Multi-interfaced Ni/C@RGO/PTFE composites for electromagnetic protection applications with high environmental stability and durability.

To efficiently address the growing electromagnetic pollution problem, it is urgently required to research high-performance electromagnetic materials that can effectively absorb or shield electromagnetic waves. In addition, the stability and durability of electromagnetic materials in complex practical environments is also an issue that needs to be noticed. Therefore, the starting point for our problem-solving is how to endow magnetic/dielectric multi-interfaced composite materials with excellent electromagnetic protection capability and environmental stability. In this study, magnetic/dielectric multi-interfaced Ni/carbon@reduced graphene oxide/polytetrafluoroethylene (Ni/C@RGO/PTFE) composites were developed to utilize as excellent EWA (electromagnetic wave absorption) and EMI (electromagnetic interference) shielding materials. Due to their diverse heterogeneous interfaces, rich conductive networks, and multiple loss mechanisms, the Ni/C@RGO/PTFE composite exhibits an optimal reflection loss of -61.48 dB and an effective absorption bandwidth of 7.20 GHz, with a filler loading of 5 wt%. Furthermore, Ni/C@RGO/PTFE composite films have an optimal absorption effectiveness value of 9.50 dB and an absorption coefficient of 0.49. Moreover, Ni/C@RGO/PTFE can hold high EWA performance in various corrosive media and maintain more than 90% of EMI shielding effectiveness, which can be attributed to the carbon coating and PTFE matrix acting as dual protective barriers for the susceptible metal Ni, thus obviously improving the stability and durability of composites. Overall, this work presents an effective strategy for the growth of high-performance EWA and EMI shielding materials with outstanding environmental stability and durability, which have wide application prospects in the future.

Carbon Nitride Grafting Modification of Poly(lactic acid) to Maximize UV Protection and Mechanical Properties for Packaging Applications.

Due to their biobased nature and biodegradability, poly(lactic acid) (PLA) rich blends are promising for processing in the packaging industry. However, pure PLA is brittle and UV transparent, which limits its application, so the exploration of nanocomposites with improved interfacial interactions and UV absorbing properties is worthwhile. We therefore developed and optimized synthesis routes for well-designed nanocomposites based on a PLA matrix and graphitic carbon nitride (g-C3N4; CN) nanofillers. To enhance the interfacial interaction with the PLA matrix, a silane-coupling agent (γ-methacryloxypropyl trimethoxysilane, KH570) is chemically grafted onto the CN surface after controlled oxidation with nitric acid and hydrogen peroxide. Interestingly, only 1 wt % of CNO-KH570, as synthesized under mild conditions, is needed to significantly improve the UV absorption, blocking even a large part of both UV-C, UV-B, and UV-A outperforming the UV absorption performance of PLA and, for instance, polyethylene terephthalate (PET). The low nanofiller loading of 1 wt % also results in a higher ductility with an increase in elongation at break (+73%), maintaining the tensile modulus. The results on a joint optimization of UV protection and mechanical properties are supported by a broad range of experimental characterizations, including FTIR, XRD, DSC, DSEM, FETEM, XPS, FTIR, TGA, and BET N2 adsorption-desorption analysis.

Scalable Fabrication of Nacre-Structured Graphene/Polytetrafluoroethylene Films for Outstanding EMI Shielding Under Extreme Environment.

