Large Surface Area Research Articles

Pitch-derived Multifunctional Carbon and Bimetallic Sulfide Composite Electrodes for Aqueous Energy Storage

With the rapid development of society, people's requirements for the ecological environment have become increasingly stringent. Coal tar pitch is a by-product of coal processing, which has low value and serious pollution. Under the circumstance, coal tar pitch-derived carbon materials (CTPC) was successfully prepared with the interconnected three-dimensional porous structure, and then NiCo2S4/CTPC composite materials were obtained. CTPC exhibits high conductivity (15.59 S m-1), large specific surface area (614.9 m2 g-1), and rich porous structure of connected carbon nanosheets. Among composite materials with different CTPC contents, the NiCo2S4/CTPC material exhibits the highest specific capacities under the same conditions. Notably, the capacity of NiCo2S4/CTPC is up to 689.6F·g-1 at 1A·g-1. The assembled asymmetrical supercapacitor (NiCo2S4/CTPC//CTPC) exhibits a long cyclic stability of 4000 cycles at 4A·g-1. When the power density is 3616.44Wkg-1, the energy density is as high as 22Whkg-1. Meanwhile, NiCo2S4/CTPC was used as cathode material to assemble an alkaline battery (NiCo2S4/CTPC//Bi2O3) and then its electrochemical properties were systematically analyzed.

Waste wood tar based porous carbon electrodes for supercapacitors with excellent performances through condensation cross-linking modification

Wood tar is an unavoidable by-product during a slow-pyrolysis process of biomass, which is usually discarded as a waste and results in environment pollution. Recently, wood tar has been used as a starting material for carbon electrodes because of its thermoplasticity and high carbon content. However, wood tar is mainly composed of various light phenolic molecules, which usually leads to a low carbonization yield after carbonization and an inferior electrochemical performance after activation. In this work, in order to improve the carbonization rate and electrochemical performance of these materials, wood tar was first condensed and crosslinked with formaldehyde and urea via a condensation reaction to produce condensed macromolecular resins, which were then carbonized at 550°C and activated with KOH at 800°C to prepare high-performance nitrogen-doped carbon electrodes for supercapacitors. The samples possess high carbonization yield, large specific surface area (3515.1 m2g-1) and moderate nitrogen content (1.11%). The high-performance carbon electrodes fabricated by this method achieves a high capacitance of 437.8Fg-1 (6M KOH electrolyte) at 1A/g-1. The assembled supercapacitor has an energy density of 13.41Whkg-1 at a power density of 124.93Wkg-1. And the capacitance retention was essentially 100% after 10000 cycles at 5Ag-1. The study presents an innovative strategy for the production of porous carbon for supercapacitors using wood tar and improves carbonization yield via condensation cross-linking modification.

Cerium oxide anchored free-standing silicon nanowires as potential anode materials for electrochemical supercapacitor

Free-standing 1 D silicon nanowires (Si-NWs) were synthesized by the metal-assisted chemical etching (MACE) technique and subsequently decorated with cerium oxide (CeO2) nanoparticles synthesized by a solvothermal process. Morphological characterization of the CeO2/Si-NWs nanocomposite validates the homogeneous growth of spherical CeO2 nanoparticles around the Si-NWs, while the N2 adsorption-desorption study indicates a large specific surface area (SSA) and the presence of ink-bottle-shaped pores possessing a significant portion of mesopores. This CeO2/Si-NWs composite electrode demonstrates excellent electrochemical behavior, attaining an impressive specific capacitance (Csp) of 830 F g–1 at a current density of 1.0 A g–1, the anodic material delivers an energy density of 19 Wh kg–1 at a power density of 2.5 kW kg–1, along with exceptional durability, retaining 94% of its capacitance after 2000 charge-discharge cycles. The results show that the CeO2/Si-NWs composite electrode has great potential as an emerging category of anodic material for supercapacitors.

