Honglei Yang

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.

Programmed synthesis of magnetic mesoporous silica nanotubes with tiny Au nanoparticles: a highly novel catalyst system

Magnetic mesoporous silica nanotubes were produced from carbon nanotubes using a well-controlled programmed synthesis method and were characterized by TEM, XRD, XPS, N2 adsorption–desorption and VSM. The well-designed nanotubes had a large specific surface area (1017 m2 g−1), a highly open mesoporous structure (∼3.2 nm) and high magnetization (18.6 emu g−1). Ultrafine gold nanoparticles were successfully supported on the thiol-modified nanotubes by a co-precipitation method. These unique multicomponent nanotubes showed high performance in the catalytic reduction of 4-nitrophenol (with a conversion of 99% in 6 min), and styrene epoxidation with high conversion (65%) and selectivity (58%). Interestingly, the new catalysts could be recovered by magnetic separation from the reaction mixture and could be recycled several times without any significant loss in activity. The unique nanostructure of the nanotubes resulted in a novel, stable and easy to use catalyst system for application in various industrial processes.

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.

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.

The high catalytic activity and reusability of the proline functionalized cage-like mesoporous material SBA-16 for the asymmetric aldol reaction proceeding in methanol–water mixed solvent

The cage-like mesoporous material SBA-16 has been successfully functionalized with L-4-hydroxyproline and characterized by Fourier transform infrared (FT-IR) spectroscopy, Small-angle X-ray powder diffraction (XRD), N2 sorption detection, transmission electron microscopy (TEM), elemental analysis and thermo gravimetric analysis (TGA). This chiral non-metallic catalyst avoided heavy metal pollution during the preparing and using process, and demonstrated high catalytic activity (up to 91%), diastereoselectivity (up to 97:3) and enantioselectivity (up to 83%) in the asymmetric aldol reaction between aldehyde acceptors and ketone donors with methanol–H2O as solvent. Moreover, the synthesized catalyst could be easily separated from the reaction mixture by filtration and reused for up to five runs without any obvious loss of activity, indicating its excellent recyclability.

Fabrication of Fe3O4-L-dopa-CuII/SnIV@Micro-Mesoporous-SiO2 Catalyst Applied to Baeyer–Villiger Oxidation Reaction

A Magnetic mFe3O4‐l‐dopa‐CuII/SnIV@micro‐mesoporous‐SiO2 catalyst was successfully prepared. The catalyst exhibits high and stable catalytic activity for the Baeyer–Villiger oxidation reaction with air as oxidant. Furthermore, the selectivity can reach nearly 100 %. Meanwhile the catalyst can be easily separated by an external magnet and reused at least up to five cycles without any notable loss in catalytic activity. In addition, the effect of Sn and Cu on the oxidation of cyclohexanone is discussed.