Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 35
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
ChemSusChem ; 2020 Jan 25.
Artigo em Inglês | MEDLINE | ID: mdl-31981404

RESUMO

High entropy materials, a new class of alloys that incorporate five or more principal elements into single-phase crystal structures, have received attractive interests in materials science and engineering. Considering the tailored composition and disordered configuration, these high entropy materials may arouse functional synergism towards electrocatalysis. Here, a new strategy for preparing high-entropy metal phosphide (HEMP) is proposed via eutectic solvent method. The as-prepared HEMP possesses a single metal phosphide phase with up to five homogenously distributed metal components. The versatile application of high entropy materials is highlighted by integrating HEMP catalyst into a two-electrode configuration for electrocatalytic water splitting.

2.
ChemSusChem ; 13(2): 321-327, 2020 Jan 19.
Artigo em Inglês | MEDLINE | ID: mdl-31729788

RESUMO

With typical nanofibrous structure, silks spun by silkworms and spiders are the representative fibrous proteins that embody excellent mechanical properties and biological functions. However, it is still a challenge to directly extract silk nanofibers (SNFs) from natural silk fibers, to retain their nanostructures and properties, by a human- and environment-friendly approach for practical applications. Here, an all-natural strategy for simple, green, and scalable extraction of silkworm and spider silk protein nanofibers in natural deep eutectic solvents has been developed. The liquid-exfoliated SNFs have adjustable diameters from 20 nm (at the single SNF scale) to 100 nm and could be dispersed in water and organic solvents, enabling the production of useful macroscopic biomaterials. The free-standing SNF membranes made from silkworm silk nanofibers (SSNFs) exhibited cytocompatibility, flexibility, and excellent mechanical performance, providing the ability to fabricate sustainable materials for tissue engineering and green electronics. Moreover, the SSNF could be used as a green and efficient dispersant of multiwalled carbon nanotubes (MWCNTs), and the SSNFs/MWCNTs nanocomposite membranes could be used in wearable devices to monitor human activities.

3.
Chem Asian J ; 14(23): 4183-4188, 2019 Dec 02.
Artigo em Inglês | MEDLINE | ID: mdl-31691519

RESUMO

Herein, the concept of "inverted" (the mode "molecules mainly interact with cations") deep eutectic solvents (DESs) is proposed. A strategy to form inverted DESs by host-guest interactions was developed, and thus numerous DESs could be designed and formed by a combination of host and guest molecules. These liquids are expected to be used as nonaqueous electrolytes in potassium-ion batteries or other fields for further exploration.

4.
ACS Appl Mater Interfaces ; 11(47): 44360-44365, 2019 Nov 27.
Artigo em Inglês | MEDLINE | ID: mdl-31692329

RESUMO

Solar-driven nitrogen fixation remains a significant challenge. Graphitic carbon nitride (g-C3N4) is considered as a promising visible light photocatalyst. However, the photocatalytic performance of g-C3N4 is unsatisfactory because of the random transfer of charge carriers in the plane and the low activation efficiency of the reactants. Herein, amorphous ZrO2 was used as a robust cocatalyst of g-C3N4 to increase the NH3 production activity. The g-C3N4/ZrO2 lamellar composites were constructed by a simple one-step pyrolysis of the deep eutectic solvent ZrOCl2·8H2O/urea. The optimum NH4+ yield could reach as high as 1446 µmol·L-1·h-1 at 30 wt % ZrO2 in the g-C3N4/ZrO2 composites, with an apparent quantum efficiency over 2.14% at 400 nm. It is 7.9 times that of pristine g-C3N4 and 27.5 times that of ZrO2. The introduction of amorphous ZrO2 restrained the hydrogen generation, and the amorphous ZrO2 and g-C3N4 together contribute to the rapid photoproduced electron transfer of less electron-hole pair recombination.

5.
Chem Asian J ; 14(19): 3350-3356, 2019 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-31449358

RESUMO

Eutectic molecular liquids (EMLs) based on hydrogen-bonding interaction and π-π stacking were prepared. We found that the thermodynamic properties like initial decomposition temperature and glass transition temperature of EMLs are mainly dominated by the hydrogen bond donor, which is beneficial for designing and preparing new EMLs. These new liquid systems could be applied in the field of environmental and material science.

