Abundant Groups Research Articles

Zr4+ and Al3+ coordinated cross-linked conductive collagen fibers/solvent-free polyurethane foam with ultra-low reflective electromagnetic shielding properties

In recent years, electromagnetic shielding materials with low reflectance have developed rapidly. However, high material cost, poor bonding fastness, weak mechanical properties and other problems seriously limit its effect in practical use. In this work, flexible conductive collagen fibers (CLF-Zr4+/Al3+-CNTs) were prepared using chromium tanned waste leather as ingredient, carbon nanotubes (CNTs) as conductive filler and transition metal ions as coordination crosslinking agents, and their molecular dynamics were investigated by quantum chemical simulation software. On this basis, a flexible conductive foam with the double layer and double core-clad structure containing carbon nanotubes was constructed using the solvent-free polyurethane (SFPU) chemical foaming technology, and their electromagnetic shielding properties and reflectance were studied. The experiment results showed that when the ratio of CLF-Zr4+/Al3+-CNTs to SFPU polyol is 1:9 and the impregnation times of CNTs are 2, the loading capacity of CNTs in conductive foam is 0.14 mg/cm3, the electrical conductivity is 57.8 S/m, and the thermal conductivity is 0.061 W/(m·K). Meanwhile, when the thickness is 3 cm, the electromagnetic shielding performance is 42.09 dB, and the reflection efficiency is 0.66 %, the lowest reflection efficiency reaches 0.16 % in the experiment. The mechanism of electromagnetic shielding in conductive foams with the double layer and double core-clad structure has been further explored. The experiment results proved that the flexible conductive foam has excellent mechanical properties, stability, heat insulation and flame retardant properties, and has excellent electromagnetic shielding and low reflection characteristics due to its abundant holes, functional group, interface and hierarchical structure.

Performance and Mechanism of Porous Carbons Derived from Biomass as Adsorbent for Removal of Cr(VI)

To solve the problem of heavy metal hexavalent chromium (Cr(VI)) pollution in water bodies, this study was carried out to prepare nitrogen-doped porous carbon by using bamboo shoots as the raw material and KHCO3 as the activator, which has a good ability to remove Cr(VI) from water bodies. The prepared N-doped carbon materials were characterized by thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FT-IR), elemental analysis, and scanning electron microscopy (SEM). The results showed that the prepared carbon material had hierarchical pore structures and abundant functional groups, which is conducive to the adsorption of Cr(VI). The effects of various factors on the adsorption performance of Cr(VI), such as the carbon materials prepared under different conditions, the pH of the initial solution, the concentration of the initial solution, and the contact time between the carbon and Cr(VI), were explored. The results showed that the bamboo shoot-based nitrogen-doped carbon materials, especially BSNC-800 (prepared at 800 °C with a mass ratio of KHCO3 to bamboo shoot of 4:1), performed well in removing Cr(VI) from a water solution. The maximum adsorption of Cr(VI) by BSNC-800 under equilibrium conditions was 385.8 mg g−1 (conditions: at the pH of 2 with the initial concentration of 400 mg L−1). The adsorption kinetics and isotherms were analyzed, and the adsorption mechanism was discussed. It can be found that the adsorption of Cr(VI) by BSNC-800 fits better with the Langmuir isotherm model and the pseudo-second-order kinetic model. The adsorption mechanism between the Cr(VI)-containing solution and BSNC-800 was controlled by membrane diffusion and chemisorption. The results broaden the ways of utilizing biomass resources as precursors of carbon materials, which is significant and helpful for applying biomass carbon materials as adsorbents for wastewater treatment.

Layered MXene Films via Self-Assembly.

MXene has attracted significant attention as a 2D material family due to its metallic conductivity and abundant surface functional groups and has been extensively studied and applied as bulk materials and microscale thin films. MXene possesses ionizable surfaces and edges, as well as high surface area. Its customizable dispersibility demonstrates unique advantages in self-assembly solution processing. Recent studies have demonstrated the application value of layered MXene films at the nanoscale thickness and the reliance of processing on self-assembly techniques. However, this field currently lacks sufficient attention. Here, the regulatory mechanisms are summarized for the preparation of layered MXene films through self-assembly techniques, as well as introduce their applications. Moreover, the future challenges of large-scale applications of MXene self-assembly techniques are proposed. It is believed that this review would provide a dynamic and promising path for the development of layered MXene self-assembly techniques.

