Development of reactive Pd/Fe bimetallic nanotubes for dechlorination reactions

From multi-segmented to core/shell nanorods: morphology evolution in Fe-Au nanorods by tuning fabrication conditions

Aiming to obtain hybrid magneto-plasmonic nanostructures, we have developed multisegmented and core/shell structured Fe-Au nanorods using template assisted electrochemical deposition. A facile method of tuning the growth pattern of multisegmented nanorods into core/shell structured is demonstrated. With a precise control of current density and deposition time, a brick-stacked wire like growth led to the formation of hollow nanotubes that could be further tuned to multilayered hollow nanotubes and core/shell structured nanorods. TEM imaging and STEM-EELS technique were used to explore the morphology, microstructure and the distribution of Au and Fe in the nanorods. The easy magnetization direction was found to be perpendicular to the nanorods' growth direction in the segmented nanorods. On the other hand, core/shell nanorods exhibited isotropic behavior. Our findings provide deeper insights into the fabrication of hybrid nanorods and the opportunity to tune the fabrication method to vary their morphology accordingly. Such studies will benefit design of hybrid nanorods with specific morphologies and physical properties and hence their integration into sensing, spintronics and other potential biomedical and technological applications.

Primary amine synthesis by hydrogen-involving reactions over heterogeneous cobalt catalysts

Co/SiO2 exhibited high selectivity for primary amines in hydrogenation of nitriles and reductive amination of carbonyl compounds.

Chiral Fe nanotubes with both negative Poisson's ratio and Poynting's effect. Atomistic simulation

Using atomistic calculations, we study the features of uniaxial deformation of nanotubes made of rolled-up thin [0 1 0] plates of Fe cubic crystals. We find that within a certain range of chiral angles these nanotubes have both negative Poisson's ratio and axial strain-induced torsion (reverse Poynting's effect) during tension and compression. The maximum torsion and the minimum value of Poisson's ratio are observed at chiral angles of [Formula: see text] and [Formula: see text], respectively. We show that Young's modulus of the chiral Fe nanotubes increases with a chiral angle. We demonstrate that in the discussed range of nanotube sizes there is a satisfactory correspondence between the results obtained by molecular statics and anisotropic theory of elasticity.

Phase diagrams of nanoalloys: influence of size and morphology

A non-monotonous variation of the critical temperature as a function of the length of the nanotubes.

Fabrication of resin supported Au–Pd bimetallic nanoparticle composite to efficiently remove chloramphenicol from water

Au–Pd bimetallic nanoparticles were loaded on the amberlite 717 to form a catalytic system (717@Au–Pd), which exhibited excellent activity for removing environmental pollutants such as chloramphenicol containing carbon–halogen bonds.

PCB 77 dechlorination products modulate pro-inflammatory events in vascular endothelial cells

Persistent organic pollutants such as polychlorinated biphenyls (PCBs) are associated with detrimental health outcomes including cardiovascular diseases. Remediation of these compounds is a critical component of environmental policy. Although remediation efforts aim to completely remove toxicants, little is known about the effects of potential remediation byproducts. We previously published that Fe/Pd nanoparticles effectively dechlorinate PCB 77 to biphenyl, thus eliminating PCB-induced endothelial dysfunction using primary vascular endothelial cells. Herein, we analyzed the toxic effects of PCB congener mixtures (representative mixtures of commercial PCBs based on previous dechlorination data) produced at multiple time points during the dechlorination of PCB 77 to biphenyl. Compared with pure PCB 77, exposing endothelial cells to lower chlorinated PCB byproducts led to improved cellular viability, decreased superoxide production, and decreased nuclear factor kappa B activation based on duration of remediation. Presence of the parent compound, PCB 77, led to significant increases in mRNA and protein inflammatory marker expression. These data implicate that PCB dechlorination reduces biological toxicity to vascular endothelial cells.

Reactivity of Pd/Fe bimetallic nanotubes in dechlorination of coplanar polychlorinated biphenyls

A new class of bimetallic materials based on palladium-decorated iron nanotubes is described that demonstrates high reactivity in dechlorination reactions. This high dechlorination efficiency was attributed to the high surface area to volume ratio of the hollow nanotubes structure. Herein, we evaluated the effect of different conditions, such as the nanotube size, and the palladium loading on the efficiency of the dechlorination of PCB 77, a model coplanar polychlorinated biphenyl (PCB), by the Pd/Fe bimetallic nanotubes system. The efficiency of the dechlorination was lowered by decreasing the tube diameter from 200 to 100 nm. In addition, the interior surface as well as the exterior surface of the as-synthesized Pd/Fe bimetallic nanotubes was found to contribute to the high efficiency of the dechlorination of PCB 77. The dechlorination of PCB 77 by Pd/Fe bimetallic nanotubes demonstrated small activation energy indicating diffusion controlled reaction. The as-prepared Pd/Fe bimetallic nanotubes showed extended lifetime activity when used in multiple dechlorination cycles.

Iron-Based Nanoparticles for Toxic Organic Degradation: Silica Platform and Green Synthesis

Iron and iron oxide nanoparticles (NPs) are finding wide applications for the remediation of various toxic chloro-organic compounds (such as trichloroethylene, TCE), via reductive and oxidative processes. In this study, Fe NPs (30-50 nm) are synthesized by reduction from ferric ions immobilized (by ion exchange) on a platform (two types of sulfonated silica particles), in order to prevent the NP agglomeration. Next, the Fe NPs are oxidized and their effectiveness for the oxidative dechlorination of TCE via the heterogeneous decomposition of hydrogen peroxide to OH• on the surface of the iron oxide NPs was demonstrated. For the reductive approach, the use of ascorbic acid as a "green" reducing agent in conjunction with a secondary metal (Pd) inhibits NP oxidation and agglomeration through surface adsorbed species. The Fe/Pd NPs have been successfully applied for the dechlorination of TCE (k(SA), surface-area normalized reaction rate, = 8.1 ×10(-4) L/m(2)h).