Excellent Absorption Performance Research Articles

Robust superhydrophobic fabrics: Rapid preparation and outstanding photothermal-induced performance

Developing material that can separate oil-water mixture and absorb spilled crude oil efficiently has become a pressing challenge. To this end, we prepared a polydopamine@octamine nano-capsules based superhydrophobic fabric with photothermal effect rapidly using UV-assisted preparation. The prepared superhydrophobic fabric exhibits excellent photothermal-induced oil absorption and oil-water separation performance. Not only oils with low viscosity can be absorbed efficiently, but also oils with high viscosity can be absorbed quickly. POS fabric could absorb crude oil up to 6.5 times of its own weight. The oil-water separation efficiency and flux could reach more than 98.8 % and 16,900 L·m−2·h−1, respectively. Moreover, the separation efficiency remained unchanged even after 50 separation cycles while the separation flux rose gradually with the increase of oil-water separation cycle. Meanwhile, the as-prepared superhydrophobic fabric reveals outstanding durability and stability. It maintains superhydrophobic performance even after exposed to various harsh conditions such as acids, alkalis, salts, organic solvents, UV light, and mechanical abrasion. Additionally, the fabric has outstanding self-healing ability and which can extend its service life. Therefore, this simple, fast, and environment-friendly preparation method together with the excellent performance of resultant materials is expected to have broad application prospects in the treatment of oily wastewater and offshore crude oil spills.

Down-film as a new non-frame porous material for sound absorption

Down-polyethylene film material has been introduced for the first time as an excellent non-frame sound absorber, showing a distinctively outstanding performance. It contains down fiber adjacent to each other without firm connection in between, forming a structure of elastic fiber network. The unique structure has broadband response to sound wave, showing non-synchronous vibration in low and middle frequency and synchronous vibration in middle and high frequency. The broadband resonance in middle and high frequency allows the structure to achieve complete sound absorption in resonance frequency band. Moreover, down-polyethylene film material possesses forced vibration, corresponding sound absorption coefficient has been obtained based on vibration theory. The down-film sound absorption material has the characteristics of light weight, soft, environment-friendly, and has excellent broadband sound absorption performance.

Sound absorber based on a sonic black hole and multi-layer micro-perforated panels

In order to achieve low-frequency and broadband sound absorption simultaneously, we propose a structure that combines a sonic black hole with multilayer micro-perforated panels. Firstly, we present finite element models for composite structures based on sonic black holes and micro-perforated panels and describe the sound absorption mechanism of the composite structure by comparing the sound absorption phenomena of micro-perforated panels with sonic black holes and micro-perforated panels with ordinary circular tubes. Secondly, the effects of the end coordinates of the sonic black hole, the number of panels and the parameters of the micro-perforated panels are discussed. Thirdly, the theoretical model of the proposed structure is developed using the transfer matrix method. Finally, the sound absorption test of the proposed structure is carried out using impedance tubes. The test results show that the sound absorption coefficient of the sample with a geometric length of 203 mm reaches 0.8 at 223 Hz and stabilizes above 0.9 at 398–1600 Hz. The sound absorber based on a sonic black hole and multi-layer micro-perforated panels has excellent sound absorption performance and has great research potential and application value.

Molecular Intercalation‐Induced Two‐Phase Evolution Engineering of 1T and 2H‐MS2 (M = Mo, V, W) for Interface‐Polarization‐Enhanced Electromagnetic Absorbers

AbstractPolarization at interfaces is an important loss mechanism for electromagnetic wave (EMW) attenuation, though the motion behavior of carriers in interfaces composed of different types of conductors has yet to be investigated. Tuning the phase structure of transition metal dichalcogenides (TMDs) MS2 (M = Mo, V, W) by organics small molecule intercalation to achieve the modulation of interfacial types is an effective strategy, where 1T‐MS2 exhibits metallic properties and 2H‐MS2 has semiconducting properties. To exclude the contribution of the intrinsic properties of TMDs materials, three TMDs (MoS2, VS2, and WS2), which also possess phase transitions, are investigated. Among them, the 1T‐MS2 composite exhibits excellent EMW absorption performance under the synergistic effect of interfacial polarization and conduction loss. 1T‐MoS2/MOF‐A exhibits the best EMW absorption performance with an RLmin of −61.07 dB at a thickness of 3.0 mm and an EAB of 7.2 GHz at 2.3 mm. The effectiveness of the modulation of the interfacial polarization using 1T‐phase and 2H‐phase MS2 is demonstrated, which is important for the analysis of the carrier motion behavior during the interfacial loss.

