Jianrui Niu

Pd immobilized on amine-functionalized magnetite nanoparticles: a novel and highly active catalyst for hydrogenation and Heck reactions

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−1 under a H2 atmosphere 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.

Entangled Pd complexes over Fe3O4@SiO2 as supported catalysts for hydrogenation and Suzuki reactions

We here report the synthesis, characterization and catalytic performance of new supported Pd(0) and Pd(II) catalysts. The catalysts were characterized by TEM, XRD, FT-IR, VSM and ICP. The catalysts were found to be active in both forms, Pd(0) and Pd(II), for hydrogenation and Suzuki cross-coupling reactions. In contrast to most supported catalysts, the newly developed catalysts were prepared using nearly the same synthetic strategy, and were easily recovered and recycled from the reaction mixture by applying an external magnet and reused in 5 cycles without significant loss in activity.

Ni@Pd/PEI–rGO stack structures with controllable Pd shell thickness as advanced electrodes for efficient hydrogen evolution

In the present work, nickel (Ni) and palladium (Pd) core–shell structure nanospheres with various thicknesses have been facilely obtained via a one-pot synthesis process. These hybrid structures allow us to correlate the Pd thickness with their performance in the hydrogen evolution reaction (HER). The HER activity increases with a decrease of the Pd thickness, and it can be ascribed to the enhancement of electron donation of Pd (111) caused by the electron flow from Ni (111) to Pd (111) based on first-principles calculations. In this hybrid system, the difference in work functions of Pd and Ni results in surface polarization on the Pd surface, tuning its charge state for hydrogen reduction. Meanwhile, with the assistance of a polyethyleneimine–reduced graphene oxide (PEI–rGO) support, the examined Ni@Pd4:1/PEI–rGO50:1 (10 wt%) electrocatalyst presents outstanding HER activity comparable with that of platinum (Pt). This work opens up possibilities for reducing Pd usage while achieving high HER performance.

Stabilizing PdII on hollow magnetic mesoporous spheres: a highly active and recyclable catalyst for carbonylative cross-coupling and Suzuki coupling reactions

A hollow magnetic mesoporous silica sphere (HMMS) catalyst has been synthesized using polystyrene microspheres as a chemical template. The catalyst was characterized by TEM, XRD, XPS and vibrating sample magnetometry (VSM). The catalyst shows high activity for the carbonylative cross-coupling reaction of aryl iodides with arylboronic acids and Suzuki coupling reactions. The newly developed catalyst is easy to recover by magnetic separation from the liquid phase of the reaction and can be recycled. Importantly, the catalyst revealed high efficiency and high stability under the reaction conditions and during recycling stages.

Palladium supported on hollow magnetic mesoporous spheres: a recoverable catalyst for hydrogenation and Suzuki reaction

A high-performance palladium catalyst was developed by the covalent binding of a Schiff base ligand, N,N′-bis(3-salicylidenaminopropyl)amine (salpr), on the surface of hollow magnetic mesoporous spheres (HMMS) followed by immobilization with Pd(0). The catalyst was characterized by TEM, EDX, FT-IR, XRD, VSM, TGA and N2 adsorption–desorption. The novel catalyst exhibited high activity in hydrogenation and Suzuki coupling reaction. Furthermore, it could be recovered from the reaction mixture in a facile manner and recycled six times without any loss of activity.

Stabilizing Pd on the surface of amine-functionalized hollow Fe3O4 spheres: a highly active and recyclable catalyst for Suzuki cross-coupling and hydrogenation reactions

A palladium-based catalyst supported on amine-functionalized hollow magnetite nanoparticles was successfully prepared by a facile template-free method. The catalyst was characterized by TEM, XRD, FT-IR, VSM and XPS. The catalyst afforded fast conversions for various aromatic nitro compounds under a H2 atmosphere in ethanol even at room temperature. Furthermore, it was found that the catalyst showed a high activity for the Suzuki reaction. Interestingly, the novel catalyst could be recovered in a facile manner from the reaction mixture and recycled five times without any significant loss in activity.

Agglomeration of Pd0 nanoparticles causing different catalytic activities of Suzuki carbonylative cross-coupling reactions catalyzed by PdII and Pd0 immobilized on dopamine-functionalized magnetite nanoparticles

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.

Preparation of recoverable Fe3O4@PANI–PdII core/shell catalysts for Suzuki carbonylative cross-coupling reactions

We report on the synthesis, characterization and catalytic performance of a palladium-based superparamagnetic catalyst of Fe3O4@polyaniline core/shell microspheres (Fe3O4@PANI–PdII). The material was characterized by TEM, FT-IR, vibrating sample magnetometry (VSM), XRD, and XPS. The catalyst showed high activity for the carbonylative cross-coupling reaction of aryl iodide with arylboronic acid. Moreover it could selectively reduce the formation of a direct-coupling product. The newly developed catalyst could be recovered from the liquid phase easily by magnetic separation and recycled 5 times without any significant loss of activity.

Preparation of Recoverable Pd Catalysts for Carbonylative Cross‐Coupling and Hydrogenation Reactions

We report on the synthesis, characterization and catalytic performance of new, supported PdII and Pd0 catalysts. The catalysts are characterized by TEM, XRD, FTIR, X‐ray photoelectron spectroscopy, and vibrating sample magnetometry. The catalysts are found to be active in both forms, PdII and Pd0, for the carbonylative cross‐coupling reaction of aryl iodides with arylboronic acids, and for the hydrogenation of aromatic nitro‐ and unsaturated compounds. The newly developed catalysts are prepared by a synthetic strategy that is similar to the one used for other supported catalysts but are easier to recover—they can be recycled by magnetic separation from liquid phase reactions—and can be used for at least 5 consecutive trials without any decrease in activity.

Preparation of cobalt(II) acetylacetonate covalently anchored onto magnetic mesoporous silica nanospheres as a catalyst for liquid-phase oxidation of cyclohexane

A cobalt-based magnetic nanocatalyst was prepared by linking cobalt acetylacetonate with (3-aminopropyl)triethoxysilane functionalized magnetic mesoporous silica nanospheres. The material was characterized by transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), a vibrating sample magnetometer (VSM), X-ray diffraction (XRD), and N2 adsorption–desorption. The results showed that the sample had a mesoporous structure with a relatively high surface area and that cobalt acetylacetonate was covalently anchored on the magnetic mesoporous silica nanospheres. The catalyst was found to be highly efficient for the oxidation of cyclohexane with oxygen as the oxidant.