High-efficiency Materials Research Articles

Two Facile Aniline-Based Hypercrosslinked Polymer Adsorbents for Highly Efficient Iodine Capture and Removal

Effective capture and safe disposal of radioactive iodine (129I or 131I) during nuclear power generation processes have always been a worldwide environmental concern. Low-cost and high-efficiency iodine removal materials are urgently needed. In this study, we synthesized two aniline-based hypercrosslinked polymers (AHCPs), AHCP-1 and AHCP-2, for iodine capture in both aqueous and gaseous phases. They are obtained by aniline polymerization through Friedel-Crafts alkylation and Scholl coupling reaction, respectively, with high chemical and thermal stability. Notably, AHCP-1 exhibits record-high static iodine adsorption (250 wt%) in aqueous solution. In the iodine vapor adsorption, AHCP-2 presents an excellent total iodine capture (596 wt%), surpassing the most reported amorphous polymer adsorbents. The rich primary amine groups of AHCPs promote the rapid physical capture of iodine from iodine water and iodine vapor. Intrinsic features such as low-cost preparation, good recyclability, as well as excellent performance in iodine capture indicate that the AHCPs can be used as potential candidates for the removal of iodine from radioactive wastewater and gas mixtures.

Bimetallic organic framework in situ fabrication nanoflower-like cobalt nickel sulfide and ultrathin layered double hydroxide arrays for high-efficient asymmetric hybrid supercapacitor

More and more attention has been attracted to regulate the morphology and structure of cobalt-nickel based compounds electrode materials through metal organic frameworks (MOFs) and explore the performance of the assembly them into asymmetric capacitors. In this study, NiCo-Metal organic framework derived carbon (NiCo-NC) is utilized as metal embedded template to in situ epitaxial fabricate nanoflower-like cobalt nickel sulfide (named NiCo2S4@NC) using alcohol heating in ethylene glycol sulfurization. Due to the dual electrochemical activity of NiCo2S4 and NiCo-NC, the NiCo2S4@NC multi-modal nanohybrid possesses a promising specific capacitance of 1021.6 F g−1 at 1 A g−1 in the voltage window of − 1 to 0 V. Besides, ultrathin cobalt nickel hydroxide nanosheets are in situ introduction on the surface of NC skeleton (NiCo-LDH@NC) with the help of absolute ethanol and L-ascorbic acid, which behave an excellent capacitance of 988.2 F g−1 (164.7 mA h g−1) at 1 A g−1, and exhibit an extraordinary charge-discharge stability. Due to the high conductivity of NC derived from NiCo-MOF, the appearance of more reaction sites after vulcanization and the specific hierarchical structure of cobalt nickel hydroxide, the assembled NiCo-LDH@NC//NiCo2S4@NC asymmetric supercapacitor device delivers a great energy density of 61.5 W h kg−1 (at 426.6 W kg−1) and pronounced cycle stability (retention of 92.7 % over 5000 cycles). This work provides a feasible strategy towards the practical application in supercapacitors using nickel cobalt multi-active centers with special morphology as high-efficiency and inexpensive electrode materials.

Lewis acidic molten salts etching route driven construction of double-layered MXene-Fe/carbon nanotube/silicone rubber composites for high-performance microwave absorption

Transition metal carbide/nitride (MXene) materials have triggered intensive research interest in the field of microwave absorption (MA). However, the complicated fabrication process and monotonous loss mechanism of MXene materials seriously hinder their practical applications. Here, we first developed a green and facile synthesis of dielectric-magnetic MXene-Fe nanocomposites via one-step Lewis acidic molten salts etching, which were combined with carbon nanotube (CNT) filler and silicone rubber (SR) matrix to fabricate double-layered MXene-Fe/CNT/SR composites by casting and curing. The in-situ growth magnetic Fe nanoparticles on MXene and unique double-layered structure composed of MXene-Fe/SR as the upper absorption layer and CNT/SR as the bottom reflection layer imparted the composites with excellent MA properties by offering appropriate impedance matching, strengthened internal reflection, polarization, magnetic loss, and conductive loss. Accordingly, the proposed double-layered composites showed superior MA properties compared with other MXene-based composites. The MXene-Fe-45%/CNT-5%/SR sample showed a reflection loss value of −65.9 dB at 12 GHz and an effective absorption bandwidth up to 8.24 GHz at 2.86 mm thickness. The double-layered composites exhibited tunable absorption frequency between the whole Ku-band and X-band by simply regulating the sample thicknesses and filler contents. These features indicate that the developed double-layered MXene-Fe/CNT/SR composites have great potential for high-performance MA applications. This study offers a novel and simple strategy to develop high-efficiency and broadband MA materials.