Enhanced electromagnetic wave absorption of magnetite-spinach derived carbon composite

The high density, high cost, and environmental pollution hinder the application of iron-based electromagnetic wave-absorbing materials. Although bio-carbon is a green and lightweight dielectric wave-absorbing material, the wave-absorbing performance of bio-carbon is still limited. This work successfully combined magnetite Fe3O4 with porous carbon derived from spinach stem using hydrothermal and calcination methods. This process optimizes the matching of the dielectric constant and magnetoconductivity of the as prepared composite material, resulting in a significant improvement in electromagnetic microwave absorption capacity. XRD, SEM, TEM, XPS, VSM and EMW absorption network analyzer are used to detect and characterize the samples. The composite material shows a excellent minimum reflection loss value of −48.81 dB and an efficacious absorption bandwidth of 4.73 GHz at the optimal raw material ratio. The tests also show the porous structure of the sample with the coercivity and saturation magnetization of 29.36 Oe and 10.75 emu/g, respectively. The test results indicate that the excellent electromagnetic wave absorption is due to the synergistic effect of multiple reflection, Debye relaxation, and interfacial polarization. This Fe3O4-bio-carbon composite is cheap and simple to prepare, and it also has excellent wave absorption performance. Therefore, it shows great application potential in civilian and military electromagnetic wave absorption fields.

Simultaneously enhanced the sound absorption coefficient and dimensional stability of Carboxymethyl cellulose/clay aerogel by impregnating polyurethane

Carboxymethyl cellulose (CMC) aerogel could be used in the manufacture of highly efficient sound-absorbing materials because of its low density and sustainability. However, owing to its low mechanical strength and brittleness, preparing porous sound absorption materials with excellent sound absorption performance has always been a challenging problem. Herein, carboxymethyl cellulose/organic exfoliation of montmorillonite/thermoplastic polyurethane (CMC/OMMT/TPU) composite aerogels were successfully obtained via a simple impregnation and freeze-drying process. The effect of TPU and OMMT on the sound absorption properties of cellulose aerogels was detailedly discussed. The results revealed that the CMC/OMMT/TPU composite aerogel had hierarchically porous structures, and the sound absorption performance was significantly improved. The average sound absorption coefficient of CMC/OMMT/TPU composite aerogel could reach as high as 0.807 (500–6500 Hz). The main reason for this improvement is caused by the multiple scattering of sound waves on the arranged porous surface, as well as the viscous damping of the air inside the structure between the TPU, CMC and OMMT. Furthermore, the dimensional stability of the prepared aerogel is also greatly enhanced after using TPU. This work provides a new approach for the development of aerogel with stable morphology and sound absorption performance, which would be widely used in construction and military fields.

Synthesis of Ti3C2Tx-MXene/PAN-derived double-loss Co/CeO2/TiO2/CNFs nanocomposites for enhanced microwave absorption performance

With the advancement of wireless communication and electronic equipment, microwave absorption materials (MAMs) have more and more broad applications in related fields. Ti3C2Tx-MXene with unique two-dimensional structure and excellent dielectric properties is often used as a precursor of nano-TiO2, which is a potential MAMs. Carbon nanofibers, as a one-dimensional material, have great electrical conductivity and can form interconnected three-dimensional conductive networks. In this study, Ti3C2Tx-MXene was prepared by in-situ HF etching method, and further combined with the benefits of Co, Ce metals, and carbon nanofibers. Co/CeO2/TiO2/CNFs were prepared via a facile technique for electromagnetic microwave (EM) absorption, exhibiting excellent EM absorption performance due to the synergistic effects of dielectric and magnetic properties. The minimum reflection loss (RLmin) and effective absorption bandwidth (EAB) reache -63.35 dB (11.2 GHz) and 3.6 GHz (9.5-13.1 GHz), with a thickness of only 2.35 mm and a filling rate of 30 wt.%, while the maximum EAB reaches 5.4 GHz (12.4-17.8 GHz) with a thickness of 1.82 mm, covering nearly the entire Ku band. By offering a novel strategy to the creation of brand-new, high-performance MAMs based on 1D carbon nanofibers with dielectric/magnetic synergy, this work is believed to support the development of upcoming MAMs.

