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The development of highly efficient and cheap electrocatalysts for the oxygen evolution reaction (OER) is highly desirable in typical water-splitting electrolyzers to achieve renewable energy production, yet it still remains a huge challenge. Herein, we have presented a simple procedure to construct a new nanofibrous hybrid structure with the interface connecting the surface of CeO2 and CoO as a high-performance electrocatalyst toward the OER through an electrospinning-calcination-reduction process. The resultant CeO2-CoO nanofibers exhibit excellent electrocatalytic properties with a small overpotential of 296 mV at 10 mA cm-2 for the OER, which is superior to many previously reported nonprecious metal-based and commercial RuO2 catalysts. Furthermore, the prepared CeO2-CoO nanofibers display remarkable long-term stability, which can be maintained for 130 h with nearly no attenuation of OER activity in an alkaline electrolyte. A combined experimental and theoretical investigation reveals that the excellent OER properties of CeO2-CoO nanofibers are due to the unique interfacial architecture between CeO2 and CoO, where abundant oxygen vacancies can be generated due to the incomplete matching of atomic positions of two parts, leading to the formation of many low-coordinated Co sites with high OER catalytic activity. This research provides a practical and promising opportunity for the application of heterostructured nonprecious metal oxide catalysts for high-efficiency electrochemical water oxidation.

A facile method for efficient synthesis of core-shell composite material was proposed. In this method, the silica microspheres were co-modified with metal organic framework (MOF-235) and polyethylene glycol polymer (PEG) and used as mixed-mode stationary phase (MOF-235@PEG@silica) for high-performance liquid chromatography. Elemental analysis, scanning electron microscopy, X-ray photoelectron spectroscopy, Fourier-transform infrared spectroscopy, and Brunauer-Emmett-Teller etc. methods were used to investigate the properties of the core-shell composite material. The MOF-235@PEG@silica stationary phase showed flexible selectivity for the separation of both hydrophilic and hydrophobic compounds especially for the separation of nine alkaloids, which showed superior hydrophilic separation performance than previous MOF-based composite stationary phases. Some factors including the pH of buffer salt, the ratio of organic phase and water phase in the mobile phase have been investigated, suggesting that the chromatographic retention mechanism of the column was a mixed mode of hydrophilic and reversed phase. The composite material also showed excellent chromatographic repeatability with the RSDs of the retention time found to be 0.2%–0.6% (n = 10) and the standard addition test in the actual sample proved that it can be used for practical sample analysis. In short, it provided a general way for preparing MOFs-based composites as mixed-mode chromatographic stationary phases, and changed the current status of MOF-based composite materials as single mode chromatographic stationary phases.

Recently, hybrid biocatalysts with a unique interfacial structure have attracted significant attention for enzyme mimicking due to their superior catalytic activity compared with the single compone...

A strategy based on in situ growth of a metal–organic framework composite material was proposed by introducing a sodium dodecyl benzenesulfonate (SDBS) group to increase the electrostatic interacti...

A new type of core-shell composite material was prepared and applied as a hydrophilic interaction liquid chromatography (HILIC) stationary phase. In this work, silica spheres were first modified with a bimetallic central metal-organic framework (ZnCoMOF) by a new strategy of static self-assembled in situ growth. This strategy was beneficial for increasing the electrostatic interaction between the MOF ligand and silica via introducing a sodium dodecylbenzenesulfonate (SDBS) group. The ZnCoMOF@silica stationary phase was characterized and evaluated in comparison with amino-modified and bare silica columns in terms of various polar analytes including eight nucleosides and nucleobases, seven carbohydrates, and multiple sulfonamides and antibiotics. The effects of organic solvent concentration, water content, the concentration of the salt and the pH of the buffer solution on the retention time were studied, which demonstrated the typical retention behavior of HILIC on the ZnCoMOF@silica column. Compared with most reported MOF-based stationary phases, the new composite material showed excellent hydrophilic properties and separation efficiency for various polar analytes. Moreover, the obtained stationary phase showed good reproducibility and stability. The relative standard deviation (RSD) of the retention time for repeatability was found to range from 0.1% to 0.6%, and the RSD of the retention time for stability was found to range from 0.3% to 0.7%. Furthermore, the column batch-to-batch reproducibility showed excellent preparation reproducibility, which few reported in most previous MOF@silica composite materials. This specific preparation method offers an easy and novel way to manipulate the amount of MOF particles on silica, which extends a universal way to produce various MOF@silica stationary phases by the method of static self-assembled in situ growth.

The rational design of metal-organic framework (MOF)-based materials with a huge specific surface area, high redox activity, and favorable conductivity is currently a hot subject for their potential usage in supercapacitor electrodes. Herein, novel bimetallic MOFs with a flowerlike nanosheet structure grown on the electrospun nanofibers (PPNF@M-Ni MOF, M = Co, Zn, Cu, Fe) have been prepared by controlling the incorporation of various types of metal ions, which display superior electrochemical performance. For example, PPNF@Co-Ni MOF possesses a large specific capacitance of 1096.2 F g-1 (specific capacity of 548.1 C g-1) at 1 A g-1 and excellent rate performance. In addition, an asymmetric solid-state device composed of PPNF@Co-Ni MOF (positive materials) and KOH-activated carbon nanofibers embedded with reduced graphene oxide (negative materials) reaches a maximum energy density of 93.6 Wh kg-1 at the power density of 1600.0 W kg-1 and long cycling life. This work may greatly advance the research toward the design of supported MOF-based electrode materials for a promising prospect in energy conversion and storage.

The mineralogical, morphological and chemical characteristics of ash deposits during combustion of Zhundong lignite (

Interfacial engineering is an efficient and versatile strategy to accelerate the catalytic performance of functional nanomaterials. Herein, we have constructed ternary titanium dioxide (TiO2)@molybdenum disulfide (MoS2)/cobalt ferrite (CoFe2O4) composite nanofibers via a two-step hydrothermal reaction. Firstly, MoS2 nanosheets are grown on TiO2 nanofibers, then acting as an interfacial barrier to load ultrafine CoFe2O4 nanoparticles. Thanks to the synergistic effects among the interfacial interactions between MoS2 and TiO2 as well as CoFe2O4 component, the prepared ternary TiO2@MoS2/CoFe2O4 composite nanofibers displayed much better catalytic activity than any single and bicomponent composite nanofibers for peroxidase mimicking. Due to the superior catalytic efficiency of the ternary TiO2@MoS2/CoFe2O4 composite nanofibers, a highly sensitive way for l -cysteine sensing was developed. Our work offers an advanced surface engineering solution to construct a peroxidase-like catalyst to detect l -cysteine, with bright future in environmental science and biological technology.