Preparation of Nylon-6 micro-nanofiber composite membranes with 3D uniform gradient structure for high-efficiency air filtration of ultrafine particles

Compared of traditional melt-blown nonwoven materials, micro-nanofiber composite membranes with uniform spatial gradient structure will be the development trend of high efficiency and low resistance filtration materials, especially against ultrafine particles with kinetic diameter less than 0.25 (PM0.25). Herein, Nylon-6 micro-nanofiber composite membranes (Nylon-6 FCMs) with three-dimensional (3D) uniform gradient structure were prepared by air jet spinning under the help of PEO. The fluffy 3D gradient structure possessed a uniform gradual pore gradient from large to small, ensuring the PM0.25 were captured by exact grading under high gas flow due to the form of special “trumpet-like” gas passage inside the membranes. The structure of Nylon-6 FCMs could be controlled and exhibited high tensile strength, good moisture permeability, excellent filtration performance. Among them, the FCM-1 with a uniform gradual pore gradient could achieve the optimal filtering performance with filtration efficiency (99.99 %) and pressure drop (144 Pa). The mask prepared using this Nylon-6 FCMs also displayed good protective effect with comparable air permeability (221.84 mm·s−1) and moisture permeability (181.84 g·m−2·h−1) compared of commercial melt-blown masks. Most importantly, this mask prepared still could maintain good filtration performance even in high temperature and high humidity environment, providing users more comfortable wearing experience and stable protection performance, especially under the current COVID-19 outbreak.

Precise Functionalization of a Multiple-Resonance Framework: Constructing Narrowband Organic Electroluminescent Materials with External Quantum Efficiency over 40.

It is of important strategic significance to develop high-efficiency narrowband organic electroluminescent materials that can be employed to fabricate ultrahigh-definition displays with wide color gamut. This topic implies a great challenge to molecular design and synthesis, especially for the development of universality, diversity, scalability, and robustness of molecular architectonics. In this work, a synthetic methodology is demonstrated for functionalizing brominated BN-containing multiple-resonance (MR) frameworks with multifarious functional groups, such as donors, acceptors, and moieties without obvious push-pull electron properties. The m-DPAcP-BNCz-based organic light-emitting diode (OLED) exhibits green emission with a full-width at half-maximum (FWHM) of 28nm and a maximum external quantum efficiency (EQE) of 40.6%. The outstanding performance of m-DPAcP-BNCz is attributed to the perfect integration of the inherent advantages of the MR framework and the donor-acceptor configuration, which can not only achieve bathochromic shift and narrowband emission, but also obtain high photoluminescence (PL) quantum yield (ΦPL ) and horizontal emitting dipole orientation ratio (Θ// ). This straightforward and efficient approach provides insightful guidance for the construction and enrichment of more high-efficiency narrowband emitters.

Insights into the pH-Dependent Adsorption Behavior of Ionic Dyes on Phosphoric Acid-Activated Biochar.