Two novel silicon allotropes in monoclinic phase

Two new monoclinic silicon allotropes P2/m Si54 and V-Silicon are proposed. Mechanical, thermal and dynamic stability of P2/m Si54 and V-Silicon were verified by elastic constants, (AIMD) simulations and phonon spectra. The enthalpy of V-Silicon exceeds that of diamond Si by only 0.04 eV/atom, which indicates that it has excellent stability. V-Silicon has an indirect band gap with a band gap of 1.00 eV, P2/m Si54 has a quasi-direct band gap with a band gap of 0.60 eV. Additionally, P2/m Si54 and V-Silicon show excellent light absorption performance in different wavelength ranges in the visible region.

A unidirectional water-transport antibacterial bilayer nanofibrous dressing based on chitosan for accelerating wound healing

Excessive accumulation of exudate from wounds often causes infection and hinders skin regeneration. To handle wound exudate quickly and prevent infection, we developed an antibacterial Janus nanofibrous dressing with a unidirectional water-transport function. The dressing consists of a hydrophilic chitosan aerogel (CS-A) as the outer layer and a hydrophobic laurylated chitosan (La-CS) nanofibrous membrane as the inner layer. These dressings achieved excellent liquid absorption performance (2987.8 ± 123.5 %), air and moisture permeability (997.8 ± 23.1 g/m2/day) and mechanical strength (5.1 ± 2.6 MPa). This performance was obtained by adjusting the density of CS-A and the thickness of the La-CS membrane. Moreover, the dressing did not induce significant toxicity to cells and can prevent bacterial aggregation and infection at the wound site. Animal experiments showed that the dressing can shorten the inflammatory phase, enhance blood vessel generation, and accelerate collagen deposition, thus promoting wound healing. Overall, these results suggest that this Janus dressing is a promising material for clinical wound care.

Ion gradient induced self-powered flexible strain sensor

To cope with energy hazards and reduce frequent battery replacement of strain sensors, various self-powered flexible strain sensors (including piezoelectric, triboelectric and electrochemical types) have developed recent years. However, the piezoelectric and triboelectric strain sensors cannot monitor static strain, and electrochemical strain sensors face the problem of performance degradation. Herein, inspired by ion gradient generators, a self-powered flexible strain sensor based on strain regulated ion gradient strategy is constructed. The sensor consists of elastic yarn coated with carbon nanotubes (CNTs), LiCl-filter paper (FP) and latex tube encapsulation. LiCl-FP with excellent water molecules absorption performance is wrapped on one side of the elastic yarn, forming a high humidity region in the sensor. The part of the elastic yarn that is not covered by LiCl-FP has weak water molecules absorption performance, forming a low humidity region in the sensor. The ions in the sensor move directionally from the high humidity region to the low humidity region, forming an ion gradient and generating voltage/current. The test results indicate that the sensor exhibits a wide strain detection range (0.5%–100%) and good repeatability (1000 times). The strain sensing mechanism can be attributed to the strain regulated ion gradient and the resistance strain effect. In addition, the strain sensing function of the sensor is verified by monitoring respiration. This work opens a new avenue for development of self-powered strain sensor using strain regulated ion gradient.

Controlled growth of polyaniline nanofibers on the surface of alkali pre-treated PI fabric as electromagnetic wave-absorbing fabrics

The electromagnetic wave attenuation network composed of PANI NFs is an efficient wave-absorbing structure. Constructing PANI NFs networks on the surface of flexible fabrics is a potential approach to improve the wave-absorbing properties of fabrics, but there are few related reports on this. In this paper, we proposed a facile method to grow PANI NFs (average diameter of 80–100 nm) on the polyimide (PI) fabric surface through a controlled nucleation and growth process. The results of FESEM, FTIR, XPS, and UV–vis indicated that the PANI and PI may first combine at the initial nucleation centers through electrostatic interactions, hydrogen bonding, and π-π stacking, and then the PANI grows linearly into elongated nanofibers under suitable polymerization conditions. As expected, the PANI NFs coated fabric achieved a strong reflection loss (RL) of -34.20 dB (>99.999 % absorption) and a broad effective absorption frequency band of 5–18 GHz. The excellent absorption performance originated from the conduction loss, scattering loss, and polarization relaxation loss of the PANI NFs network. In addition, the fabric exhibits good thermal stability (Td beyond 570 °C) and long-term stability ((90.57 % retention of conductivity after 500 bending cycles). This study provides a viable approach for designing next-generation microwave-absorbing fabric.