In this work, inspired by the great advantage of the unique "brick-mortar" layered structure as electromagnetic interference (EMI) shielding materials, a multifunctional flexible graphene nanosheets (GNS)/polytetrafluoroethylene (PTFE) composite film with excellent EMI shielding effects, impressive Joule heating performance, and light-to-heat conversion efficiency is fabricated based on the self-emulsifying process of PTFE. Both PTFE microspheres and nanofibers are employed together for the first time as "sand and cement" to build unique nacre-structured EMI shielding materials. Such configuration can obviously enhance the adhesion of composites and improve their mechanical property for the application under extreme environment. Moreover, the simple and effective repetitive roll pressing method can be used for the scalable production in industrialization. The GNS/PTFE composite film shows a high EMI shielding effectiveness (SE) of 50.85 dB. Furthermore, it has a high thermal conductivity of 16.54 W (m K)-1 , good flexibility, and recyclable properties. The excellent fire-resistant and hydrophobic properties of GNS/PTFE film also ensure its reliability and safety in practical application. In conclusion, the GNS/PTFE film demonstrates the potential for industrial manufacturing, and outstanding EMI shielding performance with high stability and durability, which has a broad application prospect for electronic devices in practical extreme outdoor environments.

Heterostructured Ni3B/Ni nanosheets for excellent microwave absorption and supercapacitive application.

The development of electronic information technology has placed higher demands on microwave absorption materials (MAMs), especially the exploration of novel MAMs to broaden their application. At present, little attention has been given the wave absorption properties of transition metal borides (TMBs). In this work, a simple and economical method is developed to prepare Ni3B/Ni heterostructure nanosheets and their possible applications for microwave absorption (MA) and supercapacitor are evaluated. It is worth noting that Ni3B/Ni nanosheets exhibit excellent MA properties due to the aggregated nanosheet-like morphology of Ni3B/Ni with enhancing interfacial polarization, as well as the synergistic effect of dielectric and magnetic losses. It is observed in experiments that the minimum reflection loss value of Ni3B/Ni is -41.60 dB at 16.8 GHz. Moreover, the maximum effective absorption bandwidth can reach 3.28 GHz. Furthermore, Ni3B/Ni has good energy storage characteristics and is able to provide a specific capacity of 1150.6F g-1 at a current density of 1 A g-1. Meanwhile, it has the ability to maintain an initial capacity of 74.4 % after 1000 cycles at a current density of 10 A g-1. Therefore, this study provides an idea to explore TMBs as high-performance MA and supercapacitor materials.

Mechanistic inference on the roles of oxygenic functional groups that activate peroxymonosulfates in graphene for advanced oxidation.

Developing carbon-based catalysts for advanced oxidation processes, owing to their abundant reserves, metal-free properties, superior biocompatibility as well as great resistance to acids and alkalis, presents an enticing prospect for environmental remediation. The thermally reduced graphene with diverse surface functional groups from vacuum-promoting thermal expansion of graphene oxide was fabricated by the progressive carbonization from 250 °C to 1000 °C (denoted as G250, G600, and G1000 according to temperature). Among them, G1000 possessed highest defective degrees, the largest specific surface area, and the most abundant, highly active oxygen-containing functional groups such as ketones and quinones. 0.10 g L-1 of G1000 could almost completely eliminate bisphenol A (19 mg L-1) within 15 min under the synergistic effect of adsorption and degradation. The structural evolution of graphene during the thermal-reduction process was systematically characterized and analyzed to understand the peroxymonosulfate-activated mechanism. The technological means included active species quenching experiments, electron paramagnetic resonance tests, and electrochemical analyses. This work presents some solid evidence to support the origin of active sites for catalytic degradation and provides new insights into the design of non-metallic catalysts in advanced oxidation processes.

Novel hierarchical CuNiAl LDH nanotubes with excellent peroxidase-like activity for wide-range detection of glucose.

Novel hierarchical CuNiAl layered double hydroxide (CuNiAl LDH) nanotubes were prepared with in situ transformation of Al2O3 produced using the atomic layer deposition (ALD) method. Based on the characterizations using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), FT-IR spectrometry, scanning electron microscopy (SEM) and transmission electron microscopy (TEM), CuNiAl LDH displays a typical nanotube-like structure consisting of uniform ultrathin nanoflakes. It is also confirmed that nitrate precursors play a crucial role in the formation of the LDH hierarchical structure. The unique hierarchical tube-like structure for CuNiAl LDH can supply more active sites and higher surface areas, leading to outstanding peroxidase mimicking property. The kinetic analyses indicate that the catalytic behavior of CuNiAl LDH follows classic Michaelis-Menten models and the affinity of CuNiAl LDH to the substrate is significantly higher than horseradish peroxidase. A simple and label-free method was developed for the colorimetric detection of glucose. As low as 2.9 µM of glucose can be detected with a broad linear range from 10 to 200 µM. The established method is also proved to be suitable for glucose detection in juice samples.

