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[Display omitted] • Niobium species in 30Nb-Beta zeolite were anchored into silanol defects in form of (SiO) 2 Nb(OH)(=O). • High-electrophilic 30Nb-Beta could achieve a cyclohexene conversion of 51.1 % and TOF of 188.2 h−1. • H 2 O 2 activation pathway over (SiO) 2 Nb(OH)(=O) sites contains three steps. Dealuminated Beta zeolite has a large amount of silanol defects on its interface, which provides an ideal place for embedding metal species and creating metal active sites in a confined microenvironment. The confined metal sites as well as their surroundings are closely related to the reactant activation and transient state achievement. Hence, unraveling the confined metal sites is of great significance for the catalytic reaction process. Herein, niobium species were incorporated into the silanol defects over dealuminated Beta zeolite with a facile dry impregnation method, co-grinding the niobium precursor with dealuminated Beta zeolite support. The successful incorporation of niobium into the silanol defects for 30Nb-Beta zeolite was verified by DRIFT, 1H MAS NMR, UV–Vis and UV-Raman characterizations. XAS characterization and DFT calculations further disclosed that the confined Nb species existed as (SiO) 2 Nb(OH)(=O), containing two Si−O−Nb bonds, one Nb=O bond as well as one Nb−OH bond. The synthesized 30Nb-Beta zeolite catalyst displayed a superior cyclohexene conversion of 51.1%, cyclohexene oxide selectivity of 83.1% as well as TOF value of 188.2 h−1 ascribed to the inherent electrophilicity of Nb(V) for confined (SiO) 2 Nb(OH)(=O) species as well as the low oxygen transfer energy barrier for NbV−OOH species. Furthermore, the prepared 30Nb-Beta zeolite can be effectively employed to other cyclic alkene epoxidation reactions. [ABSTRACT FROM AUTHOR]

[Display omitted] • Eu(DBM) 3 DETA is a newly synthesized, unreported lanthanide crystal complex. • Eu(DBM) 3 DETA has both excellent photoluminescence and triboluminescence properties. • Eu(DBM) 3 DETA can recover to its original PL and TL properties after recrystallization. • Piezoelectric effect on crystals during breakage provide excellent TL properties. • Eu(DBM) 3 DETA can display stress visualization differences of handwriting signatures. Investigation of photoluminescence (PL) and fracture-induced triboluminescence (TL) is necessary for the development of both fundamental theories and practical applications in mechanical energy conversion; however, most known PL/TL-emitting materials are confined to inorganic systems. In this study, a novel lanthanide-based crystalline complex (LnCC), Eu(DBM) 3 DETA was synthesized via the synergistic coordination of Eu3+ with DBM (Dibenzoylmethane) and DETA (Diethylenetriamine) units, leading to the formation of brighter LnCC with bright red emission, high PL quantum yields (57.19 %) and unique TL characteristics. The key to success in obtaining Eu(DBM) 3 DETA is the utilization of DETA molecule as synergistic ligand, presenting block crystals with higher coordination number of Eu3+ ions via recrystallization. Due to the dense accumulation of cross-linked three-dimensional frameworks through van der Waals interactions, the fracture-induced piezoelectric effect results in charge separation and excitation through the resultant electric field and discharge, triggering a fast TL response of Eu(DBM) 3 DETA and expanding the possibilities of the quantitative stress sensing. Importantly, amorphous powders can still recover to their original PL and TL emission intensities after recrystallization in cyclic crystal-to-amorphous phase transitions. The unique PL and TL characteristics of Eu(DBM) 3 DETA provide promising opportunities to display stress visualization differences of electronic signatures under different forces. [ABSTRACT FROM AUTHOR]