One-pot synthesis of monodisperse silver-lignin particles: Enhanced antibacterial agents against antibiotic-resistant bacteria

Lignin-based supports for metal nanoparticles (NPs) have attracted significant attention due to their abundant functional groups that facilitate NPs loading. However, many studies involve a two-step process: fabricating lignin particles and then reducing metal ions to NPs using physical energy consumption or chemical reduction. A one-step in-situ reduction method for NP synthesis on carrier surfaces, eliminating energy consumption, is needed for environmentally friendly and sustainable approach. Herein, we demonstrate that poly-l-lysine (PL) controls the self-assembly kinetics of kraft lignin (KL), and reduces silver ion (Ag+) to silver nanoparticles (AgNPs), forming highly monodisperse, co-self-assembled PL-KL particles (Ag@PL-KLPs) without chemical reducing agents or energy consumption. PL facilitated rapid KL desolvation, promoting intermolecular interactions and silver ion adsorption, followed by an efficient, separate nucleation and growth process yielded Ag@PL-KLPs approximately 270 nm in size with a narrow distribution. Notably, Ag@PL-KLPs exhibited enhanced bacteriostatic and bactericidal properties against antibiotic-resistant bacteria (ARB), including both Gram-negative and Gram-positive strains, at concentrations of 250 μg/mL. Leveraging biomass-derived lignin and this cost-effective, one-step green synthesis approach offers a sustainable method for avoiding antibiotic overuse and environmental contamination.

The beetle fauna (Coleoptera) of the arctic mainland of Norway

This paper is the first attempt to summarize the beetles present in the arctic region of the mainland of Norway since 1946. In 1995 and 1998 beetles were collected by pitfall traps and other methods in Vardø municipality on the Varanger Peninsula in Finnmark county. This area is part of the small section of the Norwegian mainland that belongs to the southern arctic vegetation zone. A total number of 159 species from 18 families were recorded, including earlier findings by others. This probably covers a substantial part of the beetle fauna present in this marginal environment. Rove beetles (Staphylinidae) are the most abundant group and made up 46% of the recorded species, whereas diving beetles (Dytiscidae) and ground beetles (Carabidae) made up 16% and 15% of the species, respectively. Considering the regional distribution of these species in Norway, 8% are found only in northern Norway (Nordland/Troms/Finnmark), 19% have mainly an alpine distribution, 27% are mainly restricted to boreal areas, whereas 53% are common all over Norway. Diacheila polita and Simplocaria elongata belong to a characteristic arctic beetle community, and the present records of these two species are the only ones from Scandinavia. The study indicates that there are very few beetles that belong entirely to the arctic mainland of Norway.

Preparation of artificial humic acid from corn straw and its high-efficiency adsorption on norfloxacin

In this study, the biomass artificial humic acid (AHA) with efficient adsorption performance for norfloxacin (NOR) was prepared by ultrasonic-assisted acid-alkaline combined hydrothermal method with corn straw as raw material. Characterization analysis showed that AHA was a typical amorphous structure, and the oxygen content of AHA prepared by ultrasonic-assisted hydrothermal method was obviously improved compared with that without ultrasonic-assisted method. The saturated adsorption capacity of AHA was 551.53 mg/g, which was higher than that of other reported materials, such high-efficiency adsorption is due to the abundant oxygen-containing groups (–OH, –C=O, etc.) in AHA, which were functional groups that can be π-π stacked, hydrogen bonded and electrostatically bonded with NOR. It had good selective adsorption for NOR, with less interference from acidity of environmental water, coexisting inorganic ions and common antibiotics. When it was applied to adsorb NOR with concentration of 10.0 mg/L in simulated water prepared by environmental water, the highest removal rate was 91%, which indicated that AHA could not only remove all the NOR in the polluted water with complex components at the highest concentration of 630 μg/L, but also its adsorption capacity far exceeded the pollution amount. The research had important practical significance in realizing the recycling of agricultural wastes and the removal of environmental pollution.

