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Usually the improved coercivity of rare earth (RE) based 2:14:1-type permanent magnets via RE-rich intergranular additives is achieved at the cost of more corrosion channels and deteriorated corrosion resistance, which remains a challenging hurdle in the RE-Fe-B community. Distinctly, here we report the concurrent improvements of corrosion resistance and coercivity in 40 wt.% Ce-substituted Nd-Ce-Fe-B sintered magnets through engineering the intergranular phase using simple (Nd, Pr)Hx additive. The dehydrogenated Nd/Pr changes the RE concentration gradients between 2:14:1 matrix and intergranular phases during sintering and enlarges the fraction of corrosion-resistant REFe2 phase, rather than the conventionally assumed Nd/Pr-rich intergranular phase with high chemical vulnerability. The spontaneous formation of REFe2 intergranular phase after (Nd, Pr)Hx addition generates the uniquely enhanced corrosion resistance against the hot/humid and acidic environments, and counts as one peculiar feature of Nd-Ce-Fe-B magnets at high Ce substitution level, being distinct from previously reported Ce-free/lean RE-Fe-B. Simultaneously, the formation of continuous grain boundaries enhances the coercivity from 8.7 to 12.5 kOe with trace addition of (Nd, Pr)Hx. Above findings may spur progress towards developing a high-performance Nd-Ce-Fe-B permanent magnet.

Advanced electromagnetic (EM) wave absorbers with wide bandwidth is crucial to avoid EM interference and radiation, while achieving compensational attenuation at different frequencies is challenging. Herein, two-dimensional (2D) sandwiched FeNi@SnO2 have been designed, for which SnO2 nanosheets provide numerous heterogeneous nucleation sites for the growth of dispersive FeNi nanoparticles with reduced size. The SnO2 exhibits dipole polarization at 21.45 GHz with a width of ∼4.00 GHz, while the FeNi nanoparticles induce exchange resonance at 18.13 GHz (∼6.00 GHz width) and interfacial polarization at 15.97 GHz (∼6.00 GHz width). Such complementary attenuation mechanisms give rise to an impressive ultra-wide effective absorption bandwidth of 11.70 GHz with strong absorption of -49.1 dB at a small thickness of 1.75 mm. Not only superior EM wave absorption is achieved in this work, it also provides a versatile strategy to integrate different loss mechanisms in the design of EM wave absorbers with extra-wide bandwidth.

Annealing has been widely recognized as a crucial approach to modify the microstructure and enhance the coercivity of Nd–Fe–B magnets. However, in the context of Nd–Y–Ce–Fe–B magnets with multiple rare earths (REs) exhibiting different diffusion behaviors, annealing effects on the magnetic properties become more complicated and remain unknown. In present work, through a comparative study between as-sintered and annealed Nd–Y–Ce–Fe–B magnet upon 50 wt% Y–Ce co-substitution of total REs, we found that annealing process surprisingly enhances the remanence from 1.17 to 1.20 T, with simultaneous coercivity increment from 612.9 to 660.7 kA·m−1, resulting in drastically improved maximum energy product from 242.0 to 263.5 kJ·m−3. Such a peculiar remanence enhancement is closely correlated to the preferential Y/Nd infiltration into RE2Fe14B main phase and Ce segregation into REFe2 intergranular phase, which consequently improve the intrinsic magnetism, as evaluated by Curie temperature (TC), saturation magnetic polarization (JS) and magnetocrystalline anisotropy field (HA). Present work delights that different metallurgical behaviors of Nd/Y/Ce exert influential effects on the intrinsic and extrinsic magnetic properties and provide a novel approach toward high-performance 2:14:1-type permanent magnets based on abundant RE mixtures.

Listeria monocytogenes (L. monocytogenes) is one of the top five dangerous foodborne pathogens which widely exists in most raw food and has approximately 30 % mortality rate in high-risk groups. Food safety caused by foodborne pathogens is still a major problem faced by humans in all world. The conventional analytical methods currently used involve complex bacteriological tests and usually take several days for incubation and analysis. Thus, in order to prevent the spread of disease, the development of a detection method with high speed, high accuracy and sensitivity is urgent and necessary. Herein, we developed an approach for the identification and magnetic capture of L. monocytogenes by using core@shell Fe3O4@silica nanoparticles terminated with hydroxyl or amine groups. Our results show that both amine- and hydroxyl-terminated Fe3O4@silica core@shell nanoparticles functionalized with specific antibodies, present 95.2 %±6.2 % and 98.6 %±0.3 % capture efficacies, respectively. However, without conjugating the specific antibodies, the hydroxyl-terminated Fe3O4@silica nanoparticles exhibit 17.6 %±1.6 % efficacy, while the amine-terminated one remains 93.2 %±9.2 % capture efficiency ascribed to the high affinity. This study quantitatively uncovers the specific and non-specific recognitions relevant to the molecular-scale physiochemical interactions between the microorganisms and the functionalized particles, and the results from this work can be generalized and extended to other bacterial species by changing antibodies, also have important implications in developing advanced analytic methods.

