Binary Composites Research Articles

Enhanced photocatalytic degradation of imidacloprid by a simple Z-type binary heterojunction composite of long afterglow with metal-organic framework

Imidacloprid (IMC) is a widely used nicotine-based pesticide that can cause severe harm to water resources. To address this issue, a simple binary heterojunction photocatalyst was constructed to degrade IMC under visible light. Furthermore, the catalyst was able to continue degrading approximately 15% of IMC within 5 h under dark. The possible photocatalytic degradation intermediate's structure and low toxicity were verified by mass spectrometry and zebrafish embryo experiments, respectively. The catalyst also exhibited good stability. Therefore, a simple photocatalyst with excellent performance and low toxicity of degradation products was successfully developed for IMC pesticide removal in water.

Thermal probing of constrained hysteresis loops of binary composites of Na0.5Bi0.5TiO3 and Ba0.85Sr0.15Zr0.1Ti0.9O3 ferroelectrics

The (1-x) Na0.5Bi0.5TiO3 (NBT)-(x) Ba0.85Sr0.15Zr0.1Ti0.9O3 (BSZT) (x = 0.1, 0.2, 0.3, 0.4, 0.5, 0.6) ceramics were prepared using solid state reaction method. The structural, microstructural, dielectric, and energy storage characteristics of the prepared system with BSZT content is examined. It is observed that Curie temperature and dielectric constant of composites suppresses with the BSZT content. The Curie Wiess fitting indicates that all ferroelectric compositions belong to diffusive class. Ferroelectric analysis emphasizes that the remnant polarization (Pr) and coercive field (Ec) decreases with BSZT content. Here, we provide detailed study on thermal scaling of constrained hysteresis loops for the synthesized system. The thermal probing reveals that the area of constraint hysteresis loop of NBT-BSZT compound are intrinsically governed by Pr parameter rather than the empirical relation 4 PrEc, observed suitable for the Mn-doped Pb(Mn1/3Sb2/3)O3–Pb(Zr,Ti)O3 ceramic (Du et al., 2013) [1]. The compositions x = 0.5 and 0.6 shows the high energy storage efficiency of ∼80% and 85%, respectively. The observed characteristics indicate that the prepared ceramics have potential applications in ferroelectrics and energy storage applications.

Bimetallic ZIF-derived heteroatomic-doped bioanode catalysts for enhanced power production in microbial fuel cells

Binary composite nanoparticles (NPs) are considered anode materials with development potential. Herein, we synthesized two composite NPs, namely Mn-Co3O4/NPs and Mn-Co9S8/NPs, by codoping O, S and C based on bimetallic zeolitic imidazolate framework (Co-Mn-ZIF) precursors. The modified carbon felt (CF) Mn-Co3O4/NPs@CF and Mn-Co9S8/NPs@CF integrated into the microbial fuel cells (MFCs) exhibited the highest volume power densities of 4.58 ± 0.11 and 5.12 ± 0.15 W m−3, respectively, which were higher than that of the precursor anode Co-Mn-ZIF (2.70 ± 0.07 W m−3). In addition, microbial community structure analysis showed that the Mn-Co3O4/NPs@CF and Mn-Co9S8/NPs@CF bioanodes were substantially enriched with electricity-producing bacteria such as Geoalkalibacter, Thermovirga, and Desulfuromonas. The synergistic effect of the binary metal composites along with their oxides and sulfides, facilitated the extracellular electron transfer and biofilm formation. These results demonstrate the advantageous properties of heteroatom-doped binary metal NPs, including high electrical conductivity and good biocompatibility. These NPs serve as excellent anode materials for fabricating high-performance MFCs.

