Search

Porous carbon fibers (PCFs) have promising prospects as electrode materials for energy storage devices. In this study, the centrifuged electrospun PCFs (cPCFs) were mainly studied. And compared with the traditional electrospun PCFs (ePCFs), cPCFs have significantly enhanced mechanical and electrochemical properties. It was found that the cPCFs exhibited a special nanochannel structures including micropores, mesopores and macropores, achieving a high specific capacitance (C spe) of 277 F/g at a current density of 0.2 A/g. The cPCFs also possessed a capacitance retention rate of 99% and 98% after 6700 cycles and 200 bends respectively, which indicated that it had excellent electrochemical stability and flexibility. In addition, the flexible binder-free symmetric supercapacitors displayed a relatively high specific capacitance of 93.2 F/g at a current density of 0.2 A/g. In this research, a high-efficiency, environmental friendly and low-cost method was used to prepare flexible, binder-free and high-performance electrode materials, which provided new possibilities for flexible wearable energy storage devices in the future. Schematic demonstration of PCF electrodes, and schematic structure of flexible all-solid-state supercapacitor. Image 1 • Centrifuged electrospinning improves the properties of the porous carbon. • PEG is used as a template to prepare nanochannels without pollution. • The carbon electrode shows high capacitance and flexibility. [ABSTRACT FROM AUTHOR]

Hydrophilic homopolymers in aqueous solution would play an important role on thermally induced physical gelation of stereocomplexable gels. Herein, the sol-gel transition, rheological behavior, crystalline structure and microstructure evolution of stereocomplexable copolymers composed of PLLA, PDLA and PEG in presence of PEG homopolymers have been systematically investigated. T s-g of systems including PEG was much lower than that of enantiomeric mixtures. T s-g was 36 °C after addition of PEG (M n = 6 kg/mol), which was 6 °C below that of additive-free counterparts. The efficiency in reducing T s-g was increased with increase of concentration of PEG, and depended on MW of PEG. Moreover, additives containing systems exhibited improved storage modulus, more compact packing of core-forming segments, larger inter-cluster distances and core radius. Essence of decrement of T s-g by presence of PEG was the enhanced stereocomplex crystallization. This study illustrates that addition agents can serve as a regulator to modulate sol-gel transition behaviors of stereocomplexable systems. Image 1 • The effect of hydrophilic homopolymers on sol-gel transition, rheological behavior, crystalline structure and microstructure evolution of stereocomplexed physical gels composed of PLLA, PDLA and PEG has been systematically investigated. • T s-g of systems including PEG homopolymers was much lower than that of PLA/PEG enantiomeric mixtures. • The efficiency in reducing T s-g was increased with the increase of concentration and MW of PEG homopolymers. • Additives containing stereocomplexed systems exhibited improved storage modulus, more compact packing of core-forming segments, larger inter-cluster distances and core radius. [ABSTRACT FROM AUTHOR]

Stereocomplexation has been an effective way to improve the physical properties of block copolymers or blends. However, the effect of stereocomplexation on the confined and fractionated crystallization of other crystallizable block has not been comprehensively investigated so far. In this work, we used poly(l -lactide) (PLLA) and poly(d -lactide) (PDLA) as stereocomplexable higher melting component and studied the confined crystallization and melting behaviors of poly(ethylene glycol) (PEG) in their block copolymers and blends. Unexpectedly, marked fractionated crystallization and fractionated melting behaviors of PEG component occurred during the two-step crystallization process, because of the constrained effect of the early formed stereocomplex (SC) crystals. The fractionated crystallization and melting behaviors were further facilitated with decreasing the isothermal crystallization temperatures of PLLA and PDLA (T ic,PLA). As revealed by polarized optical microscopy (POM), the increase of T ic,PLA favors the transformation of PEG component from the interlamellar to interspherulitic regions due to the reduced nucleation density of PLA. We proposed that fractionated crystallization and fractionated melting behaviors of PEG impacted by SC crystals were attributed to PEG component dispersed in and out interlamellar regions of PLA matrix. Moreover, small-angle X-ray scattering (SAXS) results indicated that two scattering peaks were identified for copolymers after two-step crystallization process, one consisted of mixed PEG and PLA lamellae and the other contained almost pure PEG lamellae originated from the crystallization of PEG dispersed in interfibriller/interspherulitic regions. This study has shed light on the unique fractionated crystallization and fractionated melting behaviors of the lower melting component in polymer systems with the higher melting component preferentially co-crystallized into SC crystals. Two-step nonisothermal crystallization process reveals marked fractionated crystallization and fractionated melting phenomena of the PEG block induced by SC crystals early formed in stereocomplexable polymer systems. A lower T ic,PLA is favorable for the occurrence of fractionated crystallization and fractionated melting behaviors. Image 1 • PEG- b -PLLA- b -PDLA and PEG- b -PLLA/PEG- b -PDLA are synthesized to study the effect of stereocomplexation on the confined and fractionated crystallization of other crystallizable block. • Fractionated crystallization and fractionated melting behaviors of PEG component occur upon the presence of SC crystals in polymer systems depending on PEG content and T ic,PLA. • The microstructure formed by the crystallization of SC crystals in block copolymers and blends with lower PEG content exhibits a smaller long period. • Fractionated crystallization and fractionated melting behaviors of PEG component is related to the distribution of PEG in the solidified PLA matrix. [ABSTRACT FROM AUTHOR]

