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Three core-shell structures were prepared with pyrrole, glucose, and tetraethyl orthosilicate (TEOS), respectively, encasing magnetic Fe3O4 microparticles, through three different "green" approaches without any toxic solvents. Pt nanoparticles (NPs) were immobilized onto these supports with NaBH4 as the reducing agent. The as-prepared catalysts were characterized thoroughly by TEM, VSM, XRD, FT-IR, ICP, and XPS. As expected, the shells remarkably affected the distribution of Pt NPs and catalytic activity. Pt NPs dispersed evenly on the surface of Fe3O4@PPy and Fe3O4@C, which were much better than Fe3O4@SiO2. Most attractively, the prepared catalysts exhibited better kinetics, higher activity and stability than Pt/Fe3O4 and Pt/C for selective oxidation of ethanol to acetic acid and glycerol to glyceric acid with molecular oxygen in water. Among them, the catalyst with a shell of polypyrrole (PPy) showed the best catalytic property, affording yields of 88% and 55%, respectively. Moreover, it could be recovered facilely from the reaction mixture and recycled four times without any significant loss in activity.

Solvent-dispersible magnetite nanoparticles (Fe3O4) end-functionalized with amino groups were successfully prepared by a facile one-pot template-free method to immobilize PdII and Pd0 using a metal adsorption and reduction procedure. They were characterized by TEM, XRD, XPS, FT-IR and VSM. Interestingly, the PdII catalyst exhibited better catalytic activity for carbonylative cross-coupling reactions than the Pd0 catalyst. According to the catalytic activities of a variety of arylboronic acids and aryl iodides catalyzed by two kinds of Pd catalysts, the proposed reaction mechanism of Suzuki carbonylative cross-coupling reactions using the Pd catalyst was also inferred. More importantly, agglomeration of Pd0 nanoparticles was obviously observed in the TEM images of the catalysts after reactions. Therefore, agglomeration of Pd0 nanoparticles should be considered as a significant reason for different catalytic activities of the reactions catalyzed by immobilized PdII and Pd0 catalysts. Furthermore, the PdII catalyst revealed high efficiency and stability during recycling stages. [ABSTRACT FROM AUTHOR]

Herein, a non-stacked γ-Fe2O3/C@TiO2 double-layer hollow nano photocatalyst has been developed with ultrathin nanosheets-assembled double shells for photodegradation phenol. High catalytic performance was found that the phenol could be completely degraded in 135 min under visible light, due to the moderate band edge position (VB at 0.59 eV and CB at −0.66 eV) of the non-stacked γ-Fe2O3/C@TiO2, which can expand the excitation wavelength range into the visible light region and produce a high concentration of free radicals (such as ·OH, ·O2−, holes). Furthermore, the interior of the hollow composite γ-Fe2O3 is responsible for charge generation, and the carbon matrix facilitates charge transfer to the external TiO2 shell. This overlap improved the selection/utilization efficiency, while the unique non-stacked double-layered structure inhibited initial charge recombination over the photocatalysts. This work provides new approaches for photocatalytic applications with γ-Fe2O3/C-based materials. [ABSTRACT FROM AUTHOR]

Abstract: A novel and high-performance palladium-based catalyst for Heck reaction was prepared easily by the co-precipitation method. The catalyst was characterized by transmission electron microscopy (TEM), X-ray powder diffraction (XRD), vibrating sample magnetometry (VSM), X-ray photoelectron spectroscopy (XPS) and atomic absorption spectrophotometry (AAS). The catalyst afforded a fast conversion of the 4-bromonitrobenzene to 4-nitrostilbene at a catalyst loading of 5mol%, and the efficiency of the catalyst remains unaltered even after 6 repeated cycles. The excellent catalytic performance of the Pd/Fe3O4 catalyst might be attributed to the enhanced synergistic effect between Pd nanoparticles and magnetite. [Copyright &y& Elsevier]

A palladium-based catalyst supported on amine-functionalized magnetite nanoparticles was successfully prepared by a facile one-pot template-free method combined with a metal adsorption–reduction procedure. The catalyst was characterized by TEM, XRD, XPS, FT-IR and VSM. The catalyst afforded fast conversions for various aromatic nitro and unsaturated compounds, and with a turn-over frequency (TOF) of 83.33 h−1under a H2atmosphere in ethanol, even at room temperature. Furthermore, it was found that the catalyst showed a high activity for the Heck reaction, affording over a 93% yield in all the cases investigated. Interestingly, the novel catalyst could be recovered in a facile manner from the reaction mixture and recycled eight times without any significant loss in activity. [ABSTRACT FROM AUTHOR]