Syngas from biomass gasification is being developed for alternative feedstock in the chemical industry. Palm kernel shell which is generated from palm oil industry can be potentially used as raw material for gasification process. The purpose of this study was to investigate the use of modified natural zeolite catalysts in steam gasification of palm kernel shells. Mordenite type zeolite was modified by acid leaching to be used as a tar cracking catalyst. Steam gasification was conducted at the temperature range of 750–850 °C and the steam to biomass ratio was in the range of 0–2.25. The result showed that steam gasification of palm kernel shell with the addition of zeolite catalyst at 750 °C and steam to biomass ratio 2.25 could reduce tar content up to 98% or became 0.7 g/Nm3. In this study, gasification of palm kernel shells produced syngas with the hydrogen concentration in the range of 52–64% and H2/CO ratio of 2.7–5.7. Copyright © 2021 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Anisotropy engineering serves as an effective method to achieve unique properties and enhanced performance of materials. Here MOF-71 and derivatives with tuned anisotropy have been achieved via facial tuning the proticity of the solvents, giving rise to nanoflake assemblies into bellows-, boat- and flower-like microstructures. Three anisotropy dimensions including Faceting, Aspect ratio and Arrangement have been proposed to describe the anisotropy of the assemblies, which are further evaluated by heterotype ( H ¯ ), flatness ( F ¯ ) and orderliness ( O ¯ ). Combined off-axis electron holography and electromagnetic scattered field simulation visualize uniform distribution of magnetic lines due to enhanced anisotropy of the bellows-like derivatives. This gives rise to strengthened magnetic loss and electromagnetic wave absorption for the anisotropy evolution from the flower-, boat-to bellows-like structure. As such the work not only provides versatile strategy for anisotropy engineering and reification of the anisotropy for complicated assembled structures, but also insights on impacts of the anisotropy on the distribution of stray field, magnetic dipoles and scattered field for the design of electromagnetic absorbers, which are extendable to various areas including but not limited to magnetics, electrics and optics.

MnZn soft magnetic ferrites have been widely utilized in power electronics, owing to the combined merits of high permeability and low energy loss. However, their deployment would result in a drastic increase in power dissipation at >3 MHz, thus limiting the scope extent of miniaturization, together with their efficiency. Here, we report a high-performance MnZn ferrite by doping multiple ions (La, Ti, Si, Ca) at grain boundaries, achieving the most optimized power loss of 267 kW/m3 at 5 MHz (10 m T, 100 °C) and initial permeability of 644, which is much better than the previously reported results and commercial products. Such an improvement is attributed to weakened magnetic exchange coupling at grain-boundary regions, associated with a significant transition from the multi- to mono-domain structures, originating physically from large crystallographic mis-orientations (>25°). The present study bears important significance in understanding the intrinsic correlation between the crystallographic mis-orientation and magnetic domain structure, and provides an alternative way for optimizing high-frequency soft magnetic ferrites.

Parabolic dish solar collectors gain higher solar to thermal conversion efficiency due to their maximum concentration ratio. The present research focuses by integrating the parabolic dish solar collector to the steam cycle producing power and rate of process heating. Pressurized water, therminol VP1, and supercritical carbon dioxide are the examined working fluids in the parabolic dish solar collector. The aim of the current research is to observe the optimal operating conditions for each heat transfer fluid by varying inlet temperature and flow rate of the working fluid in the parabolic dish solar collector, and combination of these parameters is predicted to lead to the maximum energy and exergy efficiencies of the collector. The operating parameters are varied to investigate the overall system efficiencies, work output, and process heating rate. Findings of the study declare that water is an efficient heat transfer fluid at low temperature levels, whereas therminol VP1 is effective for a higher temperature range. The integrated system efficiencies are higher at maximum flow rates and low inlet temperatures. The efficiency map of solar collector is located at the end of study, and it shows that maximum exergy efficiency gains at inlet temperature of 750 K and it is observed to be 37.75%.

The formation of ordered magnetic domains in thin films is important for the magnetic microdevices in spin-electronics, magneto-optics, and magnetic microelectromechanical systems. Although inducing anisotropic stress in magnetostrictive materials can achieve the domain assembly, controlling magnetic anisotropy over microscale areas is challenging. In this work, we realized the microscopic patterning of magnetic domains by engineering stress distribution. Deposition of ferromagnetic thin films on nanotrenched polymeric layers induced tensile stress at the interfaces, giving rise to the directional magnetoelastic coupling to form ordered domains spontaneously. By changing the periodicity and shape of nanotrenches, we spatially tuned the geometric configuration of domains by design. Theoretical analysis and micromagnetic characterization confirmed that the local stress distribution by the topographic confinement dominates the forming mechanism of the directed magnetization.

RDF made of municipal solid waste was pyrolyzed under simulated pyrolytic gas (PG) atmosphere and N2 atmosphere. Besides pyrolysis temperature, the atmosphere also affected the yield of three phase products and thermal conversion. By comparison of the products from two different atmospheres at same pyrolysis temperature, more tar, less char and gas were produced under PG atmosphere than the yields produced under N2 atmosphere; LHV of char produced under PG atmosphere was always lower than the value of char produced under N2 atmosphere, so that the char thermal conversion (CTC) efficiency under PG atmosphere also was lower; O/C and H/C of chars produced PG atmosphere were usually smaller than the data of char produced under N2 atmosphere, which indicated chars produced under PG atmosphere were more similar with coal, and more suitable for co-combustion of coal and char in coal power plant. In additional, highest comprehensive combustion characteristic index S was obtained at 600 °C under PG atmosphere. LHV of gas produced under PG atmosphere was always higher than the gas produced under N2 atmosphere, but gas thermal conversion (GTC) efficiency under PG atmosphere was lower because of less gas yield.

RE2Fe14B-based (RE, rare earth) permanent magnets containing abundant and cheap La/Ce have attracted intense attention recently. In comparison with Ce that can fully replace Nd in the 2:14:1 lattice, La substitution for Nd has long been limited at a low level. Here we present that through doping La35Ce65 alloy with the La/Ce ratio in natural mineral, stable 2:14:1 phase can be maintained at 1273 K within the entire substitution range of [(La35Ce65)x(Pr20Nd80)1-x]2.14Fe14B (0.6 ≤ x ≤ 1.0, at.%), as verified by composition analysis, microstructural characterization and magnetic measurements. Interestingly, the promoted La solution in 2:14:1 phase induces two unique findings upon coexisting La-Ce-Pr-Nd: i) Compared to Ce that fits well with the nominal concentration, La deviates noticeably from the nominal one; ii) Nanoscale spinodal-decomposition-like phase separation is observed due to different solubilities of La-Ce-Pr-Nd elements in 2:14:1 phase. Above joint effects induce higher Curie temperature than estimation based on the rule of mixture, which delights the prospect of La35Ce65 alloy in developing low-cost permanent materials.