Titanium niobate (Ti2Nb10O29) anchored on nitrogen-doped carbon foams as flexible and self-supported anode for high-performance lithium ion batteries.

Assembling active materials on flexible conductive matrixes for fabricating high-rate, self-supported and durable anodes is essential for the development of high-power flexible lithium-ion batteries. In this study, we report an efficient combinational strategy for producing hybrid composites (TNO@MCF) of Ti2Nb10O29 (TNO) anchored on melamine carbon foam (MCF) via a hydrothermal method. The N-doped MCF not only showed good electronic conductivity and flexibility, but also improved the ion transport performance of the composites. The TNO@MCF electrode exhibited remarkably high rate capacities (327 mA h g-1 at 1 C, and 205 mA h g-1 at 40 C) and excellent cycling stability with a high capacity retention of 81.4% after 1000 cycles at 10 C. After 100 compression-rebound cycles, the TNO@MCF electrode showed a reversible capacity of 315 mA h g-1 at 1 C and exhibited a capacity retention of 72.3% for 1000 cycles at 10 C. This compressible structure design could provide guidelines for manufacture of other flexible electrodes for energy storage devices.

Hollandite-type ß-FeOOH(Cl) as a new cathode material for chloride ion batteries.

ß-FeOOH is utilized as a new cathode material for rechargeable chloride ion batteries for the first time. ß-FeOOH has superior rate capabilities and a high reversible capacity of 122 mA h g-1 after 100 cycles. This work opens up new possibilities for the development of anion batteries.

High-performance and flexible all-solid-state hybrid supercapacitor constructed by NiCoP/CNT and N-doped carbon coated CNT nanoarrays.

The exploration of flexible supercapacitors with high energy density is a matter of considerable interest to meet the demand of wearable electronic devices. In this work, with carbon nanotubes (CNTs) grown on carbon cloth (CC) as flexible substrate, NiCoP nanoflake-surrounded CNT nanoarrays (NiCoP/CNT) and N-doped carbon coated CNT nanoarrays (CNT@N-C) were synthesized on CC and utilized as cathode and anode materials for constructing flexible all-solid-state hybrid supercapacitor. Both them exhibit excellent electrochemical performance. NiCoP/CNT/CC composites can deliver a specific capacitance of 261.4 mAh g-1, and CNT@N-C/CC exhibits a high capacitance of 256 F g-1 at the current density of 0.5 A g-1. The hybrid supercapacitor built from the two well designed electrodes can provide a specific capacitance of 123.3 mAh g-1 at current density 1 mA g-1 within a potential window of 0-1.5 V and retain almost 85% of its initial capacitance after 5000 cycles. Furthermore, the flexible devices show the maximum energy density of 138.7 Wh kg-1 and a power density of 6.25 kW kg-1, obviously superior to some recent reported supercapacitor devices, indicating its potential in practical application.

Enhanced fluoride removal from water by rare earth (La and Ce) modified alumina: Adsorption isotherms, kinetics, thermodynamics and mechanism.