Activated biochar is a promising porous carbonaceous adsorbent material for organic pollutant removal, but it remains challenging to obtain high porosity and aromaticity through a simple and low-cost synthetic method. The common adsorption mechanisms of organic dyes on activated biochar should be further investigated in order to guide the synthesis of high-efficiency adsorbent materials. Here, we proposed a high-yield (up to 40 wt %) synthetic method of phosphoric acid-activated biochar from pomelo peel (PPC) with a high specific area of 877.3 m2/g through a facile thermal treatment at a relatively low temperature (250 °C). The specific activation mechanism of H3PO4 in the preparation of the adsorbent was investigated by a range of experiments and characterizations. The kinetic and isotherm experiments are also conducted to evaluate its dye adsorption behavior. According to the adsorption experiment results, PPC exhibits high saturated adsorption capacities for methyl orange (MO, 239.1 mg/g), rhodamine B (RhB, 2821.8 mg/g), methylene blue (MB, 580.5 mg/g), and crystal violate (CV, 396.6 mg/g) according to the Langmuir model. The maximum initial concentration of each dye solution for acquiring 90% removal efficiency is estimated to be 234.55 ppm (MO), 2943.8 ppm (RhB), 633.8 ppm (MB), and 423.6 ppm (CV) at 298 K with an adsorbent dosage of 1 g/L. The characterization results also indicate PPC has a complex synergetic mechanism for ionic dye adsorption behavior. This provides perspectives regarding PPC as a promising biochar adsorbent from biomass waste, which is probably useful for high-efficiency dye removal in water treatment.

A comparative cradle‐to‐gate life cycle assessment of carbon fiber‐reinforced polymer and steel‐reinforced bridges

AbstractCarbon fiber‐reinforced polymer (CFRP) has proven to be an excellent replacement for conventionally used steel in the construction industry. This is especially relevant in bridge engineering, where its corrosion resistance, low weight‐to‐strength ratio, and outstanding fatigue properties can be put to appropriate use, for example, to prestress the bridge girders. These properties are a huge part of the success of prestressed CFRP bridges, which tremendously increase the structural and material efficiency and hence help facilitate the construction of slender and durable bridges. However, apart from the structural performance of the bridges, the aspect of sustainability (environmental viability, economic feasibility, and social acceptance) plays a vital role in determining the overall efficiency. Prior studies have illustrated that the CFRP reinforcements in themselves are relatively unsustainable as compared to conventional steel reinforcements. However, owing to the extraordinarily high material efficiency generally associated with structures built with CFRP reinforcements, it can be hypothesized that these are equally or even more sustainable as compared to their counterparts. In this study, an aspect of sustainability, namely, environmental impact, is addressed. As a first part of the study, cradle‐to‐gate CO2 emissions for conventional building materials and CFRP have been thoroughly reviewed and documented. Attributed to the heterogeneity of the data available for CO2 emissions from CFRP reinforcements, three scenarios (favorable, realistic, and unfavorable) were drawn up. Based on these values, a comparative life cycle assessment was undertaken for two bridge systems, namely, Rosensteinsteg II (already constructed) and an overpass over German highway A‐20 (design in process). For each bridge system, two separate variants with steel and CFRP reinforcements were considered. For Rosensteinsteg II, a reduction of approximately 28% was observed in the CO2 emissions (favorable global warming potential values for CFRP) once the steel was replaced with prestressed CFRP. A total of 18% reduction was observed for the A‐20 bridge with CFRP reinforcements. With the help of the current study, it could be concluded that, especially for bridges not experiencing heavy vehicular loads, prestressed CFRP bridges are the most environmentally feasible option.

Achieving excellent electromagnetic wave absorption property by constructing VO2 coated biomass carbon heterostructures

Lightweight, high-efficiency and low-cost electromagnetic wave absorption (EMA) material is playing an increasingly critical role in the areas of mobile communications, electronic machines and military science and technology. Heterostructures of biomass-derived porous carbon (BPC) from chestnut needle coated by VO 2 were constructed. Microstructure, morphology as well as EMA performance of as-prepared VO 2 /BPC composites were explored. The special porous structure of BPC-based composites boosted multi-reflections and scattering of EM wave. The higher surface area provided more channels for charge transfer, benefiting the dissipation of EM wave energy. The formed VO 2 was uniformly dispersed in BPC matrix resulting in more polarization loss. Additionally, the reduzate of VO 2 improved the impedance matching further optimizing the EMA performance immensely. With the joint action of excellent impedance matching and attenuation capacity, the VO 2 /BPC composites exhibited favorable EMA performance that the minimum reflection loss of −54.0 dB was achieved with wide effective absorption bandwidth of 2.5 GHz. The obtained results suggest the VO 2 /BPC composites would be a hopeful candidate for high-efficient, lightweight and green EMA material. • Preparation of EMA materials derived from natural biomass carbon. • Improved EMA performance was achieved that RL min was −54 dB. • The impedance matching and polarization loss was enhanced drastically by introduction of VO 2 . • The EMA mechanism was investigated.