Balancing electrochemical activity and structural reversibility of fibrous electrodes with accelerated Faradaic charge transfer kinetics and pseudocapacitive storage are highly crucial for fiber-shaped supercapacitors (FSCs). Herein, we report novel core-shell hierarchical fibers for high-performance FSCs, in which the ordered NiCoMoS nanosheets arrays are chemically anchored on Ti 3 C 2 T x fibers. Beneficial from architecting stable polymetallic sulfide arrays and conductive networks, the NiCoMoS-Ti 3 C 2 T x fiber maintains fast charge transfer, low diffusion and OH - adsorption barrier, and stabilized multi-electronic reaction kinetics of polymetallic sulfide. Consequently, the NiCoMoS-Ti 3 C 2 T x fiber exhibits a large volumetric capacitance (2472.3 F cm -3 ) and reversible cycling performance (20,000 cycles). In addition, the solid-state symmetric FSCs deliver a high energy density of 50.6 mWh cm -3 and bending stability, which can significantly power electronic devices and offer sensitive detection for dopamine., (© 2024 Wiley-VCH GmbH.)

In this study, each cobalt tetra-aminophthalocyanine (CoTAPc) molecule was immobilised with four isonicotinic acid (INA) molecules by amide bonding, a novel and highly efficient catalyst pyridine-bridged cobalt tetra-aminophthalocyanine (CoTAPc-TINA) was synthesised. The introduction of INA molecules promoted CoTAPc to expose more active sites, and increased the electron cloud density of cobalt ions promoting O-O bond homolysis of PMS to generate more active species, which significantly enhanced catalytic activity. With the pharmaceutical of carbamazepine (CBZ) as model pollutant, 0.1 g/L CoTAPc-TINA in dark in the presence of 0.4 mM PMS, 98.8% CBZ was removed within 10 min. However, under the same conditions the removed of CBZ was only 58.9% by CoTAPc/PMS system. Radical capture experiments combined electron paramagnetic resonance technology demonstrate that hydroxyl radicals, sulphate radicals, superoxide radicals and singlet oxygen are the main active species in the CoTAPc-TINA/PMS system. As the reaction proceeded, all aromatic intermediates were transformed to small molecular acids by these active species. This investigation provided a new insight for application of metal phthalocyanine in wastewater treatment.

In this study, the porous graphite phase carbon nitride photocatalyst (P-g-C 3 N 4 ) is prepared by the CaCO 3 template method, and then P-g-C 3 N 4 /T-polyethylene terephthalate (T-PET) catalytic fibre is prepared by the padding method. P-g-C 3 N 4 can provide more active sites than g-C 3 N 4 as proved by the Brunauer-Emmett-Teller and the UV-Visible diffuse reflectance test. P-g-C 3 N 4 powder catalyst successfully supports PET fibre as proved by scanning electron microscope, Fourier infrared spectroscopy and X-ray diffraction spectroscopy. The photocatalytic performance of P-g-C 3 N 4 /T-PET catalytic fibre is tested by constructing a single hexavalent chromium or hexavalent chromium/organic pollutant binary pollution system. The potential application value of P-g-C 3 N 4 /T-PET catalytic fibre is further explored by simulating the complex actual water environment. After five recycles, P-g-C 3 N 4 /T-PET catalytic fibre shows good catalytic performance. The mechanism of P-g-C 3 N 4 /PET photocatalytic degradation of organic pollutants is proposed through the capture agent experiment and electron paramagnetic resonance spectroscopy. Among them, •O 2 - is the most important active species of P-g-C 3 N 4 catalytic fibre, which is used for the oxidation of organic pollutants. At the same time, photoelectrons generated by the catalytic fibre are used to reduce hexavalent chromium. The efficiency of P-g-C 3 N 4 to remove pollutants is improved by using PET fibre as a carrier, which not only solves the problem of difficult recovery of powder catalysts but also provides more active sites.