The effect of temperature and atmosphere on the syngas yields of CO and H2 during gasification of Zhundong lignite (ZD) and water-washed Zhundong lignite (WWZD) in a fixed-bed reactor was investigated. The experiments were run over temperatures from 750 to 950 °C, atmospheres of pure steam or with CO2 addition ratios of 25–75%. The syngas yield rate, overall yield, carbon conversion rate and the activation energy for gasification of carbon in coal were obtained. Results showed that the yield rates of CO and H2 during pure steam gasification of ZD at 750 °C increased from 0 to a maximum of 5.4 and 19.4 ml/min and decreased afterwards, when H2 was found as the main syngas. Moreover, CO was not detected while H2 was identified at a later stage of gasification, indicating that the char-steam gasification and water–gas shift reaction were dominated at this stage. As the temperature increased to 950 °C, the maximum yield rates of CO and H2 increased, confirming that the increase in temperature promoted gasification. Likewise, the increase in CO2 ratio from 25 to 75% resulted in a maximum CO yield rate of 163.87 ml/min at 950 °C, promoting CO yield when CO2 was the gasifying agent. The maximum yield of H2 was, however, decreased while the Boudouard reaction was promoted. Water washing was found to significantly influence gasification. The maximum yield rates of CO and H2 were decreased and the gasification time was prolonged, indicating that the reactivity of char-steam gasification was decreased due to the removal of Na contents by water washing. In addition, the overall yield of CO was increased as temperature and the CO2 percentage increased, whereas that of H2 decreased. The activation energy for steam gasification of ZD as determined by the momogeneous model (HM), shrinking core model (SCM) and isoconversional method was in the range of 53.36–56.14 kJ/mol, all of which were applicable for determining the activation energy of ZD gasification under steam.

Controllable fabrication of novel and uniform noble metal nanoparticles on a specific support with a superior catalytic or electrocatalytic performance is of significantly importance for practical applications. In this report, we demonstrated an effective way to fabricate uniform thin-walled Pd/polypyrrole (PPy) hollow nanotubes. The prepared Pd/PPy hybrid nanotubes exhibited an excellent peroxidase-like activity to oxidize a typical peroxidase substrate such as 3,3′,5,5′-tetramethylbenzidine in comparison with traditional Pd/C and Pd black catalysts. The outstanding catalytic activity of the Pd/PPy hybrid nanotubes for peroxidase mimicking could be resulting from their unique hollow characteristic and an interfacial effect between PPy and Pd components. Based on the favorable catalytic property of the Pd/PPy hybrid nanotubes, a convenient and rapid colorimetric way to sensitively determine ascorbic acid has been presented. The detection limit was around 0.062 μM and an excellent selectivity was also achieved. The developed detection system in this study could be extended to the fields of bioscience and biotechnology with promising prospects.

In the past decade, nanomaterials-based artificial enzymes have emerged as a hot spot in the field of catalysis. However, it is a significant challenge to fabricate functional nanomaterials for multiple-enzyme mimetic activity. In this work, we have presented an efficient catalytic platform to mimic peroxidase, oxidase, and catalase-like activity by Fe3C decorated carbon nanofibers (Fe3C/C NFs). First, polyacrylonitrile nanofibers (PAN NFs) are prepared via an electrospinning technique. Next, an Fe(III)-tannic acid (TA) complex is formed on the surface of PAN NFs through a wet chemical reaction. Finally, Fe3C/C NFs are obtained from the carbonization of the PAN/Fe(III)-TA complex nanofibers. The prepared Fe3C/C NFs show an excellent triple-enzyme mimetic property including peroxidase-like, oxidase-like, and catalase-like activity, which is investigated thoroughly by the colorimetric experiment of the 3,3',5,5'-tetramethyl benzidine oxidation and the degradation of H2O2. Thanks to the superior catalytic performance of Fe3C/C NFs for oxidase mimicking, a facile and colorimetric way to determine glutathione with a high sensitivity and favorable selectivity has been achieved. This work provides an efficient platform for multiple-enzyme mimicking, which may expand their promising applications in biosensing, biomedicine, and environmental technology.

It is highly desirable to develop alternative non-noble metal hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) electrocatalysts with the advantages of low cost and high efficiency. In this study, we report the synthesis of CoS2–C@MoS2 core–shell nanofibers by using electrospun Co–carbon nanofibers as templates, followed by a one-step hydrothermal reaction accompanied with a sulfurization process. Benefiting from the unique structure and the synergistic effect between the components, the resultant CoS2–C@MoS2 core–shell nanofibers exhibit excellent electrocatalytic activity and stability toward HER, showing the overpotential of approximately 173 mV at 10 mA cm–2 and virtually immobile current density after 1000 cycles. Furthermore, the CoS2–C@MoS2 core–shell nanofibers also show a good OER catalytic activity, providing them as efficient candidates for bifunctional water splitting electrocatalysts.

Metal–organic frameworks (MOFs) and their derivatives have emerged as promising electrode materials in the energy conversion and storage field in the past few years. Herein, hierarchical Ni/Ni3S2 decorated carbon nanofibers (CNFs) have been fabricated based on the template growth of MOFs on pre-oxidized electrospun polyacrylonitrile (PAN) nanofibers followed by carbonization and sulfurization processes. The formation of Ni and CNFs provides high conductivity, while the hierarchical structure contributes to a large number of exposed redox active sites. Thus the optimized hierarchical Ni/Ni3S2/CNFs achieve a high electrochemical performance as supercapacitor electrodes, exhibiting a specific capacitance of 830.0 F g−1 at 0.2 A g−1 and ideal rate capabilities. In addition, the assembled solid-state supercapacitor delivers a high energy density of 31.6 W h kg−1 at a power density of 1800 W kg−1 and a good capacitance retention of 95.7% after 5000 charge–discharge cycles. This strategy provides a basis for the efficient construction of MOF-derived electrode materials for their application in energy storage systems.

