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Flexible all-solid-state supercapacitors (FASSCs) have attracted much attention as power supplies for portable and wearable electronic products. Herein, we report the fabrication of a foldable, extra lightweight, flexible chopped carbon fiber paper (CFP) with a porous network structure prepared via wet-mold papermaking that can serve as a conductive substrate. The conductivity and pseudocapacitance of the electrode were improved by controlling the growth of 3D Cu(OH)2 nanorod arrays on CFP substrate. The Cu(OH)2@CFP electrode has a high specific capacitance of 421.8 mF cm−2 at a current density of 0.5 mA cm−2 with capacitance retention of 82.98% at a current density of 10 mA cm−2 after 5000 charge-discharge cycles. The FASSC manifested not only a large capacitance of 196.1 mF cm−2 at 2 mA cm−2, as well as energy and power densities of 6.97 × 10−2 mWh cm−2 and 1.6 mW cm−2, respectively, but also excellent stability of 80.3% over 5000 cycles at 5 mA cm−2. In addition, we confirmed that the FASSC has a large bending angle and can be twisted into various shapes, thereby indicating its applicability in portable and wearable electronic devices.

Transition Metal Dichalcogenides based flexible photodetectors have gained importance owing to the excellent absorption and photo conductivity. However, the fabrication of layered materials requires complex processes, high thermal budget, fabrication conditions using toxic precursors with expensive experimental facilities. In this work, we report a novel combination i.e., layered bimetallic chalcogenides Bi2S3/RuS2 hybrid heterojunctions with engineered interfacial structures facilitating wide range of absorption for broadband photodetector applications. The bimetallic sulphides were grown on biodegradable cellulose paper substrate using one-step hydrothermal method and optimized to get desired 1D/1D morphology. Detailed characterization studies demonstrate the formation of 1D-Bi2S3 microneedles with an orthorhombic phase and 1D-RuS2 nano-rods with a cubic phase structure providing clear evidence of 1D/1D hybrid heterostructure formation. The fabricated photodetector displayed excellent photo response in the UV, Visible and NIR region with a maximum responsivity of 58.2 mA/W towards visible light. A maximum EQE of 78% was obtained with fast response time of 0.6, 0.4 and 0.7 s for UV, VIS and NIR light respectively, which are far more superior considering the cost-effective, scalable cleanroom free fabrication technique employed. The obtained response can be ascribed to the superior absorption property of RuS2 in the UV region and Bi2S3 in the visible and NIR region. The discrete distribution of RuS2 on the Bi2S3 device facilitates the formation of local electric fields and the contact engineering by collecting charge carriers from the Bi2S3 results in efficient separation of photogenerated charge carriers.This work demonstrates the first paper-based-bimetallic sulphides with unexplored bismuth and ruthenium complexes-based hybrid heterojunction based broadband photodetector with excellent flexibility, low cost, the strategy outlined here is ideal for various applications like wearable electronics, flexible devices, and security systems.

International audience; Thermomechanical simulation is challenging for the optimization and virtual monitoring of high temperature shape processes, such as SuperPlastic Forming (SPF) of Titanium alloys alike Ti-6Al-4V (TA6V). Part of this challenge is the accurate and process-representative knowledge of emissivity, which controls radiative heat transfer during the process. In this paper, the characterization of TA6V emissivity, with regards to its oxidation stage, is performed within the [600–1000 °C] thermal range. The main contribution of this work is the use of an in-house characterization bench, enabling the fast radiative heating of samples, and the control of oxide layers thicknesses ranging from 250 nm to 120 µm. An oxidation law is established thanks to post-mortem mass gain and oxide thicknesses measurement, and the various oxide phases are identified. Oxide thicknesses versus heating time were then calculated and implemented in the emissivity analysis. Two patterns are observed for oxide thickness versus temperature: below 900 °C, emissivity values are quasi-continuously increasing with oxide thickness, exhibiting an oxide layer mainly composed by TiO2, above 900 °C, emissivity values are also continuously increasing but with a different trend, due to the formation of alumina, confirmed by X-Ray Diffraction (XRD) measurements. Finally, the dependence of emissivity to temperature and oxide thickness emphasized in this paper constitutes a non-trivial mandatory input to increase the radiative heat transfer simulations codes accuracy.