Construction of one-dimensional hierarchical MoS2/Ni3S2 composites with enhanced interfacial polarization and improved wideband microwave absorption

The construction of one-dimensional (1D) sulfides has attracted extensive attention for improving microwave absorption (MA) performance owing to the anisotropic conductive networks. However, the synthesis of conductive 1D hierarchical materials with unique interfacial polarization and excellent MA properties remains challenging. In this study, cable-like MoS2/Ni3S2 was synthesized by a one-step hydrothermal strategy. The complex permittivity of the binary composites could be improved by tuning the thickness of the MoS2 coating. Importantly, the construction of heterogeneous contacts by MoS2 and Ni3S2 contributed to enhanced polarization loss, and the charge distribution was validated by electron holography. The wide efficient absorption bandwidth can reach above 4.8 GHz at a thin thickness. These new discoveries shed light on novel structures for 1D sulfide materials and the design of functional core-shell composites for microwave absorption.

Enhancement of the energetic performance of solid fuels with metal-fluoropolymer additives

Aluminum (Al) holds a pivotal role in augmenting the energetic potential of solid fuel formulations. Its incorporation can notably amplify the energy yield upon combustion. Nevertheless, challenges such as ignition delay and incomplete combustion have hindered its optimal utilization. In the context of hybrid rocket propulsion, where reignition and high regression rates are sought, a promising solution lies in harnessing the potential of metal-fluoropolymer combinations. This paper explores the influence of polytetrafluoroethylene (PTFE) and Viton fluoropolymer additives on the combustion and regression rates of hydroxyl‑terminated polybutadiene (HTPB)-based solid fuels loaded with nano-aluminum (nAl). To comprehensively address these objectives, binary composites of nAl-PTFE and nAl-Viton were prepared using high-energy ball-milling, and the resulting mixtures were incorporated into hydroxyl‑terminated polybutadiene (HTPB)-based fuel through a vacuum-casting technique. The ignition and combustion characteristics of the solid fuels, as well as the post-combustion products, were examined using an opposed flow burner setup to gain insights into their oxidation and combustion mechanisms. The findings demonstrate that the inclusion of PTFE and Viton in nAl has a positive impact on the ignition delay time, combustion behavior, and regression rates of the solid fuels. The HTPB-nAl-PTFE(S3) sample exhibited the shortest ignition delay time of 108 ms, outperforming the other tested samples (S1: 227 ms, S2: 182 ms, S4: 122 ms). Furthermore, the addition of nAl to pure HTPB resulted in an average regression rate of 0.3–0.6 mm/s for HTPB-nAl (S2), representing a two fold improvement compared to pure HTPB-based samples. Compared to the baseline HTPB fuel, HTPB-nAl-PTFE(S3) demonstrated a significant increase in regression rate by approximately 178%, while HTPB-nAl-Viton(S4) exhibited an increased regression rate of 122%. These results highlight the positive influence of fluoropolymers on combustion behavior, ultimately enhancing the overall performance of the fuel. Additionally, the study observed gas-phase reactions during the combustion process, including the reaction between nano-aluminum (nAl) and fluoride, the intermediate product of Al oxidation, and the decomposition products of fluoride. These reactions resulted in the faster fracture of the alumina (Al2O3) shell, leading to improved heat release and regression rate performance.

Fabrication of an efficient MXene based ternary nanocomposite of bismuth vanadate-bismuth sulfide as photocatalyst for the degradation of harmful industrial effluents