6.
J Phys Chem B ; 123(23): 4958-4966, 2019 Jun 13.
Artigo em Inglês | MEDLINE | ID: mdl-31117609

RESUMO

The concept of eutectic molecular liquids (EMLs) was defined, and a strategy to form EMLs based on noncovalent interactions was proposed. We verified the formation and investigated the properties, interaction sites, and interaction energies of the obtained 16 EMLs. Moreover, two new forms of noncovalent interactions, κ-hole and µ-hole bonding interactions, were proposed, which broaden the understanding of intermolecular interactions. Numerous EMLs can be strategically designed and prepared by simply mixing two parent molecule components based on noncovalent interactions, including hydrogen bonding interactions; π-π stacking; and σ-hole (halogen, chalcogen, pnicogen, and tetrel bonds), π-hole, κ-hole, and µ-hole bonding interactions. The properties of EMLs can be finely tailored by selecting or even designing appropriate parent compounds for task-specific applications. Our work presents a substantial step toward the innovative development of liquid systems.

7.
Phys Chem Chem Phys ; 21(22): 11810-11821, 2019 Jun 05.
Artigo em Inglês | MEDLINE | ID: mdl-31115401

RESUMO

Lithium-based deep eutectic solvents (DESs) are potential and promising electrolytes for energy-storing devices such as the lithium-ion battery and supercapacitor due to their greenness, low cost, favorable stability, and ease of synthesis. LiTf2N (lithium bis(trifluoromethylsulfonyl)imide):NMA (N-methylacetamide) is a liquid due to the strong intermolecular H-bonding interaction between the H-bonding acceptor (HBA, LiTf2N) and H-bonding donor (HBD, NMA). The properties (melting point, conductivity, viscosity, etc.) of LiTf2N:NMA change with the evaporation of NMA from LiTf2N:NMA, which would further influence the performance of the energy-storing devices. The evaporation of DES should be determined by the intermolecular interactions. Here, for the first time, the dynamic process of evaporation and intermolecular interactions of the DES LiTf2N:NMA at room temperature were investigated and we find that the evaporation mechanism of the DES LiTf2N:NMA can be divided into three stages. In the first stage (before 110 min), the H-bonding interaction between O in LiTf2N and NH in NMA is disrupted before destruction of the coordinating interaction related to amide II C[double bond, length as m-dash]O and Li cation. In the second stage (from 110 min to 270 min), the change of coordinating interaction related to amide II C[double bond, length as m-dash]O and Li cation is also higher than that of the H-bonded interaction. In the third stage (after 270 min), evaporation of NMA from LiTf2N:NMA has very little influence on the environment of LiTf2N:NMA. This work provides a guide for designing DESs as electrolytes for energy-storing devices such as the lithium-ion battery and supercapacitor.

8.
Phys Chem Chem Phys ; 21(5): 2601-2610, 2019 Jan 30.
Artigo em Inglês | MEDLINE | ID: mdl-30657495

RESUMO

Deep eutectic solvents (DESs) are one type of green solvents. Most of the DESs could absorb water from air. However, even a trace amount of water can affect the chemical structure and physical properties of DESs. To date, no study has been reported on the hygroscopicity of DESs. Consequently, in this study, a comprehensive investigation was performed on the capacity, kinetics, mechanism, and furthermore the dynamic process (by PCMW2D-COS IR spectra) of atmospheric water absorption from air by DESs. The results show that most DESs are highly hygroscopic. Surface absorption enhances the overall water absorption capacity by DESs in spite of decreasing the initial water absorption rate. In the beginning, the water absorption increases with an increase in the number of hydrophilic groups in DESs due to the retained DES nanostructure during this period. Therefore, DESs with more hydrophilic groups (ChCl:glucose than ChCl:xylitol) possess a higher water absorption initial rate. However, when the water absorption capacity is high, the hindrance from the H-bond strength from inner DESs needs to be overcome for the absorption of more water. In this case, DESs with stronger H-bonds (ChCl:glucose than ChCl:xylitol) have a lower steady-state water absorption capacity and an easier equilibrium.