Microplastic pollution has become one of the most concerned focuses in the world. Among many treatment methods, photocatalysis is considered to be one of the most environmentally friendly methods. In this work, the photodegradation behavior of polyamide microplastics is studied by using polyamide 6 PA6) as model microplastics and FeCl 3 as catalyst. It is hoped that the PA6 fiber can be effectively degraded by utilizing the strong oxidizing active species that can be produced after FeCl 3 is irradiated in water. The results shows that PA6 fiber can be almost completely degraded after 10 days of irradiation in FeCl 3 aqueous solution, indicating that it is promising to use this new method to solve the problem of PA6 type microplastics. In addition, the chain scission mechanism and degradation process of PA6 are analyzed in detail by ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS), which provides a new insight for the study of polymer degradation mechanism., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023. Published by Elsevier B.V.)

In this study, we synthesized magnetic MnFe 2 O 4 /ZIF-67 composite catalysts using a straightforward method, yielding catalysts that exhibited outstanding performance in catalyzing the ozonation of vanillin. This exceptional catalytic efficiency arose from the synergistic interplay between MnFe 2 O 4 and ZIF-67. Comprehensive characterization via x-ray photoelectron spectroscopy (XPS), x-ray diffraction (XRD), Fourier transform infrared spectrometer (FT-IR), Brunauer-Emmett-Teller (BET), field emission scanning electron microscopy (FE-SEM), and energy dispersive spectroscopy (EDS) confirmed that the incorporation of MnFe 2 O 4 promoted the creation of oxygen vacancies, resulting in an increased presence of l adsorbed oxygen (O ads ) and the generation of additional ·OH groups on the catalyst surface. Utilizing ZIF-67 as the carrier markedly enhanced the specific surface area of the catalyst, augmenting the exposure of active sites, thus improving the degradation efficiency and reducing the energy consumption. The effects of different experimental parameters (catalyst type, initial vanillin concentration, ozone dosage, initial pH value, and catalyst dosage) were also investigated, and the optimal experimental parameters (300 mg/L1.0-MnFe 2 O 4 /ZIF-67, vanillin concentration = 250 mg/L, O 3 concentration = 12 mg/min, pH = 7) were obtained. The vanillin removal efficiency of MnFe 2 O 4 /ZIF-67 was increased from 74.95% to 99.54% after 30 min of reaction, and the magnetic separation of MnFe 2 O 4 /ZIF-67 was easy to be recycled and stable, and the vanillin removal efficiency of MnFe 2 O 4 /ZIF-67 was only decreased by about 8.92% after 5 cycles. Additionally, we delved into the synergistic effects and catalytic mechanism of the catalysts through kinetic fitting, reactive oxygen quenching experiments, and electron transfer analysis. This multifaceted approach provides a comprehensive understanding of the enhanced ozonation process catalyzed by MnFe 2 O 4 /ZIF-67 composite catalysts, shedding light on their potential applications in advanced oxidation processes. PRACTITIONER POINTS: A stable and recyclable magnetic composite MnFe 2 O 4 /ZIF-67 catalyst was synthesized through a simple method. The synergistic effect and catalytic mechanism of the MnFe 2 O 4 /ZIF-67 catalyst were comprehensively analyzed and discussed. A kinetic model for the catalytic ozone oxidation of vanillin was introduced, providing valuable insights into the reaction dynamics., (© 2024 Water Environment Federation.)

