Search

Electrocatalytic nitrogen fixation in an aqueous solution is considered a promising approach to ammonia synthesis. Still, this process has low Faraday efficiency and ammonia yield, so it is necessary to develop an efficient, clean, and safe catalyst to promote nitrogen reduction process. Doping can be easily carried out during the crystal growth owing to the weak interaction between the sandwiched layers (due to van der Waals forces) of MoS 2. Here, a Ni-P codoped MoS 2 nanosheets is designed as a highly efficient catalyst for electrochemical nitrogen fixation with superior selectivity. Especially, the doping of Ni achieved the transformation of MoS 2 from 2 H phase to 1 T phase, improving the conductivity of the material. In addition, the doping of P creates more sulfur vacancies in the catalyst, thereby producing more H*, which promotes the adsorption and activation of nitrogen. The as-synthesized Ni-P codoped MoS 2 nanosheets show excellent catalytic performance with a high yield of electrocatalytic ammonia synthesis (84.29 μg NH3 h−1 mg cat −1) and Faraday efficiency (2.39 %) at −0.5 V versus reversible hydrogen electrode in acidic electrolytes (0.005 M H 2 SO 4), which outperformed most electrocatalytic ammonia synthesis catalysts. Furthermore, the Ni-P codoped MoS 2 catalyst also shows outstanding electrochemical stability and durability. This work may offer a hopeful lead for designing effective non-noble-metal NRR electrocatalysts. • Ni-P codoped MoS 2 nanosheets is designed for electrochemical nitrogen fixation. • Ni achieved the transformation of MoS 2 from 2H phase to 1T phase. • P creates more sulfur vacancies in the catalyst. • High yield of electrocatalytic ammonia synthesis and Faraday efficiency are achieved. • Ni-P codoped MoS 2 catalyst shows outstanding electrochemical stability and durability. [ABSTRACT FROM AUTHOR]

The diffusion of lithium ions and sodium ions in the anode materials is the main factor limiting the fast-charging performance of lithium and sodium-ion batteries. Due to the slow diffusion kinetics, taking lithium-ion batteries as an example, lithium ions and electrons accumulate locally in and on the surface of anode materials, especially in the process of fast-charging, resulting in uneven lithiation reaction and enormous transient stress, which leads to poor fast-charging performance. In this work, from the aspect of solving the ion diffusion rate, a capacitive type of energy storage is introduced by designing MoS 2 /rGO composite materials with pinned structures as fast-charging and stable anode materials for lithium-ion batteries and sodium-ion batteries. Combining the high ion conductivity and structural rigidity of the rGO conductive network with a few-layer MoS 2 provides a high ion diffusion rate and capacity. As expected, it can charge to 69 % in 25 min and 44 % in 3.2 min, respectively, providing a high capacity of 214.2 mAh g−1 at 10 A g−1 and a high-capacity retention of 85.31 % after 1, 000 cycles at the current density of 3 A g−1 in sodium-ion batteries. Similarly, the high reversible capacity of 910.5 mAh g−1 is achieved in the lithium-ion batteries, and there is almost no capacity loss after 1, 000 cycles at a high current density of 2 A g−1. This work may provide a reference for designing more fast-charging anode materials with high capacity. [Display omitted] • A stable structure in which MoS 2 with an interlayer spacing of 6.75 Å is uniformly dispersed on graphene. • By amino modification of MoS 2 stripped by lithium ion intercalation and the action of oxygen-containing functional groups of graphene. • MoS 2 /rGO composite materials can charge to 69 % in 25 min and 44 % in 3.2 min. • A high fast-charging capacity of 214 mAh g−1 at 10 A g−1 in SIBs, and 910 mAh g−1 in LIBs. [ABSTRACT FROM AUTHOR]

MXene, a recently discovered family of 2D materials, is well known for its application in energy storage areas due to its excellent properties. However, the low capacity of pristine MXene limits its application in energy storage devices such as lithium ion batteries. To solve this problem, we synthesized a new type of N-doped two-dimensional Nb 2 CT x MXene. The nitrogen content of N-doped MXene was 4.5 at% after thermal reaction with urea. The introduction of nitrogen into MXene nanosheets increases c-lattice parameter of Nb 2 CT x MXene from 22.32 Å to 34.78 Å. And the incorporation of nitrogen into MXene nanosheets leads to superior electrochemical performance. For example, the N-doped Nb 2 CT x shows an increased reversible capacity of 360 mAh /g at 0.2C, which is much higher than that of the un-doped Nb 2 CT x MXene (190 mAh/g at 0.2C). And the N-doped Nb 2 CT x MXene also shows excellent cycling stability (288 mAh/g at 0.5C after 1500 cycles). Our results suggest N-doped Nb 2 CT x MXene is promising for energy storage applications. Image 1 • Nitrogen doped Nb 2 CT x MXene is firstly prepared through hydrothermal reaction. • N-doping leads to increased intersheet distance and larger specific surface area. • N-doping leads to a 90% increase of capacity at 0.2C. • The N Nb 2 CT x anode shows a high level of capacity retention (92% after 1500 cycles at 0.5C). [ABSTRACT FROM AUTHOR]