[Display omitted] Transition metals with catalytic properties were expected to improve the fire resistance of the polymer. In this work, NiMoO 4 nanorods decorated with Co-Ni layered double hydroxide (LDH) were fabricated and incorporated into polyurea (PUA) to improve the flame retardancy during combustion. Thermogravimetric analysis (TGA) showed that the addition of NiMoO 4 @Co-Ni LDH slightly decreased the initial degradation and the maximum degradation temperature. With increasing loading of NiMoO 4 @Co-Ni LDH, the char residue increased obviously. The combustion performance of PUA with 3.0 wt% NiMoO 4 @Co-Ni LDH investigated by cone calorimeter (CCT) showed that the peak heat release rate (PHRR), total heat release (THR) and smoke factor (SF) decreased by 34.41%, 12.68% and 48.65%, respectively. The existence of well-dispersed NiMoO 4 @Co-Ni LDH effectively enhanced the mechanical properties and flame retardant performances of PUA. [ABSTRACT FROM AUTHOR]

[Display omitted] • CAL and PPy-CAL were prepared using hydrothermal and in situ polymerization methods. • The theoretical adsorption capacity of CAL-PPy for Cr(VI) was nearly twice than that of CAL. • CAL-PPy removed 100 mg/L of aqueous Cr(VI) efficiently and quickly. • Mechanisms included electrostatic attraction, anion exchange, complexation, and reduction. To efficiently remove high concentrations of hexavalent chromium (Cr(VI)), calcium–aluminum-layered double hydroxide (CaAl-LDH, denoted as CAL), and polypyrrole-modified CAL (CAL-PPy) were prepared by hydrothermal and in situ polymerization methods, respectively. The chemical structure, morphology, and elemental results indicated that the chain-like polypyrrole was decorated with hexagonal CAL. The specific surface area of CAL-PPy increased from 8.746 m2/g to 24.24 m2/g. The adsorption performances of CAL and CAL-PPy for aqueous Cr(VI) were investigated using batch equilibrium experiments. The decontamination process of aqueous Cr(VI) (100 mg/L) reached the equilibrium state within 50 min, and the kinetic data met the pseudo-second-order kinetic equation. The Langmuir model described the isothermal data properly, and the obtained theoretical adsorption capacity of CAL for Cr(VI) at 318 K was 34.06 mg/g, while that of CAL-PPy was 66.14 mg/g. The removal mechanisms involved electrostatic attraction, surface complexation, anion exchange, and reduction to low-toxicity Cr(III). Therefore, CAL and CAL-PPy have underlying applications in treating real wastewater containing Cr(VI). [ABSTRACT FROM AUTHOR]

Graphical abstract Abstract In this work, the magnetic alginate microsphere of Fe 3 O 4 /MgAl-LDH (Fe 3 O 4 /LDH-AM) was prepared by immobilizing the Fe 3 O 4 /LDH with calcium alginate (CA) and was used to remove Cd2+, Pb2+, and Cu2+ from aqueous solutions. The obtained Fe 3 O 4 /LDH-AM was characterized by X-ray diffraction, Fourier-transform infrared spectroscopy, scanning electron microscopy, energy dispersive spectroscopy, X-ray photoelectron spectroscopy, and Brunauer-Emmett-Teller surface area determination. The results indicated that the surface groups of the alginate and LDH were retained and so was the crystal structure in the alginate microsphere. The adsorption performance of the Fe 3 O 4 /LDH-AM for Cd2+, Pb2+, and Cu2+ in aqueous solutions was evaluated by batch and column adsorption experiments. The effects of adsorption conditions, kinetics, isotherms, mechanisms, and potential applications were investigated. The adsorption kinetic data conformed to the pseudo-second-order kinetic equation, and the isotherm data fit well with the Freundlich and Langmuir isotherm models. The adsorption mechanism of Cd2+, Pb2+, and Cu2+ by the Fe 3 O 4 /LDH-AM entailed complexation and precipitation. The experimental breakthrough curves were correlated with the Thomas model. Moreover, the Fe 3 O 4 /LDH-AM displayed superior regeneration and reusability. These results suggest that the Fe 3 O 4 /LDH-AM is an efficient adsorbent for the removal of heavy metals and can be effectively employed in practical applications. [ABSTRACT FROM AUTHOR]