Influence of water on the properties of hydrophobic deep eutectic solvent

Deep eutectic solvent (DES) shows excellent absorption performance in the field of CO2 capture. It is considered as a new green absorption solvent to replace monoethanolamine. In the industry, the presence of water not only affects the structural stability of the solvent, but also affects its thermophysical properties. In this work, three kinds of hydrophobic DES were prepared. Based on the study of their structural characteristics and thermal stability, the density and viscosity of DES with water mixture were measured in the temperature range of 298.15 ∼ 338.15 K at atmospheric pressure. It was demonstrated that the trace water did not destroy the structure of DES, but it formed hydrogen bonds with DES. The increase water destroyed the structure of DES and formed hydrogen bonds with hydrogen bond donor (HBD) and hydrogen bond acceptor (HBA), respectively. Moreover, the hard sphere model was applied to study the viscosity, and after introducing the binary interaction parameter, the average absolute relative deviation of the mixture reduced to 4.4 ∼ 7.7 %.

CO2 capture performance of a 1-dimethylamino-2-propanol/N-(2-hydroxyethyl) ethylenediamine biphasic solvent

Biphasic solvents are widely used for CO2 capture owing to their low regeneration heats; however, they typically suffer from poor regeneration performance and excessive energy consumption. In this study, a mixture of 1-dimethylamino-2-propanol (1DMA2P) and N-(2-hydroxyethyl) ethylenediamine (AEEA) was proposed for CO2 capture. By optimizing the 1DMA2P and AEEA concentrations, this biphasic solvent achieved superior phase separation and excellent absorption and regeneration performance. The proportion of CO2-rich phase was 66.67 %, with a CO2-rich phase loading of up to 5.07 mol/L. The desorption rate was improved by 106.7 % compared to that of conventional 5 mol/L monoethanolamine, and the regeneration efficiency up to 71.8 % in 60 min. Initially, CO2 reacted with AEEA at a faster rate to form a carbamate product. Subsequently, 1DMA2P acted as a proton acceptor, facilitating the formation of bicarbonates and carbonates. Nuclear magnetic resonance analysis indicated that the reaction products (AEEACOO-, AEEAH+, and HCO3–/CO32–) migrated to one phase, whereas 1DMA2P and any unreacted AEEA migrated to the other phase. Additionally, the disparity in polarity between the reactants and reaction products constituted the primary determinant for the phase transition. Notably, the regeneration heat of the 1DMA2P/AEEA biphasic solvent (1.83 GJ/t CO2) was approximately 54.1 % lower than that of conventional 5 mol/L monoethanolamine. Owing to its superior absorption properties, excellent regeneration performance, and low regeneration heat, the 1DMA2P/AEEA biphasic solvent is a promising candidate for practical CO2 capture systems.

Study on Sound Absorption Properties of Polyvinyl Chloride (PVC) Film Multicavity Structure Materials

Since the development of industry, sound absorption and noise reduction have gradually become an urgent problem to be solved. Lightweight polymer film materials are very effective in response to sound waves, and sound waves can easily cause vibration of the film, which can convert sound energy into vibration and film friction to achieve sound absorption. The application conditions of the film material are very harsh, that is, a support body is required to fix the film and the film needs to be tensioned. The film is very thin and easy to damage. The idea of this research is to transform the film into a bubble structure and use a large number of film bubbles to form a cavity structure material. As a unit of the sound absorption structure, bubbles can avoid damage to the film. In this paper, commercial polyvinyl chloride film bubble materials are used to prepare two kinds of film multicavity structure materials, and the sound absorption performance of this film multicavity structure material is studied. The research results show that this film multicavity structure material has very excellent broadband sound absorption performance, which changes the narrow band sound absorption properties of the usual film single cavity. The average sound absorption coefficient can reach 0.84 in frequency range from 500 Hz to 6400 Hz. This structural material has a single peak sound absorption curve at the middle and low frequency bands, which is the characteristic of resonance sound absorption. And at the middle and high frequency bands, it exhibits the characteristics of broadband sound absorption. The film multicavity structure material has both cavity sound absorption and broadband sound absorption characteristics.