9.
Chem Commun (Camb) ; 54(92): 13010-13013, 2018 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-30393792

RESUMO

We report the synthesis of nanostructured Fe3S4 from deep eutectic solvents via a one-step solvothermal method. The as-obtained Fe3S4 catalyst was capable of electrochemically reducing N2 to NH3 under ambient conditions, and exhibits a high NH3 yield (75.4 µg h-1 mg-1cat.) and faradaic efficiency (6.45%) at -0.4 V vs. a reversible hydrogen electrode.

10.
Chem Commun (Camb) ; 54(48): 6140-6143, 2018 Jun 12.
Artigo em Inglês | MEDLINE | ID: mdl-29808877

RESUMO

A family of FeCl3·6H2O based catalytic deep eutectic solvents (CDESs) were formed and used for the conversion of cellulose to gluconic acid with high efficiency. More importantly, gluconic acid could be separated from the reaction system by self-precipitation.

11.
Phys Chem Chem Phys ; 20(13): 8382-8402, 2018 Mar 28.
Artigo em Inglês | MEDLINE | ID: mdl-29503990

RESUMO

Research on ionic liquids has achieved rapid progress in the last several decades. Stability is a prerequisite for the application of ionic liquids. Ionic liquids may be used at elevated temperature, as electrolytes, or under irradiation. Therefore, the thermal, electrochemical, and radiolytic stabilities of ionic liquids are important and need to be known before their usage. Many research papers and some reviews on the stabilities of ionic liquids have been published. However, new results are continuously being published and a comprehensive review and perspective on this topic are still urgently needed. In this perspective, we intend to provide a comprehensive review including characterization methods, the effects of chemical composition of the ionic liquids on the thermal, electrochemical, and radiolytic stabilities of ionic liquids, respectively. Moreover, the thermal stability of some special types of ionic liquids such as poly(ionic liquids) and mixed ionic liquids, and the thermal and electrochemical stabilities of protic ionic liquids are discussed too. For thermal stability, the interactions between ions are less important than the individual anions and cations. The decomposition temperature is mainly determined by the less-stable ion, usually the anion. For electrochemical stability, the electrochemical window is determined by both the cation and anion. The less stable ion could influence the stability by interaction between the generated species from the decomposition with the more stable ion (opposite ion). This perspective is helpful for people to avoid using unstable ionic liquids and choose suitable ionic liquids.

12.
Chem Commun (Camb) ; 53(68): 9418-9421, 2017 Aug 22.
Artigo em Inglês | MEDLINE | ID: mdl-28787043

RESUMO

We report the synthesis of CoSx nanosheets from a 1,2-ethanedithiol/n-butylamine quasi-ionic liquid with the assistance of compressed CO2 at ambient temperature. The CoSx achieves a current density of 10 mA cm-2 at an overpotential of 271 mV for the oxygen evolution reaction. Furthermore, our method is applicable to the fabrication of other transition metal chalcogenides.

13.
Chem Asian J ; 12(17): 2271-2277, 2017 Sep 05.
Artigo em Inglês | MEDLINE | ID: mdl-28628724

RESUMO

Development of inexpensive, easily prepared, non-toxic, and efficient catalysts for the cycloaddition of CO2 with epoxides to synthesize five-membered cyclic carbonates is a very attractive topic in the field of CO2 transformation. In this work, we conducted the first work on the cycloaddition of CO2 with epoxides to produce cyclic carbonates catalyzed by a binary catalyst system consisting of KI and boron phosphate (BPO4 ), which are both inexpensive and non-toxic, and various corresponding cyclic carbonates could be produced with high yields (93-99 %) at 110 °C with a CO2 pressure of 4 MPa under solvent-free conditions. In the BPO4 /KI catalyst system, BPO4 , a Brønsted and Lewis acid hybrid, played the role of activating the epoxy ring through the formation of hydrogen bonds with Brønsted acidic sites and the interaction with Lewis acidic sites simultaneously, and thus enhanced the activity of KI for the cycloaddition of CO2 with epoxides significantly. Additionally, the activity of the BPO4 /KI catalyst system showed no noticeable decrease after being reused five times, indicating that the BPO4 was stable under the reaction conditions.

