Yongbin Sun

Flexible macroporous carbon nanofiber film with high oil adsorption capacity

A sublimation method using terephthalic acid (PTA) as the sublimating agent was developed to generate macropores inside electrospun carbon nanofibers. During carbonization of electrospun PTA–polyacrylonitrile composite nanofibers, PTA sublimed and macropores were created within the carbon nanofiber, resulting in flexible and self-sustained carbon film. The carbon nanofiber film showed excellent oil adsorption property with maximum capacities of 62.6, 73.8, 64.0, 94.0 and 138.4 g g−1 for ethanol, pump oil, mineral oil, corn oil and silicone oil. The film exhibited excellent recyclability by rinsing with suitable organic solvent, and promising ability in cleaning up oil spills, as well as fast and efficient separation of oil in oil–water mixtures.

One-pot synthesis of sandwich-like reduced graphene oxide@CoNiAl layered double hydroxide with excellent pseudocapacitive properties

Layered double hydroxide is one kind of promising material for pseudocapacitors. However, the poor conductivity limits their applications. One possible way to resolve this problem is to mix them with conductive carbon materials. In this work, we developed a one-pot strategy to synthesize sandwich-like nanocomposites with cobalt nickel aluminum layered double hydroxide growth on both sides of different amounts of reduced graphene oxide (RGO(X)@CoNiAl-LDH, X represents the amount of RGO). Such a unique structure is very beneficial for enhancing the conductivity and electrochemical performance. When used as an electrode material for supercapacitors, RGO(25)@CoNiAl-LDH exhibited the best specific capacitance of 1866 F g−1 at a current density of 1 A g−1 and 1360 F g−1 at 10 A g−1, respectively. Furthermore, they displayed excellent cycling performances without an obvious capacitance decrease after 5000 cycles. Such a simple synthesis method, high specific capacitance, rate capability and exceptional cycling stability of these composites offer great promise in energy storage device applications.

MgAl layered double hydroxides with chloride and carbonate ions as interlayer anions for removal of arsenic and fluoride ions in water

Layered double hydroxides (LDHs) are regarded as effective adsorbents to remove arsenic and fluoride ions in water. Compared to thorough research on calcined LDHs, very few works have focused on the adsorption properties and mechanisms of LDHs themselves for these ions. In this manuscript, three-dimensional hierarchical flower-like MgAl layered double hydroxides (MgAl-LDHs) with chloride and carbonate ions as interlayer anions were synthesized via a solvothermal method without any surfactant. When tested as adsorbents for removal of As(V) and F− ions, these hierarchical MgAl-LDHs showed maximum capacities of 125.8 and 28.6 mg g−1, respectively, under neutral conditions. The adsorption mechanisms for As(V) and F− of hierarchical MgAl-LDHs were elucidated by X-ray diffraction patterns, Fourier transformed infrared spectra, X-ray photoelectron spectroscopy and energy dispersive spectra. The results suggested that ion exchange between interlayer anions in hierarchical MgAl-LDHs and As(V) or F− ions was the main adsorption mechanism. Chloride and carbonate ions intercalated in the MgAl-LDHs layers were exchanged with As(V), while only chloride ions were exchanged with F− during adsorption.

Sandwich-like porous TiO2/reduced graphene oxide (rGO) for high-performance lithium-ion batteries

Sandwich-like porous TiO2/reduced graphene oxide (rGO) composites were prepared through a facile solvothermal method. These composites with porous structures and high electrical conductivity showed high capacity, rate capability and cycling stability when used as an anode electrode material for lithium ion batteries. A reversible capacity of 206 mA h g−1 can be retained at a current rate of 0.1 A g−1 after 200 charge–discharge cycles. Remarkably, a high reversible capacity of ∼128 mA h g−1 at a current density of 5 A g−1 can be obtained.