Enhanced anti-corrosion and microwave absorption performance of coating with TiO2-wrapped carbonyl iron-modified composites

The magnetic microwave absorption (MA) materials are prone to corrosion in high temperature and high humidity environments, leading to a deterioration in the MA performance, so, the development of composite coatings with comprehensive properties such as excellent absorption performance, corrosion resistance, and oxidation resistance holds significant importance in the field of stealth technology. In this study, a core-shell structure MA materials titanium dioxide coated carbonyl iron particle (CIP@TiO2) was prepared and utilized as a filler in the preparation of composite coatings. The results show that the low-frequency impedance modulus of composite coating improves by three orders of magnitude from 4.5 × 105 Ω cm2 to 2.5 × 108 Ω cm2, demonstrating outstanding corrosion resistance. The TiO2 shell not only improves CIP's electromagnetic parameters but also optimizes the impedance matching of the composite material. The CIP@TiO2 coating achieves a minimum reflection loss of −56.8 dB at a thickness of 1.2 mm and an effective bandwidth of 6.57 GHz at a thickness of 0.6 mm, demonstrating excellent absorption performance. This study provides a novel approach for preparing composite materials with superior corrosion-resistant and absorptive properties.

Enhancing electromagnetic properties in nickel hydroxide modified graphene composites via secondary reactions for improving multi-polarization electromagnetic absorption efficiency

Carbon-based materials exhibit excellent dielectric absorption properties, among which graphene has received particular attention in research of electromagnetic wave absorbing materials because of its high electrical conductivity and unique large-area, thin-layer two-dimensional structural features. However, the electromagnetic absorption performance of the material is hindered from further improvement due to its single component composition. It is influenced by the conductive network of graphene, making it challenging to achieve a balance in impedance matching and electromagnetic loss, thereby restricting its broader application. To address these challenges, we developed a series of nickel hydroxide-modified graphene composites. Through a structural composite design, we optimized overall impedance matching, introduced diverse loss mechanisms to enhance electromagnetic loss performance, and utilized a secondary reaction control method to precisely regulate the deposition of nickel hydroxide on the graphene surface, thereby achieving regulate of the composite material's electromagnetic parameters within a defined range. Under low sample filling ratios and a thin sample thickness of 1.8 mm, the effective absorption bandwidth reaches 6.5 GHz, demonstrating excellent electromagnetic absorption performance. This study provides a controllable design approach for modulating material electromagnetic parameters by influencing the reaction process. It also offers a design method for composites with an outstanding electromagnetic loss mechanism.

Ultralight and strain-sensitive bacterial cellulose derived carbon fiber-reinforced graphene aerogel for broadband sound absorption

The growing severity of urban noise pollution poses a threat to the physical and mental health of residents, prompting the need for the development of effective sound-absorbing materials. Herein, we present a versatile method to fabricate ultralight and flexible graphene-based aerogels by introducing one-dimensional carbon fibers as reinforcements. These carbon nanofiber-reinforced graphene aerogels (CNF/GAs) were obtained by the carbonization of freeze-casted bacterial cellulose/graphene oxide (BC/GO). Our CNF/GAs possess a low apparent density (∼3.05 mg cm−3) and exhibit broad-band sound absorption performance with a superior noise reduction coefficient (NRC) as high as 0.65 at a thickness of 30 mm. Meanwhile, their excellent elasticity endows the CNF/GAs with strain-sensing capability, enhancing their capacity for detecting deformations when utilized as sound absorbers in engineering applications. Additionally, the highly porous structure makes the CNF/GAs excellent thermal insulators, with a thermal conductivity as low as 0.011 W m−1 K−1, further expanding their environmental reliability. Therefore, our approach develops CNF/GAs with excellent broad-band sound absorption performance and mechanical-environmental reliability, showing significant practical potential.