Few-layer vertical graphene (VG) was prepared on arrayed carbon nanotubes (CNTs) without a catalyst by using radio frequency sputtering deposition and microwave plasma enhanced chemical vapor deposition, and the field emission (FE) performance of VG–CNT composites was tested and optimized. The FE performance is found to be strongly dependent on the heights (but not the actual heights) and densities of CNTs, the shapes of VG, and the diameters of VG–CNT composites. The optimal shapes for FE are demonstrated to be CNTs with middle densities and small diameters and VG with high densities and small sizes. The optimal FE performance from our large area VG–CNT composites is found to have a low threshold field of 1.28 V/μm (at 10 mA/cm 2 ), a high maximum emission current density of 87.63 mA/cm 2 (4.28 times higher than that from our previously prepared graphene–CNT composites), and excellent stability at an extremely high mean emission current density of 36.28 mA/cm 2 over a period of 50 h, far better than those of pristine CNTs, pure VG, and shape non-optimized VG–CNT composites. [ABSTRACT FROM AUTHOR]

The hydrogen evolution reaction (HER) happens at the interface between the electrolyte and the electrocatalysts. Thus, the outer surface of electrocatalysts is regarded as the most important towards the catalytic performance, considering its direct contact with the electrolyte. However, the interior part of catalysts could also have an influence on the HER performances. Herein, the HER catalytic performances of MoS 2 nanosheets are proven to be enhanced by the interior NiCo 2 S 4 nanotube skeletons, although the interior skeletons are unaccessible for the electrolyte during the HER process. The reasons may lie in the optimized electronic transport properties and much increased amount as well as intrinsic activity of active sites. The theoretical calculations and experimental results suggest enhanced adsorption of H* and accelerated Heyrovsky step of the HER process for the NiCo 2 S 4 supported MoS 2 , which may be the reason of the improved intrinsic activity of the active sites. Moreover, calculation of the densities of states suggests the metallic nature of the heterostructures, which could result in the excellent electronic transport performance for NiCo 2 S 4 supported MoS 2. In addition, the enhancement has a close relationship with the amount of the loading MoS 2. Besides, compared with bared NiCo 2 S 4 nanotubes, the MoS 2 loaded NiCo 2 S 4 nanostructures also exhibit better HER catalytic activity as well as improved catalytic stability. This work offers an effective and facile way to design and prepare efficient non-precious metal HER catalysts. [Display omitted] • HER electrocatalysts with MoS 2 outer surfaces and NiCo 2 S 4 interior skeletons are prepared. • Although the interior skeletons are unaccessible for the electrolyte, they can enhance the corresponding HER performances. • The mechanism is analyzed based on theoretical calculations and experimental results. [ABSTRACT FROM AUTHOR]

Multi-element intermetallic energetic structural materials (ESMs) can be applied as reactive fragment, reactive shell and reactive shaped charge. As typical of intermetallics ESMs, Ni-Al ESMs have been heavily studied. However, the low density limits its application. This work proposed to improve the performance of Ni-Al ESMs by adding Ta. The nearly fully dense Ta-Ni-Al ESMs with a molar ratio 4:3:3 was successfully fabricated by explosive consolidation. The density was high up to 10.52 g/cm3 (98.3% theoretical maximum density). The heat treatment was used to further improve the performance of the Ta-Ni-Al ESMs. The microstructure characteristics were analyzed by scanning electron microscopy, X-ray diffraction and transmission electron microscope. The mechanical properties, reaction and impact-induced energy release have been systematically studied. Firstly, quasi-static and dynamic compression tests were conducted to analyze the mechanical properties of the sample before and after heat treatment. Secondly, the reaction characteristics in different atmospheres were discussed by differential scanning calorimetry and thermogravimetric analysis. The effect of the additive Ta was concerned. Furthermore, Impact-induced energy release tests on the Ta-Ni-Al ESMs were performed to understand the energy release properties. Based on these tests, the characterization of Ta-Ni-Al ESMs fabricated by explosive consolidation was obtained. There was no intermetallic formed in explosive consolidated samples. After the heat treatment, Ta-Ni-Al ESMs have good plasticity and strain rate effect. Meanwhile, under high impact velocity, the impact-induced energy release capability of Ta-Ni-Al ESMs was equivalent to Ni-Al ESMs. • Ta-Ni-Al ESMs with density of 10.56 g/cm3 was prepared by explosive consolidation. • The effect of the heat treatment on the mechanical properties is analyzed. • The effect of Ta on reaction characteristics of Al–Ni composite is investigated. • Under high impact velocity, the energy release capability of Ta-Ni-Al ESMs was equivalent to Ni-Al ESMs. [ABSTRACT FROM AUTHOR]

