Electrostatic-Assisted Liquefaction of Porous Carbons.

Porous liquids are a newly developed porous material that combine unique fluidity with permanent porosity, which exhibit promising functionalities for a variety of applications. However, the apparent incompatibility between fluidity and permanent porosity makes the stabilization of porous nanoparticle with still empty pores in the dense liquid phase a significant challenging. Herein, by exploiting the electrostatic interaction between carbon networks and polymerized ionic liquids, we demonstrate that carbon-based porous nanoarchitectures can be well stabilized in liquids to afford permanent porosity, and thus opens up a new approach to prepare porous carbon liquids. Furthermore, we hope this facile synthesis strategy can be widely applicated to fabricate other types of porous liquids, such as those (e.g., carbon nitride, boron nitride, metal-organic frameworks, covalent organic frameworks etc.) also having the electrostatic interaction with polymerized ionic liquids, evidently advancing the development and understanding of porous liquids.

Three-phase catalytic system of H2O, ionic liquid, and VOPO4-SiO2 solid acid for conversion of fructose to 5-hydroxymethylfurfural.

Efficient transformation of biomass-derived feedstocks to chemicals and fuels remains a daunting challenge in utilizing biomass as alternatives to fossil resources. A three-phase catalytic system, consisting of an aqueous phase, a hydrophobic ionic-liquid phase, and a solid-acid catalyst phase of nanostructured vanadium phosphate and mesostructured cellular foam (VPO-MCF), is developed for efficient conversion of biomass-derived fructose to 5-hydroxymethylfurfural (HMF). HMF is a promising, versatile building block for production of value-added chemicals and transportation fuels. The essence of this three-phase system lies in enabling the isolation of the solid-acid catalyst from the aqueous phase and regulation of its local environment by using a hydrophobic ionic liquid, 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([BMIM][Tf2N]). This system significantly inhibits the side reactions of HMF with H2O and leads to 91 mol % selectivity to HMF at 89 % of fructose conversion. The unique three-phase catalytic system opens up an alternative avenue for making solid-acid catalyst systems with controlled and locally regulated microenvironment near catalytically active sites by using a hydrophobic ionic liquid.

Energetics of defects on graphene through fluorination.

Functionalized graphene sheets (FGSs) comprise a unique member of the carbon family, demonstrating excellent electrical conductivity and mechanical strength. However, the detailed chemical composition of this material is still unclear. Herein, we take advantage of the fluorination process to semiquantitatively probe the defects and functional groups on graphene surface. Functionalized graphene sheets are used as substrate for low-temperature (<150 °C) direct fluorination. The fluorine content has been modified to investigate the formation mechanism of different functional groups such as C-F, CF2, O-CF2 and (C=O)F during fluorination. The detailed structure and chemical bonds are simulated by density functional theory (DFT) and quantified experimentally by nuclear magnetic resonance (NMR). The electrochemical properties of fluorinated graphene are also discussed extending the use of graphene from fundamental research to practical applications.

Synthesis of porous, nitrogen-doped adsorption/diffusion carbonaceous membranes for efficient CO2 separation.

A porous, nitrogen-doped carbonaceous free-standing membrane (TFMT-550) is prepared by a facile template-free method using letrozole as an intermediate to a triazole-functionalized-triazine framework, followed by carbonization. Such adsorption/diffusion membranes exhibit good separation performance of CO2 over N2 and surpassing the most recent Robeson upper bound. An exceptional ideal CO2 /N2 permselectivity of 47.5 was achieved with a good CO2 permeability of 2.40 × 10(-13) mol m m(-2) s(-1) Pa(-1) . The latter results arise from the presence of micropores, narrow distribution of small mesopores and from the strong dipole-quadrupole interactions between the large quadrupole moment of CO2 molecules and the polar sites associated with N groups (e.g., triazine units) within the framework.

Efficient CO2 Capture by a 3D Porous Polymer Derived from Tröger's Base.

A 3D Tröger's-base-derived microporous organic polymer with a high surface area and good thermal stability was facilely synthesized from a one-pot metal-free polymerization reaction between dimethoxymethane and triaminotriptycene. The obtained material displays excellent CO2 uptake abilities as well as good adsorption selectivity for CO2 over N2. The CO2 storage can reach up to 4.05 mmol g-1 (17.8 wt %) and 2.57 mmol g-1 (11.3 wt %) at 273 K and 298 K, respectively. Moreover, the high selectivity of the polymer toward CO2 over N2 (50.6, 298 K) makes it a promising material for potential application in CO2 separation from flue gas.