High-valence molybdenum doped Ni(OH)2 nanosheets enhancing hydrogen production and glycerol oxidation to formic acid

The glycerol electrooxidation reaction (GEOR) replacing the anodic oxygen evolution reaction (OER) in water splitting is an effective strategy for hydrogen production and high value-added chemicals in an energy-saving manner in recent years. The key to this technology is to design efficient electrocatalysts to enhance the GEOR activity and effectively regulate product selectivity. Herein, a high-valence metal Mo-doped Ni(OH)2 nanosheets (Mo-Ni(OH)2/NF) was in-situ grown on the nickel foam (NF) for enhancing hydrogen production and glycerol oxidation to formic acid. The Mo-Ni(OH)2/NF exhibits unique network nanosheet morphology with large specific surface area and electron conduction, which is beneficial for exposing more active sites for reactions and promoting the mass transfer of electrolytes and products. The synergistic interaction between Mo and Ni facilitates the regulation of the electronic structure of the catalyst, and accelerates the reaction kinetics. When the Mo-Ni(OH)2/NF−1 is assembled into an overall glycerol-water splitting system, a low voltage of only 1.36 V is required to achieve a current density of 10 mA cm−2, which is 290 mV lower than the cell voltage needed for traditional water splitting under the same conditions.

An ultra-sensitive photoelectrochemical sensor based on ZnIn2S4/rGO nanocomposites for detection of oxytetracycline in water, food and organism samples

Residues of oxytetracycline (OTC) may cause the resistance of bacteria, and even have serious impacts on the ecosystem through the food chain. It was important to monitor OTC of low concentration for preserving human health and environmental safety. In this work, reduced graphene oxide doped ZnIn2S4 (ZnIn2S4/rGO) nanocomposites were composited by straightforward one-step solvothermal reaction. The nanocomposites had superior light absorption property and stable photocurrent response. Because rGO not only had a large specific surface area for immobilizing abundant ZnIn2S4, but also accelerated charge transfer as an electron mediator. Additionally, the oxidation potential of OTC was more negative than the valence band potential of ZnIn2S4. So, OTC can be oxidized by photogenerated holes of the ZnIn2S4 as electron donors, leading significant increase of photocurrent response. Based on this, a “signal-on” photoelectrochemical (PEC) sensor was constructed to achieve ultra-sensitive and specific detection of OTC. This sensor exhibited a wide detection range from 100 fM to 50 nM, an extremely low detection limit (61.2 fM) and excellent analytical performance in actual water, food and biological samples.

Efficient hybrid supercapacitor performance enabled by large surface area of 2D mesoporous zinc sulfide nano-sheets synthesized via microwaves

Researchers have shown a significant amount of interest in synthesizing high energy density supercapacitors using a simplest, fast, and low cost technique. The electrochemical performance of supercapacitors can be impacted by the surface area and morphology of electrode materials. A one-step, rapid, and economical microwave-assisted synthesis technique was employed in this study in order to prepare mesoporous nanosheets that are composed of zinc sulfide. The ZnS-based nanosheets possess a large surface area of ∼120 m2g−1 and a mesoporous structure of a pore diameter of <22 nm, which offers numerous electrochemical active sites and it facilitates an excellent super capacitive performance, which is due to its shortened ion/electron diffusion path. The prepared mesoporous nanosheets exhibit a higher specific capacitance of 2282 Fg−1 (1037 C/g) when subjected to a 1 Ag−1 in 2 M KOH aqueous electrolyte with high capability rate. The fabricated device exhibits a high specific capacitance of 252.5 Fg−1 (140 C/g) at 1 Ag−1, which produces a remarkable energy density of about 90 Whkg−1 at 800 Wkg−1 value of power density and an excellent retention of ∼95 % after 10,000 cycles at 6 Ag−1. This study designed an instant, straightforward and low-cost approach to fabricate ZnS nanosheet electrode materials that exhibit excellent performance for supercapacitor applications.

The beneficial impact of MXene on the electrochemical performance of graphene quantum dots for dopamine detection

Considerable advancements in nanocomposite design have enabled the development of electrochemical sensors with promising features such as remarkable electrocatalytic activities, high electrical conductivity, and effective surface area. For instance, designing nanocomposites using 2D MXenes and 0D nanomaterials can be beneficial to combine the advantages of both individual constituents and enhance the device’s final performance. Herein, we developed a nanocomposite based on Ti3C2 MXene to tailor the electrochemical properties of graphene quantum dots (GQDs) for sensing applications. Specifically, the electrochemical properties of different Ti3C2:GQDs ratios were evaluated by cyclic voltammetry and electrochemical impedance spectroscopy. Under optimized conditions, the nanocomposite-based sensor showed a linear response to dopamine (DA) in the concentration range of 40 – 400 μM and a limit of detection of 1.8 μM (S/N = 3). Moreover, real sample analysis indicated that spiked DA could be determined accurately by Ti3C2/GQDs/GCE in human urine and sweat samples. The improved sensing performance was attributed to the combined effect of the large surface area of GQDs and the electrical conductivity of MXene, which approach can be extended to develop other electrochemical sensors.