14.
Chem Asian J ; 12(14): 1773-1779, 2017 Jul 18.
Artigo em Inglês | MEDLINE | ID: mdl-28471506

RESUMO

There is increasing demand for superhydrophobic materials, which can be used for separating oil and water efficiently. To avoid secondary pollution, it is desirable to prepare such materials with green technology. Here, we present an environmentally benign method for fabricating superhydrophobic materials by using organic base based solvents in which cellulose can be dissolved and activated. The dissolved cellulose could be chemically modified with a silanization reagent, and the solvent could be recycled after CO2 was removed. The obtained cellulose nanocoating exhibited excellent hydrophobic effects. By spraying it on filter paper (water contact angle (WCA)=165°) for oil and water separation, the separation efficiency of more than 95 % was achieved; ultrasonication of an ordinary sponge in its dispersion (WCA=163°), meant it could be used as an oil absorber. It can also absorb a certain amount of bisphenol A (BPA), with the concentration decreasing by 66 % from the original concentration (0.1 mm). Besides the high separation efficiency, it is resistant to a wide range of pH solutions, which means that it could be used in harsh environments. More importantly, the process is cost-effective, the solvent can be recycled, and the whole process is green. Thus, the activation method provides a green route for the preparation of other cellulose-based materials.

15.
Chem Asian J ; 12(10): 1052-1056, 2017 May 18.
Artigo em Inglês | MEDLINE | ID: mdl-28374538

RESUMO

The ß-cyclodextrin-assisted aqueous-exfoliation method was used to prepare transition-metal dichalcogenide (TMD) nanosheets, in a cheap, highly efficient, scalable and environmentally friendly manner. As study cases, MoS2 and ReS2 nanoflakes were prepared according to this method. Particularly, the effective exfoliation of ReS2 crystals in an aqueous environment was observed for the first time. Moreover, exfoliated nanomaterials can be readily utilized in hydrogen evolution reactions (HERs) as noble-metal-free catalysts. This work provides new opportunities for highly efficient exfoliation of TMDs and other 2D nanomaterials into few-layer nanosheets in aqueous media. Their production process showed high biocompatibility, broad applicability and excellent sustainability.


Assuntos
Calcogênios/síntese química , Dissulfetos/química , Molibdênio/química , Nanoestruturas/química , Rênio/química , Sulfetos/química , beta-Ciclodextrinas/química , Calcogênios/química , Tamanho da Partícula , Propriedades de Superfície , Água/química
16.
Chem Rev ; 117(10): 7113-7131, 2017 May 24.
Artigo em Inglês | MEDLINE | ID: mdl-28240867

RESUMO

Ionic liquids have attracted a great deal of interest in recent years, illustrated by their applications in a variety of areas involved with chemistry, physics, biology, and engineering. Usually, the stabilities of ionic liquids are highlighted as one of their outstanding advantages. However, are ionic liquids really stable in all cases? This review covers the chemical stabilities of ionic liquids. It focuses on the reactivity of the most popular imidazolium ionic liquids at structural positions, including C2 position, N1 and N3 positions, and C4 and C5 positions, and decomposition on the imidazolium ring. Additionally, we discuss decomposition of quaternary ammonium and phosphonium ionic liquids and hydrolysis and nucleophilic reactions of anions of ionic liquids. The review aims to arouse caution on potential decomposition of ionic liquids and provides a guide for better utilization of ionic liquids.