The demand for high-performance spintronic devices has boosted intense research on the manipulation of magnetism in van der Waals (vdW) magnets. Despite great efforts, robust ferromagnetic transitions above room temperature still face significant hurdles. Strain engineering can reversibly regulate magnetic exchange, but the degree of regulation is still impractical for most magnetic applications. Hereby we employ a large-strain transferrer to produce tunable strains of up to 4.7%, which induces authentic room-temperature ferromagnetism in large-area Fe3GeTe2 nanoflakes with 20-fold improvement in magnetization. The record increment of the Curie temperature (TC) of well above 400 K originates from the strain-enhanced magnetic anisotropy and excellent magnetoelastic coupling. The correlation between the emerging ferromagnetism and Raman spectral evolution is also established, which complements well the TC phase diagram in a large-strain region. In addition, an unusual exchange bias effect with a vertical magnetization shift is tracked for the first time upon bending, which reveals the hidden competition between antiferromagnetic and ferromagnetic coupling. The reversible strain manipulation of single-domain ferromagnetic order in a single nanoflake further opens up a route to develop low-power wearable spintronic devices. The findings here provide vast opportunities to exploit the possibility of practical applications of more vdW magnets.

With the growth of chemical data, computation power and algorithms, machine learning-assisted high-throughput virtual screening (ML-assisted HTVS) is revolutionizing the research paradigm of new materials. Herein, a combined ML-assisted HTVS and experimental approach was applied to accelerate the search for energetic melt-castable materials with promising properties. The ML-assisted HTVS system is composed of high-throughput molecular generation (in a heuristic enumeration method) and five machine learning-based property prediction models (including density, melting point, decomposition temperature, detonation velocity, and detonation pressure). Using this system, we rapidly targeted 136 promising candidates from a generated molecular space containing 3892 molecules. With extensive efforts on experimental synthesis, eight new energetic melt-castable materials (MC-1 to MC-8) were obtained, and their measured properties were in good agreement with the predicted results. This work verifies the effectiveness of the combined ML-assisted HTVS and experimental approach for the accelerated discovery of energetic melt-castable materials.

The chain-like carbon nanotubes (CNTs) decorated with CoFeB (CoFeB/CNTs) prepared by oxidation-reduction method is introduced into MgH2 to facilitate its hydrogen storage performance. The addition of CoFeB/CNTs enables MgH2 to start desorbing hydrogen at only 177 °C. Whereas pure MgH2 starts hydrogen desorption at 310 °C. The dehydrogenation apparent activation energy of MgH2 in CoFeB/CNTs doped-MgH2 composite is only 83.2 kJ/mol, and this is about 59.5 kJ/mol lower than that of pure MgH2. In addition, the completely dehydrogenated MgH2−10 wt% CoFeB/CNTs sample can start to absorb hydrogen at only 30 °C. At 150 °C and 5 MPa H2, the MgH2 in CoFeB/CNTs doped-MgH2 composite can absorb 6.2 wt% H2 in 10 min. The cycling kinetics can remain rather stable up to 20 cycles, and the hydrogen storage capacity retention rate is 98.5%. The in situ formation of Co3MgC, Fe, CoFe and B caused by the introduction of CoFeB/CNTs can provide active and nucleation sites for the dehydrogenation/rehydrogenation reactions of MgH2. Moreover, CNTs can provide hydrogen diffusion pathways while also enhancing the thermal conductivity of the sample. All of these can facilitate the dehydrogenation/rehydrogenation performance and cyclic stability of MgH2.

Demonstrating highly efficient alternating current (AC) magnetic field heating of nanoparticles in physiological environments under clinically safe field parameters has remained a great challenge, hindering clinical applications of magnetic hyperthermia. In this work, exceptionally high loss power of magnetic bone cement under the clinical safety limit of AC field parameters, incorporating direct current field-aligned soft magnetic Zn0.3 Fe2.7 O4 nanoparticles with low concentration, is reported. Under an AC field of 4 kA m-1 at 430 kHz, the aligned bone cement with 0.2 wt% nanoparticles achieves a temperature increase of 30 °C in 180 s. This amounts to a specific loss power value of 327 W gmetal-1 and an intrinsic loss power of 47 nHm2 kg-1 , which is enhanced by 50-fold compared to randomly oriented samples. The high-performance magnetic bone cement allows for the demonstration of effective hyperthermia suppression of tumor growth in the bone marrow cavity of New Zealand White Rabbits subjected to rapid cooling due to blood circulation, and significant enhancement of survival rate.

Crystal morphology has a significant effect on the properties and applications of energetic materials (EMs). Here, we have combined the single-crystal X-ray diffraction (SCXRD) and rotation imaging...

Perylene-based organic semiconductors are attractive photoactive materials due to their broad visible-light absorption, large extinction coefficients, high photostability, and relatively low cost. ...

The solid-state magnetic cooling (MC) relying on magnetocaloric effect (MCE) of magnetic materials is recognized as a promising energy efficiency and environmentally friendly technology. However, there is still a large gap between the fundamental materials in the laboratory developing stage and the practically realizable applications. In this paper, a new series of B-site ordered RE2ZnMnO6 (RE = Gd, Dy and Ho) perovskites are successfully fabricated, and their structural and magnetic properties together with the cryogenic magnetocaloric performances are studied in detail. All the RE2ZnMnO6 compounds are found to crystallize in the B-site ordered orthorhombic (double perovskites) structure with the space group of P121/C1. The magnetic ground state are confirmed to be a ferromagnetic (FM) coupling for Gd2ZnMnO6, whereas, ferrimagnetic (FIM) coupling for Dy2ZnMnO6 and Ho2ZnMnO6 based on the magnetic measurements and first principle calculations. The ordering temperatures (TM) are determined to be ~6.4 K for Gd2ZnMnO6, ~10.4 K for Dy2ZnMnO6, and ~6.8 K for Ho2ZnMnO6, respectively. Furthermore, several vital parameters for determining the magnetocaloric performances including -ΔSMmax (magnetic entropy change peak values), TEC(2) (temperature-averaged magnetic entropy change) and RCP (relative cooling powers) are evaluted to be 15.17, 14.44 J/(kgK) and 226 J/kg for Gd2ZnMnO6, 8.32, 8.17 J/(kgK) and 208 J/kg for Dy2ZnMnO6, and 13.19, 12.68 J/(kgK) and 246 J/kg for Ho2ZnMnO6, with the field change ΔH = 50 kOe, respectively. It is worthly noted that Gd2ZnMnO6 exhibits relatively great magnetocaloric performances below 10 K, which suggests that Gd2ZnMnO6 is a competitive candidate for cryogenic magnetic cooling.