Optimization of conventional-zeolite-synthesis from waste pumice for water adsorption

This research reports conventionally-synthesized-zeolites with comparatively large surface area (SSA) and water-uptake prepared solely from waste-pumice. Notably, the synthesis process avoided using additional commercial raw materials, organic templates, and high temperatures, so that the process was less costly and ecofriendly. To optimize the process, the synthesis time was varied, and the mixture of the raw material and alkaline solution was stirred for 12 h. The zeolite mother liquor was also recycled. Water adsorption experiments were carried out using gravimetric measurements. The Na-P1-rich zeolite product with an optimal water uptake of 0.256 g/g was synthesized after 48 h of hydrothermal activation (H). On the other hand, the product’s optimal SSA of 186 m2/g was achieved after 36H under similar conditions (rich in faujasite). Adsorption isotherms showed that water uptake increased with activation time and with the inclusion of mother liquor recycling. Furthermore, recycling resulted in a product with enhanced SSA compared to its precursor. Un-recycled products exhibited relatively high-water uptake both at low and high relative-pressure, while the recycled product had a high uptake at high relative pressure. All products could be used in adsorption heat pump (AHP) applications (air conditioning) suited for high relative humidity (RH) environments. However, high-synthesis-time non-recycled products could also work for low RH AHP applications.

A Critical Appraisal of Functionalized 2-Dimensional Carbon-Based Nanomaterials for Drug Delivery Applications.

The development of an efficient and innovative drug delivery system is essential to improve the pharmacological parameters of the medicinal compound or drug. The technique or manner used to improve the pharmacological parameters plays a crucial role in the delivery system. In the current scenario, various drug delivery systems are available where nanotechnology has firmly established itself in the field of drug delivery. One of the most prevalent elements is carbon with its allotropic modifications such as graphene-based nanomaterials, carbon nanotubes, carbon dots, and carbon fullerenes, these nanomaterials offer notable physiochemical and biochemical properties for the delivery applications due to their smaller size, surface area, and ability to interact with the cells or tissues. The exceptional physicochemical properties of carbon-based 2D nanomaterials, such as graphene and carbon nanotubes, make them attractive candidates for drug delivery systems. These nanomaterials offer a large surface area, high drug loading capacity, and tunable surface chemistry, enabling efficient encapsulation, controlled release, and targeted delivery of therapeutic agents. These properties of the nanomaterials can be exploited for drug delivery applications, like assisting the target delivery of drugs and aiding combination molecular imaging. This review emphasizes on the recent patents on 2D carbon-based nanomaterial and their role in drug delivery systems. Carbon-based 2D nanomaterials present a wealth of opportunities for advanced drug delivery systems. Their exceptional properties and versatility offers great potential in improving therapeutic efficacy, minimizing side effects, and enabling personalized medicine and the recent patents on 2D nanomaterial.

Nanomolar level detection of phosphodiesterase 5 inhibitor drug tadalafil based on halide perovskite@HNTs nanocomposite electrode

As halide perovskites have taken a central role in the evolution of semiconductor materials, they are setting new standards for performance and revolutionizing the energy sectors. Unfortunately, little light is shed on the material's electrochemical sensing capabilities. This work reports the synthesis and characterization of a novel double halide perovskite Cs2CaSnCl6 (HDP) integrated with halloysite nanotubes (HNTs) for the electrochemical detection of Tadalafil (TAD). HDP@HNTs nanocomposite is synthesized using a simple solvothermal method and is characterized using various techniques like SEM, TEM, UV-visible, FT-IR, TGA/DTA, XRD and BET analysis. The results obtained from these characterizations confirmed the successful formation of the nanocomposite, revealed the material's endurance to high temperatures and the availability of a large surface area for reaction. Electrochemical characterization techniques like cyclic voltammetry (CV) and linear sweep voltammetry (LSV) demonstrated a linear correlation with the concentrations of TAD. Computational analysis of the TAD structure optimization, molecular electrostatic potential (MEP) of TAD and calculations regarding the HOMO-LUMO molecular orbitals are all carried out using the DFT/B3LYP method. The HDP@HNTs sensor is capable of achieving the lowest detection limit of 1.68 nM and the limit of quantification of 5.09 nM. The material showcased a remarkable sensitivity of 0.0104 µA nM-1 cm-2 from all the electrochemical parameters. Its reliability and stable performance even in the presence of real samples makes it a promising material for sensing applications. Thus, the reported framework contributes to the advancement in the development of sensors and enhanced healthcare outcomes.

