Synthesis of flowerlike vanadium diselenide microspheres for efficient electromagnetic wave absorption.

The revelation of MoS2as an efficient electromagnetic wave (EMW) absorbing material has ratcheted up people's attention to other transition metal dichalcogenides (TMDs). To date, extensive studies have been conducted on the semiconducting VIB-Group TMDs while research into metallic VB-Group TMDs has been relatively rare. In this work, we successfully fabricated VB-Group VSe2microspheres through a facile one-step hydrothermal method and used them as EMW absorbers. The flowerlike VSe2microspheres based on VSe2nanosheets exhibited a minimum reflection loss of 46.58 dB with an effective absorption bandwidth of 4.86 GHz. The influence of material morphology, microstructure, and dielectric properties on the EMW absorption performance was systematically investigated. The hierarchically layered structure promoted dielectric loss and EMW absorption by means of multiple reflection, interfacial polarization and related relaxation, and enhanced attenuation ability. This work not only demonstrates that VSe2is potentially a high-efficiency single component EMW absorber, but also provides fresh insights into exploration on the EMW loss mechanisms of the metallic TMD-based absorbing materials.

Core-shell architectured NH2-UiO-66@ZIF-8/multi-walled carbon nanotubes nanocomposite-based sensitive electrochemical sensor towards simultaneous determination of Pb2+ and Cu2.

Amino functionalized zirconium-based metal-organic framework (NH2-UiO-66) and zinc-based zeolitic imidazolate framework (ZIF-8) were integrated to develop a core-shell architectured hybrid material (NH2-UiO-66@ZIF-8, NU66@Z8). The morphology and structure evolutions of core-shell NU6@Z8 were investigated by FE-SEM, XRD, FTIR, and XPS. The NU66@Z8 combined with carboxylated multi-walled carbon nanotubes (CMWCNT) was deposited on a glassy carbon electrode (GCE) for fabricating an electrochemical platform towards detecting Pb2+ and Cu2+. The NU66@Z8/CMWCNT/GCE revealed significantly improved electrochemical performance for determination of Pb2+ and Cu2+ compared with the individual components, which can be attributed to the strong adsorption capacity, unique core-shell structure, and large electrochemical active surface area of NU66@Z8/CMWCNT. Under the optimal conditions, the developed sensor exhibited excellent sensing capability with a low limit of detection (Pb2+,1 nM; Cu2+, 10 nM) and a wide determination range (Pb2+,0.003-70 µM; Cu2+, 0.03-50 µM). The sensor showed high selectivity towards common interfering ions and good repeatability. The real sample recoveries of proposed sensor were in the range 95.0-103% for Pb2+ (RSD ≤ 5.3%) and 94.2-106% for Cu2+ (RSD ≤ 5.9%), suggesting that the NU66@Z8/CMWCNT is suitable for examining trace heavy metals in natural environment.

Ultrathin ZnIn2 S4 Nanosheets Anchored on Ti3 C2 TX MXene for Photocatalytic H2 Evolution.

Photocatalysts derived from semiconductor heterojunctions that harvest solar energy and catalyze reactions still suffer from low solar-to-hydrogen conversion efficiency. Now, MXene (Ti3 C2 TX ) nanosheets (MNs) are used to support the in situ growth of ultrathin ZnIn2 S4 nanosheets (UZNs), producing sandwich-like hierarchical heterostructures (UZNs-MNs-UZNs) for efficient photocatalytic H2 evolution. Opportune lateral epitaxy of UZNs on the surface of MNs improves specific surface area, pore diameter, and hydrophilicity of the resulting materials, all of which could be beneficial to the photocatalytic activity. Owing to the Schottky junction and ultrathin 2D structures of UZNs and MNs, the heterostructures could effectively suppress photoexcited electron-hole recombination and boost photoexcited charge transfer and separation. The heterostructure photocatalyst exhibits improved photocatalytic H2 evolution performance (6.6 times higher than pristine ZnIn2 S4 ) and excellent stability.

Dramatic red fluorescence enhancement and emission red shift of carbon dots following Zn/ZnO decoration.