Nanosized vanadium nitride (VN) wrapped onto carbon fibers was synthesized by a molten salt disproportionation synthesis method at 800–1,000 ºC, using V and melamine as raw materials in molten (Li,K)Cl salts. Molten salts could accelerate the formation of nanosized VN at a lower temperature, which is possibly associated with the disproportionation reaction of V-ions on g-C 3 N 4 surface. VN displays remarkable application prospects as an anode material for lithium-ion batteries (LIBs), delivering a reversible discharge capacity of 320.1 mAh·g−1 at 1.0 A·g−1 after 500 cycles and 669.4 mAh·g−1 at 0.1 A·g−1 after 230 cycles without capacity attenuation. Such a remarkable cyclability of VN is attributed to the increased surface area and superior structural stability, induced by the dispersion of VN nanoparticles onto high-conductive carbon fibrous network. Li-ions storage mechanism of VN is pseudocapacitive, accompanied with the conversion-type electrochemcial reaction of VN with Li-ions during the de-/lithiation process. • Nanosized VN wrapped onto carbon fibers was firstly prepared by a molten salt disproportionation synthesis method. • Formation of nanosized VN may be associated with the disproportionation reaction of V-ions on g-C 3 N 4 surface. • VN exhibits impressive electrochemical performances as an anode for LIBs. [ABSTRACT FROM AUTHOR]

Pesticide residues lead to increasingly serious harmful ecological environment, which poses tremendous threats on human health. To overcome this problem, researchers are focusing on the development of highly efficient composites with excellent photocatalytic efficiency. In this work, a new C/ZnO/BiOI photocatalyst was successfully synthesized using hydrothermal, hydrolysis and ultrasonic technique for carbaryl degradation. The as-prepared photocatalyst was characterized by XRD, FT-IR, XPS, SEM, TEM, BET, UV–vis DRS and PL. The photocatalyst exhibited better carbaryl removal performances than that of ZnO, C/ZnO and ZnO/BiOI under simulated sunlight irradiation, which might be attributed to the efficient electron-hole separation and wider region of light response. The optimum C/ZnO/BiOI (20%) composite exhibited the highest degradation efficiency (62.9%) of carbaryl and excellent cycling stability. Reactive species scavenging and ESR experiments illustrated that . OH was the most important active species. Furthermore, the identification of intermediates revealed possible degradation pathways of carbaryl. [Display omitted] • A new C/ZnO/BiOI photocatalyst was successfully synthesized. • The photocatalyst showed excellent photocatalytic activity and reusability. • . OH played a major role in the carbaryl degradation process. • The degradation mechanism and pathways of carbaryl were proposed. [ABSTRACT FROM AUTHOR]

Herein, the 3D flower-like V 2 Al 1- x CT z with an estimated petaloid nanosheet thickness of 10–20 nm were firstly obtained by etching the submicro-sized V 2 AlC precursors, which were synthesized at 1000 °C holding for 5 h in (Na,K)Cl melt by a facile molten salt method, in 40 wt% HF at room temperature. The synthesis mechanism of V 2 AlC is possibly related to the disproportionation reaction of V-ions on carbon surface in molten salts to form V 2 C, followed by the intercalation of Al into V 2 C. Subsequently, the 3D flower-like V 2 Al 1- x CT z was applied as an anode in lithium-ion batteries, releasing ~215.2 mA h g−1 in the continuous 500 cycles at 0.5 A g−1, which exhibits the superiority in the reversible capacity in contrast with some reported micro-sized layered V 2 CT z MXenes. Such excellent electrochemical characteristics of V 2 Al 1- x CT z could be mainly ascribed to its unique submicro-sized flower-like morphology with high specific surface areas and abundant electrochemical sites for accommodating the reversible insertion/extraction of Li-ions. [Display omitted] • 3D flower-like V 2 Al 1- x CT z was firstly obtained by etching the submicro-sized V 2 AlC precursors. • Thickness of the nanosheets on V 2 Al 1- x CT z with a lot of defects was estimated as 10–20 nm. • The V 2 Al 1- x CT z exhibits desirable electrochemical performances as an anode in LIBs. • It may be extended to the synthesis of MXenes with diverse morphologies as anodes for LIBs. [ABSTRACT FROM AUTHOR]