Targeted Defect Repair and Multi-functional Interface Construction for the Direct Regeneration of Spent LiFePO4 Cathodes.

Due to the low economic benefits and environmental pollution of traditional recycling methods, the disposal of spent LiFePO4 (SLFP) presents a significant challenge. The capacity fade of SLFP cathode is primarily caused by lithium loss and formation of a Fe (III) phase. Herein, a synergistic repair effect is proposed to achieve defect repair and multi-functional interface construction for the direct regeneration of SLFP. Tannic acid (TA) forms a compact coating precursor for a carbon layer on SLFP with abundant functional groups and creates a mildly acidic environment to enhance the reducibility of thiourea (TU). Therefore, TU reduces Fe (III) to Fe (II) and repairs Li-Fe anti-site defects of SLFP, while at the same time acting as a source of N/S-doping elements for the carbon layer at a lower temperature (140°C). The multi-functional carbon layer improves the properties of the regenerated LiFePO4 (RLFP) due to the enhanced conductivity, structure maintenance and protection, and the improved kinetics of Li+ transport. Furthermore, the Fe─O and P─O bonds are strengthened, further enhancing the structural stability of the RLFP. Consequently, the RLFP demonstrates outstanding performance with a discharge capacity of 141.3 mAh g-1 and capacity retention of 72% after 1000 cycles at 1C.

Preparation and Catalytic Properties of Gold Single-Atomand Cluster Catalysts Utilizing Nanoparticulate Mg-Al Layered Double Hydroxides.

Au single atoms and clusters were stabilized on Mg-Al layered double hydroxide nanoparticles (LDH NPs), and the obtained Au@LDH NPs were supported on SiO2 and CeO2. After hydrogen reduction, Au single atoms were found together with Au clusters on LDH/SiO2. In contrast to Au single-atomcatalysts which are deposited in metal vacancies of oxide supports, the LDH NPs stabilize small Au species despite the absence of metal vacancies. The obtained Au(0)@LDH/SiO2 catalyzed aerobic oxidation of alcohols, and Au single atoms maintained after the reaction. Given that only Au NPs were observed on bulk LDH, the abundant surface OH group of LDH NPs would contribute to stabilize Au, resulting in higher activity than Au/LDH-bulk. After calcination to transform LDH to mixed metal oxide (MMO), the obtained Au(0)@MMO/SiO2 also exhibited high catalytic activity. Moreover, Au(0)@LDH/CeO2 exhibited higher activity and excellent selectivity for hydrogenation of 4-nitrostyrene to 4-aminostyrene than conventional Au catalysts such as Au/CeO2 and Au/TiO2 even though onlyAu NPs were present. We demonstrated that Au size can be minimized using LDH NPs, exhibiting in high catalytic performance. The basic surface OH groups of LDH would be also beneficialfor deprotonation of alcohols and heterolytic H2dissociation in the catalytic reactions.

Rich-N highly branched COF loaded with imidazolyl ionic liquids for highly efficient catalysis of CO2 conversion under atmospheric pressure

The highly loaded ionic active centers and carbon dioxide (CO2) affinity sites play pivotal roles in catalyzing the gas-solid-liquid three-phase reaction in CO2 cycloaddition. In this study, a kind of rich-N highly branched Covalent organic framework loaded with imidazolyl ionic liquids (DhaTat-COF-IL) was synthesized through a nucleophilic substitution reaction, which bridged the highly loaded imidazolyl ionic liquids (Im-IL) active centers (20.72 %) and strong CO2-philic sites, efficiently promoting the in-situ of CO2 conversion at catalyst interface. The rich-N highly branched Covalent organic framework (DhaTat-COF) benefits from its abundant CO2-philic groups (imine and triazine groups) and microporous properties, exhibiting excellent CO2 enrichment capacity, designed as a porous crystalline material for anchoring high active Im-IL. The resultant DhaTat-COF-IL achieved a quantitative yield of 95 % (selectivity > 99 %) in converting epichlorohydrin (ECH) under ambient pressure at 80 ℃, with a turnover frequency (TOF) value reaching 1582 h⁻¹ at 120 ℃. Additionally, yields of ≥ 94 % were obtained for various terminal-substituted epoxides. Density Functional Theory (DFT) analysis reveals a synergistic effect between −CH and Br− in the DhaTat-COF-IL during catalytic cycling. This work provides valuable insights into the targeted design and performance optimization of Im-IL-grafted COF-based catalysts, emphasizing high efficiency and sustainability in CO₂ conversion.