Electronic structure modulation of active sites is critical important in Fenton catalysis as it offers a promising strategy for boosting H 2 O 2 activation. However, efficient generation of hydroxyl radicals (•OH) is often limited to the unoptimized coordination environment of active sites. Herein, we report the rational design and synthesis of iron oxyfluoride (FeOF), whose iron sites strongly coordinate with the most electronegative fluorine atoms in a characteristic moiety of F-(Fe(III)O 3 )-F, for effective H 2 O 2 activation with potent •OH generation. Results demonstrate that the fluorine coordination plays a pivotal role in lowering the local electron density and optimizing the electronic structures of iron sites, thus facilitating the rate-limiting H 2 O 2 adsorption and subsequent peroxyl bond cleavage reactions. Consequently, FeOF exhibits a significant and pH-adaptive •OH yield (~450 µM) with high selectivity, which is 1 ~ 3 orders of magnitude higher than the state-of-the-art iron-based catalysts, leading to excellent degradation activities against various organic pollutants at neutral condition. This work provides fundamental insights into the function of fluorine coordination in boosting Fenton catalysis at atomic level, which may inspire the design of efficient active sites for sustainable environmental remediation., (© 2024. The Author(s).)

The delicate design of innovative and sophisticated fibers with vertical porous skeleton and eminent electrochemical activity to generate directional ionic pathways and good faradic charge accessibility is pivotal but challenging for realizing high-performance fiber-shaped supercapacitors (FSCs). Here, hierarchically ordered hybrid fiber combined vertical-aligned and conductive Ti 3 C 2 T x MXene (VA-Ti 3 C 2 T x ) with interstratified electroactive covalent organic frameworks LZU1 (COF-LZU1) by one-step microfluidic synthesis is developed. Due to the incorporation of vertical channels, abundant redox active sites and large accessible surface area throughout the electrode, the VA-Ti 3 C 2 T x @COF-LZU1 fibers express exceptional gravimetric capacitance of 787 F g -1 in a three-electrode system. Additionally, the solid-state asymmetric FSCs deliver a prominent energy density of 27 Wh kg -1 , capacitance of 398 F g -1 and cycling life of 20 000 cycles. The key to high energy storage ability originates from the decreased ions adsorption energy and ameliorative charge density distribution in vertically aligned and active hybrid fiber, accelerating ions transportation/accommodation and interfacial electrons transfer. Benefiting from excellent electrochemical performance, the FSCs offer sufficient energy supply to power watches, flags, and digital display tubes as well as be integrated with sensors to detect pulse signals, which opens a promising route for architecting advanced fiber toward the carbon neutrality market beyond energy-storage technology., (© 2023 Wiley-VCH GmbH.)

Designing deformable supercapacitors (D-SCs) that have robust skeleton and smoothly active channels for charges kinetic migration and faradic storage are highly crucial for wearable systems. Here, we develop the high-performance D-SCs made of the covalent organic frameworks(COF)@amino-modified Ti 3 C 2 T x deposited on decorated nylon 6 (DPA) film (COF@N-Ti 3 C 2 T x /DPA) via layer-by-layer fabrication. The hierarchical COF@N-Ti 3 C 2 T x /DPA exhibits admirable specific capacitance, rate performance and cycling stability in three-electrode system due to the superior H + storage property and large interfacial charge transfer clarified by density functional theory calculations. Additionally, the solid-state D-SCs deliver favourable energy density and practical energy-supply applications. Particularly, the solid-state D-SCs present high deformable stabilities, with regard to 80.7, 80.6 and 83.4 % capacitance retention after 5000 bending cycles, 2000 stretching cycles and 5000 folding cycles, separately., (© 2023 Wiley-VCH GmbH.)