Metal atom doping, an easy and convenient method, can optimize and tune the physical-chemical properties and photometrics of carbon dots (CDs). However, there are few reports on the preparation of metal-decorated CDs that give red emission and a high photoluminescence quantum yield (PLQY). Here, we demonstrate a zinc (existing in human body) ion-doping strategy to observably enhance the PLQY and lengthen the CD emission wavelength. The prepared Zn/ZnO-decorated CDs (Zn-CDs) produced red fluorescence (623 nm) with a superior PLQY of 40.3%. Through a series of analyses, Zn-CDs were confirmed to contain an oxidation state and reduction state of Zn doping into the internal defects and surface of Zn-CDs. More valuably, the Zn-CDs had excellent chemical stability, photo-stability, long-term storage stability, and high biocompatibility, and therefore could be used as a robust red fluorescence probe for high-quality cellular imaging.

Tetrazole amphiphile inducing growth of conducting polymers hierarchical nanostructures and their electromagnetic absorption properties.

Conducting polymers (CPs) at nano scales endow materials with special optical, electrical, and magnetic properties. The crucial factor to construct and regulate the micro-structures of CPs is the inducing reagent, particular in its chemical structure, such active sites, self-assembling properties. In this paper, we design and synthesize an amphiphile bearing tetrazole moiety on its skeleton, and use this amphiphile as an inducing reagent to prepare and regulate the micro-structures of a series of CPs including polypyrrole, polyaniline, poly(3,4-ethylenedioxythiophene) and poly(p-phenylenediamine). Because of the unique electric properties of CPs and size effect, we next explored the electromagnetic absorption performances of these CPs nanostructures. A synergetic combination of electric loss and magnetic loss is used to explain the absorption mechanism of these CPs nano-structures.

Self-Assembled 3D Helical Hollow Superstructures with Enhanced Microwave Absorption Properties.

Helical structures at different scales endow functional materials with special optical, electrical, and magnetic properties. However, methods for constructing and regulating single-handed helicity, particularly complex 3D hierarchical structures, remain limited. In this study, co-self-assembly process combined with emulsion droplets is used to produce the various well-defined 3D hollow superstructures of conducting polyaniline (PANI) with single-handed helicity. The chirality of PANI is induced using enantiomeric r- or s-camphorsulfonic acid as a dopant; the chirality of the dopant is then transferred to the supramolecular chirality of PANI assemblies and consequently to the helicity of 3D superstructures by incorporating emulsion droplets to serve collectively as soft templates. The twisting and anisotropism of these superstructures vary with the enhancement of the supramolecular chirality and result in the transformation of their morphologies from seashell-like to spindle-like and their cavity becoming more slender than their original shape. Due to the supramolecular chirality and hierarchical characteristics of these superstructures, enhanced microwave absorption performance is observed under a filler content of as low as 20 wt%, suggesting their promising application as microwave absorbers.

Ultra-broad polypyrrole (PPy) nano-ribbons seeded by racemic surfactants aggregates and their high-performance electromagnetic radiation elimination.

Ribbon-like nano-structures possess high aspect ratios, and thus have great potential in the development of high-performance microwave absorption (MA) materials that can effectively eliminate adverse electromagnetic radiation. However, these nano-structures have been scarcely constructed in the field of MA, because of the lack of efficient synthetic routes. Herein, we developed an efficient method to successfully construct polypyrrole (PPy) nano-ribbons using the self-assembly aggregates of a racemic surfactant as the seeds. The frequency range with a reflection loss value of lower than -10 dB reached 7.68 GHz in the frequency range of 10.32-18.00 GHz, and surpassed all the currently reported PPy nano-structures, as well as most other MA nano-materials. Through changing the amount of surfactant, both the nano-structures and MA performance can be effectively regulated. Furthermore, the reason behind the high-performance MA of PPy nano-ribbons has been deeply explored. It opens up the opportunity for the application of conducting polymer nano-ribbons as a lightweight and tunable high-performance MA material, especially in applications of special aircraft and flexible electronics.

In situ growth of MoS2 nanosheets on reduced graphene oxide (RGO) surfaces: interfacial enhancement of absorbing performance against electromagnetic pollution.

Electromagnetic pollution is rising all over the world. Compared with electromagnetic waves reflection, electromagnetic absorption (EA) is a better choice to balance electromagnetic applications and human health. The highly conductive networks in composites, as well as in species, and the intensity of defect polarization are the most important factors to improving the EA performance of a dielectric material. In this study, an in situ one-pot hydrothermal growth of MoS2 layers on reduced graphene oxide (RGO) surfaces was developed for the synthesis of RGO/MoS2 nanosheets. With a filler loading ratio of 20 wt%, the composite of the RGO/MoS2 nanosheets could build conductive networks and exhibited an effective EA bandwidth (lower than -10 dB) of 5.7 GHz and a minimum reflection loss (RL) of -60 dB. The results revealed that the as-prepared RGO/MoS2 nanosheets are promising EA materials, with broad and strong absorption properties at a low filler loading and low thickness.