Unveiling a paradigm shift in supercapacitor dynamics: γ-Al2O3-infused ZnO nanorods with redox-active K4Fe(CN)6 alkaline electrolytes

The rapid charge-discharge capability, high specific energy, and extended cyclic stability required of supercapacitors (SCs) depend heavily on electrode materials with exceptional electrical conductivity, large surface area, and tunable morphology. In this study, we present a novel approach to enhance the electrochemical capabilities of zinc oxide (ZnO) via γ-Al2O3 doping. The material’s inherent stability, porosity, and large surface area are investigated through appropriate techniques. Results demonstrate that the hydrothermal technique, incorporating γ-Al2O3 into ZnO can transform ZnO nanoflakes into significantly elongated nanorods. The electrochemical evaluation in a redox-active electrolyte comprising 2 M KOH and 0.2 M potassium ferrocyanide (PFC) reveals a remarkable specific capacity of 267 C/g, at a current density of 3 A/g. The fabricated asymmetric coin cell (ACC) reveals an energy density of 23.52 Wh/kg, a power density of 1.5 kW/kg at 3 A/g, a coulombic efficiency (CE) of 98.9 %, and a capacity retention of 88.9 % after 9000 charge-discharge cycles. These findings highlight the significant potential of γ-Al2O3-doped ZnO as a superior electrode material for SCs. Moreover, this work underscores the effectiveness of PFC in reducing charge transfer resistance and promoting diffusion-controlled charge storage mechanisms, thereby enhancing the overall electrochemical performance.

Increased adsorption of diflubenzuron onto polylactic acid microplastics after ultraviolet weathering can increase acute toxicity in the water flea (Daphnia magna)

The ultraviolet (UV) weathering of microplastics (MPs) can lead to higher adsorption of harmful contaminants, thus increasing the potential risks of their combined effects. Because biodegradable MPs are more susceptible to UV weathering than conventional MPs, concerns have arisen about their ecological toxicity and environmental impact. Therefore, this study investigated the mechanisms associated with the adsorption of the pesticide diflubenzuron (DFB) onto polylactic acid (PLA) MP particles after UV weathering and the acute effects (48 h) of their combination on the water flea Daphnia magna. These effects were also compared with those of the conventional MP polyethylene terephthalate (PET). UV weathering led to a greater number of cracks and pores in the PLA particles compared to PET, as well as a higher number of oxygen-based functional groups and a larger surface area. These surface changes in UV-weathered PLA particles promoted higher DFB adsorption, which in turn led to stronger acute toxicity for D. magna compared to UV-weathered PET particles. Combined exposure to 25 ng L−1 DFB and both UV-weathered and non-UV-weathered MPs significantly reduced the chitin content in D. magna, while combined exposure to 12.5 ng L−1 DFB and the MPs increased the chitin content. This effect was more pronounced for UV-weathered PLA exposure than UV-weathered PET exposure. The expression of the genes for chitinase and endocrine glycoprotein, both of which are closely associated with the toxic mechanisms of DFB, showed no significant changes with the combination of 25 ng L−1 DFB and non-UV-weathered MPs but were significantly downregulated after UV weathering. Overall, the UV weathering of PLA promoted the adsorption of DFB, thus increasing its toxic effects. Our findings demonstrate the importance of considering the effects of UV weathering and interactions with environmental pollutants when assessing the ecological risks associated with biodegradable MPs.