[Display omitted] Generally, electrospun membranes have high mechanical strength, high porosity and low permeation resistance. Although covalent organic frameworks (COFs) have attracted great interest as advanced membrane materials, few works disclosed that the COFs composite membranes were synthesized on electrospun substrates. In this work, the electrospun polyvinylidene fluoride (PVDF) membranes were used as substrates for the preparation of COF composite membranes with graphene oxide and oxidized carbon nanotubes (GO-OCNTs) as an intermediate layer. The COF/GO-OCNTs/PVDF composite membranes were prepared by suction filtering the GO-OCNTs intermediate layer on the electrospun substrate, and then interfacial polymerization of COF layer. After adding the intermediate layer, the water permeance and dye retention rate of the composite COF membrane are both improved. By exploring the reaction parameters in the interfacial polymerization process, the optimized membrane shows that the rejection rate of Coomassle brilliant blue G250 (BBG-250) is about 97.1%, and the water permeability achieves 96.7 L m−2 h−1 bar−1. In addition, the COF/GO-OCNTs/PVDF composite membrane exhibits excellent chemical and mechanical stability. The long-term filtration experiment of the composite membrane shows good water permeation stability. This work provides a method to prepare dense and defect-free COF films on electrospun substrates. [ABSTRACT FROM AUTHOR]

• A dual-functional ultrafiltration membrane containing quaternary ammonium and zwitterionic polymers was prepared. • The antifouling and antibacterial behavior of the membrane was studied. • The membrane showed the improved organic-/bio fouling resistance. • The membrane showed high-efficiency broad-spectrum antibacterial performance. To overcome the organic-/bio- fouling of the membrane, a dual-functional ultrafiltration membrane containing quaternary ammonium and zwitterionic polymers via quaternization and surface radical polymerization was designed, and its antifouling and antibacterial behavior was studied. In this work, poly(vinylidene fluoride)/poly(methyl methacrylate- co -dimethylamino-2-ethyl methacrylate) (PVDF/P(MMA- co -DMAEMA)) blend membrane was quaternized by p -chloromethyl styrene (p -CMS), and the double bonds were introduced onto the membrane surface, which further participated in the polymerization of zwitterionic monomers on the membrane surface. The results indicated that the resultant membrane exhibited obviously improved hydrophilicity and weak positive charge (isoelectric point, 7.49). The membrane presented higher flux recovery ratio and lower protein adhesion compared with the pure PVDF membrane. Meanwhile, the membrane showed high-efficiency broad-spectrum antibacterial performance, that is, the bacteria killing efficiency of S. aureus and E. coli reached 98.2% and 97.0%, respectively. Moreover, the membrane effectively inhibited bacterial adhesion, which is important for the long-term antibacterial properties of membrane. This antifouling and antibacterial PVDF membrane may have potential in the long-term filtration process, especially when dealing with microbiologically contaminated water. [ABSTRACT FROM AUTHOR]