Improving the conductivity and active surface area of electrospun carbon nanofibers is beneficial to develop binder-free supercapacitor electrodes for practical application prospects in energy storage field. Herein, we propose a facile and low-cost synthesis of hybrid electrospun carbon nanofibers composites (Ni-G-CNFs) coated with polyaniline throns (Ni-G-CNFs@PANI) via a combination of electrospinning and followed by carbonization and in situ polymerization processes. The prepared Ni-G-CNFs@PANI as a novel binder-free electrode exhibits a high specific capacitance of 318.0 F g−1 at a current density of 0.5 A g−1 and an acceptable capacitance retention of 62.1% when the current density increased from 0.5 A g−1 to 10 A g−1 in three-electrode system. Furthermore, a symmetric all solid-state supercapacitor was assembled by two binder-free electrodes, and the maximum energy density of 14.4 Wh kg−1 and maximum power density of 3750.2 W kg−1 were achieved in a potential window of 1.5 V. Capacitance retention remained 85.8% after 1000 cycles of charge-discharge process even at a high current density of 10 A g−1. This strategy for growing PANI on electrospun hybrid CNFs paves a new avenue for construction of high-performance binder-free energy storage devices.

Electrolytic water splitting is a promising strategy to generate clean hydrogen energy but still restricted by the sluggish kinetics during the anodic oxygen evolution reaction (OER). A highly efficient route to significantly reduce the cell voltage of electrolytic water splitting is to replace OER with hydrazine oxidation reaction (HzOR) so as to assist hydrogen generation effectively. Here, we report the fabrication of carbon nanofibers (CNFs) embedded with palladium cobalt (PdCo) alloy nanoparticles, via an electrospinning followed by a carbonization treatment. The as-synthesized PdCo-CNFs catalyst displays a superior electrocatalytic activity toward HzOR with a working potential of 258 mV (vs. RHE) to drive a current density of 50 mA cm−2 in an alkaline solution with 0.2 M hydrazine. Furthermore, the favorable hydrogen evolution reaction (HER) activity of this catalyst enables it highly efficient electrolytic hydrogen production, and the two-electrode system using PdCo-CNFs as both the cathode and anode for overall hydrazine splitting is capable of delivering a cell voltage of 0.440 V to attain 10 mA cm−2, which is 1.496 V less than that for pure water splitting using the same electrodes and even 0.459 V less than the overall hydrazine splitting device using Pt/C//RuO2 as electrocatalysts. This work provides a reliable way for the fabrication of promising bifunctional electrocatalysts to promote energy-saving hydrogen production for practical applications.

The nickel organic framework capped with polyvinylpyrrolidone was prepared and synergistically immobilized onto porous silica surface as the mixed-mode stationary phase for high-performance liquid chromatography. Here, polyvinylpyrrolidone firstly was chosen as functional molecules to change morphology and size of the metal organic framework. The silica microspheres were then modified by them via a simple bonding method rather than in-situ growth method with the aid of electrostatic interaction commonly used before. The stationary phase showed flexible selectivity for separation of both hydrophilic and hydrophobic compounds, especially for hydrophilic compounds such as carbohydrates, alkaloids and sulfonamides etc. The chromatographic behaviors were evaluated by investigating various factors, and a typical mixed-mode retention feature of the column was observed. The composites could be prepared repetitively, and relative standard deviations of retention time of objective compounds among different batches were less than 1.75%. It also showed excellent chromatographic reproducibility, stability and potentiality for application in real samples. In short, the composites can be used for a feasible option for analysis of multiple compounds as the mixed-mode stationary phase and it provides a general approach for preparing MOFs-based composites by changing morphology and size of MOFs.

A general method was developed for preparing a metal–organic framework–polymer composite coated silica core–shell stationary phase. Silica microspheres were comodified with metal–organic framework and polyvinylpyrrolidone rather than the in situ method of silica modification by original metal–organic framework particles. Metal–organic framework particles and polyvinylpyrrolidone on silica surface were beneficial to suppress silanol activity and enhance composite material tolerance, as well as increasing the water compatibility of the original metal–organic framework-based stationary phases. The stationary phase exhibited superior hydrophilic and hydrophobic performance in terms of separation for various analytes including seven alkaloids, six sulfonamides, five antibiotics, and five polycyclic aromatic hydrocarbons. Moreover, the composite material also showed excellent stability with the relative standard deviation of the retention time of 0.4 to 0.7%. The separation performance with real samples proved that the column has good practical application potential. In summary, the poposed method provides a general way for preparing metal–organic framework–polymer composite material and changed the current status of original metal–organic framework particles modified silica as a single mode chromatographic stationary phase.

Developing highly efficient, cost-effective and extremely stable electrocatalysts toward oxygen evolution reaction (OER) is a great challenge for their promising water splitting application to promote the sluggish kinetics. In this work, an amorphous non-noble FeCoNi trimetallic aerogel (FeCoNi AG) is prepared via a one-step in situ spontaneous gelation and reduction strategy, presenting a remarkable OER activity and stability in an alkaline medium. FeCoNi AG catalyst delivers an exceptionally low overpotential of 235 mV at a current density of 10 mA cm−2 and features a small Tafel slope of 50 mV dec-1 in 1 M KOH, which is superior to the state-of-the-art RuO2 and many other reported transition FeCoNi-based catalysts. In addition, an outstanding long-term durability during 40 h chronoamperometric test and 5000 cyclic voltammetry (CV) cycles without obvious degradation of current density is achieved. This work is of high inspiration for developing transition metals-based amorphous aerogel electrocatalysts for greatly enhanced oxygen evolution.

It is a challenge to prepare high-efficiency and inexpensive electrocatalysts toward urea oxidation reaction (UOR). Herein, we report the fabrication of NiS nanotubes with hierarchical sheet-like surface morphology via a novel template-directed hydrothermal reaction as efficient UOR electrocatalyst. The unique hollow structure of NiS nanotubes provides the exposure of more active sites and excellent electron/mass transport properties, ensuring a superior UOR performance. The NiS nanotubes catalyst shows a very low potential at around 1.39 V vs. RHE at 100 mA cm−2 in 1 M KOH/0.33 M urea solution. And the UOR current density of the catalyst at 1.4 V vs. RHE reaches 135 mA cm−2, representing a superior UOR performance. The NiS nanotubes catalyst also possesses an excellent operational stability. Furthermore, a two-electrode urea-assisted overall water splitting (OWS) device assembled with NiS nanotubes as anode and Pt/C as cathode delivers a working voltage of 1.445 V to attain 10 mA cm−2, which is 188 mV less than that for the urea-free OWS electrolyzer, demonstrating its possibility to be applicable for energy efficient hydrogen production. This study provides a rationale to develop high-efficiency non-precious metal-based UOR catalysts for the efficient assistance of hydrogen fuel generation.

