Shuwen Li

Aryne cycloaddition: highly efficient chemical modification of graphene

We have developed a simple and efficient approach for the synthesis of chemically converted graphene sheets via aryne cycloaddition under mild reaction conditions. The resulting highly functionalized and thermally stable aryne-modified graphene sheets can be well dispersed in various solvents.

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.

Imidazolium ionic liquid-modified fibrous silica microspheres loaded with gold nanoparticles and their enhanced catalytic activity and reusability for the reduction of 4-nitrophenol

A new type of catalyst based on the ionic liquid (IL) modified fibrous nano-silica material KCC-1, with a high surface area, as the support and Au nanoparticles (NPs) as the active sites (KCC-1–IL/Au), has been successfully prepared through a facile and environmentally-friendly approach and characterized by Fourier transform infrared (FT-IR) spectroscopy, X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) and high resolution transmission electron microscopy (HRTEM), thermal gravimetric analysis (TGA), elemental analysis and inductively coupled plasma atomic emission spectroscopy (ICP-AES). The synthesized catalyst exhibited high catalytic activity in the reduction of 4-nitrophenol by NaBH4 due to not only the unique dendritic fibrous morphology of the support, which made the active sites accessible, but also the synergistic effect between KCC-1–IL and the small Au NPs. Additionally, KCC-1–IL/Au had good recyclability, mainly attributed to the IL groups, which acted as robust anchors to avoid Au NP leaching from the support. This synthetic method provides a green way to effectively prepare low-cost Au-based catalysts and is promising for the development of other useful materials.

Enhancing catalytic performance of Au catalysts by noncovalent functionalized graphene using functional ionic liquids

New catalyst, prepared through Au nanoparticles anchored on the Ionic Liquid of 3,4,9,10-perylene tetracarboxylic acid-noncovalent functionalized graphene (Au/PDIL-GS), was fabricated using a facile and environment-friendly approach. The information of the morphologies, sizes, dispersion of Au nanoparticles (NPs) and chemical composition for the as-prepared catalysts was verified by systematic characterizations, including transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), Raman spectra, X-ray diffraction (XRD) and X-Ray photoelectron spectroscopy (XPS). As a new catalyst, the resulting Au/PDIL-GS exhibited excellent catalytic activity in the reduction of 4-nitrophenol because of the synergistic effect between the PDIL-GS and Au NPs. The facile and environment-friendly approach provides a green way to effectively synthesize low cost Au-based catalysts for 4-NP reduction and is promising for the development of other useful materials.

Fabrication of magnetic Ni nanoparticles functionalized water-soluble graphene sheets nanocomposites as sorbent for aromatic compounds removal.

The magnetic Ni nanoparticles functionalized water-soluble graphene sheets nanocomposites (Ni@GSs-C(CH(3))(2)COONa) were fabricated via a facile and mild strategy. We designed a simple and efficient approach (the addition of cyano radicals) to improve the water solubility of nanocomposites. The Ni@GSs-C(CH(3))(2)COONa nanocomposites had great potential as an effective absorbent for removing aromatic compounds from waste water owing to their rapid absorption rate, high absorption capacity, convenient magnetic separation and re-use property.

In situ growth of Ni–Fe alloy on graphene-like MoS2 for catalysis of hydrazine oxidation

A simple method is devised for the in situ growth of Ni–Fe alloy on graphene-like MoS2. The Ni–Fe/MoS2 hybrid with a Ni:Fe molar ratio of 80 : 20 exhibits the highest electrocatalytic activity toward hydrazine oxidation. The electrocatalytic activity is remarkably enhanced by the synergistic effects between graphene-like MoS2 and Ni–Fe alloy.

Enhanced-electrocatalytic activity of Ni1−xFex alloy supported on polyethyleneimine functionalized MoS2 nanosheets for hydrazine oxidation

A high-performance Ni1−xFex on polyethyleneimine (PEI)-functionalized molybdenum disulfide (MoS2) electrocatalyst has been synthesized by an electroplating in situ growth approach. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy confirm the successful functionalization of MoS2 with PEI. The empty orbitals of Ni2+ and Fe2+ (Ni and Fe precursors) coordinated with the donated lone pairs of nitrogen atoms in PEI-mediated MoS2 and then the Ni2+ and Fe2+ were in situ reduced at a negative potential. Transmission electron microscope images and X-ray diffraction reveal that Ni85Fe15 nanoparticles with an average size of 2.25 nm are uniformly dispersed on the PEI–MoS2 sheets. The Ni1−xFex/PEI–MoS2 catalyst exhibits unexpectedly high activity towards the hydrazine oxidation reaction, which can be attributed to highly homogeneous dispersed Ni1−xFex alloy. It also shows enhanced electrochemical stability due to the structural integrity of PEI–MoS2. Finally, the Ni85Fe15/PEI–MoS2 catalyst is proved to be very valuable for applications in hydrazine fuel cells, as compared with Ni90Fe10/PANi–MoS2 and Ni85Fe15/MoS2 catalysts.