Highlights: [•] Micrometer-sized FeCO3 spheres were obtained from solvothermal method in gram-scale. [•] Porous Fe3O4 spheres could be readily acquired by heating the FeCO3 precursor. [•] Porous Fe3O4/C spheres was prepared via hydrothermal carbonization. [•] The porous Fe3O4/C spheres exhibited excellent cycling rate performance. [ABSTRACT FROM AUTHOR]

Vanadium-based MXenes are prospective as anode materials in energy-storage devices including lithium-ion batteries (LIBs) but limited by their charge-discharge capacities. Herein, partially-etched V 2 Al x CT z with the average particle size of ~400 nm was synthesized using 40 wt% HF or mixed NaF+HCl solutions as etchants, respectively. V 2 Al x CT z etched by 40 wt% HF for 96 h at room temperature (RT) has more exceptional charge-discharge performances against mixed NaF+HCl solutions, with an average reversible capacity of ~450 mAh g−1 at 0.1 A g−1 in the 120 cycles and ~301.2 mAh g−1 at 0.5 A g−1 after 200 cycles in LIBs. The effect of etchants on electrochemical performances and lithium-ion (Li-ion) storage mechanism of V 2 Al x CT z was discussed comprehensively. Additionally, a Li-ion full cell using LiFePO 4 as cathode has exhibited excellent electrochemical performance (150.4 mAh g−1 at 0.1 C). This work illustrates that partially-etched V 2 Al x CT z with the submicro-sized distribution is also a promising anode material for LIBs. • Partially etched V 2 Al x CT z with ~400 nm was synthesized by etching submicro-sized V 2 AlC with 40 wt% HF and mixed NaF+HCl solutions, respectively. • V 2 Al x CT z etched by HF solution has more prominent electrochemical performances against NaF+HCl solutions. • Increased capacity contribution of V 2 Al x CT z etched by HF solutions may come from its defects and Al-Li alloying effect. [ABSTRACT FROM AUTHOR]

Abstract: TiN nanoparticles with an average diameter of 15nm or so were prepared by the reaction of spongy Ti and NH4Cl at about 530°C. The electromagnetic parameters of the TiN nanoparticles/wax composite were measured by a coaxial line method. The nanoparticles exhibit good microwave absorbing ability owing to dielectric loss, and the measured reflection loss reaches a minimum value of −16.1dB at 13.8GHz. The interfaces between nanocrystalline TiN and the thin amorphous TiO2 layer on the TiN surface contribute dominantly to the high permittivity and good microwave absorbing properties. [Copyright &y& Elsevier]

• A series of ZBH:Tm3+/yNCDs composites were synthesized by the hydrothermal method. • The ZBH:Tm3+/yNCDs could suppress the self-quenching effect of yNCDs in state solid. • The yNCDs improve the luminescence performance of ZBH:Tm3+ materials. • The influences of yNCDs on the structure, morphologies and luminescence properties of the composites were studied. • The tunable white light were achieved under 360 nm excitation. Rare earth (RE)-doped luminescent materials have shown tremendous potential applications in the optical field. However, it is still a challenge to improve its luminescence properties further. In this study, the Tm3+-doped zinc borate (4ZnO·B 2 O 3 ·H 2 O, ZBH) with a flaky-like morphology was successfully prepared by a facile hydrothermal reaction. The photoluminescence (PL) performance of ZBH:Tm3+ is improved through incorporating yellow N-doped carbon dots (yNCDs). Simultaneously, by changing the content of yNCDs in ZBH:Tm3+ host, the morphological evolution from flaky-like to flower-like of the ZBH:Tm3+/yNCDs composite are realized. The ZBH:Tm3+/yNCDs composite with flower-like exhibits the strongest white light emission and splendid thermal stability under 360 nm excitation wavelength, matching the current mainstream near-ultraviolet (NUV) LED chip. Thus, ZBH:Tm3+/yNCDs composite might be a promising luminescent material in the NUV white lighting and display fields. The findings of this study developed a novel idea for improving the luminescent properties of RE-doped materials. Besides, it also solves fluorescence quenching problems of carbon dots in the solid-state illumination field. [ABSTRACT FROM AUTHOR]