In this work, NR/MXene/SiO 2 nanocomposites are fabricated into flexible wearable strain sensors with an island-chain structure, this unique structure promotes the selective distribution of MXene in the NR matrix and greatly improves the sensing performance of the material, which can detect human motions in real-time and provide personal health monitoring. [Display omitted] The demand for flexible strain sensors with high sensitivity and durability has increased significantly. However, traditional sensors are limited in terms of their detection ranges and fabrications. In this work, a space stacking method was proposed to fabricate natural rubber (NR)/ Ti 3 C 2 T x (MXene)/silica (SiO 2) films that possessed exceptional electrical conductivity, sensitivity and reliability. The introduction of SiO 2 into the NR/MXene composite enabled the construction of an "island-chain structure", which promoted the formation of conductive pathways and significantly improved the conductivity of the composite. Specifically, the electrical conductivity of the NR/MXene/10 wt%SiO 2 composite was enhanced by about 200 times compared to that of the NR/MXene composite alone (from 0.07 to 13.4 S/m). Additionally, the "island-chain structure" further enhanced the sensing properties of the NR/MXene/10 wt%SiO 2 composite, as evidenced by its excellent sensitivity (GF = 189.2), rapid response time (102 ms), and good repeatability over 10,000 cycles. The fabricated device demonstrates an outstanding mechanical sensing performance and can accurately detect human physiological signals. Specifically, the device serves as a strain detector, recognizing different strain signals by monitoring the movement of fingers, arms, and thighs. This study provides critical insights into composite manufacturing with exceptional conductivity, flexibility and stability, which are essential properties for creating high-performance flexible sensors. [ABSTRACT FROM AUTHOR]

DNA formylation (5-formylcytosine, 5fC) is a major epigenetic modification involved in alterations in the DNA double helix structure and protein identification. Due to the low amount in all mammalian tissues and cells, it is necessary to develop a rapid, sensitive and efficient method for detecting 5fC for further understanding the biological functions of 5fC. Thus, a novel PEC biosensor was constructed using P-g-C 3 N 4 -WS 2 nanocomposite as photoactive material. Firstly, AuNPs/P-g-C 3 N 4 -WS 2 /ITO electrode was prepared as substrate electrode. Secondly, the probe DNA and complementary DNA (containing 5fC base) was modified to the electrode surface based on the formation of Au-S bonds between AuNPs and thiol group on the probe DNA and hybridization, respectively. Finally, the amino functionalized MnO 2 nanoflowers were further modified to the electrode surface by covalent interaction between the aldehyde group on the 5fC and the amino group on MnO 2 nanoflowers. The sensitive and specific detection of 5fC can be achieved by oxidizing ascorbic acid with MnO 2 nanoflowers and quenching the photoactivity of P-g-C 3 N 4 -WS 2 nanocomposite. The sensor has a detection range of 0.01–200 nM and a detection limit of 3.8 pM. Moreover, this sensor has excellent detection specificity, stability and reproducibility. [ABSTRACT FROM AUTHOR]

[Display omitted] The conductive networks for electron hopping and migration constructed by one-dimensional (1D) composite absorbers are highly desirable to improve the electromagnetic (EM) wave attenuation capacity. Herein, the Ni@Co/C@polypyrrole (PPy) composites integrating the advantages of component and microstructure were fabricated. The addition of Co/C and PPy effectively optimized the impedance matching and improved the EM attenuation. Under the comprehensive impacts of multiple reflections/scattering, conduction loss and interface polarization, the Ni@Co/C@PPy composites showed superior EM wave absorption with the reflection loss (RL) value of −48.76 dB and the effective absorption bandwidth (EAB) of 5.10 GHz at a corresponding thickness of 2.0 mm. The largest EAB could reach 5.54 GHz (7.24–12.78 GHz) at the thickness of 2.2 mm. This work provides a great reference for fabricating 1D novel EM wave absorption materials. [ABSTRACT FROM AUTHOR]

[Display omitted] Nowadays, ferrites/carbon fibers have attracted considerable attention as microwave absorption materials (MA) due to the synergistic effect between dielectric and magnetic loss. Herein, the ZnFe 2 O 4 /C fibers were fabricated via electrospinning and calcination methods, and then polypyrrole (PPy) successfully coated on the fibers via oxidative polymerization. The ZnFe 2 O 4 /C@PPy composites exhibit enhanced EM wave absorption performance with the loading of 25 wt%. The optimal reflection loss (RL) value is up to −66.34 dB (13.80 GHz) and effective absorption bandwidth (EAB) is 5.74 GHz (11.78–17.52 GHz) with a matching thickness of 1.93 mm. Besides, high-efficient absorption performance of the ZnFe 2 O 4 /C@PPy composites is mainly attributed to the dielectric loss and ideal impedance matching. This study reveals a novel approach to development of ferrites/carbon fibers coated with PPy, and the ZnFe 2 O 4 /C@PPy composites exhibit great potential application as the materials with high-efficient absorption properties. [ABSTRACT FROM AUTHOR]