Preparation and photocatalytic properties of Bi2MO6 (M =W, Mo) semiconductor composite TiO2 nanowires

Photocatalytic degradation of pollutants using nano-TiO2 is one of the most promising strategies to solve environmental pollution problems. In this paper, we systematically studied Bi2WO6 composited TiO2 nanowires to obtain the optimum composite proportion. Moreover, the TiO2 nanowires were composited with Bi2MoO6 and Bi2WO6/ Bi2MoO6 in the optimum proportion, respectively. The results showed that the Bi2WO6/ Bi2MoO6 composited TiO2 nanowires had the best catalytic performance, and the degradation rate of methyl orange reached 78.4%, which was 3.41 times higher than that of pure TiO2 nanowires. The current work is expected to provide new ideas for the research and development of high-efficiency photocatalytic materials.

Printable high-efficiency organic ionic photovoltaic materials discovered by high-throughput first-principle calculations.

Printable solar cells are promising for low cost and large-scale production. As the two main classes of printable solar cells, organic and perovskite solar cells show distinct advantages and apparent drawbacks. The latter stand as major obstacle toward their commercialization. It is amazing if the advantages of organic and perovskite solar cells are integrated since some of them are complementary. Here, we report ionic-type high-efficiency photovoltaic materials which achieve this goal. We explore 46,388 organic materials from the Crystallography Open Database by extensive quantum mechanical calculations. Through photovoltaic-functionality-directed materials screening, we identify 5 organic ionic-type photovoltaic materials. They show the merits of nontoxic, high dielectric constant (27.03), high theoretical efficiency (28.7%), and superior thermal stability. Our findings propose ionic-type photovoltaic materials, which may surpass traditional organic and perovskite materials and open the door to next-generation printable solar cells.

Manipulation of the thermal conductivity for two-phase WC-Ni composites through a microstructure-based model along with key experiments

Thermal conductivity, one of critical properties for composite materials, constitutes an indispensable part of high-efficient materials design. However, a quantitative model to describe the thermal conductivity of two-phase composites has yet to be developed. In this work, we proposed an effective evaluation framework of a microstructure-based thermal conductivity model with key inputs from CALPHAD-type approach. Two-phase WC-Ni composites with Ni–W solid-solution matrix were used as the target system to validate this framework combined with key thermal conductivity measurements. Calculated thermal conductivities agree well with experimental results within the experimental error of 10%. Applying this well-established framework, thermal conductivities depending on wide ranges of temperature, WC grain size (dWC), and phase constitution are predicted, suggesting some unique features. The thermal conductivity becomes less dependent on dWC when dWC is >3 μm. Additionally, the thermal conductivity of nano-sized WC-Ni shows a quite different temperature-dependent variation tendency in contrast to that of micron-sized WC-Ni. These correlations are found and quantitatively described in the present work. Furthermore, the thermal conductivity for WC-Ni carbide rolls is predicted by the established framework, demonstrating a high accuracy. The present work is expected to guide the design of composite materials with desirable thermal properties efficiently.

Efficient Removal of Inorganic and Organic Pollutants over a NiCo2O4@MOF-801@MIL88A Photocatalyst: The Significance of Ternary Heterojunction Engineering.