With the rapid development of electronic technology and the integration of electronic chips, electromagnetic wave pollution and thermal management have become two critical issues hindering the growth of electronic equipment. In this work, an effective strategy has been developed for the synthesis of well-designed core-shell layered structures with hydroxylated boron nitride (HO-BNNS) core and Fe 3 O 4 shell. The as-prepared HO-BNNS@Fe 3 O 4 composites have both microwave absorption and thermal management properties. Moreover, these two performances show a synergistic effect. It is worth noting that the minimum reflection loss (RL min) of HO-BNNS@Fe 3 O 4 composite materials are −45.31 dB at 8.64 GHz with a thickness of 2 mm. Additionally, the thermal conductivity of HO-BNNS@Fe 3 O 4 composites are 1.75 W m−1K−1 at an HO-BNNS weight of 30%, which increases approximately 400% than the initial Fe 3 O 4. These comprehensive properties of HO-BNNS@Fe 3 O 4 composites make it have potential applications in the field of electronic equipment packaging. Image 1 The highlights of this paper are list below: ● An effective strategy has been developed for the synthesis of well-designed core-shell layered structures with hydroxylated boron nitride (HO-BNNS) core and Fe 3 O 4 shell. ● The as-prepared HO-BNNS@Fe 3 O 4 composites have both microwave absorption and thermal management properties. ● The microwave absorption and thermal management performance of the HO-BNNS@Fe 3 O 4 composites show a synergistic effect. [ABSTRACT FROM AUTHOR]

Abstract In order to improve the toughness of W, a series of W/Ti multilayer composites are prepared by spark plasma sintering ranging from 1000 °C to 1400 °C. The relation between the microstructure and the properties is systematically investigated. The W/Ti multilayer laminates have a better comprehensive property when the sintering temperature is between 1000 °C and 1200 °C. Under those conditions, the elongated grains in the W layers are maintained. Meanwhile, the interface microstructure of the laminates can be divided into three layers, including β-W(Ti) solid solution with lamellas, β-Ti(W) solid solution and nanosized martensite with a β-matrix and α phase in basketweave microstructure. The orientation relationship between the α-Ti variants and the β-Ti matrix is determined to be the Burgers orientation relationship. The intervariants boundaries between different α colonies are 60°/[11 2 ¯ 0]. The fracture mechanism of the composites shows a mixed facture mode and debonding of the interfaces. The fracture of the W layers is transgranular cleavage fracture and lamellas fracture, and the fracture of the Ti layers is ductile fracture with dimples. Highlights • A series of W/Ti multilayer composites are prepared by spark plasma sintering. • The relation between the microstructure and the mechanical properties is investigated. • The microstructure of W/Ti multilayer laminates can be divided into five regions. • The orientation relationship between the α-Ti variants and matrix β-Ti is determined. • The fracture mechanism of the W/Ti multilayer composites is proposed. [ABSTRACT FROM AUTHOR]

Monte Carlo simulation has been used to study magnetic and thermodynamic properties of a ferrimagnetic mixed-spin (1, 3/2) Ising nanowire with hexagonal core-shell structure. The ground phase diagrams are obtained for different exchange couplings. The critical values of the exchange couplings have been found, determining whether the compensation points appear in the present system. In particular, the effects of the exchange couplings and the temperature on the magnetization, the internal energy, the specific heat, the compensation points and hysteresis loops are discussed in detail. Under certain physical parameters, multiple cycle hysteresis loops such as triple and quintuple hysteresis loop patterns have been observed in the system. It is found that the exchange coupling and the temperature strongly affect the coercivity and the remanence of the system. Compared our results with other theoretical and experimental studies, a good agreement has been obtained qualitatively. [ABSTRACT FROM AUTHOR]

N-doped TiO 2 nanowire/N-doped graphene (N–TiO 2 /NG) heterojunctions are fabricated by a simple hydrothermal method in a solution containing urea. In this hybrid structure, a three-dimensional hybrid photocatalyst was fabricated by using one-dimensional N-doped TiO 2 nanowires penetrating through two-dimensional graphene nanosheets. Compared with TiO 2 nanowire/graphene and N-doped TiO 2 nanowire/graphene composites, the N–TiO 2 /NG heterostructures demonstrate a better photocatalytic performance for the degradation of methylene blue under visible light irradiations, as well as displaying a better recyclability. It is found that the nitrogen atoms originated from the decomposition of urea were not only entered into the lattice of TiO 2 nanowires but also doped into the skeleton of graphene nanosheets. Results show that N doping expands the visible light absorption region of TiO 2 , and N-doped graphene additionally improves the separation and transportation of photogenerated electron–hole pairs plus generating a higher photocurrent, which plays a critical role for enhancing the photocatalytic activity. [ABSTRACT FROM AUTHOR]