17.
Phys Chem Chem Phys ; 18(48): 32772-32779, 2016 Dec 07.
Artigo em Inglês | MEDLINE | ID: mdl-27878171

RESUMO

In this study, the fine regulation of the dissolution and regeneration of microcrystalline cellulose (MCC) using very low pressure (0-0.2 MPa) CO2 in a mixed solvent of dimethyl sulfoxide (DMSO) and 1,8-diazabicyclo-[5.4.0]-undec-7-ene (DBU) at a very low temperature (30 °C) was achieved. The solubility of MCC in DMSO/DBU (weight ratio of DMSO WDMSO = 0.90) could reach 9.0% at 30 °C and under CO2 pressure of 0.2 MPa. A similar phenomenon was observed in the mixed solvent DMSO/1,1,3,3-tetramethylguanidine (TMG). Moreover, ATR-FTIR, NMR, UV-Vis, TGA, XRD and DFT computational analyses were used to investigate the dissolution mechanism. It was concluded that in the mixed solvent (DMSO and organic base), DMSO helped to dissociate ion-pairs into free ions by balancing the concentration of free ions and the number of hydrogen bonds at WDMSO = 0.90. Interactions between CO2 and the solvent mixture were explored, and the results indicate that the optimum CO2 pressure not only promotes the formation of ionic bonds but also accelerates the formation of covalent bonds. In this way, these interactions prevent the MCC molecules from aggregating and facilitate the dissolving of MCC. This study gives a thorough insight into the dissolution mechanism and specificity of MCC in the CO2-DMSO/organic base solvent system, which could be helpful for the utilization and transformation of cellulose.

18.
Chemphyschem ; 17(20): 3309-3314, 2016 Oct 18.
Artigo em Inglês | MEDLINE | ID: mdl-27412827

RESUMO

The Hofmeister series, which originally described the specific ion effects on the solubility of macromolecules in aqueous solutions, has been a long-standing unsolved and exceptionally challenging mystery in chemistry. The complexity of specific ion effects has prevented a unified theory from emerging. Accumulating research has suggested that the interactions among ions, water and various solutes play roles. However, among these interactions, the binding between ions and solutes is receiving most of the attention, whereas the effects of ions on the hydrogen-bond structure in liquid water have been deemed to be negligible. In this study, attenuated-total-reflectance Fourier transform infrared spectroscopy is used to study the infrared spectra of salt solutions. The results show that the red- and blue-shifts of the water bending band are in excellent agreement with the characteristic Hofmeister series, which suggests that the ions' effects on water structure might be the key role in the Hofmeister phenomenon.

19.
ACS Appl Mater Interfaces ; 7(50): 27608-12, 2015 Dec 23.
Artigo em Inglês | MEDLINE | ID: mdl-26642883

RESUMO

We developed a facile, large-scale, and environmentally friendly liquid-exfoliation method to produce stable and high-concentration dispersions of mono- to few-layer black phosphorus (BP) nanosheets from bulk BP using nine ionic liquids. The prepared suspensions can stabilize without any obvious sedimentation and aggregation in ambient air for one month. In particular, the concentration (up to 0.95 mg mL(-1)) of BP nanoflakes obtained in 1-hydroxyethyl-3-methylimidazolium trifluoromethansulfonate ([HOEMIM][TfO]) is the highest reported for BP nanosheets dispersions. This work provides new opportunities for preparing atomically thin BP nanosheets in green, large-scale, and highly concentrated processes and achieving its in situ application.

20.
Chem Commun (Camb) ; 51(54): 10811-4, 2015 Jul 11.
Artigo em Inglês | MEDLINE | ID: mdl-25985823

RESUMO

A controllable synthetic route has been developed for the preparation of chitosan supported Pd catalysts in an ionic liquid, 1-butyl-3-methylimidazolium acetate ([Bmim]OAc), by using compressed CO2 as the anti-solvent and regulator. It was found that the dispersion of Pd particles on chitosan and the catalytic activity of the as-prepared catalysts for the hydrogenation of styrene could be tuned by changing the pressure of CO2.


Assuntos
Dióxido de Carbono/química , Quitosana/química , Líquidos Iônicos/química , Paládio/química , Catálise , Hidrogenação , Imidazóis/química , Espectroscopia de Infravermelho com Transformada de Fourier
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA