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[Display omitted] • The SP-COPs exhibited high catalytic efficiency of CO 2 conversion and excellent I 2 adsorption capacity. • The synergistic mechanism of CO 2 conversion was proved by experimental and kinetics. • The iodine adsorption kinetic process was described. The fixing reactions of carbon dioxide with epoxides will not only help to ameliorate the problem of global warming, but also facilitate the synthesis of cyclic carbonates that have a multitude of applications. Herein, a new sequence of Salen cobalt complexes adjusted with different counterions and interconnected with pyrene group were synthesized through Friedel–Crafts alkylation, which were served as conjugated organic polymers (SP-COPs) for taking advantage of catalytic CO 2 fixation reactions and iodine adsorption. Further characterizations were carried out through FT-IR, UV, TGA, and SEM to comprehend the intact structure, thermal stability, morphology and other physical and chemical properties. All materials exhibited effective catalytic performance, and in particular, SP-COP-1 with co-catalyst of TBAI achieved 96.2% conversion under ultra-mild conditions. The E a was obtained to be 46.4 kJ·mol−1 by performing kinetic experiments at different temperatures by fitting the experimental data. The performance of iodine vapor adsorbed by these materials at ambient pressure of 75°C reached 2.8 g·g−1, 2.2 g·g−1 and 2.6 g·g−1 respectively, and the adsorption process is describable in terms of pseudo-first-order and pseudo-second-order adsorption kinetics. [ABSTRACT FROM AUTHOR]

It is well known that hydrogen promotes catalyst activity in Cr/PNP‐catalyzed ethylene tetramerization, but the mechanism of this effect is unclear. A density functional theory (DFT) study was conducted to explore this effect, and conformation changes were carefully taken into consideration to build a clear reaction pathway. Three components in the ethylene tetramerization catalytic cycle were examined in detail: the production of 1‐hexene from metallacycloheptane, the production of 1‐octene from metallacyclononane, and the formation of an active centre on the Cr/PNP catalyst. This result indicates that the formation of an active centre on the catalyst becomes more favorable upon the imposition of hydrogen, where hydrogen functions as a second ligand. This easing effect could be the key factor leading to the outperformed Cr/PNP catalyst activity in ethylene tetramerization. [ABSTRACT FROM AUTHOR]

The preparation of ultra–small silver nanoparticles (average diameter ≤10 nm) is a technical problem because of their aggregation tendency. Therefore, the preparation conditions are usually harsh and complex. It is widely recognized that covalent organic frameworks (COFs) represent a novel class of porous crystalline compounds with broad applications in various fields. In this work, an environmentally and economically friendly new method has been developed for synthesizing ultra–small silver nanoparticles by reducing silver ions in ethanol solution with a covalent organic framework (TPB–DMTP–COF) as a template and reductant at room temperature. Interestingly, the TPB–DMTP–COF not only serves as a template and reductant but also functions as a stabilizer. Moreover, the TPB–DMTP–COF can be utilized repeatedly as a reductant. The morphology and structure of the silver nanoparticles were examined using transmission electron microscopy and showed that they were spherical with an average particle size of approximately 7.5 nm. Compared with the previously reported silver nanoparticles, the silver nanoparticles synthesized by this new method are not coated with Surfactant, such as Polyvinylpyrrolidone (PVP). As a result, they possess a larger exposed surface area, exhibit increased activity, and demonstrate excellent antimicrobial properties against both Gram–negative Escherichia coli and Gram–positive bacteria Staphylococcus aureus. [ABSTRACT FROM AUTHOR]

To improve the electrochemical performance of supercapacitors, pseudocapacitive electrode materials must be synthesized with high surface activity, high electrical conductivity, and ultralong cycle life, which presents a significant challenge. In this study, we reported on the synthesis of sulfur-vacancy-enriched sheet-like Ni 3 S 2 @ZnS composites based on 3D network porous nickel foam (NF) using a two-step electrodeposition protocol. The Ni 3 S 2 @ZnS/NF exhibited a specific capacitance of 1141.9 C g−1 (241.0 mC cm−2) at a current density of 19 A g−1 (5 mA cm−2). The Ni 3 S 2 @ZnS/NF positive electrode was used to fabricate an all-solid asymmetric supercapacitor, which demonstrated an ultrahigh energy density of 12.0 μWh cm−2 at a power density of 7.2 mW cm−2, as well as an ultrahigh capacitance retention rate of 86.7% after 50,000 cycles. Experimental and theoretical results indicated that the introduction of sulfur vacancies could improve the surface activity of the electrode, as well as its hydroxide diffusion and adsorption ability by adjusting the surrounding local electron concentration of cations around them. This accelerated the interfacial redox reaction and resulted in remarkable electrochemical performance for the Ni 3 S 2 @ZnS/NF electrode. This research provides a pathway for the controlled synthesis of 2D nanosheets with vacancy-rich structures and their potential electrochemical applications. • The sulfur-vacancy-enriched sheet-like Ni 3 S 2 @ZnS composite has been conceived. • Abundant sulfur vacancies make the material have high capacitive properties. • The theoretical studies further deepen structure-activity relationship of sulfur vacancies. • An ultrahigh capacitance retention supercapacitor is fabricated. [ABSTRACT FROM AUTHOR]