• O-Co x Ni y P was synthesized by the coprecipitation followed by a phosphorization treatment step. • O-Co 1 Ni 4 P electrode containing Co:Ni molar ratio equal to 1:4 showed the best performance. • Optimized content of O dopant in Co x Ni y P is essential for promoting electrochemical reactivity. • The asymmetric supercapacitor displayed outstanding capacitive performance. Tailoring of the electrode microstructure and its active components for the development of high-performance supercapacitors was rather indispensable to advance current technologies. Therefore, we fabricated a novel O-doped Co-Ni nanophosphide (O-Co x Ni y P) with a porous structure. Our approach included the synthesis of 3D Co-Ni precursors with tunable Co/Ni ratio utilizing a phosphorization treatment. Our characterization results indicated that incorporating the optimized O content into Co x Ni y P could tune its electronic structure and yield mixed valences of metals and P, which was beneficial to enhance electrochemical reactivity. The O-Co 1 Ni 4 P-based electrode with the 1:4 Co:Ni molar ratio manifested the best performance as demonstrated by its specific capacity, which was equivalent to 717.1 C/g (at 1 A/g). This value was significantly higher than those of other O-Co x Ni y P family electrodes. The cycling stability of the electrode containing O-Co 1 Ni 4 P as an active material was found to be excellent: it demonstrated a 95.1% capacity retention after 5000 10 A/g cycles. We also assembled an asymmetric supercapacitor containing O-Co 1 Ni 4 P as a positive electrode material and commercial activated carbon as a negative electrode material. The device demonstrated very high energy density (47.5 Wh/kg) and 90.3% capacity retention after 10,000 cycles. These results established that our anion-doping method represented a novel strategy for improving the electrochemical performance of transition metal-based material. These discoveries were useful for energy storage applications. [ABSTRACT FROM AUTHOR]

In this study, the recrystallization process in deformed high-purity aluminum was investigated by using the internal friction (IF) and hardness measurement. In the heating process, two IF peaks were detected when the heating rate is 2 °C/min: a sharp peak (P 1 peak) at ~139 °C and a wide peak (P 2 peak) at ~278 °C (0.5 Hz). In the subsequent cooling process, the P 1 peak disappears while the P 2 peak remains. The P 2 peak shifted towards higher temperatures with increasing frequency and can be ascribed to grain boundary relaxation. For the P 1 peak, however, its position did not change with increasing frequency but shifted towards higher temperatures with increasing heating rate in the range of 1–5 °C/min, and the corresponding modulus varied abnormally in the temperature range of 115–160 °C. These facts indicated that the P 1 peak is a non-relaxational peak and can be ascribed to the recrystallization process. The recrystallization activation energy deduced via the shift of peak position with heating rate by using the Kissinger equation is 57± 3 kJ/mol, which is as same as that deduced from the classical isothermal recrystallization process as assessed by microhardness measurement. The classical isothermal recrystallization temperature can be deduced from the peak temperature of P 1 peak by simply adjusting the heating rate. This provided a method to determine the recrystallization temperature via internal friction measurement in a continuously heating process, which needs only two or three samples. • The P 1 peak associated with the recrystallization process of Al was detected. • Recrystallization activation energy of Al during continuously heating was estimated. • Classical recrystallization process was simulated via continuously heating process. • Feasibility of determining recrystallization temperature by IF was investigated. [ABSTRACT FROM AUTHOR]

Self-sealed microarc oxidation (MAO) coatings were prepared on 7075 aluminium alloy by incorporating different concentrations of ZrO 2 particles. The wear resistance and corrosion behaviour of MAO- and MAO/ZrO 2 -coated alloys were investigated. The results show that the tribological behaviour of the coatings was controlled by an abrasive mechanism. The coefficient of friction (COF) for the MAO/ZrO 2 -coated samples decreased to 0.82, indicating that the wear resistance was significantly improved due to the incorporation of hard ZrO 2 particles and the enhanced compactness and surface roughness of the coatings. The sealed pores effectively prevented the permeation of the corrosion solution, thus increasing the electrochemical corrosion resistance. Pores and microcracks would be enlarged and preferentially fractured during slow strain rate testing (SSRT) and thus were the initial sites for corrosion pitting and SCC crack propagation. The interlocking mechanism between the pores (microcracks) and ZrO 2 particles enhanced the strength of the pores (microcracks); therefore, the stress corrosion cracking (SCC) susceptibility of the MAO/ZrO 2 -coated samples was also reduced. Moreover, the MAO/ZrO 2 coatings formed with the addition of 4 g/L ZrO 2 particles had the best corrosion resistance, and the SCC susceptibility was reduced by 8.1% compared with that of the Al matrix. • MAO/ZrO 2 coatings were prepared by incorporating different concentration of ZrO 2 particles. • The compactness and surface roughness were significantly improved by ZrO 2 addition. • The wear and corrosion resistance of MAO/ZrO 2 coatings were remarkably enhanced. • The SCC susceptibility of MAO/ZrO 2 coatings was reduced due to interlocking mechanism. [ABSTRACT FROM AUTHOR]