This paper presents the magneto-structural study on orthoferrite TmFeO3 and Sm substituted TmFeO3 across spin reorientation transition (SRT) temperature. A strong change in magnetic anisotropy due to the substitution of the Sm3+was observed, which is reflected as a change in spin reorientation transition (SRT) temperature. The SRT temperature of Tm0.5Sm0.5FeO3is found to be around 200–230 K, which is relatively high in comparison to TmFeO3. A sudden decrease in the value of coercivity has been observed in the SRT region for both the sample. The lattice dynamics of TmFeO3 and Tm0.5Sm0.5FeO3were investigated by temperature-dependent x-ray diffraction and Raman spectroscopy. We observed unusual contractions in the lattice parameter at low temperatures due to complex exchange interaction between RE3+ and Fe3+ ions sub-lattice. Anomalous behavior in lattice parameters was observed in the vicinity of SRT, which confirms the system’s spontaneous magnetostriction.The strong anomaly was observed in line width and phonon frequency of Raman modes of around SRT, which established the spin-lattice coupling in TmFeO3 and Tm0.5Sm0.5FeO3 nanoparticles. Observation of spin-lattice coupling utilizing Raman scattering substantiates our magnetic and structural correlation and supports its candidature for magneto-elastic applications.

In order to prepare anode materials with a high specific capacity, super rate performance and relatively good stability, the N, S dual-doped porous graphene aerogels/natural graphite composites (denoted as N, S-pGA/NG) were designed via annealing incorporation with hydrothermal method in this paper. Commercial graphite anode materials were modified by adding a small amount of N/S dual-doped Porous graphene aerogels to make them have excellent electrochemical properties. At the same time, in order to further explain the internal mechanism of nitrogen and sulfur atoms doped graphene to improve the properties of natural graphite anode electrodes, we used density functional theory to calculate the adsorption energy, static charge and density of states, which proved that the this optimization’s mechanism may lie in the effect of nitrogen and sulfur co-doping on the adsorption behavior of lithium atoms. Therefore, the N, S-pGA/NG exhibited high capacities (531 mAh g−1 at 0.1 C), improved rate performance (277 mAh g−1 at 2 C), and good cycling stability.

This paper deals with the synthesis of cubic phase KYF4:Eu3+ nanophosphors via wet chemical route. Morphological studies such as XRD, SEM and EDAX mapping were done to ascertain shape, size and composition of the as prepared nanophosphors. Debye Scherrer formula applied to the XRD spectral features of the as prepared nanophosphors reveals the average size in the range 3–4 nm. The JCPDS data analysis for KYF4:Eu3+ nanophosphors confirm cubic structure with lattice constant a = b = c = 5.448 A and α = β = γ = 90 °. The SEM EDAX image mapping clearly demonstrates the uniform distribution of all the constituent elements. Up-conversion (UC) studies carried out using 800 nm femtosecond laser produces peaks at 576, 590, 612, 650, 700 nm pertaining to the transitions 5D0 → 7Fj (J = 0, 1, 2, 3, 4) respectively. In addition to this, three higher order peaks are also observed at 523, 531, 552 nm pertaining to 5D1 → 7Fj (J = 0, 1, 2) transitions respectively. Down-shifting (DS) studies under 393 nm and 405 nm excitation were recorded to understand the utility of the as prepared phosphors for lighting applications. These nanophosphors are capable of emitting visible emission under UV/NIR excitations. The laser power dependence studies conducted on UC and DS reveals the excitation process as two photon and single photon respectively. DS temperature dependent PL spectral revels good thermal stability for the as prepared phosphor. The interesting results obtained allows us to contemplate that the as prepared KYF4:Eu3+ nanophosphors are useful for bio-imaging (through UC) as well as lighting applications (through DS).

In the present paper, a transverse magnetic field was applied to gas tungsten arc welding (GTAW) for 2205 DSS in order to regulate the weld microstructure, which has not been investigated so far. The results indicated that the application of magnetic field not only can increase the austenite/ferrite phase ratio of the welds, but also refine the ferrite grains, and a magnetic field with a frequency of 1 Hz worked best. Both of the above can be attributed to the slower cooling rate of the welding pool with arc oscillation. Hardness test showed that the arc oscillation exerted a significant influence on hardness distribution. Under the effect of a low frequency (1 Hz) magnetic field, the hardness level of the weld metal was close to that of the base material. However, when no magnetic field was applied, the hardness level of the weld increased.

The high-temperature oxidation resistance is a critical evaluation index for the practical applications of Nd-Fe-B sintered magnets. In this paper, the high temperature (> 523 K) oxidation behavior of the recycled Nd-Fe-B sintered magnets was investigated and compared with the original magnets. The results show that both magnets exhibit similar high-temperature oxidation characteristics. The recycled magnets oxidized after 300 h at 673 K possesses remanence (Br) of 1.189 T, coercivity (Hci) of 1688 kA/m, and maximum energy product [(BH)max] of 268 kJ/m3. Compared with the recycled magnet before oxidizing, the oxidized recycled magnets retain 96.0% of Br, 85.2% of Hci, and 92.2% of (BH)max, respectively. The recycled magnets negatively influence the high-temperature oxidation resistance compared with the original magnets, demonstrating the recycled magnets' applicability.