The removal of F- from aqueous solution using lanthanum and cerium modified mesoporous alumina (La/MA and Ce/MA) was studied, and characteration of the adsorbents by XRD, BET, XRF, FTIR, TEM, XPS and the pHZPC measurements were carried out. The adsorption was investigated in both batch and column adsorption systems. Batch experimental results showed that adsorption capacities of adsorbents were recorded in the following order: La/MA > Ce/MA > mesoporous alumina (MA). Besides, adsorption datas were fitted well by Sips isotherm model and Elovich kinetics model, and the maximum adsorption capacity of La/MA was 26.45 mg·g-1 in Sips model at the dosage of 2.0 g·L-1 and near neutral condition (pH = 6.0 ±â€¯0.1). Moreover, thermodynamic parameters were illustrated that adsorption process of fluoride ion over La/MA was spontaneous and endothermic. In the adsorption process, the interaction between metal and fluoride, the adsorption capacity was increased due to form the bond of M···F (M = La or Ce). Furthermore, the influence of coexisted anions on F- removal was investigated, and it was indicated that removal efficiency was slightly affected by the presence of Cl- and NO3-, while SO42- and CO32- caused a sharp fall in removal efficiency. Column experiments results were indicated that time of break-through of La/MA was twice as much as that of MA.

Strong and thermal-resistance glass fiber-reinforced polylactic acid (PLA) composites enabled by heat treatment.

Polylactic acid (PLA) is a biodegradable polymer derived from renewable resources, showing potentials in replacing traditional petroleum-based polymers, yet its brittleness and low thermal-resistance limits its applications. Thus, glass fibers (GF) combined with heat treatment were used to prepare high-performance PLA. Differential scanning calorimetry (DSC) and X-ray diffraction (XRD) were employed to analyze crystallization behavior of PLA/GF composite. Tensile, flexural and impact tests were conducted to investigate mechanical properties, and heat deflection temperature was measured to evaluate thermal resistance. GF can coincidently enhance strength, rigidity, and toughness of PLA. Isothermal heat treatment can further improve the mechanical properties regardless of GF content. Compared with neat PLA, the tensile strength, flexural modulus, and impact strength can be increased by 162.5%, 266.4%, 232.5%, respectively, in the presence of 20 wt% GF after isothermal heat treatment, and meanwhile heat deflection temperature can be increased from 50.6 °C to 148.8 °C. Both DSC and XRD analysis results indicated that GF can significantly enhance crystallization of PLA. Thus, not only GF but also enhanced crystallization led to the outstanding mechanical performance of PLA/GF composites. While GF shows little effect on thermal resistance, heat treatment can remarkably improve thermal stability, in particular for PLA/GF composites.

Ultrathin manganese oxide nanosheets uniformly coating on carbon nanocoils as high-performance asymmetric supercapacitor electrodes.

Two key limitations affecting supercapacitor application of manganese oxide (MO) are the poor electric conductivity and low accessible surface area. In this work, we reported an effective method to fabricate lamellar MO coating on carbon nanocoil (CNC) and investigated its supercapacitive properties. The elegant MO/CNC core shell structure enabled synergistic effects from both MO nanosheets and CNC by using nanosheets to provide a large interaction area for ion transport and CNC to improve the electric conductivity of composites. The investigation of electrochemistry showed that the specific capacitance of MO could reach 435 F g-1 at current density of 1 A g-1. Moreover, the composites presented an excellent rate capability and cycling performance with 92.7% capacitance retention at current density of 2 A g-1 after 5000 cycles. In addition, the asymmetric supercapacitor fabricated with MO/CNC as the positive electrode and CNC as the negative electrode demonstrated excellent energy density of 21.58 Wh kg-1 at a power density of 100 W kg-1. And the asymmetric supercapacitor exhibited an excellent electrochemical cycling stability with 96.3% initial capacitance remained after 1000 cycles.

Ti2Nb10O29 microspheres coated with ultrathin N-doped carbon layers by atomic layer deposition for enhanced lithium storage.

A novel design of 3D porous Ti2Nb10O29 microspheres coated with ultrathin N-doped carbon layers, which can improve electron/ion transport, shows remarkable high-rate capacity (267 mA h g-1 at 10C and 199 mA h g-1 at 40C) and stable cycle lives with a high capacity retention rate of 90.2% after 500 cycles.