Massive rare earth oxides inevitably form at high La–Ce substitution, causing inadequate liquid-phase-sintering, direct exchange coupling of ferromagnetic grains, obscure core–shell morphology and severe coercivity degradation of multi-main-phase (MMP) Nd–La–Ce–Fe–B sintered magnets. To fully exploit the abundant La–Ce for application, here we designed a facile approach, (Pr, Nd)Hx grain boundary diffusion that combines the joint benefits of forming thick non-ferromagnetic grain boundary layer and PrNd-rich hardening shell, yielding a nearly threefold coercivity of 14.2 kOe with enhanced energy product of 38.5 MGOe for LaCe-40 magnet. These findings suggest a reliable recipe for relieving the main constraints of MMP Nd–La–Ce–Fe–B magnets.

A crystal engineering strategy has been adopted to prepare porous high explosive, cyclotrimethylenetrinitramine (RDX). Raw RDX was crystallized with TMS, CAM and HMPT (TMS=Tetramethylene Sulfone, C...

MnZn power ferrites are technologically important for miniaturization and efficiency of electronic devices. It is of practical significance to obtain high working frequency and temperature in the MnZn ferrites. In this study, MnZn ferrites capable of working above 1 MHz and 80 °C have been successfully prepared by Nb2O5 and TiO2 doping. Nb2O5 promotes the densification process during sintering and exists as a resistive layer in the grain boundary region, leading to improved permeability and power losses. TiO2 doping results in the formation of localized Ti4+-Fe2+ pairs and offers extra cation vacancies for Nb5+ diffusion, which further enhances the effect of Nb2O5. The sample doped with 250 ppm of Nb2O5 and 2500 ppm of TiO2 presents optimal magnetic properties with the lowest power loss value of 394 kW/m3 at 1 MHz and 80 °C , along with an initial permeability of 1510, thus, serving as a good candidate for MHz, high-temperature and high-permeability power applications.

The influences of minor Y addition on the thermal stability, crystallization behavior, magnetic property and bending ductility of Fe–Si–B amorphous ribbons have been systematically investigated. The results show that all the ribbons with Y addition are fully amorphous structure, and the introduction of Y can enhance the glass forming ability of Fe–Si–B amorphous alloy. With Y addition, crystallization temperature of the first and second phase shift to high temperature side, the temperature interval between the two crystallization peaks are enlarged, the third phase transitions process of Fe–Si–B amorphous alloy with Y addition corresponds to the precipitation of Fe3B phase. The activation energy of the first and second phase calculated by Kissinger’s formula increased with Y addition. Appropriate Y addition is beneficial for Ms. The measured coercivity Hc gradually decreased with the Y addition increased. The amorphous alloys exhibit good bending ductility in the quenched state. The ductile to brittle temperature increase to 300 °C with 1 at% Y addition. Furthermore, the mechanism of ductile to brittle for amorphous alloy was discussed.

Parabolic trough collector is the most mature and widely deployed concentrated solar power technology with temperature ranging from 325 to 700 K. In this study, three different absorber tube geometries (smooth absorber tube, absorber tube with twisted tape insert and tube with longitudinal fins) of commercially available LS-2 collector are modeled and investigated using engineering equation solver. The objective of this study is to present a numerical comparative analysis of the available thermal enhancement techniques. Comprehensive energetic and exergetic performance of different tube geometry configurations using Al2O3/water as a heat transfer fluid has been compared to assess the nature of exergy destruction due to the fluid’s pressure, due to the heat transfer between sun and the receiver wall and due to the temperature difference between receiver wall and heat transfer fluid temperature. Furthermore, pure base fluid (water) along with the nanofluid is used to evaluate the system’s performance (thermal efficiency, exergetic efficiency, heat transfer coefficient, receiver temperature, pressure drop, pumping work demand and friction factor). Smooth absorber tube with pure base fluid is the reference case, while five cases (smooth tube with nanofluid, tube with pure water and fins inserted, tube with nanofluid and fins inserted, tube with pure water and twisted tape inserted, tube with nanofluid and twisted tape inserted) are investigated. Thermal efficiency of absorber tube with twisted tape insert and nanofluid is almost 72.26%, followed by tube with internal fins (72.10%), while smooth absorber tube has nearly 71.09%. Heat transfer coefficient of twisted tape inserted tube with nanofluid and longitudinal fins tube with nanofluid is greater than smooth absorber tube to almost 118.23% and 103.26%, respectively. The emphasis is also given to the pressure drop of the examined cases as it depends up on the friction factor of the absorber tubes. The use of nanofluid and twisted tape inserts leads to higher thermal enhancement, followed by the nanofluid and internal fins inserted tube. The nanoparticle concentration is also varied to investigate its effect on different performance parameters of the system.