Gut bacteria of lepidopteran herbivores facilitate digestion of plant toxins

Lepidopterans commonly feed on plant material, being the most significant insect herbivores in nature. Despite plant resistance to herbivory, such as producing toxic secondary metabolites, herbivores have developed mechanisms encoded in their genomes to tolerate or detoxify plant defensive compounds. Recent studies also highlight the role of gut microbiota in mediating detoxification in herbivores; however, convincing evidence supporting the significant contribution of gut symbionts is rare in Lepidoptera. Here, we show that the growth of various lepidopteran species was inhibited by a mulberry-derived secondary metabolite, 1-deoxynojirimycin (DNJ); as expected, the specialist silkworm Bombyx mori grew well, but interestingly, gut microbiota of early-instar silkworms was affected by the DNJ level, and several bacterial species responded positively to enriched DNJ. Among these, a bacterial strain isolated from the silkworm gut (Pseudomonas fulva ZJU1) can degrade and utilize DNJ as the sole energy source, and after inoculation into nonspecialists (e.g., beet armyworm Spodoptera exigua), P. fulva ZJU1 increased host resistance to DNJ and significantly promoted growth. We used genomic and transcriptomic analyses to identify genes potentially involved in DNJ degradation, and CRISPR-Cas9-mediated mutagenesis verified the function of ilvB, a key binding protein, in metabolizing DNJ. Furthermore, the ilvB deletion mutant, exhibiting normal bacterial growth, could no longer enhance nonspecialist performance, supporting a role in DNJ degradation in vivo. Therefore, our study demonstrated causality between the gut microbiome and detoxification of plant chemical defense in Lepidoptera, facilitating a mechanistic understanding of host-microbe relationships across this complex, abundant insect group.

Co-based carbon material as CYP3A4-like nanozyme with both biocatalytic activity and inhibition behaviors

Up to now, the biocatalytic activity of nanozymes has been extensively studied, while little research focus on their inhibitory behaviors. Here, Co-based carbon material (Co-DMOF) containing abundant carboxylic acid groups was prepared, with defects introduced by COx escape during pyrolysis to achieve controllable activity. As a result, Co-DMOF exhibited biocatalytic activity similar to cytochrome P450 3A4 (CYP3A4) in the metabolism of 1,4-Dihydropyridine (1,4-DHP, a calcium channel blocker). Excitingly, studies on IC50 and drug-drug interaction (DDI) suggested that Co-DMOF had similar inhibitory behaviors to CYP3A4. Moreover, Co-DMOF displayed excellent stability even under high temperature (100 °C), organic solvents, and a wide range of pH (4–9). Additionally, it can be reused for at least 7 times with only slight loss of activity. Therefore, Co-DMOF has great potential to become a low-cost alternative to CYP3A4 for drug dosage guideline, drug metabolism and DDI. This work provides more possibilities for expanding the CYP3A4-like nanozyme library.

Carbon Dots and Their Films with Narrow Full Width at Half Maximum Orange Emission.

To obtain carbon dots (CDs) with narrow full width at half maximum (FWHM) and long-wavelength emission, carbon sources with high conjugate sizes and abundant functional groups can be employed to synthesize CDs. In this study, orange-emissive carbon dots (OCDs) were synthesized with phloroglucinol and rhodamine B as precursors. When the molar ratio of them was 30:1, and ethanol was served as the solvent, OCDs with optimized emission wavelength at approximately 580 nm, an FWHM of 30 nm, and a quantum yield (QY) of 27.31% were obtained. Subsequently, the OCDs were incorporated into polyvinyl alcohol (PVA) to fabricate solid-state OCD/PVA fluorescent films, which exhibited an FWHM of 47 nm. The PVA matrix facilitated the dispersion of OCDs, thereby suppressing non-radiative energy transfer among the OCDs and enhancing luminescence efficiency. Consequently, compared with OCDs, the OCD/PVA film exhibited significant luminescent enhancement, and the QY of the composite film was increased to 84.74%. Moreover, OCD/PVA film showed good transmittance and thermal stability. This research offers a solid theoretical and experimental foundation for the potential applications of CDs in the field of solid-state lighting.