The current research work is based on the synthesis of BiVO4 (BVO), Bi2S3 (BS), a binary composite of BiVO4 and Bi2S3 (BVO-BS), and MXene-based ternary nanocomposite of BiVO4 and Bi2S3 (BVO-BS/MXene). BVO nanoparticles and BS nanorods were synthesized by co-precipitation and hydrothermal approaches respectively. While the binary (BVO-BS), and ternary (BVO-BS/MXene) nanocomposites were synthesized by an ultra-sonication method. The fabricated semiconducting materials were characterized by X-ray diffraction analysis, Fourier transforms infrared spectroscopy, and Scanning electron microscopy. Furthermore, the optical and electrochemical properties of synthesized samples were studied by UV–visible spectroscopy and Mott-Schottky/Electrochemical impedance spectroscopy analysis respectively. The photocatalytic removal efficiency of prepared samples was tested against an organic dye (Congo red) and pharmaceutical drug (Ciprofloxacin). The experimental results showed that (BVO-BS/MXene) ternary nanocomposite removed 92.5% congo red and 36.95% ciprofloxacin from wastewater under the visible light irradiation of about 70 min. While the binary composite; BVO-BS removed only 71.30% congo red and 22.61% ciprofloxacin within 70 min of irradiation. This outstanding degradation ability of BVO-BS/MXene for both Congo red and Ciprofloxacin as compared to binary composite (BVO-BS) was due to its large surface area, low charge transfer resistance (Rct = 0.96 ohm), and low electron-hole pair recombination. Hence, BVO-BS/MXene is a novel and promising photocatalytic material that could be used as an efficient photocatalyst for environmental pollution remediation applications.

Exploration of synergic effect assessment on the electrochemical behaviour of graphene and multiwall carbon nanotube (MWCNT) modified BiFeO3-MoS2 heterogeneous composites

Nanocomposite systems of BiFeO3-MoS2, BiFeO3-MoS2-MWCNT, and BiFeO3-MoS2-graphene have been synthesized through the sol-gel method. The synthesized composite powders were taken for various characterization tools like XRD, Raman, FT-IR, UV–Vis-NIR, FE-SEM, and electrochemical studies. XRD, Raman, FT-IR, and FE-SEM studies have confirmed the formation of binary and ternary composites. The loading of graphene and MWCNT on the BiFeO3-MoS2 systemsis reasonably tuned to the band gaps. Electrochemical measurements suggest that the synergic effect was found to have decreased in ternary composites (BiFeO3-MoS2-graphene and BiFeO3-MoS2-MWCNT) when compared to the binary composites (BiFeO3-MoS2). The electrochemical results of the synthesized composite have been discussed in detail.

Graphitized-MWCNT/CaCu3Ti4O12 metacomposites for tunable ε′-negative and ε′-near-zero response with enhanced electromagnetic shielding

Metacomposites with extraordinary electromagnetic (EM) parameters recently offered a brand-new strategy for EM shielding, but still suffered from the unclear paradigm and regulation mechanism for ε′-negative and ε′-near-zero response. Herein, we presented an effective paradigm of binary composites consisting of CaCu3Ti4O12 (CCTO) and graphitized-multiwall carbon nanotube (g-MWCNT) which was designed by percolation theory. The ε′ switched from positive to negative with increasing frequency was obtained in g-MWCNT/CCTO composites, which could be explained by electrical dipole resonance of interconnected g-MWCNT clusters. Once the percolated g-MWCNT network is formed, Drude-type ε′-negative response would be obtained due to the low-frequency plasma oscillation. Epsilon-near-zero effect (at ∼385 MHz and ∼135 MHz) were tuned by adjusting g-MWCNT content, which respectively corresponds to the loss peaks. The EM medium of CCTO/g-MWCNT composites with ε′-negative or ε′-near-zero response showed great EM shielding performance at specific frequency region. The g-MWCNT/CCTO metacomposites provide a classical paradigm of ceramic matrix composites for ε′-negative and ε′-near-zero response which will guide the practical application of metacomposites in dielectric ceramics and metamaterials, and promote the next steps in EM shielding field.

Dual Z-scheme heterojunction NH2-UiO-66/BiOBr/AgI with enhanced performance on visible light driven elimination of tetracycline and Cr(VI)