In order to improve the hydrogen storage performance of MgH2, graphene and CeF3 co-catalyzed MgH2 (hereafter denoted as MgH2+CeF3@Gn) were prepared by wet method ball milling and hydriding, which is a simple and time-saving method. The effect of CeF3@Gn on the hydrogen storage behavior of MgH2 was investigated. The experimental results showed that co-addition of CeF3@Gn greatly decreased the hydrogen desorption/absorption temperature of MgH2, and remarkably improved the dehydriding/hydriding kinetics of MgH2. The onset hydrogen desorption temperature of Mg + CeF3@Gn is 232 °C，which is 86 °C lower than that of as-milled undoped MgH2, and its hydrogen desorption capacity reaches 6.77 wt%, which is 99% of its theoretical capacity (6.84 wt%). At 300 °C and 200 °C the maximum hydrogen desorption rates are 79.5 and 118 times faster than that of the as-milled undoped MgH2. Even at low temperature of 150 °C, the dedydrided sample (Mg + CeF3@Gn) also showed excellent hydrogen absorption kinetics, it can absorb 5.71 wt% hydrogen within 50 s, and its maximum hydrogen absorption rate reached 15.0 wt% H2/min, which is 1765 times faster than that of the undoped Mg. Moreover, no eminent degradation of hydrogen storage capacity occurred after 15 hydrogen desorption/absorption cycles. Mg + CeF3@Gn showed excellent hydrogen de/absorption kinetics because of the MgF2 and CeH2-3 that are formed in situ, and the synergic catalytic effect of these by-products and unique structure of Gn.

Municipal Solid Waste (MSW) was converted into high-grade solid fuels (biochar) and gaseous product via thermal pyrolysis under pyrolytic gas atmosphere. The experiment was carried out in a packed-bed reactor at the temperature range of 600–800 °C in both atmospheres of N2 and pyrolytic gas. Gas, liquid, and solid products were analyzed by gas chromatograph and elemental analysis. Amount of biochar obtained from both atmospheres were not significantly different. CH4 and CO2 in pyrolytic gas promoted the release of volatile in the MSW, resulting in lower ratio of VM/FC, ca. 0.13. The atomic ratios of O/C and H/C were around 0.02–0.11 and 0.005–0.035, respectively. These values were equivalent to anthracite coal type. On the other hand, the liquid fuel yield under pyrolytic gas condition was found to be higher, compared with that under N2 condition. In addition, the enhancement of H2 and CO production was accompanied by the decrease in CH4 and CO2 output. Overall, the operating condition at 800 °C or higher with reaction times longer than 4 min were recommended for production of biochar with fuel qualities approaching anthracite coal.

Prussian blue analogues hold great promise as cathodes in sodium ion batteries. Among Prussian blue analogues, manganese hexacyanoferrate is desirable because of its high working voltage, as well as its high specific capacity and low cost. However, poor cycling stability and unsatisfactory rate capability of manganese hexacyanoferrate, which are mainly caused by poor intrinsic conductivity, phase transition, side reactions, and transition metal dissolution, extremely limit its practical application. In this work, we demonstrate a high-rate and long-life MnHCF@PEDOT sodium ion battery cathode through a facile in situ polymerization method. Benefitting from the synergistic effect of the inhibited Mn/Fe dissolution, suppressed phase transition, and improved capacitive storage, the composite electrode exhibits a high capacity of 147.9 mA h g−1 at 0.1C, 95.2 mA h g−1 at a high rate of 10C, and 78.2% capacity retention after 1000 cycles. Furthermore, even at a low temperature of −10 °C, MnHCF@PEDOT still delivers a high capacity of 87.0 mA h g−1 and maintains 71.5 mA h g−1 (82.2%) after 500 cycles.

Ni/Al2O3 catalyst is the one of promising catalysts for enhancing H2 production from supercritical water gasification (SCWG) of biomass. However, due to carbon deposition, the deactivation of Ni/Al2O3 catalyst is still a serious issue. In this work, the effects of lanthanum (La) as promoter on the properties and catalytic performance of Ni/Al2O3 in SCWG of food waste were investigated. La promoted Ni/Al2O3 catalysts with different La loading content (3–15 wt%) were prepared via impregnation method. The catalysts were characterized using XRD, SEM, BET techniques. The SCWG experiments were carried out in a Hastelloy batch reactor in the operating temperature range of 420–480 °C, and evaluated based on H2 production. The stability of the catalysts was assessed by the amount of carbon deposition on catalyst surface and their catalytic activity after reuse cycles. The results showed that 9 wt% La promoter is the optimal loading as Ni/9La–Al2O3 catalyst performed best performance with the highest H2 yield of 8.03 mol/kg, and H2 mole fraction of 42.46% at 480 °C. La promoted Ni/Al2O3 catalysts have better anti-carbon deposition properties than bare Ni/Al2O3 catalyst, resulting in better gasification efficiency after reuse cycles. Ni/9La–Al2O3 catalyst showed high catalytic activity in SCWG of food waste and had good stability as it was still active for enhancing H2 production when used in SCWG for the third time, which indicated that La promoted Ni/Al2O3 catalysts are potential additive to improve the SCWG of food waste.

Scalable and low cost fabrication of light weight flexible electromagnetic (EM) wave absorbers is highly desirable for the rapid development of wearable electronic devices. A simple method has been developed involving incorporation of rationally designed FeNi3/Mo2C into cellulose fibers in the formation of thin and flexible absorbing papers with tunable electromagnetic parameters. High-performance absorption has been achieved with the minimum reflection loss (RL) reaching −51.50 dB at 13.7 GHz and an effective absorption bandwidth of 5.1 GHz with a thickness of 2.0 mm due to the synergic effects of dielectric and magnetic loss. For emerging flexible absorbers, accurate electromagnetic measurements by using a conventional coaxial method are challenging without the addition of wax or paraffin as the solidification agent. A stacking and compressing method has been developed to prepare standard-sized core samples for coaxial measurements for which the validity has been confirmed by comparison with the waveguide and arch methods. Consequently, not only a new type of effective EM absorber has been developed and verified by all the available measurement methods, but this simple and scalable method applied to fabricate flexible electronic devices is also extendable for applications in sensing, catalysis and energy storage.

The integrated gasification combined cycle (IGCC) has been applied as an alternative technology for power plant due to the higher thermal efficiency than that of conventional pulverized coal-fired ...

