Jeong Gil Seo

Hierarchical Mesoporous 3D Flower-like CuCo2O4/NF for High-Performance Electrochemical Energy Storage.

Ternary spinel CuCo2O4 nanostructure clenches great potential as high-performance electrode material for next-generation energy storage systems because of its higher electrical conductivity and electrochemical activity. Carbon free and binder free 3D flower-like CuCo2O4 structure are grown on nickel foam (NF) via a facile hydrothermal synthesis method followed by annealing. The obtained CuCo2O4/NF is directly used as electrode for lithium ion batteries (LIBs) and supercapacitors (SCs) application. The electrochemical study of 3D flower-like CuCo2O4 as an electrode for LIB and SC shows highly mesoporous unique architecture plays important role in achieving high capacity/capacitance with superior cycle life. The high surface area and mesoporous nature not only offer sufficient reaction sites, but also can accelerate the liquid electrolyte to penetrate electrode and the ions to reach the reacting sites. In outcome, it exhibits highest capacity of 1160 mA h g−1 after 200 cycles when used as an anode for LIB and specific capacitance of 1002 F g−1 after 3000 cycles. The superior electrochemical of synthesized material is attributed to direct contact of electrode active material with good intrinsic electrical conductivity to the underneath conductive NF substrate builds up an express path for fast ion and electron transfer.

Fine-Tuning of the Carbon Dioxide Capture Capability of Diamine-Grafted Metal-Organic Framework Adsorbents Through Amine Functionalization.

A combined sonication and microwave irradiation procedure provides the most effective functionalization of ethylenediamine (en) and branched primary diamines of 1-methylethylenediamine (men) and 1,1-dimethylethylenediamine (den) onto the open metal sites of Mg2 (dobpdc) (1). The CO2 capacities of the advanced adsorbents 1-en and 1-men under simulated flue gas conditions are 19 wt % and 17.4 wt %, respectively, which are the highest values reported among amine-functionalized metal-organic frameworks (MOFs) to date. Moreover, 1-den exhibits both a significant working capacity (12.2 wt %) and superb CO2 uptake (11 wt %) at 3 % CO2 . Additionally, this framework showcases the superior recyclability; ultrahigh stability after exposure to O2 , moisture, and SO2 ; and exceptional CO2 adsorption capacity under humid conditions, which are unprecedented among MOFs. We also elucidate that the performance of CO2 adsorption can be controlled by the structure of the diamine ligands grafted such as the number of amine end groups or the presence of side groups, which provides the first systematic and comprehensive demonstration of fine-tuning of CO2 uptake capability using different amines.

Homodiamine-functionalized metal–organic frameworks with a MOF-74-type extended structure for superior selectivity of CO2 over N2

A porous Mg2(dondc) framework (H4dondc = 1,5-dioxido-2,6-naphthalenedicarboxylic acid) with open metal sites was prepared and functionalized with primary or secondary diamines (en = ethylenediamine, mmen = N,N′-dimethylethylenediamine, or ppz = piperazine). The CO2 adsorption was substantial under post-combustion flue gas conditions as compared to other reported metal–organic frameworks. Interestingly, the IR spectroscopic measurements demonstrated that the CO2 adsorption mechanism is based on the combination of physisorption and chemisorption. The CO2 adsorption capacity of 1-mmen was greater than that of 1-en and 1-ppz, which can likely be attributed to the basicity of the free amine groups tethered to the open coordination sites. Ultrahigh selectivity and superior dynamic separation of CO2 over N2 were evident in 1-ppz. Such exceptional CO2 uptake and CO2/N2 selectivity of diamine-functionalized materials hold potential promise for post-combustion CO2 capture applications.

Metal-free mild oxidation of 5-hydroxymethylfurfural to 2,5-diformylfuran

The potential of 4-hydroxy-2,2,6,6-tetramethyl-piperidine-1-oxyl (4-hydroxy-TEMPO radical) as an oxidant with [bis(acetoxy)-iodo]benzene (BAIB) and acetic acid (CH3COOH) as co-oxidants to convert 5-hydroxymethylfurfural (5-HMF) into 2,5-diformylfuran (2,5-DFF) was investigated. The effects of oxidant/acid dosages, choice of appropriate solvent, reaction temperature and time were determined to maximize the 2,5-DFF yield. Optimally, 66% 2,5-DFF yield was achieved in TEMPO/BAIB/CH3COOH system at 30 °C after 45 min in ethyl acetate. The reaction system is environmentally benign (metal-free) and energy efficient (mild at short reaction period). With scarce reports on 2,5-DFF production, the developed system provides an alternative route for a better access and wider application of this important platform chemical.