To tackle the challenges for photocatalysts efficacy enhancement, a novel dual Z-scheme NH2-UiO-66/BiOBr/AgI (NUBA) ternary composite photocatalyst was constructed and systematically characterized. NUBA displayed much higher visible light photocatalytic efficacies in tetracycline (TC) degradation and Cr(VI) reduction than the corresponding single components and binary composites. With employment of NUBA and visible light irradiation, 97% of TC was removed in 40 min whereas 96% of Cr(VI) was reduced in 30 min for the individual TC and Cr(VI) solution. Furthermore, NUBA manifested superior efficacy in simultaneously and synergistically removing TC/Cr(VI) mixture than for corresponding single pollutant. A dual Z-scheme charge transfer mechanism was established which confirmed that •O2− and h+ dominated TC degradation, whereas photo-induced electrons implemented Cr(VI) reduction. The promoted activity of NUBA was attributed to the synergism through incorporating the advantages furnished by individual components with rich charge transfer channels, larger specific surface areas, and strengthen visible light harvest, thus preeminently reinforced the production, separation and transportation of photogenerated charge carriers. NUBA demonstrated good anti-interfering ability and wide applicability for organic pollutants degradation, along with exceptional stability and durability for cyclic use. This work may supply an inspiration for the construction of efficacious dual Z-scheme photocatalytic systems for wastewater remediation.

Bi-salts composites to enhance the hydration kinetics and heat storage capacity

In this study, salt hydrates were deposited on a porous carbon (PC) support to address the challenges associated with maintaining heat capacity and slow hydration kinetics in thermochemical heat storage (THS) systems. Mono-salt (MgSO4) or binary salt (MgSO4-MgCl2) composites on the PC were analyzed by thermogravimetry/differential scanning calorimetry (TG/DSC). The results show that binary salt composites exhibit faster hydration kinetics and higher water adsorption capacity than monosalt composites. The addition of MgCl2 overcomes the kinetic drawbacks caused by the hydrophobic nature of the support and the presence of salt aggregates. The PC_60binary composite achieves a water uptake of 0.75 g/g, exceeding the water uptake of PC_60MgSO4 (0.48 g/g). Furthermore, the heat released by the composites follows a similar trend to water sorption. PC_60MgSO4 produces 52 % (1356 J/g) of the heat released by pure MgSO4, while PC_60binary achieves 70 % (1840 J/g) of the heat released by pure mixed salts. These results suggest that the newly developed binary salt composites are promising for long-term heat storage applications. These experimental results highlight the improved performance of binary salt composites in terms of hydration kinetics, water adsorption and heat release. This study provides valuable pointers for the development of more efficient THS systems.

Tuning the Electromechanical Response of P(VDF-TrFE)/ZnSnO3-Based Binary Piezoelectric Composites for Biomechanical Energy-Harvesting and Self-Powered Mechanosensing

Tuning the Electromechanical Response of P(VDF-TrFE)/ZnSnO₃-Based Binary Piezoelectric Composites for Biomechanical Energy-Harvesting and Self-Powered Mechanosensing

Thermally responsive flexible self-luminous binary fatty alcohol eutectic-based reversible thermochromic passive energy-saving eucalyptus wood aerogel composites

The development of flexible self-luminous reversible thermochromic passive energy-saving composites (TPCMs) is self-challenge due to the defects of easy leakage, non-visibility, solid phase rigidity, and weak light absorption. So, the emerging TPCMs were cleverly constructed using wood aerogel as support skeleton and different mass ratios of natural latex/long afterglow components as flexible and self-luminescent matrix based on optimal binary fatty alcohol eutectic (C14C20). Among them, C14C20R-TEW-1R and C14C20G-TEW-0.35 P stand out with suitable phase transition temperatures (28.8 °C and 29.7 °C), high latent heat values (100.5 J g−1 and 119.4 J g−1), and low supercooling (0.7 °C and 0 °C). Induced by phase change, they change from rigid to flexible, from red/green to milky white, and can absorb light to achieve self-luminescence in the dark (orange red and blue-green) and enhanced photothermal efficiency. Beyond the traditional thermal/light stability and excellent anti-leakage performance, TPCMs realizes the combination of temperature sensitivity/control and self-luminous, providing broad application prospects in home automation, passive energy-saving in buildings, luminescent response switches, and other fields.