The aggregation-induced quenching effect and poor thermal stability issues of carbon dots (CDs) limit their further development in the solid-state lighting and display field. In this work, a red carbon dot/boron nitride nanosheet (rCDs/BNNS) composite was synthesized using boron nitride as a carrier by in-situ embedding of rCDs. Thanks to the uniform dispersion of rCDs and the restraint of BNNS, the prepared rCDs/BNNS composite has excellent fluorescence stability and thermal stability. rCDs/BNNS composites as fluorescent markers can be used to detect potential fingerprints on various surfaces. Furthermore, rCDs/BNNS were dispersed into polyvinyl alcohol (PVA) polymers to prepare rCDs/BNNS/PVA flexible luminescent films. In addition to the excellent stability inherited from rCDs/BNNS, the thin film also exhibits high heat dissipation by reason of the establishment of a heat transfer channel in the PVA by rCDs/BNNS. Moreover, thin films can still maintain original fluorescence after undergoing hundreds or thousands of bends, while possessing sufficient tensile strength. This study provides a facile pathway for the preparation of highly stable CDs luminescent materials, and has a promising application in the forensic identification and flexible luminescent devices' thermal management fields. • A novel rCDs/BNNS composite was synthesized with excellent fluorescence stability and thermal stability. • The rCDs/BNNS/PVA film was obtained by encapsulating rCDs/BNNS into PVA. • Fluorescent film has good luminescence stability and mechanical flexibility. • The film displays outstanding heat dissipation in the application of LED lamp. [ABSTRACT FROM AUTHOR]

In this work, graphene quantum dots/sulfur (GQDs/S) composite was prepared as cathode material for lithium sulfur (Li-S) batteries by a feasible chemical method. Multiple polar functional groups in GQDs can provide more active absorption sites to significantly strengthen the chemical absorption with polysulfides, suppressing the 'shuttle effect'. In addition, the highly dispersed GQDs particles in the solution served as nucleation sites, the dissolved sulfur are reprecipitated around the GQDs, forming a dendritic interlaced network structure to prevent the aggregation of the sulfur, and further enhance the utilization of active substances. A high initial discharge capacity of 1125 mA h g−1 at 0.1C has been obtained in the GQDs/S cell, which is much higher than the initial discharge capacity of 658 mA h g−1 of GQDs/S R prepared by physical melting method. The superior performance of GQDs/S is attributed to the unique dendritic interlaced framework and multiple polar functional groups. The strong chemical effects between polar functional groups and polysulfides have been confirmed by the absorption experiment and DFT calculation. This work develops a new strategy in cathode material design for Li-S batteries. Image 1 • GQDs with polar groups can absorb the polysulfides proved by absorption tests and DFT calculations. • Well-dispersed GQDs serves as nucleation sites and dendritic interlaced sulfur framework was obtained. • Dendritic network structure of GQDs/S is beneficial to improve the utilization of sulfur and accelerate the ion transfer. [ABSTRACT FROM AUTHOR]

ZrC dispersion-strengthened FeCrAl alloys with enhanced high-temperature strength and good ductility were fabricated through spark plasma sintering (SPS) and hot-forging. Nanosized ZrC particles with an average particle size of 56 nm were homogeneously dispersed in the FeCrAl-ZrC alloys. The addition of a small proportion of ZrC nanoparticles effectively refines the grain size and improves the strength and hardness of FeCrAl alloys. However, the ductility of FeCrAl alloys decreases gradually when the ZrC content increases from 0 wt% to 2.0 wt%. The tensile strength of SPSed FeCrAl-1.0 wt% ZrC alloy at 800 °C is 91 MPa, which is about 69% higher than that of pure FeCrAl, while the percentage elongation after fracture of FeCrAl-1.0 wt% ZrC is 15.0%, which is lower than that of FeCrAl (48.2%). To improve the ductility of FeCrAl-ZrC alloys, the SPSed samples were subjected to hot forging at 1000 °C. Through hot-forging, significant enhancement in ductility of FeCrAl-ZrC alloys was achieved without reducing the strength. The mechanical properties and microstructure of FeCrAl-1.0 wt% ZrC are stable after annealing at 1000 °C for 5 h, exhibiting superior thermal stability as compared with FeCrAl. Image 1 • FeCrAl-ZrC alloys with enhanced strength and favorable ductility were fabricated. • ZrC nanoparticles effectively refine grains and improve the strength of FeCrAl. • Hot-forging significantly enhances the ductility without reducing the strength. • The high-temperature stability of FeCrAl alloys is improved by ZrC nanoparticles. [ABSTRACT FROM AUTHOR]