Synthesis of Porous CoFe2O4 and Its Application as a Peroxidase Mimetic for Colorimetric Detection of H2O2 and Organic Pollutant Degradation.

Porous CoFe2O4 was prepared via a simple and controllable method to develop a low-cost, high-efficiency, and good-stability nanozyme. The morphology and microstructure of the obtained CoFe2O4 was investigated by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), high-resolution TEM (HRTEM), specific surface area and pore analysis, and Raman spectroscopy. The results show that the annealing temperature has an important effect on the crystallinity, grain size, and specific surface area of CoFe2O4. CoFe2O4 obtained at 300 °C (CF300) exhibits the largest surface area (up to 204.1 m² g−1) and the smallest grain size. The peroxidase-like activity of CoFe2O4 was further verified based on the oxidation of peroxidase substrate 3,3’,5,5’-tetramethylbenzidine (TMB) in the presence of H2O2. The best peroxidase-like activity for CF300 should be ascribed to its largest surface area and smallest grain size. On this basis, an effective method of colorimetric detection H2O2 was established. In addition, the porous CoFe2O4 was also used for the catalytic oxidation of methylene blue (MB), indicating potential applications in pollutant removal and water treatment.

The Fabrication and High-Efficiency Electromagnetic Wave Absorption Performance of CoFe/C Core-Shell Structured Nanocomposites.

CoFe/C core-shell structured nanocomposites (CoFe@C) have been fabricated through the thermal decomposition of acetylene with CoFe2O4 as precursor. The as-prepared CoFe@C was characterized by X-ray powder diffraction, X-ray photoelectron spectroscopy, Raman spectroscopy, transmission electron microscopy, and thermogravimetric analysis. The results demonstrate that the carbon shell in CoFe@C has a poor crystallization with a thickness about 5-30 nm and a content approximately 48.5 wt.%. Due to a good combination between intrinsic magnetic properties and high-electrical conductivity, the CoFe@C exhibits not only excellent absorption intensity but also wide frequency bandwidth. The minimum RL value of CoFe@C can reach - 44 dB at a thickness of 4.0 mm, and RL values below - 10 dB is up to 4.3 GHz at a thickness of 2.5 mm. The present CoFe@C may be a potential candidate for microwave absorption application.

The construction of carbon-coated Fe3O4 yolk-shell nanocomposites based on volume shrinkage from the release of oxygen anions for wide-band electromagnetic wave absorption.

The demand for microwave absorbing materials with strong absorption capability and wide absorption band is increasing due to serious electromagnetic interference issues and defense stealth technology needs. Here the carbon-coated Fe3O4 (Fe3O4@C) yolk-shell composites were successfully synthesized in a large scale for the application of microwave absorption through an in-situ reduction process from carbon-coated γ-Fe2O3 precursor. The results show that the Fe3O4 nanoparticles are uniformly coated with a thin carbon layer about 10nm in thickness and a clear void about 1 nm in width between Fe3O4 core and carbon shell are formed due to the volume shrinkage during the reduction treatment. The obtained yolk-shell composites exhibit excellent microwave absorption properties. The absorption bandwidth with RL values exceeding -10dB is up to 5.4GHz for the absorber with a thickness of 2.2mm. The optimal RL can reach up to -45.8dB at 10.6GHz for the composite with a thickness of 3.0mm. The outstanding microwave absorption properties may be attributed to the multiple interfacial polarization, good impedance match and multiple reflections and scattering owing to the unique yolk-shell structures.

The Preparation of Au@TiO2 Yolk-Shell Nanostructure and its Applications for Degradation and Detection of Methylene Blue.