Graphene-based composite supercapacitor electrodes with diethylene glycol as inter-layer spacer

Diethylene-glycol/graphene nano-composites were produced by a simple mild solvothermal method, in which diethylene glycol was grafted onto the surfaces of reduced graphene oxides (RGO) as an inter-layer spacer to spatially separate graphene sheets, i.e. to prevent the aggregation of graphene single sheets. The presence of diethylene glycol was confirmed by several characterizations, including IR, XPS, and AFM. Because of the chain length and electrolyte affinity of the diethylene glycol spacer, most of the surface area of graphene single layer sheets could be accessed by electrolyte, leading to high capacity as supercapacitor electrodes with an impressive electrochemical capacitance (237.8 F g−1 at a charging current of 0.1 A g−1), outstanding rate performances (182.9 F g−1 at 20 A g−1), and excellent cycling stabilities (less than 5 and 10% decline after 2000 and 10 000 cycles). The diethylene-glycol/graphene nano-composites are thus particularly promising for “high-power densities” and “long cycle life” supercapacitor electrodes.

Hierarchical flowerlike magnesium oxide hollow spheres with extremely high surface area for adsorption and catalysis

Three-dimensionally hierarchical flowerlike MgO hollow spheres with an extremely high surface area of 343 m(2) g(-1) were prepared through a facile and environmentally friendly solvothermal route. The maximum adsorption capacity at natural pH reached 569.7 mg g(-1) for the removal of arsenic in water, which is the highest among all of the reported adsorbents. In addition, flowerlike MgO hollow spheres also displayed excellent catalytic activity and stability for the Claisen-Schmidt condensation reaction as a solid base catalyst.

Monodispersed Pd clusters generated in situ by their own reductive support for high activity and stability in cross-coupling reactions

Uniform 3D flower-like hierarchical-structured CoAl–LDH spheres were prepared via a simple one-pot surfactant-free solvothermal method. Monodispersed tiny Pd nanoclusters (about 2 nm) were loaded on the CoAl–LDH support through a facile in situ reduction between the oxidative Pd precursors and the reductive Co(II) in the support. The resultant CoAl–LDH/Pd composite catalyst showed excellent activities in cross-coupling reactions. In addition, the abundant Co(II) sites in the support can efficiently capture and regenerate leached Pd species during the reaction process, leading to excellent stability of the composite. These two features are desirable in organic synthesis, and may be used on a large scale for cross-coupling reactions with lower cost and easier operation.

Highly Active and Stable Palladium Nanoparticles Encapsulated in a Mesoporous Silica Yolk–Shell Nanoreactor for Suzuki–Miyaura Reactions

A yolk–shell nanoreactor with nitrogen‐doped carbon spheres as the yolk and mesoporous silica (mSiO2) as the shell, together with Pd nanoparticles uniformly encapsulated in the void space, were prepared. They showed excellent catalytic activity and stability in the Suzuki–Miyaura reaction between bromobenzene and phenylboronic acid with 99 % yield in 5 min.

Improving the electrochemical performance of Fe3O4 nanoparticles via a double protection strategy through carbon nanotube decoration and graphene networks

Iron oxide is a promising anode material for lithium ion batteries, but it usually exhibits poor electrochemical property because of its poor conductivity and large volume variation during the lithium uptake and release processes. In this work, a double protection strategy for improving electrochemical performance of Fe3O4 nanoparticles through the use of decoration with multi-walled carbon nanotubes and reduced graphene oxides networks has been developed. The resulting MWCNTs-Fe3O4-rGO nanocomposites exhibited excellent cycling performance and rate capability in comparison with MWCNTs-Fe3O4, MWCNTs-Fe3O4 physically mixed with rGO, and Fe3O4-rGO. A reversible capacity of ∼680 mA·h·g−1 can be maintained after 100 cycles under a current density of 200 mA·g−1.

Amines functionalized C60 as solid base catalysts for Knoevenagel condensation with high activity and stability

Four kinds of amines functionalized C60 were prepared through an amination reaction of C60 with organic amines. Their surface structures and basic properties were studied by Fourier transform infrared spectrometry (FTIR), X-ray photoelectron spectroscopy (XPS) and temperature-programmed desorption (TPD) with CO2 as the probe molecule. When used as solid base catalysts, N-aminoethylpiperazine functionalized C60 (C60-AEP) showed the best catalytic activity in the Knoevenagel condensation reaction due to the highest basic strength. In addition, the C60-AEP catalyst also showed impressive catalytic stability. All these features endowed C60-AEP with characteristics of both homogeneous and heterogeneous catalysts. More interestingly, chiral L-lysine functionalized C60 (C60-L-L) can be used for asymmetric intermolecular aldol reactions.