The hydrogen and oxygen generation has been regarded as the most promising solution through electrochemical water splitting for the sake of alleviating the energy crisis and climate change. In this paper, we developed an in-situ deposition approach for depositing NiCo2O4 on the surface of Co9S8, and then the loading amount of NiCo2O4 was controlled by regulating the deposited number of cycles. In addition, the materials were used as catalysts for oxygen production and hydrogen production for the first time. When Co9S8@NiCo2O4-10 cycles, Co9S8@NiCo2O4-70 cycles and Co9S8 is used as a bifunctional catalyst, Co9S8@NiCo2O4-70 cycles // Co9S8@NiCo2O4-10 cycles displays a smaller cell voltage (1.55 V@10 mA cm−2) than Co9S8 (1.68 V@10 mA cm−2). Density functional theory calculation is used to calculate the water adsorption energy on the surface of the material to further reveal the reaction mechanism of water oxidation process. The work provides a new idea for the development of a relatively low toxicity and environmental friendly bifunctional electrocatalyst for industrial water electrolysis applications.

Lignosulfonate, a by-product spent sulfite pulping liquor from the paper and pulping industry, was a suitable natural sulfur dopant for improving electrochemical performance of chitin derived carbon materials. Herein, a cost-effective method of possible large-scale production was reported to fabricate heteroatoms-doped porous carbon (CLs) as advanced electrode materials for lithium-ion batteries applications. After a simple pyrolysis process of chitin mixed with lignosulfonate, generated CLsequipped with abundant defect structures. Remarkably, although portion of lignosulfonate (1/3 of chitin) was introduced, the specific surface area (SSA) of CLs enhanced to 411.64 m2g−1 (CL800). In addition, its capacitive characteristic improved, effectively, delivering high a reversible specific capacity of up to 644.5 mA h g−1 at current density of 50 mA g−1. After 300 cycles at the current density of 100 mA g−1, it still remained a specific capacity of 350.7 mA g−1. Such anode material presented excellent electrochemical performance, good rate capability and cycling stability, attributed to containing abundant N and S elements, providing a green avenue for converting biomass waste to high electrochemical performance heteroatoms-doped carbon materials, having promising application in the energy storage field.

As a widely used water-soluble azo dye, methyl blue has aroused widespread concern for its environmental problems. In this paper, magnetic nickel-magnesium ferrites were deemed as a promising dye adsorbent, and they could be synthesized through a rapid combustion process. The properties of the nanoparticles were acquired by the scanning electron microscope (SEM), the energy dispersive spectroscopy (EDS), the X-ray diffraction (XRD), the vibrating sample magnetometer (VSM), the high resolution transmission electron microscopy (HRTEM), the N2 adsorption-desorption isotherms, and the Fourier transform infrared spectroscopy (FTIR). The structure analysis demonstrated that the average particle size of magnetic nickel-magnesium ferrites was 59.2 nm, the saturation magnetization was 34.1 A·m2/kg and the specific surface area was 94.69 m2/g. After investigating the ratio of nickel to magnesium and the key parameters affecting the properties of ferrites, the adsorption of methyl blue onto the nanoparticles was discussed. Adsorption kinetics and isotherm models were employed to fit the relevant data, and the adsorption capacity of nanoparticles on methyl blue reached 306.4 mg/g when the initial concentration of methyl blue was 900 mg/L. The effect of pH value on the adsorption was explored, and seven cycles of the sample were recorded. Subsequently, the cyclic voltammetry (CV) and the electrochemical impedance spectroscopy (EIS) curves of the nanoparticles before and after adsorption were measured. To sum up, nickel-magnesium ferrites had the advantages of low cost, magnetic separation, facile preparation, high adsorption efficiency, and reusability, which suggested it had a broad application prospect in the field of dye removal.

The efficient tuning of defects in the host lattice to obtain the desired electrical and optical properties is the recent trend in the research arena. Here we aim to tune to oxygen vacancies in TiO2 lattice by dopant incorporation and also investigated the influence of rGO on the electrical properties of doped TiO2 lattice. In this paper, Yttrium incorporated TiO2 (YTO) and YTO/rGO nanocomposites are synthesized. YTO and YTO/rGO nanocomposites are characterized by X-Ray Diffraction (XRD), UV-Differential reflectance spectroscopy (UV-DRS), Raman, X-ray photoelectron spectroscopy (XPS), Hall measurement studies, electrical impedance spectroscopic studies and TRPL measurements. Yttrium (6 mol%) in the TiO2 lattice introduces more oxygen defect sites, modifying the charge carrier dynamics of the lattice (improved electron concentration, enhanced electrical properties, lowered the charge transfer resistance). To improve the average lifetime of the charge carrier, YTO was composited with rGO. YTO/rGO nanocomposite formation was confirmed by XPS and Raman analysis. Nyquist plot of YTO/rGO nanocomposites exhibited reduced charge transfer resistance and lesser relaxation time. TRPL measurements of YTO/rGO nanocomposites showed a significant improvement in the average lifetime of the charge carriers from 19.7 ns for YTO to 30.7 ± 0.5 ns. This improved lifetime of electrons in the nanocomposite system signifies efficient charge separation and reduced charge recombination at the YTO and rGO interface, thus proving YTO/rGO nanocomposite as a better electron extraction layer.