Abstract: Adsorption of ammonia (NH3) onto activated carbons prepared from palm shells impregnated with sulfuric acid (H2SO4) was investigated. The effects of activation temperature and acid concentration on pore surface area development were studied. The relatively large micropore surface areas of the palm-shell activated carbons prepared by H2SO4 activation suggest their potential applications in gas adsorption. Adsorption experiments at a fixed temperature showed that the amounts of NH3 adsorbed onto the chemically activated carbons, unlike those prepared by CO2 thermal activation, were not solely dependent on the specific pore surface areas of the adsorbents. Further adsorption tests for a wide range of temperatures suggested combined physisorption and chemisorption of NH3. Desorption tests at the same temperature as adsorption and at an elevated temperature were carried out to confirm the occurrence of chemisorption due to the interaction between NH3 and some oxygen functional groups via hydrogen bonding. The surface functional groups on the adsorbent surface were detected by Fourier transform infrared spectroscopy. The amounts of NH3 adsorbed by chemisorption were correlated with the contents of elemental oxygen present in the adsorbents. Mechanisms for chemical activation and adsorption processes are proposed based on the observed phenomena. [Copyright &y& Elsevier]

In this study, ammonium thiocyanate functionalized graphene oxide (ATGO)-supported nanoscale zero-valent iron composite (ATGO-nZVI) employed to extract Cr(VI) from aqueous solution, was successfully synthesized by chemical oxidative polymerization and sodium borohydride reduction method. Characteristics of X-ray diffraction and high-resolution transmission electron microscopy confirmed the high disperse and activity of nZVI after supported by ATGO. Batch experiments showed that the removal efficiency of ATGO-nZVI was higher than that of bared nZVI and ATGO. Furthermore, the stability of ATGO-nZVI composite was higher than that of nZVI, which was proved by the Tafel polarization curves. Dynamic experiments suggested that the removal process was confirmed to be in agreement with not only the pseudo-second-order model for adsorption but also Langmuir-Hinshelwood first-order model for reduction process, which revealed that the removal of Cr(VI) by ATGO-nZVI composite was dominated by chemical surface-limiting step. Considering the experiments and characterization, the removal mechanism containing rapid adsorption of Cr(VI) onto the ATGO-nZVI surface and reduction by nZVI was clarified. The above results suggested that ATGO-nZVI would become a promising remediation material for Cr(VI) pollution cleanup. [ABSTRACT FROM AUTHOR]

In this study, a regenerable magnetic ligand material (EDTA-mGO) was fabricated by binding chelating groups (EDTA) onto Fe 3 O 4 /graphene oxide and applied to remove U(VI) from aqueous solution. The sorption experiments were investigated under different experimental conditions, such as temperature, contact time and pH. EDTA-mGO showed fast removal capacity for U(VI) (<1.5 h) with high sorption ability (277.43 mg/g). The removal mechanisms mainly attributed to the metal-binding organic ligand (EDTA) and the electrostatic attractions between U(VI) and oxygenic functional groups. In addition, the as-prepared EDTA-mGO dispersed in water could be easily collected after the sorption by the external magnetic field within 10 s. The removal of U(VI) by EDTA-mGO followed the pseudo-second-order rate better than the pseudo-first-order. The thermodynamic data indicated the endothermic and the spontaneous nature of U(VI) sorption. Furthermore, the reproducibility studies suggested that EDTA-mGO has a good reusability and a high stability. [ABSTRACT FROM AUTHOR]