Carbon nanolayer-mounted single metal sites enable dipole polarization loss under electromagnetic field.

Surface modulation strategies have spurred great interest with regard to regulating the morphology, dispersion and flexible processability of materials. Unsurprisingly, customized modulation of surfaces is primed to offer a route to control their electronic functions. To regulate electromagnetic wave (EMW) absorption applications by surface engineering is an unmet challenge. Thanks to pyrolyzing surface-anchored metal-porphyrin, here we report on the surface modulation of four-nitrogen atoms-confined single metal site on a nitrogen-doped carbon layer (sM(N4)@NC, M = Ni, Co, Cu, Ni/Cu) (sM=single metal; NC= nitrogen-doped carbon layer) that registers electromagnetic wave absorption. Surface-anchored metal-porphyrins are afforded by attaching them onto the polypyrrole surface via a prototypical click reaction. Further, sM(N4)@NC is experimentally found to elicit an identical dipole polarization loss mechanism, overcoming the handicaps of conductivity loss, defects, and interfacial polarization loss among the current EMW absorber models. Importantly, sM(N4)@NC is found to exhibit an effective absorption bandwidth of 6.44 and reflection loss of -51.7 dB, preceding state-of-the-art carbon-based EMW absorbers. This study introduces a surface modulation strategy to design EMW absorbers based on single metal sites that enable fine-tunable and controlled absorption mechanism with atomistic precision.

Anion-substitution interfacial engineering to construct C@MoS2 hierarchical nanocomposites for broadband electromagnetic wave absorption.

Developing an effective strategy to regulate the interfacial properties of hierarchical structure is of great significance for preparation of high-performance electromagnetic wave absorption (EMA) materials. Ion-substitution can change intrinsic structure and properties of a materials, but its effect on the interfacial properties of hierarchical structure remained to be explored. Herein, we first constructed a C@MoS2 hierarchical structure via simple hydrothermal reaction, then used the ion-substitution strategy to replace the S atoms in MoS2 with O, F and Se, and finally obtained anion-substituted hierarchical structure (C@X-MoS2, X = O, F, Se). The results show that ion-substitution destroys the MoS2 crystal structure and realizes tunable dielectric properties of C@MoS2, which leads to further enhancement of overall interfacial polarization. After optimization, the absorption strength and width of C@O-MoS2 has been significantly improved. The minimum reflection loss (RLmin) reaches -62.17 dB, and the maximum effective absorption bandwidth (EABmax) is 7.0 GHz. The simulation results show the obtained absorbent can greatly reduce the radar cross section of target, indicating it has broad application potential. Therefore, this work provides a novel method for regulation of EMA performance of hierarchical structure and preparation of high-performance absorbents.

Leveraging DNA-Based Nanostructures for Advanced Error Detection and Correction in Data Communication.

This study demonstrates the implementation of the Hamming code using DNA-based nanostructures for error detection and correction in communication systems. The designed DNA nanostructures conduct logical operations to compute check codes and identify and correct erroneous data based on fluorescence signals. The execution of intricate DNA logic operations requires individuals with specialized training. By interpretation of the fluorescence signals generated by the DNA nanostructures, binary language can be extracted, effectively protecting data security. The findings highlight the potential of DNA as a versatile platform for reliable data transmission.

Pyrene-based sulfonated organic porous materials for rapid adsorption of cationic dyes in water.

Porous organic polymers (POP) have gained attention because of their high specific surface area, porosity and their simplicity in synthesis, but for the most part, they are hydrophobic because of their organic backbone, making it difficult to expand their applications. Here, we have obtained poly(pyrene) porous organic polymers (PyPOP) through the polymerization of pyrene monomers catalysed by aluminium trichloride, which is a simple and inexpensive synthesis method. The sulfonated poly(pyrene) porous organic polymers (PyPOP-SO3H) obtained showed rapid adsorption of cationic dyes, especially malachite green (MG adsorption 1607 mg/g) and methylene blue (MB adsorption 1220 mg/g) in pH = 7 aqueous solution, room temperature. The results show that the Freundlich model is more in line with the adsorption process than the Langmuir model, whether for methylene blue or malachite green. In addition, the PSO kinetic model fits better than PFO kinetic model, whether it is for the adsorption of methylene blue or malachite green. The excellent adsorption performance of PyPOP-SO3H for cationic dyes may be due to the introduction of sulfonic acid groups, which not only increases the specific surface area but also allows better dispersion in water, increasing contact points and adsorption efficiency. This research expands the scope of exploration and application of POP.