The synthesis of functional nanomaterials with unique structures and morphologies as efficient biocatalysts for sensing application has attracted tremendous interest. Herein, Fe3C nanoparticles encapsulated within nitrogen-doped carbon (Fe3C/N–C) nanofibers have been prepared through a facile electrospinning strategy and a carbonization process. The resulting Fe3C/N–C hybrid nanofibers display a superior oxidase-like performance toward the oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) and other substrates, which is dependent on the formation of Fe3C nanoparticles and their crystallinity. The obtained Fe3C/N–C hybrid nanofibers-based oxidase-like catalyst shows a good long-term stability and reusability. Thanks to the unique catalytic activity for oxidase mimicking, an efficient sensing platform to sensitively determine sulfite and l-cysteine with low detection limits of 24.9 and 23.0 nM (S/N = 3), respectively, as well as excellent selectivity and anti-interference ability has been developed. This wor...

Platinum is the most commonly used dye-sensitized solar cell (DSSC) counter electrode (CE) due to its superior electrocatalytic activity and high transparency. However, the scarcity and high-cost of Pt restrict its practical application for the large-scale production of DSSCs. Herein, a facile approach for fabricating highly dispersed Co9S8 nanoparticles with small diameters in the range of 5–10 nm on the surface of carbon nanofibers (CNFs) via an electrospinning followed by calcination and hydrothermal reaction was developed. The composite material could be used as an efficient and low-cost Pt-free CE for DSSCs. The DSSC assembled with the prepared Co9S8/CNFs composite as a CE exhibited excellent electrocatalytic activity and a power conversion efficiency (PCE) of 8.37%, which is comparable to that of the DSSC with conventional thermally deposited Pt as the CE (8.50%). Therefore, the Co9S8/CNFs composite can be used as an efficient and low-cost promising alternative CE in DSSCs.

Fabrication of core-shell nanostructured catalyst is a promising way for tuning its catalytic performance due to the highly active interface and rich redox properties. In this work, hierarchical Co3O4@NiO core-shell nanotubes are fabricated by the deposition of NiO shells via a chemical bath treatment using electrospun Co-C composite nanofibers as templates, followed by a calcination process in air. The as-prepared Co3O4@NiO core-shell nanotubes exhibit a uniform and novel hollow structure with Co3O4 nanoparticles attached to the inner wall of NiO nanotubes and excellent catalytic activity toward the oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) in the presence of H2O2. Due to the synergistic effect, the peroxidase-like activity of the Co3O4@NiO core-shell nanotubes is much higher than that of individual Co3O4 and NiO components. Owing to the superior peroxidase-like activity, a simple and rapid colorimetric approach for the detection of dopamine with a detection limit of 1.21µM and excellent selectivity has been developed. It is anticipated that the prepared Co3O4@NiO core-shell nanotubes are promising materials applied for biomedical analysis and environmental monitoring.

The development of highly sensitive and low-cost biosensors for the detection of dopamine is of paramount importance for medical diagnostics. Herein, we report the preparation of a new peroxidase-like catalyst with a uniform heterostructure by using a technique involving electrospinning, annealing and solvothermal reaction. In this catalyst system, cobalt sulfide (CoS) nanoparticles were homogenously distributed and supported on the surface of cobalt ferrite (CoFe2O4) nanotubes. The as-prepared CoFe2O4/CoS hybrid nanotubes showed remarkably high catalytic efficiency as peroxidase mimics toward the oxidation of 3,3,5,5-tetramethylbenzidine (TMB) in the presence of H2O2. Owing to the synergistic effect between the CoFe2O4 and CoS component, the prepared CoFe2O4/CoS hybrid nanotubes exhibited enhanced peroxidase-like activity, exceeding that of either the CoS nanoparticles or CoFe2O4 nanotubes alone. Dopamine has been widely investigated due to its unique function in the nervous system. Consequently, various approaches have been developed for the sensitive determination of dopamine. In this work, a simple and sensitive colorimetric route for the detection of dopamine was established based on the ability of dopamine to induce the reduction of oxidized TMB to TMB with consequent fading of the blue color. This method shows a wide linear range (0-50μM) and a low detection limit of 0.58μM. The unique heterostructure with spinel/sulfide interfaces represents a new concept for the construction of highly efficient and multifunctional biocatalysts.

Nanomaterials with ABX3-type perovskite structure have attracted considerable and increasing attention due to their unique physical and chemical properties as well as promising applications in various fields. In this work, we have developed a simple electrospinning followed by a calcination process to prepare ABO3-type perovskite LaMnO3+δ nanofibers as efficient oxidase mimics for the detection of L-cysteine. The oxidase-like catalytic activity of the prepared LaMnO3+δ nanofibers is heavily dependent on the calcination temperature which results in different sizes of the LaMnO3+δ crystals and their crystallinity, and the maximum activity is achieved at the calcination temperature of 700 °C. Based on the high oxidase-like catalytic activity of the as-prepared perovskite LaMnO3+δ nanofibers, a simple and accurate colorimetric detection method towards L-cysteine has been developed. The detection limit is as low as 109.8 nM and an excellent selectivity for L-cysteine detection with common substances in human blood as interferents is also achieved. In addition, the LaMnO3+δ nanofibers can be retained as a monolithic membrane after the calcination process, making them an oxidase mimic for on-demand colorimetric sensing. This work reveals the promising prospects for the perovskite LaMnO3+δ materials in biosensing, medical diagnosis, food safety and environmental monitoring.

A self-templated approach has been developed for the preparation of FeMnO3 nanoparticles filled in the hollow core of polypyrrole (PPy) nanotubes by an in situ polymerization process accompanied by the etching of FeMnO3 nanofibers. The prepared FeMnO3@PPy nanotubes exhibited a superior peroxidase-like activity. The catalytic reaction system has been used for the sensitive colorimetric detection of glutathione with a low detection limit and good selectivity.