Microenvironment Effects in Electrocatalysis: Ionic‐Liquid‐Like Coating on Carbon Nanotubes Enhances the Pd‐Electrocatalytic Alcohol Oxidation

A new catalyst consisting of ionic liquid (IL)-functionalized carbon nanotubes (CNTs) obtained through 1,3-dipolar cycloaddition support-enhanced electrocatalytic Pd nanoparticles (Pd@IL(Cl(-))-CNTs) was successfully fabricated and applied in direct ethanol alkaline fuel cells. The morphology, structure, component and stability of Pd@IL(Cl(-))-CNTs were systematic characterized by transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), Raman spectra, thermogravimetric analysis (TGA) and X-ray diffraction (XRD). The new catalyst exhibited higher electrocatalytic activity, better tolerance and electrochemical stability than the Pd nanoparticles (NPs) immobilized on CNTs (Pd@CNTs), which was ascribed to the effects of the IL, larger electrochemically active surface area (ECSA), and greater processing performance. Cyclic voltammograms (CVs) at various scan rates illustrated that the oxidation behaviors of ethanol at all electrodes were controlled by diffusion processes. The investigation of the different counteranions demonstrated that the performance of the IL-CNTs hybrid material was profoundly influenced by the subtly varied structures of the IL moiety. All the results indicated that the Pd@IL(Cl(-))-CNTs catalyst is an efficient anode catalyst, which has potential applications in direct ethanol fuel cells and the strategy of IL functionalization of CNTs could be available to prepare other carbonaceous carrier supports to enhance the dispersivity, stability, and catalytic performance of metal NPs as well.

The role of reducing agent in perylene tetracarboxylic acid coating on graphene sheets enhances Pd nanoparticles-electrocalytic ethanol oxidation

New catalysts, consisting of perylene tetracarboxylic acid functionalized graphene sheets support-enhanced electrocatalytic Pd nanoparticles (Pd/PTCA–GS), were fabricated using different reducing agents, including H2, NaBH4 and ethylene glycol (EG). The graphene sheets (GS) were functionalized via π–π stacking and hydrophobic forces. The information of the morphologies, sizes, and dispersion of Pd nanoparticles (NPs) for the as-prepared catalysts was verified by transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), Raman spectra and X-ray diffraction (XRD). As the ethanol electro-oxidation anode catalysts, the new catalysts exhibited better kinetics, higher electrocatalytic activity, better tolerance and better electrochemical stability than the Pd/GS and Pd/C, which illustrated that the new catalysts had potential applications in direct ethanol alkaline fuel cells (DEAFCs). Most attractively, the role of the chemical reduction methods (the NaBH4, EG and H2 as reducing agents) were studied systematically for the ethanol electro-oxidation anode catalysts in DEAFCs. As expected, the chemical reduction method remarkably affected the electrochemical behavior. Among all the Pd/PTCA–GS catalysts tested, Pd/PTCA–GS(NaBH4) exhibited the highest catalytic activity and stability, which may be due to the Pd NPs for Pd/PTCA–GS(NaBH4) having a narrow size distribution, uniform distribution and more perfect crystal structure than that of other as-prepared nanocomposites. These Pd/PTCA–GS are promising catalysts for developing a highly efficient direct ethanol alkaline fuel cells system for power applications.

Well-dispersed graphene-polydopamine-Pd hybrid with enhanced catalytic performance

Inspired by the discovery of adhesive proteins in mussels, we prepared a graphene-polydopamine (GPDA) hybrid, in which the commonly used graphene oxide was replaced by graphene synthesized through physical routes. Then, the hybrid was decorated with ultrafine Pd nanoparticles to obtain a catalyst that was stable and well-dispersed in polar solvents. The Pd nanoparticles on graphene-polydopamine (GPDAP) were 2.0 nm on average and showed good monodispersibility on the polydopamine-modified graphene, whereas the Pd particles on unmodified graphene (GP) were larger than 4.5 nm and were obviously aggregated. The catalytic activity of the catalyst was investigated in the reduction of 4-nitrophenol (4-NP), K3[Fe(CN)6], methylene blue (MB) and rhodamine B (RhB), which are common industrial pollutants. A comparison between Pd/C (CP), GP and GPDA showed that the prepared catalyst, GPDAP, showed superior activity even when just a tiny amount of catalyst was added.