Governance, institutional quality and economic complexity in selected African countries

AbstractNew economic thinking speculates that the diversification and sophistication of economic capabilities/structures is key in explaining why African countries lag in development behind the rest of the world. We question the extent to which non-traditional growth factors such as governance and institutional quality are related to economic complexity for 35 African countries. We estimate panel GMM regressions using 8 different measures of governance/institutional quality for both linear and kinked regressions using annual data collected between 1996 and 2021. The baseline estimates reveal a positive linear relationship between most measures of governance and institutional quality and economic complexity. Our sensitivity analysis further show that institutions/governance have stronger relationship with economic complexity in the post-global financial crisis era. Moreover, nonlinear or kinked relationships emerge once the data is segregated into different income and resource abundant groups. Altogether, our findings of a nonlinear relationship between institutions/governance and economic complexity are novel to the literature and offer unique insights on how African policymakers can use governance/institutions for improving the complexity of production processes.

Garlic Peel-Based Biochar Prepared under Weak Carbonation Conditions for Efficient Removal of Methylene Blue from Wastewater

Background: Due to it containing cellulose, hemicellulose, and lignin with abundant specific functional groups which could interact with organic dyes, garlic peel (GP) might be used as an efficient biosorbent. The aim of this study is to evaluate the adsorption performances of GP-based bio-adsorbents and obtain optimum preparation conditions. Methods: GP-based bio-adsorbents were prepared by thermal pyrolysis under different temperatures (150–400 °C). The morphologies, chemical states, and surface functional groups of the adsorbents were analyzed by X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). Batch experiments were conducted to investigate the adsorption of methylene blue (MB) under various conditions, including contact time, contact temperature, initial dye concentration, and initial pH value. The equilibrium adsorption data were fitted to different kinetic and isothermal models, and the adsorption thermodynamics were also calculated. Significant Findings: The physicochemical properties of the GP-based bio-adsorbents were primarily dominated by the pyrolysis temperature, because their morphologies and surface functional groups of GP-based bio-adsorbents significantly varied with the changes in pyrolysis temperature. The adsorption capacity of GP materials for MB decreased as the pyrolysis temperature increased. At an initial concentration of 50.00 mg L−1, GP150 possessed a higher adsorption capacity of 167.74 mg g−1 toward MB. The possible adsorbate–adsorbent interactions, including electrostatic attraction, hydrogen bonding, and π-π stacking, were recognized. After 10 consecutive adsorption–desorption cycles, GP150 maintained a high removal rate (88%) for MB, demonstrating its excellent adsorption performance, good reusability, and potential application in the treatment of MB-contaminated water.

Exploring the constituents and thermal characteristics of miscanthus floridulus for biomass composites

Miscanthus floridulus (MF) possesses notable attributes including high photosynthetic efficiency, rapid growth, robust adaptability, and substantial biomass yield. It is widely researched in fields such as genetics, special materials, bioenergy, and ecological protection. However, the research on the addition of MF for biomass composites remains limited due to the absence of comprehensive analysis concerning the composition, internal molecular structure, and properties of MF. A thorough exploration of the fundamental properties of MF has the potential to broaden their advantages and facilitate the advancement of biomass. This investigation delves into the structural characterization and properties of MF, focusing on its stems, leaves, and tassels. Firstly, the primary constituents of MF comprise cellulose, hemicellulose, and lignin. Cellulose predominates in the stem, exhibiting the highest crystallinity, while lignin content peaks in the tassel with the lowest crystallinity. The leaf falls between these extremes in terms of crystallinity. Secondly, carbon and oxygen elements constitute over 95 % of MF's primary components, alongside trace elements like phosphorus and sulfur. Additionally, chemical structure of MF features abundant characteristic functional groups such as hydroxyl, carbonyl, and benzene rings. Studies indicate that samples with low hemicellulose and high lignin content demonstrate superior thermal stability. Consequently, the stem of MF exhibits optimal low-temperature thermal stability, while the tassel excels in high-temperature conditions. Finally, the data highlights a significant influence in the mechanical properties of polylactic acid materials upon the addition of MF. With a 5 % addition of MF, the tensile modulus and flexural strength of the PLA composite reached their optimal values of 933.91 MPa and 55.28±8.77 MPa, respectively. This research establishes a theoretical groundwork for integrating MF into biomass composite materials.