In recent years, the design of high-performance and low-cost electrocatalysts for oxygen evolution reaction (OER) has captured great interest in the field of energy conversion and storage. Layered double hydroxide (LDH) with special configuration usually shows a highly electrochemical activity and become a desirable functional material for OER. In this work, carbon nanofibers embedded with Co nanoparticles have been prepared via an electrospinning and carbonization process, which can be served as a conductive support for the growth of NiFe LDH nanosheets through an electrodeposition route to produce a hierarchical 3D structure (denoted as 3D core-shell Co-C@NiFe LDH nanofibers). Owing to the high conductivity, large surface area and strong electron transfer between NiFe LDH nanosheets and Co-C nanofibers, the as-prepared 3D core-shell Co-C@NiFe LDH nanofibrous catalyst shows an excellent OER performance with an overpotential of only 249 mV at the current density of 10 mA cm−2 and a small Tafel slope of 57.9 mV dec−1, demonstrating an outstanding electrocatalytic activity for water oxidation. Furthermore, the 3D core-shell Co-C@NiFe LDH nanofibers also exhibit a superior long-term stability, with no obvious decrease in current density after nearly 190 h testing. Hence, the low-cost 3D core-shell Co-C@NiFe LDH nanofibrous electrocatalyst with an outstanding OER performance offers a novel chance for practical electrochemical water splitting application.

We prepared two-dimensional (2D) bimetallic metal-organic frameworks (Ni-ZIF-8) nanosheets by a simple solvent-free method at room temperature. The morphology and composition of Ni-ZIF-8 can be controlled through adding different amounts of Ni. And then, the 2D magnetic mesoporous nanosheets (Ni/ZnO@C) were synthesized by directly pyrolyzing Ni-ZIF-8 under argon atmosphere and explored as magnetic solid phase extraction (MSPE) adsorbents for the determination of nitroimidazole antibiotics (NIABs). Magnetic Ni nanoparticles embedded in carbon nanosheets uniformly resulted in high magnetization saturation of Ni/ZnO@C for easy separation. The Ni/ZnO@C can form hydrogen bond and π-π interaction with three NIABs resulting from their rich N-H containing imidazole, π-electron. Due to the high specific surface area and high mass transfer rate of 2D Ni/ZnO@C, the materials showed satisfactory adsorption capacity and rapid adsorption kinetics for NIABs. A rapid and effective method of Ni/ZnO@C-MSPE combined with high-performance liquid chromatography was proposed for the determination of NIABs. Several main parameters affecting MSPE were investigated. Under the optimal conditions, wide linear was achieved ranging from 0.1 to 500 µg⋅L-1 with a low detection limit of 0.025-0.05 µg⋅L-1. The established method has been successfully applied to analyze NIABs from environmental water samples with satisfactory recovery from 74.33 to 105.71%.

In the present work, thermogravimetric analysis was employed to investigate co-combustion behaviors of Fushun low calorific oil shale and its semi-coke. The synergy effect was estimated by using the interaction coefficient and the relative error of mean square root. In addition, activation energy was also calculated by means of Coats-Redfern, distributed activation energy model and Flynn-Wall-Ozawa methods. Results indicated that with the increase of oil shale mass fraction and oxygen concentration, combustion characteristics of the samples were improved. And some little interaction did occur during the co-combustion process, but it was relatively slight. Consequently, the co-combustion of oil shale and semi-coke still could be expressed roughly by the addition of individual components of the mixtures. Furthermore, activation energy of the samples decreased slowly at the initial stage attributed to the minerals’ catalytic effects, and in the final stage, it jumped to a high value, suggesting that the burnout of the samples was difficult. Besides, the mix proportion of oil shale which was added to stabilize the combustion in the circulating fluidized bed was also theoretically calculated.

Mixed transition-metal oxides (MTMOs) have attracted much research interest because of their promising applications in artificial enzymes. In this work, uniform hollow MnCo2O4 nanofibers have been fabricated via an electrospinning technique followed by a calcination process, which can be used as efficient oxidase mimics. In detail, the as-prepared hollow MnCo2O4 nanofibers display excellent oxidase-like activity toward the oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) superior to their corresponding single-metal oxides without the addition of H2O2. Based on the high catalytic activity of hollow MnCo2O4 nanofibers and their inhibition effect by specific substances, the system of hollow MnCo2O4 nanofibers–TMB has potential to be applied in assays to detect sulfite and L-cysteine using a colorimetric approach with high sensitivity and selectivity. This work implies a broad application prospect of MTMOs in biosensors, environmental protection, food safety and medical science.

A simple and low cost detection of l-cysteine is essential in the fields of biosensors and medical diagnosis. In this study, we have developed a simple electrospinning, followed by calcination process to prepare FeCo nanoparticles embedded in carbon nanofibers (FeCo-CNFs) as an efficient peroxidase-like mimic for the detection of l-cysteine. FeCo nanoparticles are uniformly dispersed within CNFs, and their diameters are highly influenced by the calcination temperature. The calcination temperature also influences the peroxidase-like catalytic activity, and the maximum activity is achieved at a calcination temperature of 550 °C. Owing to the high catalytic activity of the as-prepared FeCo-CNFs, a colorimetric technique for the rapid and accurate determination of l-cysteine has been developed. The detection limit is about 0.15 μM with a wide linear range from 1 to 20 μM. In addition, a high selectivity for the detection of l-cysteine over other amino acids, glucose and common ions is achieved. This study provides a simple, rapid and sensitive sensing platform for the detection of l-cysteine, which is a promising candidate for potential applications in biosensing, medicine, environmental monitoring.

In recent years, the fabrication of functional nanostructures with multicomponents for a variety of novel biosensors has received considerable attention due to their synergistic improved sensitivity. Herein, we report a facile approach for the preparation of Fe3O4/nitrogen-doped carbon (Fe3O4/N–C) hybrid nanofibers, and construct a sensing platform for the sensitive colorimetric detection of H2O2 and ascorbic acid (AA). During the synthetic process, a discontinuous layer of polypyrrole (PPy) is first polymerized in situ on the surface of the α-Fe2O3 nanofibers under hydrothermal reaction using α-Fe2O3 nanofibers as both a template and an oxidant. Then the prepared α-Fe2O3/PPy nanofibers are converted into Fe3O4/N–C hybrid nanofibers through pyrolysis with a thermochemical reduction process. The resulting Fe3O4/N–C hybrid nanofibers are used as a novel peroxidase mimic towards the oxidation of 3,3,5,5-tetramethylbenzidine (TMB) in the presence of H2O2, with a superior catalytic activity over individual α-Fe2O3 nanofibers, α-Fe2O3/PPy nanofibers, Fe3O4/C nanofibers, and commercial Fe3O4 nanoparticles. Based on the high peroxidase-like activity of Fe3O4/N–C hybrid nanofibers, a sensing platform for the colorimetric detection of AA is developed. A good linear relationship from 0 to 50 μM and a detection limit of 0.04 μM are achieved. This work offers a new method for the preparation of Fe3O4/N–C hybrid nanofibers and presents new potential applications in biosensing, medical diagnostics and environmental monitoring.