This paper reports the synthesis of a new type of Au@TiO2 yolk-shell nanostructures by integrating ion sputtering method with atomic layer deposition (ALD) technique and its applications as visible light-driven photocatalyst and surface-enhanced Raman spectroscopy (SERS) substrate. Both the size and amount of gold nanoparticles confined in TiO2 nanotubes could be facilely controlled via properly adjusting the sputtering time. The unique structure and morphology of the resulting Au@TiO2 samples were investigated by using various spectroscopic and microscopic techniques in detail. It is found that all tested samples can absorb visible light with a maximum absorption at localized surface plasmon resonance (LSPR) wavelengths (550-590 nm) which are determined by the size of gold nanoparticles. The Au@TiO2 yolk-shell composites were used as the photocatalyst for the degradation of methylene blue (MB). As compared with pure TiO2 nanotubes, Au@TiO2 composites exhibit improved photocatalytic properties towards the degradation of MB. The SERS effect of Au@TiO2 yolk-shell composites was also performed to investigate the detection sensitivity of MB.

Highly effective synthesis of NiO/CNT nanohybrids by atomic layer deposition for high-rate and long-life supercapacitors.

In this work, we report an atomic layer deposition (ALD) method for the fabrication of NiO/CNT hybrid structures in order to improve electronic conductivity, enhance cycling stability and increase rate capability of NiO used as supercapacitor electrodes. A uniform NiO coating can be well deposited on carbon nanotubes (CNTs) through simultaneously employing O3 and H2O as oxidizing agents in a single ALD cycle of NiO for the first time, with a high growth rate of nearly 0.3 Å per cycle. The electrochemical properties of the as-prepared NiO/CNT were then investigated. The results show that the electrochemical capacitive properties are strongly associated with the thickness of the NiO coating. The NiO/CNT composite materials with 200 cycles of NiO deposition exhibit the best electrochemical properties, involving high specific capacitance (622 F g(-1) at 2 A g(-1), 2013 F g(-1) for NiO), excellent rate capability (74% retained at 50 A g(-1)) and outstanding cycling stability. The impressive results presented here suggest a great potential for the fabrication of composite electrode materials by atomic layer deposition applied in high energy density storage systems.

Uniform Fe3O4 coating on flower-like ZnO nanostructures by atomic layer deposition for electromagnetic wave absorption.

An elegant atomic layer deposition (ALD) method has been employed for controllable preparation of a uniform Fe3O4-coated ZnO (ZnO@Fe3O4) core-shell flower-like nanostructure. The Fe3O4 coating thickness of the ZnO@Fe3O4 nanostructure can be tuned by varying the cycle number of ALD Fe2O3. When serving as additives for microwave absorption, the ZnO@Fe3O4-paraffin composites exhibit a higher absorption capacity than the ZnO-paraffin composites. For ZnO@500-Fe3O4, the effective absorption bandwidth below -10 dB can reach 5.2 GHz and the RL values below -20 dB also cover a wide frequency range of 11.6-14.2 GHz when the coating thickness is 2.3 mm, suggesting its potential application in the treatment of the electromagnetic pollution problem. On the basis of experimental observations, a mechanism has been proposed to understand the enhanced microwave absorption properties of the ZnO@Fe3O4 composites.

Size-selective catalytic growth of nearly 100% pure carbon nanocoils with copper nanoparticles produced by atomic layer deposition.

In this paper, Cu nanoparticles with narrow size distribution are synthesized by reduction of CuO films produced by atomic layer deposition (ALD), which are used as catalysts for the catalytic growth of carbon nanostructures. By properly adjusting the ALD cycle numbers, the size of produced Cu nanoparticles can be well controlled. Uniform carbon nanocoils with near 100% purity can be obtained by using 50-80 nm Cu nanoparticles, while thin straight fibers and thick straight fibers are produced by applying 5-35 and 100-200 nm Cu nanoparticles, respectively. The mechanism of the particle size-dependent growth of the carbon nanostructure was analyzed based on the experimental results and theoretical simulation. Our results can provide important information for the preparation of helical carbon nanostructures with high purity. Moreover, this work also demonstrates that ALD is a viable technique for synthesizing nanoparticles with highly controllable size and narrow size distribution suitable for studying particle size-dependent catalytic behavior and other applications.