Efficient CO(2) capture by porous, nitrogen-doped carbonaceous adsorbents derived from task-specific ionic liquids.

The search for a better carbon dioxide (CO(2) ) capture material is attracting significant attention because of an increase in anthropogenic emissions. Porous materials are considered to be among the most promising candidates. A series of porous, nitrogen-doped carbons for CO(2) capture have been developed by using high-yield carbonization reactions from task-specific ionic liquid (TSIL) precursors. Owing to strong interactions between the CO(2) molecules and nitrogen-containing basic sites within the carbon framework, the porous nitrogen-doped compound derived from the carbonization of a TSIL at 500 °C, CN500, exhibits an exceptional CO(2) absorption capacity of 193 mg of CO(2) per g sorbent (4.39 mmol g(-1) at 0 °C and 1 bar), which demonstrates a significantly higher capacity than previously reported adsorbents. The application of TSILs as precursors for porous materials provides a new avenue for the development of improved materials for carbon capture.

A superacid-catalyzed synthesis of porous membranes based on triazine frameworks for CO2 separation.

A general strategy for the synthesis of porous, fluorescent, triazine-framework-based membranes with intrinsic porosity through an aromatic nitrile trimerization reaction is presented. The essence of this strategy lies in the use of a superacid to catalyze the cross-linking reaction efficiently at a low temperature, allowing porous polymer membrane architectures to be facilely derived. With functionalized triazine units, the membrane exhibits an increased selectivity for membrane separation of CO(2) over N(2). The good ideal CO(2)/N(2) selectivity of 29 ± 2 was achieved with a CO(2) permeability of 518 ± 25 barrer. Through this general synthesis protocol, a new class of porous polymer membranes with tunable functionalities and porosities can be derived, significantly expanding the currently limited library of polymers with intrinsic microporosity for synthesizing functional membranes in separation, catalysis, and energy storage/conversion.

Potential application of fabricated sulfide-based scintillation materials for radiation detection.

In our laboratories, we have produced ZnS(Ag)/6Li sol-gel scintillation materials which produce an excellent light output with an alpha radiation (compared to commercial high temperature lithiated glass; KG-2 and a plastic scintillator; BC-400). However, when tested with a neutron radiation, the opacity of the ZnS(Ag)/6Li sol-gel scintillation materials, which were composed of a homogeneous micron-sized ZnS(Ag), prevented a clear neutron energy peak formation, thus making it difficult to set a threshold for neutron-gamma discrimination. In an effort to increase the transparency of the scintillation materials and to develop new technologies to fabricate sulfide-based scintillation materials for neutron detection, we turned to the methods of a chemical bath deposition (CBD) and a nano-particle synthesis for possible solutions.

Neutron scintillators of transparent silica xerogel monolith via a sealed container system and pi-pi interactions.

Transparent crack-free lithiated sol-gel scintillating monoliths were developed by taking advantage of a sealed container system for a syneresis and the pi-pi interactions between sol-gel components and organic fluors to yield a better homogeneity and scintillating efficiency. The transparency of the resulting materials indicates that the new scintillating material composites are mesoscopically dispersed. The silica monolith can be prepared without cladding the monolith with an engineering plastic such as a poly(ether ether ketone) (PEEK) or a liquid mounting medium. A successful detection of neutron particles by using these lithiated scintillating monoliths was demonstrated.

Facile, alternative synthesis of lanthanum phosphate nanocrystals by ultrasonication.

Highly luminescent, rhabdophane (Ce(0.33)La(0.66))PO4.nH2O nanorods and nanoparticles were prepared in aqueous solutions by ultrasonication, at pH 1 and pH 12, respectively. Both nanorods (5 to 9 nm wide and several tens to several hundreds nm long) and nanoparticles (elongated, connected 5 nm particles) were as small and as uniform as products obtained from methods that utilize complexing agents or surfactants, only with no complexing agent. This method of synthesis by ultrasonication is a fast and simple method and it is expected to be applicable for the synthesis of other nanocrystalline lanthanide phosphates.