires (AgNPs/SiO 2 NWs) with the nearly uniform diameters of 35 ± 5 nm were successfully fabricated by two steps consisting of the preparation of the silica nanowires (SNWs) by chemical dispersing and acid leaching from the natural mineral chrysotile and an in situ reduction approach (for AgNPs). The highly dispersed AgNPs assembled on the surface of SiO 2 NWs through the in situ reduction of Ag + by NaBH 4 were confirmed by transmission electron microscopy (TEM) and UV−vis absorption spectra. The catalytic activities of the as-prepared Ag/SiO 2 NWs (silver nanoparticles/silica nanowires) nanocomposites with different concentrations were assessed via using a classical reaction based on the reduction process of 4-nitrophenol (4-NP) into 4-aminophenol (4-AP) in the presence of NaBH 4 as the reductant. The results demonstrated that all the nanocomposite catalysts exhibited high catalytic activities because the nearly monodispersed AgNPs were embedded on the surface of SiO 2 NWs, allowing effective active contact with the reactants and catalysis of the reaction. In particular, the asprepared Ag/SiO 2 NWs nanocomposites with 5 mL of AgNPs exhibited excellent catalytic activitiy. These AgNPs/SiO 2 NWs nanocomposites could be easily reused without a decline of the catalytic activities due to chrysotile natural mineral frameworks with large amounts of active sites.

Fabrication of Sesame Sticks-like Silver Nanoparticles/Polystyrene Hybridnanotubes and Their Catalytic Effects

“…For instance, silver nanoparticles (AgNPs) have received considerable attention as a potentially useful catalyst12345. So far numerous methods have been developed to prepare stable noble metal nanoparticles with a controllable shape and size.…”

Ag Nanoparticles-Based Zinc Hydroxide-Layered Hybrids as Novel and Efficient Catalysts for Reduction of 4-Nitrophenol to 4-Aminophenol

“…The ZHL particles presented a layered structure with the sheets separated by a d-spacing of 0.98 nm, where the nitrate ions are occluded between the inorganic lamellae ( Figure 1a). [11][12][13][14] This pattern is identified as zinc hydroxide nitrate layered (JCPDS card 24-1460) and it is characterized by an intense and sharp reflection at 0.98 nm (2θ = 9.05), due to the (200)-plane of the monoclinic structure. 11,14 All AgNPs(x)/ZHL hybrids (curves ii and iii in Figure 1a) exhibited the same diffraction peaks of pristine ZHL indicating that the AgNPs do not disturb the layered structure of inorganic support.…”

“…[11][12][13][14] This pattern is identified as zinc hydroxide nitrate layered (JCPDS card 24-1460) and it is characterized by an intense and sharp reflection at 0.98 nm (2θ = 9.05), due to the (200)-plane of the monoclinic structure. 11,14 All AgNPs(x)/ZHL hybrids (curves ii and iii in Figure 1a) exhibited the same diffraction peaks of pristine ZHL indicating that the AgNPs do not disturb the layered structure of inorganic support. In addition, the basal spacing of ZHL (d 200 = 0.98 nm) did not change upon the reduction reaction with AgNPs, suggesting that they are localized on the external surfaces of the ZHL support.…”

“…9 In fact, layered material-NPs hybrids are attracting attention for practical applications due to their mechanical and catalytic properties. 1,9,11 AgNPs have been deposited in different inorganic substrates for use as catalysts in reduction of 4-NP to 4-AP with NaBH 4 in excess. Recently, Hsu and Chen 10 showed a rapid microwave-assisted green route for the uniform deposition of Ag nanoparticles on graphene oxide surface with L-arginine acting as the external reducing Vol.…”

“…1, 2017 agent. Zhang et al 11 investigated also the catalytic properties of hybrids based on silica nanowires and AgNPs using in situ reduction of Ag + ions by NaBH 4 on silica nanowires. According to the studies performed by these authors, AgNPs/ silica hybrids exhibited high catalytic activities because the nearly monodispersed AgNPs were embedded on the surface of SiO 2 nanowires, allowing active contact between the reactants (4-NP and NaBH 4 ) and catalyst of the reaction.…”