Synergistic effects play an important role in improving the catalytic activity for enzyme-like reactions. Compared to individual nanomaterials, a system consisting of multiple components usually exhibits enhanced catalytic activity as an enzyme mimic. Herein we describe the synthesis of CuFe2O4/Cu9S8/polypyrrole (PPy) ternary nanotubes as an efficient peroxidase mimic via a three-step approach involving an electrospinning process, annealing treatment and hydrothermal reaction. The remarkably enhanced catalytic activity of CuFe2O4/Cu9S8/PPy ternary nanotubes as peroxidase mimics over individual CuFe2O4 nanofibers, CuFe2O4/CuO composite nanofibers, CuFe2O4/CuS composite nanofibers, and PPy materials has been achieved, demonstrating the presence of a synergistic effect among the components. The steady-state kinetic experiment suggests a good catalytic efficiency of the CuFe2O4/Cu9S8/PPy ternary nanotubes. On the basis of high catalytic activity, a colorimetric platform for the sensitive detection of H2O2 and dopamine has been developed. This work not only offers a simple approach for the fabrication of a high performance peroxidase-like nanocatalyst, but also provides its promising potential applications in biosensors, medical diagnosis, and environmental monitoring.

The self-assembly of noble metal nanoparticles into new-fashioned one, two and three-dimensional structures is very important due to their superior properties in optics, electrics, catalysis, and chemical sensing compared with individual nanoparticles. Here, we first report a facile one-step approach that allows the fabrication of assembled Au nanorices induced by polyaniline (PANI). During the synthesis, a complex of HAuCl4-(3-aminopropyl)triethoxysilane (APTES) acts as both a soft template and an oxidant; then the reduction of HAuCl4 is accompanied by the oxidation of aniline, resulting in the formation of Au nanorices within a PANI matrix. The application of the prepared Au/PANI nanorices as enzyme mimics toward the oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) is demonstrated. The resultant Au/PANI nanorices display an enhanced peroxidase-like catalytic activity compared with individual Au nanospheres and PANI nanofibers alone, revealing a synergistic effect between Au and PANI components in the Au/PANI nanorices. The Au/PANI nanorices are also used as efficient surface-enhanced Raman scattering (SERS) substrates for in situ monitoring of the oxidation process of TMB during the peroxidase-like catalytic reaction. On the basis of the SERS technique, a discernible detection level of H2O2 as low as 10−8 M is obtained. We envision that such a system may show more potential applications in biocatalysis, disease diagnosis and environmental monitoring.

Developing a low-cost and durable non-noble metal eletrocatalyst for hydrogen evolution reaction (HER) is critical in efficient hydrogen production. Herein, tungsten carbide nanoplates (WC NPs) with typical mesoporous structure were prepared by a controlled hydrothermal reaction followed by a gas-solid carburization process. The crystal phases, microstructure and chemical components of the nanoplates were characterized, and their electrochemical properties were measured. The results show that the as-prepared WC NPs expose active sites upmost, and exhibit enhanced conductivity and superior HER performance in acid solution in terms of a small η 10 (overpotential to obtain a current density of 10 mA cm−2) of 120 mV, a Tafel slope of 58 mV dec−1 and outstanding long-term cycling stability. These indicate that the HER properties of WC NPs are dramatically enhanced compared to that of all phase pure WC materials reported in recent years. This enhancement can be attributed to their unique structural and electronic properties, which can be exploited to improve the electrochemical properties of traditional non-noble metal material.

The development of highly efficient, earth-abundant and low-cost counter electrode materials is of significant importance and challenge for practical application in dye-sensitized solar cells. In this work, morphology-controlled NiCo2S4 nanoparticles (NPs) and nanorods (NRs) decorating carbon nanofibers (CNFs) have been prepared via an electrospinning and hydrothermal or solvothermal strategy, which are further utilized as counter electrodes (CEs) in dye-sensitized solar cells (DSSCs). Benefitting from the rich nickel and cobalt ions redox chemistry and more exposed catalytically active sites from NiCo2S4 NRs grown vertically on the surface of CNFs as well as faster electron transporting capability providing by the highly conductive CNFs, the DSSC device based on NiCo2S4 NRs/CNFs CE yields an excellent power conversion efficiency of 9.47%, which is higher than that of the devices with NiCo2S4 NPs/CNFs (8.63%), Pt (8.18%) and CNFs (6.06%) as CEs under AM 1.5 G irradiation. Furthermore, the NiCo2S4 NRs/CNFs CE shows an excellent electrochemical stability in an iodine-based electrolyte. This study highlights a controllable and versatile route to rational design efficient counter electrode catalysts for high-performance CEs application.

Sample pretreatment is an important prerequisite for analyzing complex samples due to the low concentration of targets and numerous interferences in sample matrix. As a group of emerging absorbents, metal-organic frameworks (MOFs)-derived porous carbons (MPCs), obtained by high-temperature pyrolysis of MOFs, have been brought into stage recently due to their intrinsic advantages such as high porosity, permanent nanoscale cavities and open channels. The morphology of the original MOF precursor is well maintained after calcination produces. Furthermore, by directly calcinating MOFs comprised of magnetic metal centers (Co, Fe, Ni), magnetic porous carbon with excellent magnetism and separation efficiency can be fabricated. The uniformly distributed magnetic metal nanoparticles in the carbon matrix is helpful to reduce the agglomeration problem of magnetic nanoparticles and the porosity of carbon materials inherited from MOFs is beneficial to evaluate the adsorptive property. So MPCs has been widely used in sample preparation of environmental, biological samples and food matrices. In this review, we summarize the performances and different process for the preparation of MPCs. Moreover, this review mainly focuses on providing a detailed discussion about the application of MPCs for extracting analytes from complex matrix in different sample pretreatment modes such as solid-phase extraction, magnetic solid phase extraction and solid-phase microextraction. In addition, the efforts recently on the automation of magnetic solid phase extraction processes by means of MPCs are also described.