How to improve the selectivity and sensitivity of semiconductor metal oxide (SMO) based gas sensors at room temperature is still a big challenge. In this paper, different content of Ce doped ZnO porous nanosheets were successfully synthesized via a facile and controllable hydrothermal method and their sensing properties were investigated. 1 at% Ce doped ZnO (CZO-1) sensor exhibited a high response (S = 15.1 for 100 ppm aniline), and excellent selectivity toward aniline against other gases at room temperature compared with pristine ZnO. The abundant oxygen vacancies (OV), high specific surface area and the interface interaction between of CeO2 and ZnO effectively enlarged the resistance variation due to the change in oxygen adsorption. The two-dimensional (2D) porous structure also plays an important role in the excellent sensing performance due to the excellent electron transport capability and abundant gas diffusion channels. DFT study results indicated the interaction between ZnO and aniline could be enhanced by introducing OV and Ce doping. Thus, this work indicated that the CZO composites could be a potential candidate for aniline detection at room temperature.

Mechanical properties of soft magnetostrictive FeCo-based thin films is one of the critical properties along with their magnetic properties. To fully exploit their potential in magnetic-microelectromechanical (MagMEMs) application, the elastic and inelastic properties as well as the strength need to be considered. This paper presents the mechanical properties of soft magnetostrictive FeCoCr films at varied Cr concentrations from 2.6 to 9.6 at% fabricated by RF Sputtering. Nanoindentation was performed to determine the hardness, elastic recovery, Young’s modulus, and the yield strength of the FeCo and FeCoCr films. Although the Cr substitutions slightly reduced the hardness and the Young’s Modulus, the yield strength of the films improved, with a maximum of 1014 MPa for 9.6 at% Cr. This suggests that the Cr atoms were responsible for inhibiting the dislocations motion in the soft magnetostrictive FeCo-based films and helped to overcome the brittleness of the FeCo.

In this paper, we report the synthesis of gadolinium (Gd) and niobium (Nb) co-doped barium titanate (BT) ceramic oxides prepared using a conventional solid-state reaction method. The X-ray diffraction pattern confirmed the formation of tetragonal phase – with the space group P4mm – in all samples. X-ray photoelectron spectroscopy shows the formation of oxygen vacancies with a variable concentration that depends on the site preference of Gd ions. Fourier – Transform infrared analysis shows the presence of the most prominent peak between 544 cm−1 and 588 cm−1. Raman spectroscopy shows the tetragonal phase, with a most prominent peak around 514 cm−1 due to A1(TO3)E(TO4) mode. Shifting of this peak suggests the formation of GdBa defects. UV measurement suggests an increase in bandgap from 2.928 eV to 3.047 eV with Gd doping. Photoluminescence shows the presence of multiple level emission mechanisms for all samples. The dielectric constant increases while dielectric loss decreased with increasing dopant concentration, which is attributed to the self-compensation mechanism and defect dipole formation. Impedance spectra, Z ′ and Z ′ ′ vs frequency, suggest the presence of space charge polarization. Modulus spectra, M ′ and M ′ ′ vs frequency indicates the presence of short-range mobility at low frequency and long-range mobility at high frequency. AC conductivity shows almost negligible change with variable dopants concentration. Thus, electrical properties were observed to improve with Gd and Nb co-doping on BT ceramic oxides.

The evolution of grain structure and corresponding texture development of Mg alloys under the assist of multiple physical fields are interesting and meaningful topics, and are investigated in this paper in detail. The results show that the texture development of stress free (SF) aged alloy exhibits a remarkable difference in type and intensity to those of 100 MPa tensile stress (100-TS) and 100 MPa compressive stress (100-CS) aged alloys at 160 °C. In the early stage of SF aging, preferential growth of //ED grains give rise to the enhancement of //ED fiber component. The increased pinning force caused by considerable precipitates at high energy boundaries reduce the boundary mobility, and therefore lead to a weak basal texture at the end of aging. Heavily activated prismatic dislocations under the action of 100-TS aging facilitate the precipitation of secondary phases at grain boundaries and lattice rotation induced continuous static recrystallization (CSRX) in the early stage of aging, which contributes to a weak basal texture and the formation of non-fiber texture. Upon further aging, the preferential growth of pre-existing //ED grains and recrystallized grains formed by CSRX contribute the enhancement of //ED basal fiber component. In the case of 100-CS aging, the slight growth of grains and lattice rotation caused by prismatic dislocations lead to the enhancement of //ED texture component in the early stage of aging. After long-time compressive stress aging, preferential growth of //ED grains gives rise to the formation of - double fiber components.

