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An easy and facile hydrothermal method is presented to synthesize hybrid materials of hollow mesoporous Zn0.76Co0.24S nanospheres anchored on reduced graphene oxide (rGO) sheets (Zn0.76Co0.24S@N/S-rGO), in which the obtained Zn0.76Co0.24S nanospheres are composed of numerous nanoparticles. Being evaluated as anode materials for lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs), the Zn0.76Co0.24S@N/S-rGO composites exhibited a high reversible capacity of 804 and 605 mA h g−1 at the current density of 1 A g−1 after 500 cycles for LIBs and SIBs, respectively. The excellent electrochemical performance of Zn0.76Co0.24S@N/S-rGO composites originates from the synergistic effect between hollow Zn0.76Co0.24S nanospheres and reduction graphene, as well as the void spaces between the neighbouring nanoparticles of Zn0.76Co0.24S providing large contact areas with electrolyte and buffer zone to accommodate the volume variation during the cycling process.

The development of green, controllable, and simplified pathways for rapid dopamine polymerization holds significant importance in the field of polydopamine (PDA) surface chemistry. In this study, a green strategy is successfully devised to accelerate and control the polymerization of dopamine through the introduction of ozone (O3). The findings reveal that ozone serves as an eco‐friendly trigger, significantly accelerating the dopamine polymerization process across a broad pH range, spanning from 4.0 to 10.0. Notably, the deposition rate of PDA coatings on a silicon wafer reaches an impressive value of ≈64.8 nm h−1 (pH 8.5), which is 30 times higher than that of traditional air‐assisted PDA and comparable to the fastest reported method. Furthermore, ozone exhibits the ability to accelerate dopamine polymerization even under low temperatures. It also enables control over the inhibition–initiation of the polymerization process by regulating the "ON/OFF" mode of the ozone gas. Moreover, the ozone‐induced PDA coatings demonstrate exceptional characteristics, including high homogeneity, good hydrophilicity, and remarkable chemical and mechanical stability. Additionally, the ozone‐induced PDA coatings can be rapidly and effectively deposited onto a wide range of substrates, particularly those that are adhesion‐resistant, such as polytetrafluoroethylene (PTFE). [ABSTRACT FROM AUTHOR]

With the rapid development of high-frequency communication and large-scale integrated circuits, insulating dielectric materials require a low dielectric constant and dielectric loss. Poly (aryl ether ketone) resins (PAEK) have garnered considerable attention as an intriguing class of engineering thermoplastics possessing excellent chemical and thermal properties. However, the high permittivity of PAEK becomes an obstacle to its application in the field of high-frequency communication and large-scale integrated circuits. Therefore, reducing the dielectric constant and dielectric loss of PAEK while maintaining its excellent performance is critical to expanding the PAEK applications mentioned above. This study synthesized a series of poly (aryl ether ketone) resins that are low dielectric, highly thermally resistant, and soluble, containing cyclohexyl and diphenyl fluorene. The effects of cyclohexyl contents on the properties of a PAEK resin were studied systematically. The results showed that weakly-polarized cyclohexyl could reduce the molecular polarization of PAEK, resulting in low permittivity and high transmittance. The permittivity of PAEK is 2.95–3.26@10GHz, and the transmittance is 65–85%. In addition, the resin has excellent solubility and can be dissolved in NMP, DMF, DMAc, and other solvents at room temperature. Furthermore, cyclohexyl provided PAEK with excellent thermal properties, including a glass transition temperature of 239–245 °C and a 5% thermogravimetric temperature, under a nitrogen atmosphere of 469–534 °C. This makes it a promising candidate for use in high-frequency communications and large-scale integrated circuits. [ABSTRACT FROM AUTHOR]

As one of the most promising sodium-ion battery (SIB) anodes, transition metal sulfides (TMSs) have been extensively studied for their high capacity and abundant resources. However, the performance of TMS electrodes has been plagued by the poor rate capability and short cycle life, resulting from the huge volume change and the shuttling of polysulfides during cycling. Here, rationally-designed nitrogen-doped carbon-coated Co9S8–Co1−xS yolk–shell hollow spheres (Co9S8–Co1−xS@NC) are synthesized as the SIB anode. The hollow nanostructure shortens the diffusion length of sodium ions/electrons and affords abundant space to accommodate the volume expansion during sodiation. The Co9S8–Co1−xS@NC anode delivers a large sodium-ion storage capacity of 578 mA h g−1 even after 500 cycles at 0.5 A g−1 and superior rate capability and cycling stability (323 mA h g−1 at 5 A g−1 over 1200 cycles) in a half cell. In addition, when combined with the advanced Na3V2(PO4)2O2F electrode, the full SIB shows a highly stable specific capacity and reversibility. The reaction mechanism of Co9S8–Co1−xS@NC was studied using operando X-ray diffraction (operando XRD), revealing the reversible conversion between cobalt sulfides and Co/Na2S. [ABSTRACT FROM AUTHOR]