Adsorption of fulvic acid on clay subfractions isolated from mineral horizons of peat-podzol-gley soil

We studied the adsorption of fulvic acid (FA) obtained from the H horizon of peaty-podzolic-gleyic soil on sludge subfractions isolated from the ELG and Ecng horizons of the same soil: 0–0.2 µm (I), 0.2–0.06 µm (II) , 0.06–0.02 µm (III) and &lt;0.02 µm (IV). It has been established that, in terms of unit mass, more FAs are sorbed by subfractions III and IV, which have a larger surface area. In terms of per unit surface area, an inverse relationship is observed: the larger the fraction, the more FA is sorbed on it. All subfractions of sludge isolated from both horizons sorb predominantly hydrophobic components of FA, but in the finer subfractions, which practically do not contain kaolinite, the contribution of hydrophilic components in total sorption increases. Under the experimental conditions, FA molecules with a molecular weight of 20 kDa were not adsorbed in micropores with an average size of ≈ 3.7 nm. The main mechanism of FA sorption on sludge subfractions is hydrophobic interactions. The hydrophilic components of FA are sorbed through electrostatic interactions, through ligand exchange on lateral cleaved clay minerals and with the formation of bridging bonds with the Ca2+ ion occupying exchange positions in clays.

Constructing ultrahigh capacitance (Co,Mn)(Co,Mn)2O4/Ni(OH)2 electrode for boosted all-solid-state fiber asymmetric supercapacitors

To meet the practical demands of flexible fiber-shaped supercapacitors (FSSCs) for wearable electronics, it's crucial to develop electrodes with both high energy density and flexibility. In this work, an ultrahigh capacitance (Co,Mn)(Co,Mn)2O4/Ni(OH)2 (CMO/Ni(OH)2) fiber electrode is designed. The (Co,Mn)(Co,Mn)2O4 (CMO) nanosheets possessing large specific surface area and enriched active sites, which can be served as nano-substrate for the electrodeposition of Ni(OH)2. This special structure facilitates the exposure of more electroactive sites and accelerate rapid electrons transfer, resulting in boosted electrochemical performance. Benefiting from these advantages, the area capacitance of the CMO/Ni(OH)2 electrode is up to 4787.6 mF cm−2 at 1 mA cm−2, which is approximately 15 times higher than that of the CMO (311 mF cm−2), and 6.7 times higher than that of the Ni(OH)2 (718 mF cm−2). Coupled with activated carbon (AC) electrode, the assembled all-solid-state CMO/Ni(OH)2//AC FSSCs demonstrate a high energy density of 89.45 μW h cm−2 at 1505 μW cm−2, along with great flexibility and stability. Moreover, these devices can be integrated into clothes, and electronic watch, serving as an energy supply. This work offers a novel approach to designing high-performance fiber electrode for wearable flexible energy storage devices.

Rational design of cobalt oxide nanocubes arrays on Ni foam as durable and robust electrocatalyst for urea electro-oxidation

BackgroundCobalt oxide (Co3O4) is a promising electrocatalyst for efficient urea electro-oxidation, tackling power consumption and environmental challenges. The controllable design of free-standing Co3O4 nanostructures grown on Ni foam (NF) substrates was achieved using a green and facile hydrothermal approach. Different reducing agents were applied to synthesize various morphological structures of Co3O4, including nanoparticles, nanowires, and nanocubes (NCs) morphologies.ResultsThe as-fabricated electrodes were investigated as electrocatalysts for enhanced urea electro-oxidation. Because of its 3D nanostructure with minimal agglomeration and a large interfacial surface area with adequate electroactive sites, the Co3O4 NCs/NF had the best energy conversion efficiency of any electrode toward the urea oxidation process. These distinctive features facilitated the electron and urea routes used in the urea electro-oxidation process. It had a low-onset potential of 194.2 mV (vs. Hg/HgO) and a current density of 90.2 mA cm−2 in a 1 M KOH electrolyte. The electrocatalyst demonstrated excellent anodic activity for urea electro-oxidation with an onset potential of 196.7 mV and a current density of 256.1 mA cm−2 in 1 M KOH + 0.3 M urea concentration. Furthermore, the Co3O4 NCs/NF exhibited long-term stability, as shown by chronoamperometry and stepwise tests after 3600 s in the presence of urea under various operating conditions.ConclusionsCompared to all the fabricated Co3O4 nanostructures, the Co3O4 nanocubes revealed the highest electrocatalytic performance toward urea electro-oxidation in all concentrations. Therefore, Co3O4 NCs/NF is a promising, robust, and efficient electrocatalyst for direct urea fuel cell applications.

Engineering Metal-MOF Interfaces for Selective CO2 Hydrogenation to Methanol.