Strength, ductility, and electrical conductivity are always mutually exclusive to each other in conductor materials. Although numerous strategies were proposed, aiming at breaking the dilemmas between strength and ductility, or strength and conductivity, a better solution to solve them all is still a thirst for Al alloys. In this paper, we produced an Al-7.5Y alloy with heterogeneous lamella structure and stacking faults (SF) via cold rolling. The results indicate that the as-rolled Al-Y specimen shows a simultaneous increase in strength and electrical conductivity compared to that of the as-cast counterpart. Interestingly, the as-rolled Al-Y specimen has nearly the same uniform elongation as the pure Al counterpart. The deformation behavior, strengthening mechanism as well as the conductive mechanism of the as-rolled Al-Y alloy were revealed by electron microscopy and in-situ X-ray diffraction. Data Availability The authors confirm that the data supporting the findings of this study are available within the article.

A great impact of the multifunctional or multiferroic materials on device applications has gained tremendous attention from scientific research groups in the field of materials science. The multiferroic materials bear superior properties of alternating the ferroic orders in a pre-designed way to match the device specifications. Materials in which there is a coupling between the primary ferroic orders (ferroelectric, ferromagnetic, ferroelastic) are termed multiferroics. This paper shows the investigation of a room temperature multiferroic material bearing a chemical composition LaFeO3 (LFO) also known as rare-earth orthoferrites. The particles of LFO are synthesized employing mixed oxide processing with heat treatment. The Rietveld analysis of the material shows that the LFO crystallizes having an orthorhombic symmetry and Pbnm space group. The complex impedance spectra indicate the distribution of relaxation time and non-Debye-type behavior. The dielectric parameters measured at various frequencies and temperatures suggest the formation of a colossal dielectric constant and low loss. The elemental analyses of the material show that there is no impurity present in the material. The pellet of the LFO arranged in a metal-insulator-metal arrangement is tested for gas sensing application. The LFO material has an excellent selectivity towards NO2 gas at relatively low operating temperatures ranging from 50 °C to 300 °C along with a sub-ppm limit of detection. A set of cyclic testing confirms that LFO can carry out stable and lengthy gas sensing operations while demonstrating outstanding adsorption and desorption characteristics. Such superior gas sensing properties and dielectric characteristics can pave the way toward the ultra-high sensitive gas sensors based on lead-free orthoferrites perovskites.

In this paper, a novel three-dimensional sulfur-doped graphene (3DSG)/cobalt molybdate-molybdenum oxide (CoMoO4-MoO2) framework is prepared by hydrothermal method followed by high-temperature calcination, which effectively combine the advantages of highly conductive sulfur-doped graphene with big specific surface area as well as excellent pseudocapacitive performance of molybdenum cobalt oxide. Comparing with CoMoO4/3DSG, CoMoO4-MoO2/3DSG has the better specific capacity (1022.7 C g−1 at 1 A g−1) and stability performance (retention 95.2% after 5000 cycles). Furthermore, the porous carbon prepared from lotus leaf (PLLC) has uniform pore structure and unique flower surface structure, which is excellent conducive to charge storage. Finally, the asymmetric supercapacitor device is assembled by CoMoO4-MoO2/3DSG as positive electrode and PLLC as negative electrode, which exhibits a specific capacitance of 262.3 F g−1 at a current density of 1 A g−1, provides a maximum energy density of 58.6 Wh kg−1 at a power density of 801.0 W Kg−1, and satisfies the reversibility with a cycling efficiency of 95.0% after 5000 cycles. Particularly, when the two devices are connected in series, the window range of the device can be widened to 3.2 V, and the device still has low impedance and cycle stability (maintain 92.3% after 5000 cycles).

This paper reports the effects of different process control agents (PCA) (methanol, n-heptane, and stearic acid) and aluminum concentration (x = 0.5, 1.0, and 1.5 at%) on the particle size distribution, structure, microstructure, stability, and prediction of phases in AlxCoCrFeMnNi high-entropy powder synthesized by mechanical alloying. The results showed that the vapor pressure, the polar nature of the different process control agents used, and type of milling (dry/wet) generating changes in the particle size distribution, microstructure, and crystalline structure since the use of PCA modifies the balance between the cold-welding and fracture processes. Quantitative analysis showed that the PCA chemical decomposition generated residual oxygen and carbon in all systems. X-ray diffraction showed that all systems present a mixture of crystal structures BCC-FCC with nanometric crystallite size, and the peak intensities changed in function of lattice deformation generated by type milling employed. On the other hand, the results also showed that the boundary between BCC-FCC and FCC regions is even broader and extends to higher Al concentration than those reported by the valence electron concentration criterion.