Serotonin suppresses intraspecific aggression in an agrobiont spider, Pardosa pseudoannulata, without affecting predation on insects.

Spiders are an abundant group of natural enemies preying on insect pests in agroecosystem. But their potential in biological control has not been fully realized due to difficult mass production. One hindrance is the intense intraspecific aggression in spiders. Neurotransmitters such as serotonin play important roles in modulating aggression. Here, we investigated the regulatory function of serotonin (5-hydroxytryptamine [5-HT]) signaling in the intraspecific aggression in a wandering spider Pardosa pseudoannulata (Araneae, Lycosidae). The aggression was quantified with 5 escalated aggression behaviors as approach, chasing, lunging, boxing, and biting. Virgin (VG) females exhibited higher aggression levels but less 5-HT content than post-reproductive (PR) females. Systemic increase of 5-HT via 5-HT injection decreased aggression, while decrease of 5-HT via RNA interference (RNAi) of the tryptophan hydroxylase gene, increased aggression. The involvement of the four 5-HT receptors were determined via individual or combined RNAi. Co-RNAi of the three 5-HT1 genes increased overall aggression with decreased incidents of approach, chasing, lunging, and increased biting. RNAi of 5-HT1B decreased approach and increased biting, whereas RNAi of 5-HT1A or 5-HT1C did not affect aggression. RNAi of 5-HT7 decreased approach only. Therefore, different 5-HT receptor types contribute to different aspects of the inhibitory effects of 5-HT on aggression and provide several pharmacological targets for manipulating spider aggression. 5-HT injection did not affect spiders' predation on their insect prey, the brown planthopper Nilaparvata lugens. The findings reveal 1 neuronal mechanism regulating intraspecific aggression in spiders and provide an insight in developing aggression suppression strategies for spider mass rearing.

The first complete genome of Robbsia andropogonis reveals its arsenal of virulence system causing leaf spot disease of areca palm

Robbsia andropogonis is one of the most destructive leaf spot disease pathogens of numerous host plants and causes heavy economic damage. In the present study, the complete genome of R. andropogonis strain BLB1, causing the leaf spot disease of areca palm, was generated using a hybrid method combining ONT PromethION long reads and BGISEQ-500 short reads. The resulting genome consists of seven replicons totaling 6,828,120 bp, and 5,808 genes were annotated, including 788 virulence-related genes. Function analysis showed that genes involved in metabolism were the most abundant group. Impressively, the bacteria were well-equipped with four, two, and four sets of type three, four, and six secretion systems, respectively, highlighting the virulence features of R. andropogonis BLB1. As the first complete genome sequence of the species of genus Robbsia, the BLB1 genome provides a solid foundation for investigation of mechanisms underlying the pathogen virulence and disease control, and will promote further discovery and characterization of the genus Robbsia.

Comparative study between low and high-water quality and the zooplankton community of the Niger river, Niger

Seasonal variations in zooplankton abundance, diversity and the physicochemical properties of the Niger River were studied during 2018 and 2019.The aim of this study is to carry out a comparative study of water quality and the zooplankton community in the River Niger between the high-water period (February 2019) and the low-water period (April 2018). To do this, three water samples were taken at each period and at each station, in order to determine the physico-chemical parameters and then identify the zooplankton. Qualitative analysis of zooplankton revealed the presence of 48 taxa belonging to three main taxonomic groups: Rotifera, Cladocera and Copepoda. During low-water periods, the most frequent taxa were rotifers (74.89%), followed by copepods and copepodites (20.17%) and cladocera (4.93%). In contrast to high-water sampling, copepods and copepodites are the most important (53.2%), followed by rotifers (32.63%) and cladocerans (14.09%).Rotifers are the most abundant group and the most resistant to changes in environmental variables. The physicochemical parameters that significantly influence zooplankton populations are pH, dissolved oxygen, temperature, total phosphorus, silica and chlorophyll-a.