Esterification of carboxylic acids with alkyl halides using imidazolium based dicationic ionic liquids containing bis-trifluoromethane sulfonimide anions at room temperature

Task-specific room temperature ionic liquids (RTILs) composed of symmetrical N-methylimidazolium rings linked with a short oligo (ethylene glycol) chain (cationic part) and bis-trifluoromethane sulfonimide (NTf2, anionic part) were successfully synthesized, and their physicochemical properties were determined by various modern analytical techniques. The catalytic activity of the synthesized RTILs was evaluated in the esterification reaction of acids with alkyl halides in solvent-free conditions at room temperature. From the screening test, all the synthesized RTILs showed a high yield with significant selectivity for respective esters in a very short reaction time. Especially, 0.1 equimolar of RTIL-1 ([tetraEG(mim)2][NTf2]2) was found to be, the most efficient and reusable catalyst for this reaction. As a result, 100% conversion and up to a 94% yield of the respective ester product was obtained in a 30 min reaction time. This might be due to their synergetic effect of Lewis acidity, wide liquid range, and high miscibility compared to the other homogeneous and heterogeneous catalysts. Beside this, RTIL was easily separated from the reaction mixture and reused several times without any significant loss of catalytic activity and structural property. The present dicationic ionic liquids (ILs) under a solvent-free catalytic system were found to be kinetically fast, naturally benign, and achieved good yields for esterification of carboxylic acids with alkyl halides.

Green solvent ionic liquids: structural directing pioneers for microwave-assisted synthesis of controlled MgO nanostructures

Magnesium oxide (MgO) is one of the auspicious metal oxides which attracts much attention because of its superior performance in scientific applications. Controlled facial arrangement of MgO nanostructures with tailored properties is highly important in nanotechnology and nanoscience. Here, various MgO nanostructures were obtained via one-pot microwave (MW)-assisted synthesis in various structural directing ionic liquids (ILs). These selected ILs are based on monocationic and dicationic moieties which consist of N-methyl imidazolium and 3-methyl pyridinium cations with various halide anions. Different designer solvents with respect to their counter anions produced various nanostructures, varying from nanoflakes, interconnected nanoparticles, hexagonal nanoparticles, irregular nanoparticles and nanocapsules. In this method, green solvent ILs not only act as solvent but also act as structural directing agents. In addition, a plausible mechanism of nanomaterial formation under MW irradiation in the presence of ILs was also determined. Formation of hydrogen bonding with favorable π–π interactions by simply tailoring the IL structures by means of MW conditions is the key factor for the development of different morphology. To define the catalytic activity of the prepared nanostructures, a Claisen condensation reaction was performed. The results showed that all the nanostructures have efficient catalytic activity due to their tailored structure, basicity, and surface area. Particularly, a catalytic amount of hexagonal morphology MgO obtained from dicationic [C4(mIm)2Cl2] IL showed 100% conversion and a remarkable 95% selective yield of the respective product. The proposed approach for nanomaterial preparation does not require an additional template and harsh reaction conditions which establishes this as a simple method to reduce the cost of production using environmentally benign solvents.

One-pot synthesis of 2,5-diformylfuran from fructose using a magnetic bi-functional catalyst