The fabrication of a p-n heterojunction structure is known to be a strategy for realizing efficient separation and migration of charges in photocatalysts to improve their photocatalytic activity. In this paper, a series of Bi2MoO6/CuBi2O4 p-n heterostructured photocatalysts were mechanochemically synthesized in-situ. The synthesized products were characterized by various techniques and evaluated for their photocatalytic capacities with photocatalytic degradation of ciprofloxacin under visible light irradiation, which qualitatively confirmed the synchronous formation of the binary heterojunction with matched band structure in a solid-state system. Compared with pristine Bi2MoO6 or CuBi2O4, the Bi2MoO6/CuBi2O4 p-n composites showed enhanced performance in photocatalytic degradation of ciprofloxacin (CIP), owing to the formation of p-n junctions and the subsequent enhancement in separation and migration efficiency of photogenerated carriers. Moreover, the Bi2MoO6/CuBi2O4 composites maintained good stability after four cycles of CIP photodegradation. Based on the obtained results, a possible photocatalytic mechanism for the as-synthesized Bi2MoO6/CuBi2O4 composites was proposed.

Biomass-derived porous carbon electrode material is becoming a research focus recently for application in energy storage fields, however directly fabricating high-performance porous carbon fibrous film electrode based on biomasses still remains a great challenge. Herein, we adopted the hydrothermally-treated and manganese-acetate-soaked bamboo pulp to form paper by suction filtration and then directly carbonized it to prepare hierarchically porous carbon fibrous film. We found that KOH-Na2SO3-assisted hydrothermal treatment endows bamboo-pulp-derived carbon fibrous film with superior mechanical flexibility capable of being repeatedly folded and that manganese acetate post-soaking greatly improves the electrochemical performance. The targeted super-flexible carbon fibrous film possesses outstanding electrochemical performance with a specific capacitance of up to 331 F g−1 at a current density of 1 A g−1. The assembled all-solid-state symmetric supercapacitor shows a high energy density of 10.3 W h kg−1 at a power density of 250 W kg−1.

In the present work, a series of zinc ferrite nanoparticles of 11 nm on average size were synthesized following an electrochemical method in aqueous medium. The nanoparticles were structurally characterized by X-ray diffraction (XRD), inductively coupled plasma spectroscopy (ICP), transmission electron microscopy (TEM), X-ray absorption spectroscopy (XAS) and neutron diffraction (ND). The magnetic characterization was carried out by vibrating sample magnetometer (VSM) and superconducting quantum interference device (SQUID) measurements. The electrochemical synthetic methodology used in this paper yields zinc ferrite monocrystalline nanoparticles with a controlled size, shape and composition, in a reproducible manner. The control of such parameters enables obtaining ferrite nanoparticles with tuneable magnetic properties. The results show that the Zn cations are situated in tetrahedral sites in the crystalline spinel structure, which causes a progressive decrease in the magnetic moments of the ferrites with Zn content due to the breakdown of the super-exchange interactions., We acknowledge financial support from the Spanish Ministerio de Ciencia, Innovación y Universidades through the projects PGC2018–095642-B-I00, PIB2019–104600RB-I00, MAT2017–86540- C4–1-R and RTI2018–095303-A-C52 and Spanish Ministry of Economy and Competitiveness under project MAT2015–67557- C2–2-P. A.S. acknowledges the Comunidad de Madrid for an “Atracción de Talento Investigador” contract (No. 2017- t2/IND5395). The European Synchrotron (ESRF), Institut Laue-Langevin (ILL) and Consejo Superior de Investigaciones Científicas (CSIC) are also ac- knowledged for the provision of synchrotron radiation facilities and neutron diffraction experiments. We also thank the BM25-SpLine and ILL staff for the technical support beyond their dutie