Nanofibrous Covalent Organic Frameworks as the Cathode, Separator, and Anode for Batteries with High Energy Density and Ultrafast-Charging Performance.

To meet the demand for longer driving ranges and shorter charging times of power equipment in electric vehicles, engineering fast-charging batteries with exceptional capacity and extended lifespan is highly desired. In this work, we have developed a stable ultrafast-charging and high-energy-density all-nanofibrous covalent organic framework (COF) battery (ANCB) by designing a series of imine-based nanofibrous COFs for the cathode, separator, and anode by Schiff-base reactions. Hierarchical porous structures enabled by nanofibrous COFs were constructed for enhanced kinetics. Rational chemical structures have been designed for the cathode, separator, and anode materials, respectively. A nanofibrous COF (AA-COF) with bipolarization active sites and a wider layer spacing has been designed using a triphenylamine group for the cathode to achieve high voltage limits with fast mass transport. For the anode, a nanofibrous COF (TT-COF) with abundant polar groups, active sites, and homogenized Li+ flux based on imine, triazine, and benzene has been synthesized to ensure stable fast-charging performance. As for the separator, a COF-based electrospun polyacrylonitrile (PAN) composite nanofibrous separator (BB-COF/PAN) with hierarchical pores and high-temperature stability has been prepared to take up more electrolyte, promote mass transport, and enable as high-temperature operation as possible. The as-assembled ANCB delivers a high energy density of 517 Wh kg-1, a high power density of 9771 W kg-1 with only 56 s of ultrafast-charging time, and high-temperature operational potential, accompanied by a 0.56% capacity fading rate per cycle at 5 A g-1 and 100 °C. This ANCB features an ultralong lifespan and distinguished ultrafast-charging performance, making it a promising candidate for powering equipment in electric vehicles.

Cationic Covalent Organic Framework-Modified Polypropylene Separator for High-Performance Lithium Metal Batteries.

As an important component of lithium batteries, the wettability and thermal stability of the separator play a significant role in cell performance. Despite the availability of numerous commercial separators, issues such as low ion selectivity and poor thermal stability continue to limit the efficiency and reliability of the batteries. Herein, two cationic covalent organic frameworks (Br-COF and TFSI-COF) with abundant imidazole cationic groups were designed to modify commercial polypropylene (PP) separators. The strong lithium-ion affinity of the cationic COF enables the effective dissociation of lithium salt ion clusters, simplifying the solvent structure of lithium ions to promote lithium ions transport. Additionally, solvent anions can be anchored to the cationic COF by electrostatic interactions, reducing side reactions on the lithium metal anode surface to form a favorable SEI layer, which can effectively inhibit the growth of lithium dendrites. The rapid dissociation of anions in lithium salts with some organic solvents and cationic COFs was revealed by a molecular dynamics simulation. A LiF-rich SEI layer on the lithium metal anode surface was formed, which can speed up Li+ transport at interfaces, leading to consistent lithium deposition and outstanding battery performance. The ordered porous structure of the cationic COF provides interconnected and continuous channels, improving the wettability between the liquid electrolyte and separators, which is conducive to ion transport. When paired with a LiFePO4 cathode and electrolyte (1.0 M LiTFSI in DEC: EC: DMC = 1:1:1), the LiFePO4/TFSI-COF@PP/Li cell demonstrates a prominent cycling capacity of 148.0 mAh g-1 at 0.5 C with a Coulombic efficiency of 98.0% in the first cycle, and the capacity retention is 82.0% after 100 cycles, showing good cycling stability. Thus, this investigation provides inspiration for the expansion of cationic COF-modified separators for next-generation lithium metal batteries.