Energy problems are a substantial concern in a global society that can be solved by replacing with sustainable energies. In recent years, designing nanomaterials as photocatalysts that can produce chemical energy with the utilization of infinite visible light energy became a new solution for water treatment. In the present study, NiCo2O4@MOF-801 has been synthesized with multiple properties, and then, a novel three-layer NiCo2O4@MOF-801@MIL88A photocatalyst has been successfully synthesized to improve meropenem degradation and Cr(VI) reduction. The prepared photocatalyst was characterized by XRD, IR, XPS, TEM, SEM, TGA, BET, EIS, PL, and UV-vis. According to the structural and optical analysis performed, the interaction between the components formed a heterojunction structure that prevented the recombination of charge carriers and increased the photocatalytic performance. Photocatalytic simulation tests also proved the reduction of chromium and degradation of antibiotics to find the optimal heterogeneous performance. As a result, the NiCo2O4@MOF-801@MIL88A composite can completely reduce Cr(VI) in 45 min, which is strongly preferable to any pure component's performance. Overall, this work offers a low-cost but high-efficiency material that can remove organic and inorganic contaminants from water.

Mg/Ti doping co-promoted high-performance P2-Na0.67Ni0.28Mg0.05Mn0.62Ti0.05O2 for sodium-ion batteries

Transition-metal layered oxides (such as P2-Na2/3Ni1/3Mn2/3O2) are suggested as one type of the most potential cathode candidates for sodium ion batteries (SIBs) owing to their high capacity and low cost; however, they suffer from the structural damage and sluggish Na+ kinetics resulting from the undesirable phase transformation of P2−O2 and the Na+/vacancy ordering, respectively. Herein, a Mg/Ti co-doped P2-Na0.67Ni0.28Mg0.05Mn0.62Ti0.05O2 layered oxide is demonstrated as a high-efficiency cathode material for SIBs. The cathode delivers a high reversible capacity of 135.5 mAh g−1, good cycling stability (82.7 mAh g−1 upon 100 cycles at 0.1C), and an attractive energy density of 479.4 Wh Kg−1. Furthermore, the phase transition from the undesirable P2−O2 to the reversible P2−OP4 demonstrated by in situ XRD and the partially suppressed Na+/vacancy ordering as well as the improved electronic and ionic conductivities all give rise to the enhancement. These results show the important role of cationic co-doping in designing and preparing high-efficiency layered oxide cathode materials for SIBs.

Efficient and facile preparation of pure silica CHA zeolite membranes by gel-less method

To bring zeolite membranes to commercial application, corresponding preparation technology must solve the following issues like low permeance, poor reproducibility, high manufacturing cost and scale-up etc., which is still a grand challenge. The imhomogeneous slurry-like mother liquor required by the preparation of pure silica CHA membrane makes this challenge even tougher. Herein, we realized facile and efficient preparation of pure silica CHA membrane for the first time. The use of an active silica source, ammonium hexafluorosilicate ((NH4)2SiF6), enabled facile membrane synthesis in a homogeneous mother liquor at mild temperature and ambient pressure. The replacement of conventional imhomogeneous slurry-like mother liquor with homogeneous mother liqour significantly improved the reproducibility of membrane synthesis and favored the formation of thin membrane. The high activity of (NH4)2SiF6 allowed low temperature synthesis at ambient pressure without sacrificing synthesis time. Moreover, gel-less synthesis significantly reduced material waste at no cost of selectivity and permeance. All these factors combined together resulted into a facile and reproducible preparation of thin pure silica CHA membrane with high material efficiency, energy efficiency and low equipment cost. Calcined pure silica CHA membrane exhibited outstanding CO2 permence of 2.9 × 10−6mol/(m2⋅s⋅Pa) and high CO2–CH4 selectivity ∼170. This efficient and facile preparation method has great potential for large scale synthesis.

Z-scheme Bi4O5Br2/MIL-88B(Fe) heterojunction for boosting visible light catalytic oxidation of tetracycline hydrochloride