Design of morphology-controlled cobalt-based spinel oxides for efficient X-band microwave absorption

The cobalt-based spinel structure oxides with synergistic effect of magnetic loss and dielectric loss have important applications in electromagnetic wave absorption. And the excess 0.5 oxygen atoms in MnCo2O4.5 provide more vacancies than traditional MnCo2O4 spinel structure and improve the electrical conductivity. In the current study, MnCo2O4.5 microsphere clusters, MnCo2O4.5 microcubic spheres and MnCo2O4.5 flowery spheres were prepared by solvothermal method and annealing process. Among the final samples with different morphologies, MnCo2O4.5 microcubic spheres showed outstanding microwave absorption capabilities, with a minimum reflection loss (RLmin) of -51.52 dB at 2.2 mm. When the thickness was further increased to 2.3 mm, the effective absorption bandwidth could be as wide as 5.36 GHz, covering most of the X-band. The excellent absorption performance of electromagnetic waves is related to the modulability of the complex dielectric parameters, the optimization of impedance matching, and the enhancement of the polarization relaxation process through the improvement of the morphologies. This work provides guidance and support for refining the electromagnetic wave absorption potential of cobalt-based spinel oxides and for designing highly efficient electromagnetic wave absorbers in the X-band.

Multifunctional graphene/Ti3C2Tx MXene aerogel inlaid with Ni@TiO2 core-shell microspheres for high-efficiency electromagnetic wave absorption and thermal insulation

The demand for high-performance electromagnetic wave absorbing (EMA) materials featured with strong attenuation ability, extended absorption bandwidth and ultralight property is imperative yet remains challenging. Herein, a three-dimensional hierarchically porous reduced graphene oxide (rGO)/Ti3C2Tx MXene aerogel embedded with Ni@TiO2 core–shell microspheres was prepared via directional freeze-drying followed by a mild annealing process. The divergence in structure and multicomponent dielectric/magnetic features bring about optimized impedance matching characteristic, multiple polarization and loss pathways, collectively contributing to the excellent absorption performance. As a result, the Ni@TiO2/MXene/rGO (NTMRG-2) aerogel exhibits optimized EMA capability with a maximal effective absorption bandwidth (EABmax) of 6.48 GHz at a lower loading level of 5 wt% in the supporting matrix, covering the whole Ku band. Additionally, it achieves a minimum reflection loss (RLmin) of −71.4 dB with a matching thickness of 2.04 mm. Moreover, the aerogel also exhibits an ultra-light density of 5.58 mg cm−3, superior thermal insulation capacity (close to air) and hydrophobicity, underscoring its potential for multiple applications in various scenarios.

Regulating the Electronic Structure of MAX Phases Based on Rare Earth Element Sc to Enhance Electromagnetic Wave Absorption.

MAX phases are highly promising materials for electromagnetic (EM) wave absorption because of their specific combination of metal and ceramic properties, making them particularly suitable for harsh environments. However, their higher matching thickness and impedance mismatching can limit their ability to attenuate EM waves. To address this issue, researchers have focused on regulating the electronic structure of MAX phases through structural engineering. In this study, we successfully synthesized a ternary MAX phase known as Sc2GaC MAX with the rare earth element Sc incorporated into the M-site sublayer, resulting in exceptional conductivity and impressive stability at high temperatures. The Sc2GaC demonstrates a strong reflection loss (RL) of -47.7 dB (1.3 mm) and an effective absorption bandwidth (EAB) of 5.28 GHz. It also achieves effective absorption of EM wave energy across a wide frequency range, encompassing the X and Ku bands. This exceptional performance is observed within a thickness range of 1.3 to 2.1 mm, making it significantly superior to other Ga-MAX phases. Furthermore, Sc2GaC exhibited excellent absorption performance even at elevated temperatures. After undergoing oxidation at 800 °C, it achieves a minimum RL of -28.3 dB. Conversely, when treated at 1400 °C under an argon atmosphere, Sc2GaC demonstrates even higher performance, with a minimum RL of -46.1 dB. This study highlights the potential of structural engineering to modify the EM wave absorption performance of the MAX phase by controlling its intrinsic electronic structure.