The hydrogenation of CO2 to methanol is a promising pathway toward sustainable fuel production and carbon recycling. A key factor in the efficiency of this process lies in the interaction between the metal catalyst and its support. Metal-Organic Frameworks (MOFs) have emerged as highly effective platforms due to their tunable structures, large surface areas, and ability to form stable interfaces with single-atom metals or metal nanoparticles. These metal-MOF interfaces are crucial for stabilizing active sites, preventing sintering, and enhancing catalytic performance. In this concept paper, we explore the role of these interfaces in promoting CO2 hydrogenation, focusing on Cu-Zn, Cu-Zr, and Zn-Zr interfaces. The formation of strong interactions between metal sites and MOF nodes enables precise control over the dispersion and electronic environment of the active species, significantly improving methanol selectivity and long-term stability. By analyzing recent advancements in MOF-supported catalysts, this work highlights the concept of engineered metal-MOF interfaces to drive the development of next-generation catalysts for efficient methanol synthesis from CO2.

Impact of gibberellic acid GA3, quantum dot biochar, and rhizosphere bacteria on fenugreek plant growth and stress responses under lead stress

Lead (Pb) is a stress that can cause problems with several aspects of a plant’s metabolism, potentially impeding the plant’s ability to grow and develop. The use of gibberellic acid (GA3), quantum dot biochar (QDBC), and rhizobacteria (RB) can be effective methods to overcome this problem. Gibberellic acid is a crucial plant hormone that regulates plant growth, cell division, tissue differentiation, flowering, photosynthesis, and transpiration rate. It also significantly impacts crop resilience to stress, affecting plant morphology, enzymatic activity, and physiology. Biochar, a soil supplement, enhances plant development soil health, and reduces stress effects. Due to its large surface area and porosity, it increases soil water-holding capacity, nutrient retention, and microbial activity. Quantum dots, semiconductor nanoparticles, have been proposed as a potential method to alleviate plant stress by acting as antioxidants, reducing oxidative stress, and controlling nutrient and growth regulators. Rhizobacteria, soil bacteria in plant roots, stimulate plant growth, nutrient absorption, and harvesting capacity. They produce phytohormones, increase mineral and nitrogen accessibility, and can induce systemic resistance (ISR), affecting plant defense. This study investigates the effects of combining GA3, QDBC, and RB as amendments to fenugreek, both with 500 Pb stress and without Pb stress. Treatments (control, 0.25 GA3mg/L-QDBC, 0.5 GA3mg/L-QDBC, 0.25 GA3mg/L-QDBC + RB, and 0.5 GA3mg/L-QDBC + RB) were applied in six replications using a completely randomized design. Results demonstrate that the combination of 0.5 GA3mg/L-QDBC + RB with 500 Pb stress led to significant enhancements in fenugreek shoot fresh weight (15.62%), root fresh weight (73.53%), shoot dry weight (24.00%), and root dry weight (36.53%) compared to the control. Additionally, there were notable improvements in chlorophyll a (57.23%), chlorophyll b (19.21%), and total chlorophyll (36.23%) compared to the control under Pb stress, also showing the potential of 0.5 GA3mg/L-QDBC + RB with 500 Pb stress. The study suggests that combining 0.5 GA3mg/L-QDBC + RB with 500 Pb stress can effectively mitigate Pb stress in fenugreek.

The preparation and modulation of 1D porous nanofibers loaded with Co@NC for efficient microwave absorption through electrospinning

1D nanofibers have been extensively applied in field of microwave absorption (MA) by virtue of large specific surface area, low percolation thresholds, and high aspect ratios. Through the modification of its physical properties and components, enhancement of MA capability is expected to be achieved. Herein, we modified the nanofibers by porous structure construction and dielectric/magnetic coupling, and further altered the chemical composition and microstructure of the absorbers through adjustment of annealing temperature and porogen addition, thus leading to effective modulation of electromagnetic properties. Specifically, we first prepared a polyacrylonitrile-based nanofiber by electrospinning. Subsequently, in situ growth of ZIF-67 and the construction of pore structure of the nanofibers were achieved simultaneously in aqueous solution. Ultimately, 1D (ZIF-67 derivatives)@(porous carbon nanofiber) were acquired by thermal field modulation. It suggests that, with the increase of annealing temperature, graphitization degree rises, enhancing conductive loss. Meanwhile, more divalent cobalt is reduced, leading to a rise in polarization loss and the effective modulation of magnetic properties. Besides, the rise in porogen addition is accompanied by a decrease in pore volume and an increase in pore size, enhancing electrical conductivity while increasing the number of defects, thus enhancing dielectric loss. Notably, when annealing temperature is 700 °C and porogen addition is 29 wt%, obtained material exhibits excellent reflection loss (−52.49 dB at 1.53 mm) and broad bandwidth (5.29 GHz at 1.62 mm). This approach offers a novel perspective for the preparation and modulation of electromagnetic properties of 1D nanofibers.