Bi4O5Br2/MIL-88B(Fe) Z-scheme heterojunction photocatalyst is fabricated by a facile hydrothermal followed by a coprecipitation method. The heterojunction catalyst greatly improved the visible light utilization and has shown excellent photodegradation performance for tetracycline hydrochloride (TCH). The high oxidation capability, unique charge migration, and enhanced photogenerated charge carrier separation of Z-scheme Bi4O5Br2/MIL-88B(Fe) heterojunction simultaneously contributed to improved catalytic performance. Meanwhile, Z-scheme Bi4O5Br2/MIL-88B(Fe) heterojunction has achieved the highest photodegradation of TCH with ∼93.04 % within 80 min. In addition, the time-resolved photoluminescence (PL) emission decay spectra confirmed a prolonged lifetime of electron excitation with a fluorescence lifetime of ∼1.08 ns compared with Bi4O5Br2 (t = 0.95 ns). Furthermore, following operating conditions, such as pH, solution concentration, various ionic species, etc., the Bi4O5Br2/MIL-88B(Fe) heterojunction has shown excellent photodegradation of TCH in various environmental conditions with high photostability. Additionally, a substantial charge transfer mechanism and TCH photodegradation pathway were explained. This work demonstrates a promising approach to constructing other high-efficiency Z-scheme heterojunction materials for wastewater treatments.

Highly efficient stable blue organic light-emitting diodes based on a novel anthracene[2,3-b]benzofuran framework

Organic blue fluorescent emitters’ emissions are highly desirable for high-resolution organic light-emitting diode (OLED) display technology. In this work, a design strategy to realize narrowband emission of organic blue fluorescent emitters by connecting carbazole and amine, named ABFCz and ABFAn, respectively, with anthracene[2,3-b]benzofuran as rigid groups is reported for the first time. The developed materials can achieve high efficiency and long life. Studies of the doped devices show that ABFCz-based blue-emitting OLEDs achieve a maximum current efficiency of 6.96 cd A−1 with a narrow full width at half maximum (FWHM) of 44 nm, as well as a Commission Internationale de l’Eclairage (CIE) coordinate of (0.15, 0.14). A maximum external quantum efficiency (EQEmax) of 7.7% is also achieved. Meanwhile, the ABFAn emitter-based devices exhibit blue emission with a maximum current efficiency of up to 9.20 cd A−1 (EQEmax of 11.4%) with a FWHM of 44 nm, as well as a CIE coordinate of (0.14, 0.13). The devices are based on an ABFAn operating lifetime test LT90 (luminance decays to 90% of the initial brightness) of 202 h at an initial luminance of 1000 cd m−2. The results show that anthracene[2,3-b]benzofuran can be modified with a higher glass transition temperature (T g) to achieve high-efficiency and stable-operating-lifetime blue light devices. Our work may provide a new approach for designing high-efficiency blue materials.

Electro-adsorption of Sr(II) from aqueous solution by activated carbon cloth/nickel hexacyanoferrate composite electrode through capacitive deionization

The activated carbon cloth/nickel hexacyanoferrate (ACC/NiHCF) electrode was successfully synthesized by a co-precipitation method, and the performance was comprehensively evaluated as CDI electrode materials for Sr2+ removal. The as-prepared ACC/NiHCF electrode had the mesoporous and the coordination framework structure, which provided convenient transport channels for ions or electrons. As a result, the ACC/NiHCF electrode exhibited the high Sr2+ removal efficiency. The maximum removal efficiency was 77.20% at 0.6 V in 5 mg L−1 SrCl2 solution, much higher that of pristine ACC. The isotherm models and mass transfer models suggested that the adsorption process of Sr2+ onto ACC/NiHCF was mainly through the multi-layer adsorption, and adsorption onto the active sites was the main rate-limiting step. In addition, the comprehensive characterizations elaborated the mechanism involved physic-chemical adsorption and electrostatic adsorption. Above all, ACC/NiHCF is an efficient electrode for Sr2+ removal. This study provided new insight into the fabrication of high-efficiency composite electrode materials for Sr2+ removal by CDI.