Highlights A cooperative solvation/surface engineering approach is reported to achieve the reversible Mg plating/stripping in conventional carbonate electrolytes.Benefitting from the strategy, Mg2+ can easily overcome the reduced desolvation barrier and penetrate the Mg2+-conducting polymer coating, deposited on the Mg metal anode successfully, promoting the application of magnesium anode in carbonate electrolytes toward high-energy rechargeable batteries. Supplementary Information The online version contains supplementary material available at 10.1007/s40820-021-00716-1., Magnesium metal anode holds great potentials toward future high energy and safe rechargeable magnesium battery technology due to its divalent redox and dendrite-free nature. Electrolytes based on Lewis acid chemistry enable the reversible Mg plating/stripping, while they fail to match most cathode materials toward high-voltage magnesium batteries. Herein, reversible Mg plating/stripping is achieved in conventional carbonate electrolytes enabled by the cooperative solvation/surface engineering. Strongly electronegative Cl from the MgCl2 additive of electrolyte impairs the Mg…O = C interaction to reduce the Mg2+ desolvation barrier for accelerated redox kinetics, while the Mg2+-conducting polymer coating on the Mg surface ensures the facile Mg2+ migration and the effective isolation of electrolytes. As a result, reversible plating and stripping of Mg is demonstrated with a low overpotential of 0.7 V up to 2000 cycles. Moreover, benefitting from the wide electrochemical window of carbonate electrolytes, high-voltage (> 2.0 V) rechargeable magnesium batteries are achieved through assembling the electrode couple of Mg metal anode and Prussian blue-based cathodes. The present work provides a cooperative engineering strategy to promote the application of magnesium anode in carbonate electrolytes toward high energy rechargeable batteries. Supplementary Information The online version contains supplementary material available at 10.1007/s40820-021-00716-1.

In order to gain the combustion flow characteristics in the secondary combustor and direct-connect inlet of the solid ducted rocket with multiple gas nozzles, the flow field parameters distribution and combustion performance of the engine under cold flow and combustion conditions were studied by experimental and numerical simulation methods. The results show that under the cold flow state, the supersonic airflow enters the secondary combustor at the high subsonic state after compressing by the oblique shock, which enhances the mixing effect of the secondary combustor. After the fuel-rich gas enters the secondary combustor through the multi-nozzles, the flow field structure becomes extremely complex, and multiple vortex recirculation zones are formed in the head area of the combustor. The distribution of the fuel-rich gas in the secondary combustor is more uniform, and the residence time of the gas and air increases, which enhances the effect of mixing and combustion organization, and the engine has better combustion performance. With the increase of fuel-rich gas flow, the pressure of the secondary combustor rises, and the oblique shock waves of pre-combustion moves forward continuously. The experimental and simulation results accurately capture the forwarding process and stable position of the oblique shock waves, which provides guidance for the subsequent design optimization of the solid ducted rocket.

Two-dimensional metal-organic frameworks (2D-MOFs) and their derivatives are promising for catalysis, energy storage, gas separation, etc. due to their unique microstructure and physicochemical properties. Many efforts have been devoted to fabricating 2D-MOFs with challenges remaining in yield and fine control of their thickness and lateral size. Here a versatile strategy has been used involving epitaxial, anisotropic, and confined growth of CoNi-MOF-71 nanosheet arrays, giving rise to excellent quantity and controllability of the 2D-MOFs. Electromagnetic (EM) wave absorption performance has been investigated for the resultant 2D Co/Ni/C derivatives. Compared with the bulk counterpart, significantly increased surface area, conductivity, and shape anisotropy for the 2D derivatives result in enhanced interfacial polarization, conductive loss, and magnetic resonance. As such, optimum EM wave absorption of minimum reflection loss RLmin = -49.8 dB and an ultrawide effective adsorption bandwidth EAB = 7.6 GHz can be achieved at a thickness of 2.6 mm. This work not only sheds light on the performance enhancement for 2D absorbers via synergistic effects of multiple attenuation mechanisms but also provides an effective fabrication route of ultrathin MOFs with high yield and uniform size for extended applications in catalysis, electrochemistry, and optoelectronics fields.

Cross-linking network structures are critical to construct flexible and lightweight electromagnetic (EM) wave absorbers, for which effective regulation of the EM parameters is essential. Herein, a versatile strategy has been developed by interconnecting carbon fibers with NiFe-layered double hydroxide (NiFe LDH)/MXene derivatives. The large-sized flaky morphology and conductive nature of the interconnectors induce the percolation effect in the fabric networks with ultralow addition. As such, efficient adjustment of the EM parameters can be achieved by tuning the content of the interconnectors around the percolation threshold, giving rise to an optimal reflection loss (RL) of -58.0 dB and a wide effective absorption band (EAB) of 7.0 GHz at a thickness of 2.5 mm under the incorporation of 7.0 wt % NiFe LDH/MXene. This work provides insights on constructing percolation networks and effective manipulation of electronic and magnetic properties, which can be extended to various areas such as sensing, catalysis, and energy storage.

The sensitivity and performance of energetic materials strongly depend on their microstructure. Different solvation and desolvation methods were applied to prepare high explosive HNS with m...

REFe2 (RE = rare earth) phase has been considered to form spontaneously in Nd-Ce-Fe-B cast strips and inherit into sintered magnets. However, here we report that REFe2 phase, which is absent in starting strip, occurs in as-sintered magnet with an identical composition of 25 wt% Ce. More interestingly, the formation of REFe2 induces apparent Ce-enriched shell surrounding RE2Fe14B grain, which is further exacerbated in annealed magnet containing a higher fraction of REFe2 phase. Influences of increasing REFe2 fraction on magnetic performance are revealed. Above findings on REFe2 phase evolution and resultant Ce segregation may shed lights on fabricating high-performance Nd-Ce-Fe-B.