Evaluation of calcined coal slime in binary and ternary ordinary portland cement composites: The role of calcination temperature

Coal slime is a by-product of coal washing plants, which accounts for around 8.3% of total coal production. China generates about 200 million tons of coal slime annually, and most of which can not be utilized efficiently. As a result, the disposal of coal slime leads to serious environmental problems and high costs. To provide a green utilization of coal slime, this study investigated the preparation of binary and ternary cement binder systems by using various calcined coal slime particles. The effects of calcination temperatures (600 °C, 700 °C, 800 °C, and 900 °C) on the evolution of mineral phases, microstructure and morphology of coal slime were addressed and discussed. The feasibility of calcined coal slime in blended cement preparation was tested and evaluated in comparison with calcined coal gangue. The results indicated that kaolinite in coal slime can be effectively transformed into metakaolin at 600 °C. The increase of calcination temperature after 600 °C reduced the reactivity, porosity and water demand of calcined coal slime. 600 °C Calcined coal slime effectively promoted the formation of monosulfate and the monocarboaluminate in binary and ternary cement, respectively, as well as the hydration process. The highest compressive strength of the calcined coal slime blended sample achieved 48.04 MPa, which presented a higher performance than the calcined coal gangue. The organic components in coal slime could be the key to reaching a high reactivity at a low (600 °C) calcination temperature. The calcined coal slime has the potential to be a reactive additive in cement-based materials.

Evaluation of polyetheretherketone composites modified by calcium silicate and carbon nanotubes for bone regeneration: mechanical properties, biomineralization and induction of osteoblasts.

Desired orthopedic implant materials must have a good biological activity and possess appropriate mechanical property that correspond to those of human bone. Although polyetheretherketone (PEEK) has displayed a promising application prospect in musculoskeletal and dentistry reconstruction thanks to its non-biodegradability and good biocompatibility in the body, the poor osseointegration and insufficient mechanical strength have significantly limited its application in the repair of load-bearing bones and surgical operations. In this study, carbon nanotubes (CNT)/calcium silicate (CS)/polyetheretherketone ternary composites were fabricated for the first time. The addition of CS was mainly aimed at improving biological activities and surface hydrophilicity, but it inevitably compromised the mechanical strength of PEEK. CNT can reinforce the composites even when brittle CS was introduced and further upgraded the biocompatibility of PEEK. The CNT/CS/PEEK composites exhibited higher mechanical strengths in tensile and bending tests, 64% and 90% higher than those of brittle CS/PEEK binary composites. Besides, after incorporation of CNT and CS into PEEK, the hydrophilicity, surface roughness and ability to induce apatite-layer deposition were significantly enhanced. More importantly, the adhesion, proliferation, and osteogenic differentiation of mouse embryo osteoblasts were effectively promoted on CNT/CS/PEEK composites. In contrast to PEEK, these composites exhibited a more satisfactory biocompatibility and osteoinductive activity. Overall, these results demonstrate that ternary CNT/CS/PEEK composites have the potential to serve as a feasible substitute to conventional metal alloys in musculoskeletal regeneration and orthopedic implantation.

Polypyrrole/ silver/graphene ternary nanocomposite synthesis and study on photocatalytic property in degrading Congo red dye under visible light

In this report, a simple chemical synthesis of polypyrrole/silver/graphene (Ppy/Ag/Gr) ternary nanocomposites with varying concentrations of graphene are described. The XRD spectra of the samples polypyrrole/silver (Ppy/Ag) and Ppy/Ag/Gr show all the peaks of the face-centered cubic structure of silver. A broad peak between 10° and 20° and a peak at 26.7° corresponds to Ppy and graphene respectively. Using FTIR, and UV–Vis. spectroscopies the interaction between polypyrrole, silver, and graphene were studied. In our work, we explored the photocatalytic property of the synthesised samples by using them to degrade the aqueous solution of a cancer-causing dye, Congo red. The percentage degradation of Congo red dye using the sample Ppy/Ag/Gr (0.5 wt.%) is obtained as 96% and the reaction rate calculated is 0.162/min., greater than that of Ppy/Ag and Ppy/Gr binary composites. Thus, the addition of the optimum concentration of graphene into Ppy/Ag enhanced its photocatalytic property. The BET analysis shows an increased surface area for the sample Ppy/Ag/Gr (0.5 wt.%) and the reason for the enhancement of photocatalysis with this sample is confirmed since it is a surface-dependent property. The biodegradability of the dye solution was investigated by Chemical Oxygen Demand (COD) analysis and the COD value was reduced from 432 mg/L to 216 mg/L after 20 min of irradiation of light.