Constructing an acidic microenvironment by sulfonated polymers for photocatalytic reduction of hexavalent chromium under neutral conditions.

Hexavalent chromium (VI) heavy metal contamination is considered a serious threat to human health and the environment. The photocatalytic reduction of Cr(VI) basically occurs in the acidic environment, severely limiting the application of photocatalysts for the reduction of Cr(VI). Therefore, we designed a microenvironment strategy to achieve efficient reduction of Cr (VI) under neutral conditions by introducing sulfonic acid onto the aromatic conjugated skeleton. A series of characterizations and experiments have shown that the sulfonated aromatic ring conjugated polymer (Arcp-SO3H) can efficiently remove Cr(VI) under neutral or even alkaline conditions. In neutral solutions, Arcp-SO3H has a rate constant of 0.054 min-1 within 90 min and has an efficiency of nearly 100 %, which is 16 times faster than before sulfonation (k = 0.0316 min-1). the Arcp-SO3H surpasses all organic polymers and most metal-based photocatalysts in the related field. The capture experiments have proved that •O2- is the main role of reducing Cr(VI), and e- is secondary, which is quite different from the mechanism reported in the previous literature. The efficiency of reducing Cr (VI) in the four-cycle experiment is still 96 %, which also proves that Arcp-SO3H has strong stability and reproducibility. Thus, Arcp-SO3H has great practical application potential in the treatment of wastewater, and microenvironmental strategies also offer new possibilities in the field of environmental remediation.

Bionic electroluminescent perovskite light-emitting device.

A perovskite light-emitting-diode (PeLED) displaying green color is combined with a brown fluorescent coating (FC) layer to form a hybrid FC-PeLED system. The FC-PeLED system can simulate the natural process of bionics of plant colors from green to brown through a low energy (<0.6 mW) input, promoting the development of future low-cost and low-power consumption bionics technology.

Machine learning-assisted array from fluorescent conjugated microporous polymers for multiple explosives recognition.

The fluorescent properties of conjugated microporous polyphenylene (CMPs) were tuned through a wide range by inclusion of small amount of comonomer as chromophore in the network. The multi-color CMPs were used for explosives sensing and demonstrated broad sensitivity (ranging from -0.01888 µM-1 to -0.00467 µM-1) and LODs (ranging from 31.0 nM to 125.3 nM) against thirteen explosive compounds including nitroaromatics (NACs), nitramines (NAMs) and nitrogen-rich heterocycles (NRHCs). The CMPs were also developed as a sensor array for discrimination of thirteen explosives, specifically including NT, p-DNB, DNT, TNT, TNP, TNR, RDX, HMX, CL-20, FOX-7, NTO, DABT and DHT. By using classical statistical method "Linear Discriminant Analysis (LDA)", the thirteen explosives at a fixed concentration were completely discriminated and unknown test samples were indentied with 88% classification accuracy. Moreover, explosives in different concentrations and the mixtures of explosives were also successfully classified. Compared with LDA, Machine Learning algorithms have significant advantages in analyzing the array-based sensing data. Different Machine Learning models for pattern recognition have also been implemented and discussed here and much higher accuracy (96% for "neural network") can be achieved in predicting unknown test samples after training.

Rapid chromium reduction by metal-free organic polymer photocatalysis via molecular engineering.

The conversion of hexavalent chromium (Cr(VI)), a highly poisonous heavy metal found in natural environment, to less poisonous trivalent chromium (Cr(III)) has attracted a lot of interest. However, little interest has been paid to the development of metal-free catalysts. Here, we demonstrate for the first time a molecular engineering strategy to synthesize a range of donor-acceptor conjugated polymer photocatalysts, which can significantly increase the reduction efficiency of Cr(VI) by a factor of 5.2, corresponding to a significant change in the reduction reaction rate constant (from 0.0337 to 0.1740 min-1). In addition, the apparent quantum efficiency (AQE) of Cr(VI) removal was obtained, and the optimized photocatalyst (Py-SO1) could achieve the highest apparent quantum efficiency at wavelength of 420 nm in those samples. Despite the narrow light absorption of Py-SO1 polymer, its excellent exciton separation efficiency and efficient electron output enabled it to achieve excellent performance in photoreduction of Cr(VI), surpassing that of the reported metal-free photocatalysts. The results show that the present work provides a new perspective for designing suitable environmental remediation catalysts based on molecular engineering strategies.