The efficient production of high calorific value solid fuel from palm oil empty fruit bunch (EFB) was investigated by experimenting hydrothermal carbonization (HTC) with initial absolute pressures of 0.1 MPa, 1.3 MPa, and 3.1 MPa in N2 atmosphere and in CO2 atmosphere. The pressure increase in HTC is expected to promote the improvement of calorific value in efficient way, while the alteration of reaction atmosphere from N2 to CO2 is aimed at obtaining higher extent of carbonization. Increasing the initial pressure of N2 improved calorific value of the derived fuel from 19.3 MJ/kg to 22.2 MJ/kg, while creating only trivial effect on energy yield. Increasing the initial pressure of CO2 further enhanced the carbonization and resulted in fuel with maximum calorific value of 23.6 MJ/kg. However, it also resulted in up to 6% reduction on energy yield compared with the cases with N2. The advantages of pressurized HTC in N2 atmosphere and in CO2 atmosphere over conventional HTC were evident when used for the production of fuels with comparable heating value. Process efficiencies of the pressurized HTC in both N2 and CO2 atmospheres were shown to be 4–8% higher than those of conventional HTC with normal initial reaction pressure.

Advanced electromagnetic (EM) wave absorbing materials containing both magnetic and dielectric components have attracted considerable attention for the ever-developing electronic and telecommunication devices. It is however, rather challenging to combat the sacrificed magnetic loss due to magnetic dilution by the introduction of the dielectric component. Here a novel confinement strategy has been adopted to develop porous heterogeneous Fe7Co3/ZnO nanosheets where Fe7Co3 nanoparticles with single domain size and dispersed distribution can be achieved for enhanced natural resonance. The nanosheets exhibit unique porous feature with significantly reduced density. Also, tunable dielectric loss achieved via interruption of the Fe7Co3 conductive network functions synergistically with the magnetic loss for enhanced absorption over a wide frequency range (7.92 GHz), covering the complete Ku band and half of the X band. The confinement strategy proposed in this study not only paves the way for designing high-performance EM wave absorber with low density and broad bandwidth, but also provides a versatile method for the synthesis of two-dimensional composites with tunable composition for extended applications in energy storage, catalysis, biomedicine and sensing.

Surface nitridation has been used to fabricate the insulation coatings of the Fe, FeSi, FeSiAl and FeSiCr soft magnetic composites (SMCs). Effects of the nitridation conditions on the magnetic performance of the SMCs have been investigated. Detailed growth mechanism and models of the coating layers for different alloy systems have been established based on combined thermodynamic and kinetics analysis. For Fe and FeSi SMCs, nitride coatings containing α-Fe(N) forms, while coexistenc of α-Fe(N) and Fe4N is obtained for the FeSiAl SMCs. For the FeSiCr system, the nitride coating is composed of α-Fe(N) and CrN with relatively large electrical resistivity, giving rise to enhanced magnetic performance compared with that of the SMCs prepared via traditional phosphoric acid passivation.

This paper presents the results from experimental study of syngas production by catalytic cracking of tar in wastewater under supercritical condition. Ni/Al2O3 catalysts were prepared via the ultrasonic assisted incipient wetness impregnation on activated alumina, and calcined at 600 °C for 4 h. All catalysts showed mesoporous structure with specific surface area in a range of 146.6–215.3 m2/g. The effect of Ni loading (5–30 wt%), reaction temperature (400–500 °C), and tar concentration (0.5–7 wt%) were systematically investigated. The overall reaction efficiency and the gas yields, especially for H2, were significantly enhanced with an addition of Ni/Al2O3 catalysts. With 20%Ni/Al2O3, the H2 yield increased by 146% compared to the non-catalytic experiment. It is noteworthy that the reaction at 450 °C with the addition of 20%Ni/Al2O3 had a comparable efficiency to the reaction without catalyst at 500 °C. The maximum H2 yield of 46.8 mol/kgtar was achieved with 20%Ni/Al2O3 at 500 °C and 0.5 wt% tar concentration. The catalytic performance of the catalysts gradually decreased as the reuse cycle increased, and could be recovered to 88% of the fresh catalyst after regeneration. 20%Ni/Al2O3 has a potential to improve H2 production, as well as a good reusability. Thus, it is considered a promising catalyst for energy conversion of tar in wastewater.

A 3D large-sized nanocrystalline (NC) copper bulk was prepared by inert gas condensation and in situ warm compress, the density of which was 99.51% of theoretical value. Electrochemical methods and...

Low-dimensional soft magnetic materials are technologically important for miniaturization of magnetic devices. It is, however, challenging to maintain ferromagnetic response in nanosized magnetic material. In this work, ultrafine FeCo nanoparticles have been prepared by reactive pulsed laser deposition, which can be exchange coupled through ultrathin dielectric shells, even though their diameters are far below the superparamagnetic blocking limit. This unique core/shell structure guarantees ferromagnetic coupling and insulation of neighboring magnetic nanoparticles simultaneously. The nanoparticle film exhibits large saturation magnetization of 1.13 T, high electrical resistivity of 4200 μΩ·cm, maximum permeability of 120, a cutoff frequency of 1.7 GHz, and it is a promising material for microwave application.

The rapid advancement of modern electronic technology requires MnZn ferrites capable of handling high-frequency signals, offering very low power loss and reasonably high permeability. MnZn ferrites were developed by using the conventional ceramic processing technique and the effects of Co2O3 and SnO2 doping on high-frequency magnetic properties were investigated. Co2O3 and SnO2 co-doping resulted in a sharp decrease of eddy-current loss and residual loss of the MnZn ferrites at 3–5 MHz and improved the temperature characteristics at 20–120 °C. The minimum power losses at 20 °C, 10 mT for 3 MHz and 5 MHz were 20 kW/m3 and 81 kW/m3, while the power losses at 100 °C, 10 mT for 3 MHz and 5 MHz were 60 kW/m3 and 205 kW/m3 respectively. The optimal saturation magnetic flux density and initial permeability were 480 mT and 675 respectively. The cut-off frequency of the sample was 12 MHz, establishing it as an ideal material for high-frequency applications.