Here, we report a simple one-step procedure to fabricate coaxial Te@poly(3,4-ethylenedioxythiophene) (PEDOT) nanocables via a self-assembly redox polymerization between 3,4-ethylenedioxythiophene monomer and the oxidant of sodium tellurite without the assistance of any templates and surfactants. The as-synthesized Te@PEDOT coaxial nanocables have diameters of center cores in the range of 5-10 nm, and the size of the outer shell from several nanometers to 15 nm. More interestingly, the as-prepared Te@PEDOT nanocables can be converted to Pd@PEDOT nanocables via a galvanic replacement reaction. The center core of the Pd nanowire exhibits a high crystallinity. The application of the synthesized Pd@PEDOT nanocables as peroxidase-like catalysts for the colorimetric detection of H2O2 is reported. The synergistic effect between the Pd nanowire and electrically conducting PEDOT enhances the catalytic activity toward the oxidation of the peroxidase substrate 3,3',5,5'-tetramethylbenzidine in the presence of H2O2. A detection limit toward H2O2 is as low as 4.83 μM, and a linear range from 10 to 100 μM has been achieved. This work offers a potential versatile route for the fabrication of cable-like nanocomposites with conducting polymers and other active components, which display great promise in applications such as catalysis, nanoelectronic devices, and energy storage and conversion.

Reduced graphene oxide (rGO)/CuS/Au composite nanosheets were prepared herein via a two-step approach based on a simple hydrothermal reaction combined with an in situ reduction process. The rGO/CuS/Au composite nanosheets exhibited good peroxidase-like catalytic activity toward the oxidation of a peroxidase substrate 3,3′,5,5′-tetramethylbenzidine (TMB) in the presence of H2O2. The rGO/CuS/Au composite nanosheets were also utilized as a new surface-enhanced Raman scattering (SERS) substrate, enabling monitoring of the peroxidase-like catalytic reaction on their active surface. The oxidized intermediate of TMB formed during the peroxidase-like reaction was captured and clearly identified by SERS spectroscopy, providing an avenue for quantitative in situ monitoring of the oxidation of TMB. This approach could also be used to directly detect H2O2 with a detection limit of about 2.1 μM.

Herein, we report a simple procedure to decorate small palladium nanoparticles (Pd NPs) on the surface of CoFe2O4 nanotubes; the decorated nanotubes possess intrinsic peroxidase-like activity for the sensitive detection of H2O2. The CoFe2O4 nanotubes are prepared via an electrospinning technique, followed by a calcination process in air. The functionalization of Pd NPs on the surface of CoFe2O4 nanotubes was achieved through an in situ reduction process using ascorbic acid (AA) as a reducing agent. The synthesized Pd nanoparticles, which are small in size, are evenly dispersed on the surface of the CoFe2O4 nanotubes. The hollow structure of the CoFe2O4 nanotubes and the uniform distribution of the Pd nanoparticles enhance peroxidase-like activity toward the catalytic oxidation of the peroxidase substrate 3,3′,5,5′-tetramethylbenzidine (TMB) in the presence of H2O2. The peroxidase-like property of the Pd/CoFe2O4 composite nanotubes provides a facile approach for the colorimetric detection of H2O2 with a low detection limit. This work provides great potential for Pd/CoFe2O4 nanotubes as enzyme-like nanocatalysts to sensitively detect H2O2 in biological systems.

A novel composite nanostructure of C–CoOx–C with CoOx nanoparticles embedded in N-containing porous graphite carbon nanofibers (CNF) is successfully prepared via sintering the electrospun polyacrylonitrile–cobalt acetate tetrahydrate nanofibers covered by a polypyrrole (PPy) sheath that were attained from the chemical vapor-phase polymerization of pyrrole monomers using concentrated nitric acid as both the dopant and oxidant for the first time. The unique configuration with a well-defined morphology possesses a large specific surface area and prominent conductivity contributed to by the catalysis of metallic Co and the external PPy-derived carbon envelope, which could facilitate effective electron transfer and rapid ion penetration in C–CoOx–C, thus improving its electrochemical performance. As expected, when employed as an electrode active material for supercapacitors, the resultant C–CoOx–C showed a more acceptable specific capacitance, better rate capability and higher cycling stability than individual CNF and CoOx nanoparticle-decorated CNF without the coating of a N-doped carbon layer from PPy (C–CoOx).

Rational design of highly efficient electrocatalyst for oxygen evolution reaction (OER) is essential to construct high-performance energy devices. In this study, we have developed an electrospinning, in situ polymerization and carbonization process to fabricate Fe doped CoO/C (Fe-CoO/C) nanofibers as efficient OER electrocatalysts. In the synthesized Fe-CoO/C nanofibers, ultrathin carbon layer can be used as conductive network to promote electron transfer and thus improve the electrocatalytic activity. At the same time, additional active sites, like bridged site, formed by Fe doping, also provides the catalyst excellent electrochemical activity in OER. The as-prepared Fe-CoO/C nanofibers exhibit an excellent OER activity with an overpotential of 362 mV at the current density of 10 mA cm−2 in an alkaline medium, which is comparable with the commercial RuO2 catalyst. After 2500 cyclic voltammograms (CVs) cycles test, the catalyst still maintains the initial electrocatalytic activity, demonstrating a great durability. This strategy introduces both carbon layer and Fe doping to increase the conductivity and the density of active sites of CoO nanofibers, thus enhancing the electrocatalytic activity and stability. This work offers an efficient route to develop low-cost and highly active transitional metal oxide-based OER electrocatalyst for potential renewable electrochemical energy conversion and storage.

In this work, carbon dot decorated copper sulphide/carbon nanotubes (CuS@CD-CNTs) composite with a unique three-dimensional (3D) grape string-like structure was directly prepared via in situ hydrothermal process at the temperature of 180 °C for 12 h and applied for supercapacitors. The chemical composition and morphology were systematically tested by XRD, Raman, SEM and TEM characterization techniques. The as-prepared CuS@CD-CNTs composite brings out a novel 3D grape string-like structure, where the CuS spheres are distributed homogeneously with CNTs as a result of the addition of carbon dot. As the active material of pseudocapacitor electrode, the CuS@CD-CNTs composite delivers superior electrochemical properties with a decent specific capacitance of 736.1 F g−1 at the current density of 1 A g−1. Also, the CuS@CD-CNTs composite showed exceptional cycling stability, maintaining 92% retention after 5000 charge-discharge cycles. Such superior electrochemical properties owe to the collective contribution of CuS, CD and CNTs and 3D grape string-like architecture. The excellent electrochemical results above suggest that CuS@CD-CNTs composite has promising electrochemical energy storage application in supercapacitors.