Sodium-ion batteries (SIBs) have attracted widespread attention as future energy storage systems. However, the development of advanced anodes for SIBs still lags far behind. Metal sulfides exhibit high theoretical capacity yet suffer from low rate-capability and limited life span, resulted from their poor electric conductivity, volumetric fluctuation, and polysulfide dissolution and shuttling. Herein, a two-dimensional (2D) vertical aligned nickel sulfide nanosheets grown uniformly on reduced graphene oxide (rGO) is designed. The unique 2D on 2D structure enhances the electrolyte/electrode contact and reduces the migration/diffusion path of electrons/Na+, thereby greatly improving the rate-performance. Besides, the rGO provides sufficient surface area to absorb polysulfides, which effectively mitigates the shuttling of the intermediates. The NiS@rGO composite delivers 360 mAh/g after 800 cycles at 5 A/g, and a capacity of 540 mAh/g is maintained after 100 cycles at 0.1 A/g. In-situ XRD diffraction confirmed the reversible transformation between NiS and Ni during cycling. Furthermore, when coupled with the well-developed Na 3 V 2 (PO 4) 3 @C (NVP@C) cathode, the NiS@rGO/NVP@C full cell achieves a stable discharge capacity of around 200 mAh/g. [Display omitted] [ABSTRACT FROM AUTHOR]

Iron sulfides, as promising anode materials, have been intensively studied, but still encounter problems due to their limited cycle life caused by huge volume changes. In the present work, a facile method has been presented to prepare Fe2O3 nanobiscuits followed by poly(dopamine) coating. After thermally induced sulfurization, Fe7S8@C nanobiscuits have been successfully obtained, which show high specific capacities, excellent rate capabilities and stable cycling stability as anodes for lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs). They exhibit high reversible capacities of 547.3 mA h g−1 after 600 cycles and 530.8 mA h g−1 after 1000 cycles at a high current density of 5 A g−1 for LIBs and SIBs, respectively. This outstanding electrochemical performance may be attributed to the stress-buffering effect owing to the biscuit-like nanostructure and conformal surface coating with carbon. [ABSTRACT FROM AUTHOR]

The current routes to couple dispersive liquid-liquid microextraction with capillary electrophoresis are the evaporation of water immiscible extractants and the back-extraction of analytes. In this study, a new methodology for this combination using water-in-oil microemulsion electrokinetic chromatography coupled with normal stacking mode on-line sample concentration was developed to analyze chlorophenols in water samples. The analytes were extracted with tributyl phosphate and the extractant dilution (3×) was directly injected into an electrophoresis buffer (7.7 cm) containing 5% sodium dodecyl sulfate, 78% 1-butanol, 2% 1-heptane, and 15% sodium acetate solution (pH 8.0). This proposed method is very simple and convenient compared to the conventional procedures. The key parameters affecting separation and concentration were systematically optimized. Under the optimized conditions, dispersive liquid-liquid microextraction contributed an enrichment factor of 45-50, and the overall sensitivity improvement was 312-418-fold. Limits of detection between 1.4 and 3.0 ng/mL and limits of quantification between 4.5 and 10.2 ng/mL were achieved. Acceptable repeatability lower than 3.0% for migration time and 9.0% for peak areas were obtained. The developed method was successfully applied for analysis of the chlorophenols in real water samples. [ABSTRACT FROM AUTHOR]

Sodium-ion batteries (SIBs) have attracted tremendous interest and become a worldwide research hotpot owing to their low cost and abundant resources. To obtain suitable anode materials with excellent performance for SIBs, an effective and controllable strategy is presented to fabricate SnS 2 nanosheets coating on nanohollow cubic CoS 2 /C (CoS 2 /C@SnS 2 ) composites with a hollow structure using Co-metal-organic frameworks as the starting material. As anodes for SIBs, the CoS 2 /C@SnS 2 electrode exhibits ultralong cycle life and excellent rate performance, which can maintain a high specific capacity of 400.1 mAh g -1 even after 3500 cycles at a current density of 10 A g -1 . When used in a full-cell, it also shows enhanced sodium storage properties and delivers a high reversible capacity of 567.3 mAh g -1 after 1000 cycles at 1 A g -1 . This strategy can pave a way for preparing various metal sulfides with fascinating structure and excellent performance for the potential application in energy storage area., (© 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)