The Fe–Si–B amorphous ribbons with various CO ventilation amount were prepared by planar-flow melt spinning method. The effect of CO gas on surface quality, magnetic properties and core loss of amorphous ribbons were investigated. With the increasing CO ventilation, the wheel side surface roughness, average air pocket size and air pocket quality decrease, the ribbon grows thicker, but air side surface roughness remains almost no changes. The three samples have reached to a fully amorphous structure. Meanwhile the diffraction angle corresponding the maximum intensity of each broad diffraction peak decrease slightly with increasing CO ventilation. There is no significant differences in the onset temperate of second exothermic peak (Tx2) and the crystallization peak temperature (Tp1 and Tp2) among the amorphous ribbons prepared with various CO ventilation, but the onset temperate of first exothermic peak (Tx1) increases slightly with the increasing CO ventilation. The room temperature hysteresis loops of amorphous ribbons show that surface quality have significant effect on magnetic properties. The coercivity (Hc), core loss (P1.35/50), magnetic polarization (B80) and permeability (µ) among the ribbons are improved with better surface quality, though the saturation magnetic flux density almost keeps same. Core loss are separated by the scaling theory, and experiment dates show a good agreement with the predicted data. Thus the scaling theory is suitable for Fe–Si–B amorphous alloys. The surface quality has more significant effect on hysteresis losses than eddy current loss at low frequency.

The future trend toward flexible electronics creates a demand for flexible power sources using rechargeable batteries, where freestanding and flexible electrodes are of critical importance. The utilization of high capacity anode materials like metal sulfides in flexible batteries is highly desirable for the miniaturization of electronic devices but is nevertheless very challenging in the fabrication of an electrode that is freestanding and flexible. Herein, a universal electrospinning strategy to fabricate freestanding and flexible metal sulfides@carbon electrodes is proposed based on the formation of chelate complexes between l-cysteine and metal cations. Taking SnS as a model material, flexible fiber electrodes are realized with SnS nanoparticles well embedded in the continuous and interwoven carbon fibers. As freestanding electrodes for lithium and sodium storage, a high capacity, good rate capability, and excellent cycling stability are simultaneously achieved. Such a strategy is also successfully extended to the fabrication of Ni 3S 2/C fibers and Fe 7S 8/C fibers, suggesting the universality in fabricating freestanding and flexible high capacity electrodes.

Metacomposite absorbers could be optimized either by the magnetic and dielectric properties of absorbents or by periodically arranged structural units at macroscopic scale. Herein, high-performance microwave absorption Ni@C nanocapsules synthesized by a modified arc-discharge method were mixed with polyvinyl acetate adhesive and then formed a periodic millimetric pattern on a polyethylene terephthalate substrate. Such a metacomposite structure results in a significant tunability and enhancement for the microwave absorption, associated with the maximum absorption of structured absorbers presenting 52.34% absorption efficiency higher than 29.20% of the non-structured absorber. In particular, it is demonstrated that the anisotropic absorption resonances can be tuned by changing the rotation angle of multi-layered assembly. This enhanced absorption is well explained by theoretical simulation, owning to the millimeter “capacitor-like” dielectric couplings between the microstructural units. The present study thus shows an alternative way to design tunable metacomposite absorbers.

Magnetostriction deterioration has been observed in slowly cooled Fe-Ga alloys when compared with the high temperature quenched ones. To reveal the underlying origin, here we investigated the microstructure of Fe81Ga19 thin-sheet samples quenched after slow cooling (at ∼0.3 K/min) to near and below the decomposition phase boundary between A2 and (A2’ + L12) phases. In comparison with the sample quenched at 1273 K (much higher than the decomposition phase boundary, ∼793 K) or the one quenched near the decomposition boundary (773 K), magnetostriction deterioration is observed for the one quenched below the decomposition boundary (673 K). Besides the A2 matrix phase, quenching at 673 K also promotes the formation of secondary L12 phase with negative magnetostriction and the phase transformation induced dislocations located close to the grain boundaries. Simultaneously, weak D03 ordering of the untransformed bcc matrix is also observed. All these microstructural changes deteriorate the magnetostriction. Our work provides important information why the magnetostriction of Fe81Ga19 greatly depends on the thermal history.

Two-step post-sinter annealing (PSA) treatment, due to its universal applicability, has been one of the most effective strategies for enhancing the coercivity of Nd-Fe-B sintered magnets. Here we report a peculiar phenomenon that the as-sintered multi-main-phase (MMP) Nd-La-Ce-Fe-B magnet exhibits the highest reported to date coercivity of 13.0 kOe upon 25 wt% La-Ce substituting for Nd, combined with Br = 13.12 kG, and (BH)max = 41.67 MGOe. Further annealing cannot enhance the coercivity whereas the remanence and energy product are drastically lowered, i.e. to 11.0 kOe, 12.57 kG, and 38.71 MGOe after two-step PSA, being remarkably different from the conventional Nd-Fe-B. Microstructural analysis reveals that the as-sintered Nd-La-Ce-Fe-B magnet with coexisting REFe2 (Fd 3 ¯ m) and RE-rich (Fm 3 ¯ m) intergranular phases possesses continuous GB layer isolating adjacent ferromagnetic grains. Hence the beneficial role of PSA on modifying the microstructure and strengthening the coercivity is tiny. Additionally, high-temperature PSA destroys the initial chemical heterogeneity of MMP magnets, leading to the formation of REs homogeneously distributed grains and resultant reduction of the intrinsic magnetic properties. As evidenced by in-situ Lorentz TEM characterization, PSA sample with reduced chemical gradient exhibits quick domain wall motion, compared to the as-sintered one with basically unchanged magnetic domain structure upon the same applied field. The proof-of-principle micromagnetic simulation further confirms that retaining the inhomogeneous La/Ce/Nd distribution is essential to suppress the magnetic dilution effect. These findings demonstrate the realistic prospect of skipping PSA treatment in MMP magnets, which can not only reduce the production process and cost, but also delight the scenario for designing high-performance 2:14:1-type sintered magnets based on abundant La/Ce.