Water-soluble multifunctional red luminescent materials constructed by macrocycle–ligand–lanthanide synergetic assembly strategy

The high-efficiency red luminescent materials in water are attractive in the field of luminescent materials. In particular, those red luminescent materials with multifunctional intelligent responsiveness and good stability are very challenging and important. In this work, a purplish red emission is achieved by a synergetic supramolecular amphiphilic assembly strategy based on the water-soluble macrocyclic calixpyridinium, the bidentate ligand bathophenanthrolinedisulfonic acid disodium salt (BPhDS) and the lanthanide Eu3+. BPhDS and Eu3+ could only form a simple complex emitting a purplish blue fluorescence. Calixpyridinium and BPhDS could construct a spherical assembly. Benefitting from its pH-responsive fluorescence emission, by precise fine-tuning of its pH, a perfect white light emission was obtained and applied in a fluorescent ink. White light is an ideal light source because it has a perfect color reproducibility and stability. More excitingly, a purplish red emission is achieved by calixpyridinium-assisted amphiphilic assembly of non-red emissive BPhDS−Eu3+ complex in water. It paves a new way to construct the high-efficiency red luminescent material based on a lanthanide complex in water and exhibits many advantages: (1) all the assembly components are easy-to-get and the synergetic assembly process is very simple; (2) the supramolecular amphiphilic assembly has a synergetic effect on the luminescence of lanthanide complex in water: the natural hydrophobic inner of the assembly can expel the water molecules around lanthanide complexes and reduce the number of coordination water; the binding of the ligand by macrocycle can limit its rotation, increase its rigidity and reduce its energy loss; the synergetic assembly can shorten the distance of donor–acceptor complexes and enhance their energy transfer efficiency; (3) although the luminescent material does not contain any responsive site, the multiple weak and therefore reversible non-covalent interactions endow it with many intelligent responsiveness in various applications, such as temperature-controlled switch, anti-counterfeit material, and confidential material.

ZIF-67 Derived Co-Ni/C Composites for High-Efficiency Broadband Microwave Absorption

The development of broadband and high-efficiency broadband microwave-absorbing materials is one of the keys to resisting electromagnetic radiation and electromagnetic interference. In this paper, we used zeolitic imidazolate framework-67 (ZIF-67) as the template to obtain Ni-doped ZIF-67 via Ni(NO3)2 etching followed by pyrolysis to prepare Co-Ni/C composites successfully. The morphology and microstructure of Co-Ni/C composites can be well-tuned by altering the Ni doping content. ZIF-67-derived Co-Ni/C porous materials exhibit extremely strong microwave absorption performance thanks to dielectric loss, magnetic loss, and the synergistic effect between different components. When the dosage of Ni(NO3)2 used reaches 0.32 g, the obtained composite possesses the optimal absorbing properties with a maximum reflection loss (RL) of −72.88 dB and an effective bandwidth (fe, representing RL ≤ −10 dB) of 7.04 GHz (9.76–16.8 GHz) corresponding to a thickness of 2.53 mm. The results of this work indicate that Co-Ni/C composites have potential application value in the field of microwave absorption.

Hierarchical core-shell FeS2/Fe7S8@C microspheres embedded into interconnected graphene framework for high-efficiency microwave attenuation

With the imminent era dominated by high-tech electronic products, the development of high-efficiency electromagnetic wave absorption materials has become a critical task. Rational component regulation and structural design are considered to be effective methods to optimize the electromagnetic wave absorption performance of materials. Herein, we first prepared a Fe-PBA@ PDA@GO precursor via solvothermal method; then, vulcanization was used to develop a FeS2/Fe7S8@C@rGO composite with a core-shell heterostructure, in which core-shell FeS2/Fe7S8@C microspheres were embedded on the wrinkled reduced graphene oxide layer. FeS2/Fe7S8@C@rGO, as a multi-component composite, demonstrates superior impedance matching and can thus capture more electromagnetic waves, while the multiple losses facilitate the dissipation of incident electromagnetic waves. Concretely, FeS2/Fe7S8@C@rGO can display significant attenuation of incident electromagnetic waves through multi-interface polarization, dipole polarization, resonance loss and eddy current loss. Additionally, the three-dimensional hierarchical structure not only improves the conductive loss, but also promotes multiple reflections and scattering. The FeS2/Fe7S8@C@rGO composite exhibits a minimum reflection loss of −62.7 dB and an effective absorption broadband (6.1 GHz) with a filler loading of 20 wt% at 2.2 mm, and the effective absorption bandwidth reaches 7.6 GHz at a layer thickness of 2.5 mm. These results provide a valuable reference for the preparation of high-performance microwave absorbers through composition adjustment and controlled structural design.