A review on effect of conducting polymers on carbon-based electrode materials for electrochemical supercapacitors

Supercapacitors, commonly referred to as electrochemical capacitors, are a significant type of energy storage devices with more energy density than capacitors, greater power density, and longer cycle life than batteries. Conventionally, the electrode material of supercapacitors is composed of metal oxides, inorganic complexes, carbon-based materials, and conducting polymers. Researchers have attempted numerous combinations of aforementioned materials to create electrode material with enhanced electrochemical properties. However, supercapacitor (SC) electrodes constructed with pure conducting polymers (CPs) have poor cycling stability, resulting in a rapid decrease in specific capacitance. To improve the electrochemical property of such materials, researchers have attempted to construct binary and ternary composites of various CPs by mixing them with carbonaceous materials and metal oxides. In this review, SC electrode materials prepared from CPs, such as polyaniline (PANI), polythiophene (PTh), polypyrrole (PPy) and their composites with carbonaceous materials such as activated carbon (AC), carbon nanotubes (CNTs), reduced graphene oxide (rGO), graphene and carbon quantum dots have been discussed.

Flexible polyaniline/MXene/CNF composite nanofibrous mats as high‐performance supercapacitor electrodes

AbstractIn this study, we presented a facile synthesis of ternary composite by depositing polyaniline (PANI) onto electrospun MXene‐embedded carbon nanofibers (CNF) using in situ polymerization. Polymerization duration was varied between 2 and 8 hours to tune fiber diameter and surface area. The physicochemical properties of binary and ternary composites were characterized, such as surface morphology and chemical functional groups and surface area and pore volume. Results indicated that the fiber diameter and micropore volume increased with the deposition of PANI. In order to examine the effect of PANI deposition and other electrode properties on electrochemical performance, electrochemical impedance, galvanostatic charge–discharge, and cyclic voltammetry tests were performed. Flexible binder‐free PANI/MXene/CNF composite electrode with maximum PANI deposition exhibited the maximum specific capacitance of 356 F g−1 at current density of 0.5 A g−1. Further, this electrode demonstrated excellent capacitance retention after 5000 cycles, with 91%. The ternary composite's outstanding performance is primarily related to PANI's enhanced surface area and micropore volume as well as pseudocapacitive charge storage.Highlights Synthesis of a flexible binder‐free novel ternary composite electrode. In‐situ PANI deposition to enhances the ternary electrode surface area and wettability. Flexible ternary composite electrodes with maximum PANI loading exhibit excellent electrochemical performance. Comparison of binary and ternary electrode performance with pristine carbon nanofibers.

Surface-modified graphene oxide-based composites for advanced sequestration of basic blue 41 from aqueous solution