Hierarchical micro-meso-macroporous xAIL@HP UIO-66-NH2 catalysts used for efficient biodiesel production from low-grade acidic oils

The utilization of hierarchical porous supports to fabricate an efficient solid catalyst is a feasible strategy due to their remarkable merit in ameliorating the diffusion of reactants on the catalyst surface and increasing the exposure of active species in particular for the bulky molecule-involving reactions. In this research, to abatement the mass transfer resistance of large triglycerides, the hierarchical porous solid catalyst (xAIL@HP UIO-66-NH2) was prepared by grafting acidic ionic liquid (AIL) with double acidic sites of -SO3H and HSO4- onto micro-meso-macroporous metal-organic gels (HP UIO-66-NH2) through acid-base interactions between -NH2 moiety of HP UIO-66-NH2 and acidic moiety of AILs. The catalyst characterization results showed that the xAIL@HP UIO-66-NH2 catalyst owned the hierarchical porous structure and double Brønsted-Lewis acid centers with large BET surface area and pore volume. This catalyst was adopted for efficient biodiesel production from low-grade acidic oils, exhibiting high catalytic activities for triglyceride transesterification and free fatty acid (FFA) esterification reactions. By using acidic oils as feedstocks, the oil transesterification conversion could reach 91.3 % and the FFAs were completely converted to biodiesel under the conditions of 130 °C for 8 h at methanol-to-oil molar ratio of 35: 1 and catalyst dosage of 8 wt%. Based on the kinetic study, the activation energy Ea of this catalyst was 56.6 kJ/ mol, and the reaction complied with pseudo-first-order kinetics. This solid catalyst demonstrated satisfactory acid and water resistance, with good reusable performance, posing great potential in the efficient biodiesel preparation by the one-pot method using the low-grade acidic oils.

Microwave Irradiation-Assisted Synthesis of Anisotropic Crown Ether-Grafted Bamboo Pulp Aerogel as a Chelating Agent for Selective Adsorption of Heavy Metals (Mn+)

Crown ether is widely used in water purification because of its ring structure and good selective adsorption of specific heavy metals. However, its high cost and difficulty in recycling limit the purification of heavy metals in water. The anisotropic [2,4]-dibenzo-18-crown-6-modified bamboo pulp aerogel (DB18C6/PA) is successfully synthesized by microwave irradiation and directional freezing technology. The physical and chemical properties of DB18C6/PA are analyzed by FTIR, XPS, SEM, TEM, TGA, surface area and porosity analyzers. Single or multivariate systems containing Pb2+, Cu2+ and Cd2+ are used as adsorbents. The effects of the DB18C6 addition amount, pH, initial concentration and adsorption temperature on the adsorption of DB18C6/PA are systematically explored. Pseudo-first-order kinetic models, pseudo-second-order kinetic models and the isothermal adsorption models of Langmuir and Freundlich are used to fit the experimental data. The adsorption selectivity is analyzed from the distribution coefficient and the separation factor, and the adsorption mechanism is discussed. The results show that anisotropic DB18C6/PA has the characteristics of 3D directional channels, high porosity (97.67%), large specific surface area (103.7 m2/g), good thermal stability and regeneration (the number of cycles is greater than 5). The surface has a variety of functional groups, including a hydroxyl group, aldehyde group, ether bond, etc. In the single and multivariate systems of Pb2+, Cu2+ and Cd2+, the adsorption process of DB18C6/PA conforms to the pseudo-second-order kinetic model, and the results conform to the Freundlich adsorption isothermal model (a few of them conformed to the Langmuir adsorption isothermal model), indicating that chemical adsorption and physical adsorption are involved in the adsorption process, and the adsorption process is a spontaneous endothermic process. In the single solution system, the maximum adsorption capacities of Pb2+, Cu2+ and Cd2+ by DB18C6/PA are 129.15, 29.85 and 27.89 mg/g, respectively. The adsorption selectivity of DB18C6/PA on Pb2+, Cu2+ and Cd2+ is in the order of Pb2+ &gt;&gt; Cu2+ &gt; Cd2+.