Direct methanol fuel cells (DMFCs) require high-performance electrocatalysts for utilization at the commercial scale. In this paper, a novel, high-efficiency electrocatalyst composed of silver-platinum hollow nanodendrites based on N doping graphene quantum dots (N-GQDs/AgPt HNDs), which were synthesized via an easy wet chemical method, for the methanol oxidation reaction (MOR) is demonstrated. The photomediated Ag/N-GQDs nanoparticles (Ag/N-GQDs NPs) were firstly prepared under the condition of visible light illumination (the central wavelength is 589 nm), and then galvanic replacement reaction occurred between PtCl62- and Ag nanoparticles to obtain the final product. The morphology of the catalyst exhibits a uniform hollow structure by transmission electron microscopy (TEM) and energy-dispersive X-ray spectroscope (EDX). The effects of the different mole ratio of Ag/Pt on the catalytic activity have been studied by cyclic voltammetry (CV) and chronoamperometry (CA). Under the optimal conditions, N-GQDs/AgPt HNDs show the excellent electrocatalytic activity of 2207.6 mA mgPt−1 towards MOR, which is about 21-fold higher than that of the commercial Pt/C. Interestingly, the photomediated Ag/N-GQDs NPs also caused the N-GQDs/AgPt HNDs catalysts to display a 1.7-fold enhancement in catalytic activity compared to that of the untreated Ag/N-GQDs NPs. Moreover, the CO tolerance and stability of the catalysts for MOR are also greatly improved. The present approach would provide an environment-friendly and valuable way to prepare multi-component catalysts with hollow nanostructures.

Continuous evolution of electrode materials still has not correspond today’s energy storage system necessity and limits their application range. Numerous approaches are proposed to improve lithium ion batteries (LIBs) energy density including advancement of positive electrode materials. Olivine structured cathodes as LiCoPO4 and LiNiPO4 are excellent candidates due to their working potentials of exceeding 5.0 V vs. Li+/Li. Despite the efforts, these materials still have several intrinsic problems which demand various strategies to overcome. The paper systematically reviews the recent progress of these cathode materials. The approaches based on particle size manipulation via synthesis route variation and carbon addition, surface modification by coating with electron conducting carbon layer, and doping the structure with other metal ions were discussed and analyzed as the most impactful towards achieving competitive performance. Furthermore, the computational technique was discussed due to its importance in understanding and designing the materials from atomic to microscale levels. The potential applications of these cathodes in a new generation of all-solid-state Li-ion and aqueous batteries were described.

In the present paper, the La1–2xBaxBixFeO3 (x = 0.00, 0.05, 0.10, 0.15 and 0.20) nanosized perovskite materials have been successfully prepared by the auto-combustion route using the glycine as fuel. The structural, morphological, and gas sensing properties of these samples have been investigated. The Rietveld refinement has revealed a single orthorhombic phase (Pnma space group) for the compounds with x ≤ 0.10, while the samples with x = 0.10 and 0.20 have been found to contain a minor amount of two secondary phases. We have confirmed that the La0.8Ba0.1Bi0.1FeO3 (x = 0.10) compound possesses the smallest average particle size (34.58 nm) with the purely orthorhombic structure and exhibits a high surface roughness, as determined by atomic force microscopy measurements. Importantly, the gas sensing tests have been carried out for all prepared compounds with different ethanol and H2S gas concentrations (from 5 to 100 ppm). The La0.8Ba0.1Bi0.1FeO3 (x = 0.10) compound has been proven to exhibit excellent performance in ethanol and H2S gas response even for very low concentrations (5 ppm) with an optimum operating temperature of 180 and 200 °C, respectively. Furthermore, the response and recovery times analyzed for both these gases were found to be very short (between 5 and 10 s).

Hydrogen is considered as a potential alternate energy to fossil fuels in the future. However, no matter in hydrogen production, storage, transportation or application, there are still huge challenges hindering the development of hydrogen energy. Transition metal carbides (TMCs) and nitrides (TMNs) have been received widespread attention in electrocatalytic water splitting to obtain hydrogen due to its noble-metal-like characteristic. In this review, we make a basic introduction including the structure, physical properties, and common prepared method of TMCs/TMNs. Then briefly introduce the reaction mechanism and evaluation criteria of electrochemical water splitting. After that, this paper reviews the recent progress of in the development of transition metal carbides and nitrides which discussion focused on the different modification methods such as nanostructuring, heteroatom doping, heterostructure construction and defect engineering. Furthermore, this review summarizes the electrocatalytic performances of recent reported TMCs and TMNs in hydrogen evolution reaction (HER), oxygen evolution reaction (OER) and overall water splitting. Finally, we conclude several effective strategies on the catalysts design and raise challenges remained on the electrocatalytic water splitting.

High-entropy alloys (HEAs) are a new class of alloys that consist of at least five major elements in equimolar or near-equimolar ratios with atomic concentration between 5% and 35%. Many HEAs containing the ferromagnetic elements Fe, Co and Ni show soft magnetic properties, while few HEAs present hard magnetic properties. In this paper, we design and prepare the Nd20Pr20La20Fe20Co10Al10 HEA with hard magnetic property. The magnetic property and microstructure of this alloy have been investigated. The intrinsic coercivity (Hcj), saturation magnetization (Ms), and remanence (Mr) of Nd20Pr20La20Fe20Co10Al10 alloy is 280.0 kA/m, 14.0 Am2/kg and 8.9 Am2/kg, respectively, which is slightly lower than 301.0 kA/m, 14.9 Am2/kg and 9.6 Am2/kg of Nd60Fe20Co10Al10 bulk amorphous alloy. The elasticity modulus (Er) of Nd20Pr20La20Fe20Co10Al10 alloy is 58.7 GPa, 4.6% higher than that of Nd60Fe20Co10Al10 alloy. SEM results show that there are two kinds of amorphous phases with different chemical compositions. TEM results show that Nd (Pr) and La nanocrystals are embedded in the amorphous matrix. The high coercivity of the alloy may originate from the combined effect of exchange coupling and domain wall pinning. Our findings provide a new idea to design HEAs with hard magnetic property leading to widen their applications.