Schematic figure showing climate driving mechanisms on wetland hydrological and vegetational evolution. The relatively strong East Asian summer monsoon (EASM) with high precipitation tends to generate a higher water-level condition with more hygrophilous herbaceous plants while blocking the deposition of coarse grain-size fractions (a), and vise versa for weak EASM stages (b). [Display omitted] • The late-Holocene hydrological and vegetational regimes were reconstructed. • An ecological lake-to-wetland transition occurred at ~4.5 ka BP. • The wetlands evolution was largely controlled by monsoonal precipitation. The responding mechanism of wetland ecosystem to climate change is currently unclear due to a lack of long-term records incorporating multiple ecological factors. This paper presents a well-dated and multi-proxy cored record from a natural freshwater wetland developed in a paleo-pingo-related depression on the Sanjiang Plain. The study aims to reconstruct the wetland water-level and vegetational regimes during the past ~6.0 ka BP and discuss the wetland evolution response to the East Asian summer monsoon (EASM) circulation. The results show that a shallow-water lake with hygrophilous herbs developed in the depression with a strong EASM during ~6.0–4.5 ka BP. The paleolake was succeeded by a wetland with a lowered mean water level and an increase in tree cover controlled by the weakened EASM during the past 4.5 ka BP. Such an ecological lake-to-wetland transition corresponds well to the sharp decline of the EASM around 4.5 ka BP which has been well documented in various geological records across the EASM domain. During the wetland developing stage over the past 4.5 ka BP, the water-level and vegetational changes in the studied depression were also closely related to the EASM variations. The strengthened EASM usually generated higher water levels with more hygrophilous herbs around 4.0 ka BP, 3.5 ka BP, 3.0 ka BP, 2.0 ka BP, and 1.3 ka BP. Considering the prevalent EASM climate serving as the predominant water supply for the wetlands on the modern Sanjiang Plain, we suggest the EASM circulation has played a critical role in driving the wetland ecological evolution during the mid-to-late Holocene Epoch. The past 0.4 ka BP is an exception as the local Trees/Herbs ratio visibly increased with the declined water level, while the monsoonal precipitation shows no equivalent shift. The wetland evolution at this stage was attributed to human interference. [ABSTRACT FROM AUTHOR]

The sandwich-structured fluorinated graphene (FGN)/poly(vinylidene fluoride-hexafluoro- propylene) [P(VDF-HFP)] composites with various FGN constituents were fabricated via a layer-by-layer solution casting technique, and their dielectric relaxation phenomenons of the trilayered composites were studied in a systematic way by dielectric relaxation spectroscopy (DRS) at various temperatures (25°C–200 °C) in the range of 20 Hz to 5 M Hz. The variations in dielectric parameters (ε ′ and ε ") with frequency at each studied temperature show that ε ′ and ε " increase with the rise of temperature and ε " significantly decreases with the addition of FGN. Moreover, the asymmetric shapes of electric modulus spectra (M″) and Cole-Cole plots exhibit the relaxation process of non-Debye, especially in trilayered FGN/P(VDF-HFP) composites. AC conductivity is irrelevant to frequency and temperature under low frequency-high temperature, but frequency sensitive under high frequency region. Furthermore, the two activation energies (E τ and E σ) gradually increased with the addition of FGN, showing that the mobility of charge carriers is suppressed, thus they are unable to overcome the relaxing and conducing barrier. Polymer-based dielectric materials play a important role in the field of high energy density capacitors such as hybrid electric vehicles (HEV), medical defibrillators, and high power pulse systems. In this work, dielectric relaxation behavior (e. g. dielectric loss, DC electric conductivity) of sandwich-structured FGN/P(VDF-HFP) composites at high temperature was studied, which will provide the theoretical support for the development and application of polymer-based dielectric materials. [Display omitted] • The sandwich-structured Fluorinated Graphene/P(VDF-HFP) films were fabricated using a facile solution casting method. • Decreased ε" and σ dc of sandwich-structured FGN/P(VDF-HFP) films at high temperature was studied. • Activation energy of sandwich-structured FGN/P(VDF-HFP) films was tuned leading to the improvements of dielectric properties. [ABSTRACT FROM AUTHOR]