Titanium dioxide (TiO 2 ) nanoparticles have been extensively used to modify the optical properties of various types of materials. In particular, they have been intensively loaded onto polymer fibers to quench the light reflection. In situ polymerization and online addition are two common strategies for fabricating TiO 2 -loaded polymer nanocomposite fibers. The former does not require separate preparation of masterbatches as the latter does and therefore has its advantages in terms of decreasing the fabrication steps and economic costs. Moreover, it has been found that in situ-polymerized TiO 2 -loaded polymer nanocomposite fibers (e.g., TiO 2 /poly(ethylene terephthalate) fibers) usually have enhanced light-extinction properties over those prepared by the online addition process. Intuitively, there should be a difference in the filler particle dispersion for the two fabrication processes. This hypothesis has not yet been tackled due to the technical difficulty in acquiring the three-dimensional (3D) filler morphology inside the fiber matrix. In this paper, we report a study using the powerful focused ion beam-scanning electron microscopy (FIB-SEM) with a resolution of 20 nm to directly acquire the 3D microstructure of TiO 2 /poly(ethylene terephthalate) nanocomposite (TiO 2 /PET) fibers. This microscopy technique allows us to characterize the particle size statistics and the dispersion inside TiO 2 /PET fibers. We have found that the particle size of TiO 2 inside the fiber matrix can be well modeled by Weibull statistics. Surprisingly, we find that TiO 2 nanoparticles form more significant agglomeration in the in situ-polymerized TiO 2 /PET fibers. This observation is contrary to our common understanding of the two fabrication processes. Namely, slightly altering the particle dispersion with increased TiO 2 filler size helps improve the light-extinction properties. The slightly increased filler size may have altered the Mie scattering between the nanoparticles and the incident visible light, leading to enhanced light-extinction properties of in situ-polymerized TiO 2 /PET nanocomposite fibers.

Fiber-shaped supercapacitors (FSCs) have become one of the significantly strategical flexible energy-storage materials towards future wearable textile electronics and metaverse technologies. Here, we develop the high-performance FSCs based on multiscale dot-wire-sheet heterostructure microfiber of nitrogen-doped carbon dots-Ti 3 C 2 T x /silk nanofibers (NCDs-Ti 3 C 2 T x /SNFs) hybrids via microfluidic fabrication. Due to the enlarged interlayer spacing, plentiful porous channels, accelerated H + ion transport dynamics, large electrical conductivity and excellent mechanical strength/flexibility, the NCDs-Ti 3 C 2 T x /SNFs possesses high volumetric capacitance (2218.7 F cm -3 ) and reversible charge-discharge stability in 1 M H 2 SO 4 electrolyte. Furthermore, the solid-state FSCs present high energy density (57.9 mWh cm -3 ), good capacitance (1157 F cm -3 ), long-life cycles (82.3 % capacitance retention after 40000 cycles), which realize the actual energy-supply applications (powering lamp, watch and toy car)., (© 2023 Wiley-VCH GmbH.)

Thiocarbonylation of alkynes offers an ideal procedure for the synthesis of unsaturated thioesters. A robust ligand-controlled regioselective thiocarbonylation of alkynes is developed. Utilizing boronic acid and 5-chlorosalicylic acid as the acid additive to in situ form 5-chloroborosalicylic acid (5-Cl-BSA), and bis(2-diphenylphosphinophenyl)ether (DPEphos) as the ligand, linear α,β-unsaturated thioesters were produced in a straightforward manner. Switching the ligand to tri(2-furyl)phosphine can turn the reaction selectivity to give branched products. Remarkably, this approach also represents the first example on thiocarbonylation of internal alkynes., (© 2021 Wiley-VCH GmbH.)

Iron (II) phthalocyanine (FePc) supported on electrospun polyester/poly-4-vinylpyridine nanofibers (PET/P4VP NFs) was prepared by stirring in tetrahydrofuran. The resulting product was confirmed and characterized by ultraviolet-visible diffuse reflectance spectroscopy, attenuated total reflection Fourier transform infrared spectra, X-ray photoelectron spectroscopy, gas chromatography/mass spectrometry, and ultra-performance liquid chromatography. More than 95% of sulfaquinoxalinum (SQX) could be removed by the activation of hydrogen peroxide in the presence of FePc-P4VP/PET with a PET and P4VP mass ratio of 1:1. This system exhibited a high catalytic activity across a wide pH and temperature range. The degradation rates of SQX achieved 100, 95, and 78% at a pH of 3, 7, and 9, respectively, and the degradation rates of SQX are more than 80% at the temperature ranging from 35 to 65 °C. DMSO 2 could be detected by gas chromatography/mass spectrometry after the addition of DMSO, suggesting the formation of the high-valent iron intermediates in this catalytic system. In addition, the electron paramagnetic resonance experiments proved that free radicals did not dominate the reaction in our system. Therefore, the high-valent iron intermediates were proposed to the main active species in the FePc-P4VP/PET/hydrogen peroxide system. In summary, the heterogeneous catalytic processes with non-radical catalytic mechanism might have better catalytic performance for the removal of organic pollutants, which can potentially be used in wastewater treatment.