Cheap, environmentally-friendly zinc antimonide is considered more favorable than conventional tellurite-based and skutterudite thermoelectric (TE) materials. Although the highly mobile zinc atoms located in the interstitial sites of the Zn4Sb3 crystalline structure greatly increase the figure of merit (ZT) of TE materials, the high chemical activity of zinc also makes it difficult to find suitable barrier layer and electrode materials. This paper introduces a method of joining titanium with Zn4Sb3 by means of diffusion bonding, in which the critical mutual-interdiffusion phenomenon is prevented. Optimal process parameters for manufacturing TE modules are suggested in this work. The intermetallic compounds (IMCs) that formed at the interface of Zn4Sb3/Ti diffusion couples were proved to be stable at the temperature with the highest conversion efficiency of Zn4Sb3. The growth kinetics of IMCs were also investigated, and the joint strength could be enhanced to 13.9 MPa after long-term reliability tests of 1000 h without deterioration. The results indicated that titanium is feasible barrier layer and electrode material for Zn4Sb3 TE modules.

Developing advanced catalysts for water splitting is the kernel in hydrogen clean-energy technologies. In this paper, an Al82Ni6Co3Mn3Y3Au3 nanocrystalline ribbon is dealloyed as the catalyst in hydrogen evolution reaction (HER), which exhibits outstanding catalytic activity in acidic solution. Its overpotential is about 24 mV @ 10 mA cm−2 and the Tafel slope is about 43 mV dec−1, which are comparable to commercial noble Pt/C electrodes (30 mV @ 10 mA cm−2 and 28 mV dec−1). Such a superior catalytic performance is attributed to the large specific surface area and low charger transferring resistivity of the dealloyed nanocrystalline electrode. The hybrid nanoporous structures composed of nanoporosity and nanoparticles of Au-Ni-Co-Mn-Y alloys and the synergic effects among the multiple components are desirable in catalysts. These results suggest that nanocrystalline multicomponent alloys are promising precursors for fabricating advanced HER catalysts.

Green synthesis and the adjustable microwave attenuation capability are crucial for the microwave absorption materials. In this paper, we report a green metal-sericin complexation method to synthesize the core-shell structured multicomponent alloy/carbon nanocomposites. The experimental characterizations demonstrate that by controlling the chemical compositions the alloy nanoparticles can be uniformly embedded in the carbon shell, forming a unique heterostructure that is able to enhance the dielectric loss of the nanocomposites. In specific, the optimized 1.49 mm-thick FeCoNiZn alloy@carbon nanocomposite exhibits the minimum reflection loss (RLmin) of −54.46 dB at 16.65 GHz and the 1.62 mm-thick one shows the maximum effective bandwidth (RL ≤−10 dB) of 4.19 GHz. Notably, the robust heterostructure of the synthesized nanocomposite leads to the synergistic effect of the impedance matching and the multi-loss mechanisms that involve the conduction loss, dielectric loss, and the magnetic loss, resulting in the enhanced microwave absorption performance. In short, this experimental work presents a novel and green fabrication method for constructing the magnetic metal/carbon absorbers. Based on their remarkable and adjustable microwave absorption performance, we envision the great potential applications of the FeCoNiZn alloy/carbon nanocomposite.

In this paper, we synthesized graphene-supported TiO2 nanoparticles (TiO2@rGO) via solvothermal method with different solvents. The combined effect of ethylene glycol (EG) and graphene makes fine, uniform TiO2 nanoparticles during solvothermal process. The effects of milling time and TiO2 content on hydrogen storage performance of MgH2 were investigated systematically. The MgH2-70TiO2@rGO-EG composite milled for 10 h starts to release hydrogen at 240 °C. The composite can desorb 6.0 wt% hydrogen within 6 min at 300 °C, while it can absorb 5.9 wt% hydrogen within 2 min at 200 °C. XPS and TEM results indicate that Mg encapsulated with catalyst as well as Ti4+ partially reduced to Ti2+ can make more intimate contacts and promote the charge transfer, which are responsible for the good de-/hydrogenation kinetics performance of MgH2.