A magnetic bi-functional WO3HO-VO(salten)-SiO2@Fe3O4 nanocatalyst was prepared to directly synthesize 2,5-diformylfuran (2,5-DFF) from fructose. The chlorosilylated SiO2@Fe3O4 (Cl-SiO2@Fe3O4) nanoparticles served as the platform for the two functionalities. Tungstic acid was generated via protonation of sodium tungstate, which was directly attached on the platform via nucleophilic –Cl displacement. Meanwhile, oxovanadium was complexed with a salten ligand which was functionalized on the Cl-SiO2@Fe3O4. Characterization results confirmed the successful preparation of the WO3HO-VO(salten)-SiO2@Fe3O4 nanocatalyst. Under the optimal one-pot system, tungstic acid-mediated fructose dehydration afforded 82% 5-hydroxymethylfurfural (5-HMF) in 1 h. Upon co-oxidant H2O2 addition, in situ 5-HMF oxidation by the activated oxoperoxovanadium species produced 71% of 2,5-DFF after 15 h under ambient air. The stability of 5-HMF formation was found critical to 2,5-DFF production. Aside from the catalytic efficiency and process simplicity, the WO3HO-VO(salten)-SiO2@Fe3O4 nanocatalyst was readily retrieved magnetically and re-used multiple times with marginal losses in its activity.

Liquid–liquid extraction of Li+ using mixed ion carrier system at room temperature ionic liquid

AbstractAn environmentally benign technique for the separation and recovery of lithium (Li+) from aqueous streams, containing mixed metal ions was developed via liquid–liquid extraction (LLE). Hydrophobic room temperature ionic liquids (RTIL) were tested as the main extracting solvents. To increase the metal extraction, a proton-ionizable agent bis(2-ethylhexyl) phosphoric acid (DEHPA) was added into the RTIL. To enhance the metal uptake selectivity, three Li+-selective neutral ion carriers such as 6-hydroxy-dibenzo-14-crown-4, dibenzo-14-crown-4, and tri-n-octyl-phosphine (TOPO) were also used and tested as extractant additives. Among the tested RTILs, phosphonium-based CYPHOS IL 109 was the most stable extractant as it exhibited the lowest loss when contacted with water. Addition of proton-ionizable agent DEHPA in CYPHOS IL 109 afforded a high extraction of multivalent cations with negligible recovery of monovalent metals. On the other hand, the addition of neutral ion carrier TOPO in DEHPA/CYPHOS IL 10...

SBA-15 supported ionic liquid phase (SILP) with H2PW12O40− for the hydrolytic catalysis of red macroalgal biomass to sugars

A supported ionic liquid phase (SILP) catalyst for biomass hydrolysis was prepared via immobilization of an acidic ionic liquid (IL) with a phosphotungstic counter-anion H2PW12O40− (HPW) on ordered mesoporous silica (SBA-15). Characterization results from XRD, N2 physisorption, FT-IR, TGA and SEM/TEM image analyses confirmed the successful preparation of the SILP catalyst (SBA-IL–HPW). Meanwhile, its catalytic performance was evaluated in terms of sugar production from the hydrolysis of different biomasses in water. Under optimal hydrolysis conditions, SBA-IL–HPW yielded 73% D-galactose from agarose and 58% D-glucose from cellobiose. Moreover, SBA-IL–HPW effectively hydrolyzed the red macroalgae G. amansii as it afforded 55% total reducing sugar and 38% D-galactose yields. SBA-IL–HPW was easily separated from the hydrolysates after reaction and was re-used five times without significant loss of activity. Overall findings reveal the potential of SBA-IL–HPW as a durable, environmentally benign catalyst for sugar production from renewable resources.

Mesoporous magnesium oxide nanoparticles derived via complexation-combustion for enhanced performance in carbon dioxide capture

Magnesium oxide (MgO) is a promising candidate for carbon dioxide (CO2) capture at high temperature applicable to pre-combustion capture in an integrated gasification combined cycle (IGCC) scheme. In this work, mesoporous MgO nanoparticles were synthesized via simple complexation-combustion method by using glycine (G) and urea (U) as fuels (F). The obtained sorbents were thoroughly characterized in terms of the crystalline structure, morphology, nature of the fuel, F/O ratio, and their consequent effects on CO2 sorption. It was observed that due to the complexation followed by combustion in the presence of glycine, MgO with crystallite size as small as∼8nm could be derived. The synthesized MgO nanoparticles exhibited exceptionally high CO2 sorption at elevated temperatures. Furthermore, CO2 sorption isotherms in assistance with FT-IR and DSC experiments demonstrated that the low CO2 uptake at ambient temperature (25-100°C) may be due to the formation of monodentate carbonates, whereas predominant bicarbonates enhance the CO2 uptake at elevated temperatures (100-300°C). MgO-1.5(G) obtained the highest sorption corresponding to 1.34mmol/g at 200°C.