Heteroatom-free conjugated tetraphenylethylene polymers for selectively fluorescent detection of tetracycline.

The antibiotic tetracycline (Tc) is a major contaminant in food and water, with adverse effects on both ecosystems and human health. The development of novel sensors for tetracycline detection is of great importance. In this work, we develop a novel heteroatom-free conjugated tetraphenylethylene polymer (TPE-CMP) fluorescence sensor for the detection of tetracycline. In the presence of Tc, the emission fluorescence of TPE-CMP was quenched by the photoinduced electron transfer mechanism to achieve high sensitivity. The polymers can detect tetracycline at a concentration of 0-100 µg/mL with a good linear correlation (0.99), and the limit of detection (LOD) is 1.23 µg/mL. Furthermore, TPE-CMP has excellent selectivity in detecting Tc in the presence of various anti-interference analytes, including ions and antibiotics. In addition, the practical feasibilities of TPE-CMP for Tc sensing were further investigated in milk, urine and wastewater samples with satisfactory recoveries (from 94.96% to 112.53% for milk, from 96.41% to 99.31% for urine and from 98.54% to 100.52% for wastewater). We have designed and synthesized TPE-CMP based on heteroatom-free for the specific fluorescence detection of tetracycline, expanding the range of fluorescence detection sensors and offering great promise for practical applications.

Dendritic Hydrogels with Robust Inherent Antibacterial Properties for Promoting Bacteria-Infected Wound Healing.

Bacterial infections are a common problem associated with wound treatment that imposes a significant burden on healthcare systems and patients. As a result, healthcare providers urgently need new treatment strategies to protect people. Hydrogel biomaterials with inherent antimicrobial properties offer an attractive and viable solution to this issue. Here, for the first time, we have developed a new efficient synthetic strategy to prepare cationic hydrogels (PHCI) with intrinsically efficient antimicrobial properties by chemically cross-linking trans-1,4-cyclohexanediamine with 1,3-dibromo-2-propanol using a condensation reaction without the use of toxic cross-linking agents. As expected, the prepared PHCI hydrogel possessed an inherent antibacterial ability that can adsorb and kill Staphylococcus aureus and Escherichia coli electrostatically. Notably, in vivo experiments on normal and diabetic rat models confirmed that the PHCI hydrogel can quickly stop bleeding, efficiently kill bacteria, promote the conversion of macrophages from the proinflammatory M1 phenotype to the repaired M2 phenotype, and accelerate collagen deposition and blood vessel formation, thereby achieving rapid wound healing. Overall, this work presents an effective antibacterial dressing that might provide a facile but effective approach for clinical wound management.

Recent Advances in Design and Fabrication of Nanocomposites for Electromagnetic Wave Shielding and Absorbing.

Electromagnetic (EM) pollution has raised significant concerns to human health with the rapid development of electronic devices and wireless information technologies, and created adverse effects on the normal operation of the sensitive electronic apparatus. Notably, the EM absorbers with either dielectric loss or magnetic loss can hardly perform efficient absorption, which thereby limits their applications in the coming 5G era. In such a context, the hotspot materials reported recently, such as graphene, MXenes, and metal-organic frameworks (MOF)-derived materials, etc., have been explored and applied as EM absorbing and shielding materials owing to their tunable heterostructures, as well as the facile incorporation of both dielectric and magnetic components. In this review, we deliver a comprehensive literature survey according to the types of EM absorbing and shielding materials, and interpret the connectivity and regularity among them on the basis of absorbing mechanisms and microstructures. Finally, the challenges and the future prospects of the EM dissipating materials are also discussed accordingly.

Tetraphenylethylene-vitamin E Conjugates as sensitive aggregation-induced emission probes for selective detection of explosive FOX-7.

With the increasingly severe international security situation, the application of explosives is more and more extensive, and the probes that can detect the explosives quickly and efficiently have attracted people's attention. In this work, two novel probes T1 and T2 were synthesized through vitamin E succinate and tetraphenylethylene derivative. Fluorescence spectra showed that both T1 and T2 had a typical aggregation-induced emission (AIE) effect in THF/H2O solution, and explosive FOX-7 could effectively quench this fluorescence without being affected by other explosives or ions. The filter paper and cotton rods prepared with these two probes could detect FOX-7 specifically, which also provided the possibility for practical application on the battlefield.