It is extremely necessary to develop high-performance noble-metal-free hydrogen evolution reaction (HER) electrocatalysts applied over the whole pH values to replace expensive Pt-based catalysts. Herein, a typical metal-semiconductor heterostructure with metallic Mo and Mo2C nanoparticles encapsulated in nitrogen-doped carbon nanofibers (N-CNFs) is fabricated via the pyrolysis of electrospun polyacrylonitrile (PAN)/cellulose acetate (CA)/bis(acetylacetonato)dioxomolybdenum (MoO2(acac)2) nanofibers. The unique porous and channel-rich structure of Mo/Mo2C/N-CNFs can be manipulated by varying the mass ratio of polyacrylonitrile and cellulose acetate, leading to the exposure of abundant active centers and the acceleration of rapid mass transport. In addition, the synergetic effect among metal and semiconductor as well as the excellent conductivity of the N-CNFs result in excellent HER activity and stability over a wide pH range. To achieve the current density of 10 mA cm−2, the optimized Mo/Mo2C/N-CNFs exhibit overpotentials of 175, 162 and 294 mV in 0.5 M H2SO4, 1 M KOH and 0.1 M phosphate buffer solution (PBS), respectively. This work provides a feasible approach to synthesize high-performance and economical hydrogen evolution electrocatalysts at all pH values for renewable energy-related applications.

Scavenging of sodium and ash deposition characteristics during co-combustion of Zhundong lignite with an oil shale semi-coke in a circulating fluidized bed (CFB) were investigated. Zhundong lignite (ZD) and its blends with the semi-coke (SC) of 10 and 20 wt% were combusted in the CFB furnace at 950 °C. Two air-cooled probes were placed in the furnace chamber (P1) and at the cyclone outlet (P2), respectively, to simulate ash deposition. The bottom ash, fly ash and ash deposits on the probes were collected and analysed by using XRD, SEM-EDX, ICP-OES and laser particle analyser. Results show that the fly ash burning ZD was comprised of sub-micron particles and agglomerates enriched in CaSO4 and SiO2, with Na being NaAlSi3O8, Na2SiO3, Na2Si2O5 and NaAlSiO4. When SC of high Si/Al was added, the fly ash was comprised of sub-micron particles with less agglomerates, where Na-bearing minerals were also evidently reduced. Likewise, the bottom ash was coarse-grained particles rich in SiO2, (Ca,Na)(Si,Al)4O8 and CaSiO3 during ZD combustion but changed to SiO2, (Na,Ca)Al(Si,Al)3O8 or NaAlSi3O8 as SC was added, suggesting that Na was captured by SC and retained in the bottom ash. The deposit on P1 was enriched in Na2SO4 and CaSO4 when ZD was burned but turned into coarse-grained particles rich in Ca/Na aluminosilicates while SC presented, showing a decreased sintering propensity. Likewise, the P2 deposit was of Ca/Na sulphates agglomerates, but became refractory SiO2, Ca sulphate and aluminosilicates as SC added. Ash deposition in CFB burning ZD is consequently mitigated with SC addition.

Developing high‐performance, low‐cost, and robust bifunctional electrocatalysts for overall water splitting is extremely indispensable and challenging. It is a promising strategy to couple highly active precious metals with transition metals as efficient electrocatalysts, which can not only effectively reduce the cost of the preparation procedure, but also greatly improve the performance of catalysts through a synergistic effect. Herein, Ru and Ni nanoparticles embedded within nitrogen‐doped carbon nanofibers (RuNi‐NCNFs) are synthesized via a simple electrospinning technology with a subsequent carbonization process. The as‐formed RuNi‐NCNFs represent excellent Pt‐like electrocatalytic activity for the hydrogen evolution reaction (HER) in both alkaline and acidic conditions. Furthermore, the RuNi‐NCNFs also exhibit an outstanding oxygen evolution reaction (OER) activity with an overpotential of 290 mV to achieve a current density of 10 mA cm−2 in alkaline electrolyte. Strikingly, owing to both the HER and OER performance, an electrolyzer with RuNi‐NCNFs as both the anode and cathode catalysts requires only a cell voltage of 1.564 V to drive a current density of 10 mA cm−2 in an alkaline medium, which is lower than the benchmark of Pt/C||RuO2 electrodes. This study opens a novel avenue toward the exploration of high efficient but low‐cost electrocatalysts for overall water splitting., A facile strategy based on electrospinning and a postcarbonization process is demonstrated to prepare carbon nanofibers incorporating Ru and Ni nanoparticles, which exhibits admirable Pt‐like hydrogen evolution reaction activity and superior oxygen evolution reaction performance. The electrolyzer with this hybrid as both anode and cathode displays a remarkable electrocatalytic activity and outstanding long‐term durability, which outperforms the commercial Pt/C||RuO2 electrocatalyst.

We report a facile strategy to synthesize a hierarchical core-sheath PANi@MoS 2 nanocomposite as an advanced electrode material for high-performance electrochemical capacitor applications. Hierarchical core-sheath PANi@MoS 2 nanostructure is prepared in a one-pot synthesis via a hydrothermal redox reaction between ammonium tetrathiomolybdate and polyaniline nanofibers. Structural and morphological characterizations of the as-prepared PANi@MoS 2 nanocomposite are investigated by Fourier-transform infrared (FT-IR), X-ray diffraction (XRD), X-ray photoelectron spectrum (XPS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) measurements. The obtained PANi@MoS 2 electrode displays a good electrochemical capacitance performance with a specific capacitance of 450 F g −1 under 0.5 M H 2 SO 4 . More importantly, the core-sheath structure of PANi@MoS 2 electrode enhances the structural stability during the electrochemical process and thus improves the electrochemical cycling stability of the electrode significantly, which retains 80% in specific capacitance after 2000 charge/discharge processes.

In this study, effects of molecular weight distribution (M-d) on the performances of polyethersulfone (PES) ultrafiltration membrane were studied. PES samples with similar weight average molecular weight (M-w), number average molecular weight (M-n), or viscosity average molecular weight (M-eta) but different M-d, were obtained by blending. The thermodynamic and the kinetic factors were studied through ternary phase diagram and shear viscosity data, respectively. Experimental results showed that PES membranes with different structures can be obtained by blending. This can be due to the combined effects of the thermodynamic factor and kinetic factor of casting solution. The filtration experiments showed that wider M-d would lead to higher permeability and lower rejection when the M-n values of PES were similar, and on the other side, wider M-d could lead to lower permeability and rejection when the M-w values of PES were similar. In addition, under conditions of similar M-eta values of PES, the membranes showed similar performances irrespective of the M-d. (C) 2015 Elsevier B.V. All rights reserved.