Advanced materials for the efficient treatment of textile wastewater need to be developed for the sustainable growth of the textile industry. In this study, graphene oxide (GO) was modified by the incorporation of natural clay (bentonite) and mixed metal oxide (copper-cobalt oxide) to produce GO-based binary and ternary composites. Two binary composites, GO/bentonite and GO/Cu–Co Ox (oxide), and one ternary composite, GO/bentonite/Cu–Co Ox, were characterized by Fourier transform-infrared spectroscopy (FTIR), scanning electron microscope (SEM), energy dispersive spectrometer (EDS) and Brunauer-Emmett-Teller (BET) analysis. The adsorption efficiency of these composites was evaluated against a cationic dye, Basic Blue 41 (BB41). The composites had several surface functional groups, and the ternary composite had tubular porous structures formed by the cross-linking of the bentonite and GO planes. The BET surface area of the ternary composite was 50% higher than that of the GO. The BB41 removals were 92, 89, 80, and 69% for GO/bentonite/Cu–Co oxide, GO/bentonite, GO and GO/Cu–Co oxide, respectively. The pseudo-2nd-order and intraparticle diffusion models best describe the kinetics results, indicating chemisorption and slow pore diffusion-controlled adsorption processes. The Langmuir isotherm-derived adsorption capacity of GO/bentonite/Cu–Co oxide was 351.1 mg/g, which was very close to the measured value. After five consecutive cycles, the ternary composite retained 90% BB41 removal efficiency compared to its 1st cycle. Electrostatic interaction and pore diffusion were predicted to be the controlling mechanisms for the adsorption of the BB41. The GO-based ternary composite can be a feasible and scalable adsorbent for BB41 in wastewater treatment.

Ni0.85Se@CoFe LDH heterostructure nanosheet arrays on Ni foam as efficient electrocatalysts for enhanced oxygen evolution

Exploring high-efficient, earth-abundant and stable electrocatalyst for oxygen evolution reaction (OER) is of vital importance for large-scale implementation of energy converting and storing. Thus, we fabricated a free-standing hierarchical heterostructure electrode of Ni0.85Se@CoFe LDH/NF via a rational combination of hydrothermal, selenization and electrodeposition process, among which the ultrathin CoFe LDH nanosheets intimately assembled onto the vertical aligned Ni0.85Se nanosheets supported on Ni foam. The constructed core-shell nanosheet arrays hold the plentiful hetero-interfaces and intimate interactions through metal-oxygen bonds between two individuals, which guarantee the fast OER kinetic processes. Additionally, CoFe LDH with crystalline/amorphous hybrid structure favors providing more reaction sites. Remarkably, the optimal Ni0.85Se@CoFe LDH/NF binary composites possess outstanding OER activity with a low overpotential of ∼223 and 280 mV at 10 mA cm−2 and 100 mA cm−2 in alkaline solution as well as good durability. This research offers an alternative approach for improving electrocatalytic water splitting through constructing 3D hierarchical heterostructures.

Fabrication of nitrogen-doped reduced graphene oxide/porous magnesium ferrite@silica dioxide composite with excellent dual-band electromagnetic absorption performance

In order to solve the increasingly serious problem of electromagnetic radiation pollution, it is urgent to develop advanced electromagnetic wave (EMW) absorbers with low filling ratio, wide bandwidth and strong absorption. In this work, nitrogen-doped reduced graphene oxide/porous magnesium ferrite@silicon dioxide (NRGO/MgFe2O4@SiO2) composite was prepared by a three-step route of solvothermal reaction, Stöber method and hydrothermal synthesis. The results of microscopic morphology analysis showed that a large number of MgFe2O4@SiO2 core–shell microspheres were uniformly distributed on the wrinkled surface of NRGO in the ternary composite. Furthermore, the effect of dielectric SiO2 coating on the electromagnetic parameters and EMW absorption performance of NRGO/MgFe2O4 composite was also investigated. Significantly, the EMW absorption capacity of the obtained ternary composite was better than that of the other two binary composites. When the filling ratio was 20.0 wt.% and the matching thickness was 2.0 mm, the ternary composite exhibited the widest absorption bandwidth of 6.2 GHz and the strong absorption strength of -58.8 dB at 14.6 GHz (Ku band). It was worth noting that when the thickness was increased to 4.2 mm, the optimal reflection loss of -61.0 dB was achieved at 5.8 GHz (C band). In addition, the potential EMW absorption mechanism was also proposed. Therefore, this work would provide a valuable reference for the preparation of graphene-based magnetic composites as lightweight, broadband and efficient EMW absorbers.