In the present work, CeO 2 nanocrystals with three well-defined morphologies including nanooctahedra, nanosphere and nanocube are synthesized and used as the promoter to Pt catalyst toward methanol electrooxidation reaction (MOR). The promotion effects of the CeO 2 nanocrystals are investigated through electrochemical techniques including cyclic voltammetry (CV), linear sweep voltammetry (LSV), electrochemical impedance spectroscopy (EIS) and chronoamperometry (CA). Results indicate that the promotion effects are closely related to the nanostructure of CeO 2 nanocrystals. Among the Pt-CeO 2 /C catalysts, Pt-CeO 2 /C- S catalyst with CeO 2 nanosphere as the promoter shows the highest catalytic performance for MOR, which arises from both physical interaction and electronic effects between CeO 2 and Pt. The loosened nanosphere structure with rough surface allows the Pt nanoparticles (NPs) to highly disperse onto the surface and thereby produce a strong physical interaction between Pt and CeO 2. In addition, the change in the valence state from Ce4+ to Ce3+ generates abundant oxygen vacancies (V O) into the crystal lattice, and the increased vacancies lead to surplus electrons which would transfer from CeO 2 to Pt. The increased electron density lowers the d-band center and thus improves the intrinsic activities (IA) of Pt. These data are used to discuss the role of physical interaction and electronic effects between the promoter and Pt and would be promising in designing the nanostructure of the Pt-based catalysts for DMFCs and other applications. • CeO 2 nanooctahedron, nanosphere and nanocube are prepared. • The CeO 2 nanocrystals are used as the promoter to Pt electrocatalyst for MOR. • Morphology effects of CeO 2 on the catalytic properties of Pt are investigated. • CeO 2 nanospheres show the highest promotion effects. [ABSTRACT FROM AUTHOR]

Gd-based metallic microfibers have been the research highlights due to the significant magnetocaloric effect. Herein, the atomic cluster micro-regions are constructed in Gd-based microfibers to further improve the magnetocaloric effect. The results show that the continuous and amorphous microfibers with excellent softly magnetic and thermal stability properties are obtained. The maximum magnetic entropy change -Δ S m max of Gd-based microfibers increases first and then decreases with Ni alloying degree increase. Among which, the better magnetocaloric properties is obtained in (Gd 60 A 20 lCo 20) 95 Ni 5 microfibers. The maximum magnetic entropy change, refrigeration capacity (RC), and relative cooling power (RCP) at 5 T reach 11.57 J/kg K, 834.14 J/kg, and 1138.16 J/kg, respectively. The outstanding magnetocaloric properties of microfibers are attributed to the indirect interaction coupling caused by Ni elements and the atomic cluster micro-regions, which lead to a fundamental shift in magnetic entropy. The findings of this study promote the application of Gd-based microfibers in the field of magnetic refrigeration. • The excellent magnetocaloric properties are obtained in GdAlCoNi5 microfibers after Ni alloyed. • The -Δ S m max, RC and RCP of GdAlCoNi5 microfibers reach 11.57 J/kg·K, 834.14 J/kg and 1138.16 J/kg, respectively. • The atomic cluster micro-regions promote the transformation of magnetic entropy disorder to order after Ni alloyed. [ABSTRACT FROM AUTHOR]

Abstract Additive manufacturing (AM) has a substantial capability to produce superior and divergent properties of titanium alloys for biomedical implants, unlike the existing conventional technologies. This work investigated the mechanical properties and microstructure evolution of a β-type Ti-35Nb-2Ta-3Zr alloy prepared by selective laser sintering (SLS) process. The superelastic properties of the resultant specimen were characterized by cyclic loading-unloading tensile testing to evaluate the effect of SLS-process on the β-type Ti alloy specimen. The zigzag and V-shaped formation of {112}<111> β twins, coexisting with stress-induced ω-formation, were observed by the transmission electron microscopy (TEM). The formation of Type I twin martensite along with β-structure is attributed to superelastic recovery and elastic recovery of SLS-produced specimen. High resolution TEM (HRTEM) observation was used to investigate the transition between β and ω phases. Thin layers of ω-formation in weak interfacial stress regions along with the longitudinal twin boundaries were also analyzed. The orientation relationship between ω-structure and parent β-phase involves an overlapping of ω-phase, observed along with longitudinal β-matrix and β-twins. Moreover, dislocation tangles and dislocation pile-ups form along with twin martensite, stress-induced ω-phase, and β-phase. Highlights • β-type Ti-35Nb-2Ta-3Zr alloy specimen was prepared by a selective laser sintering. • The zigzag and V-shaped formation of {112}<111>β twins, coexisting with stress-induced ω-formation were observed. • Thin layers of ω-formation in weak interfacial stress regions along with the longitudinal twin boundaries were analyzed. [ABSTRACT FROM AUTHOR]

Abstract In order to investigate the effect of high strain amplitude (maximum 1.6 × 10−3) and large pre-deformation (maximum 15%) on the damping properties of Fe-Mn alloys, the damping properties of the alloys were measured by a computer controlled automatic inverted torsion pendulum, microstructures were observed by SEM and EBSD, and phases were identified by XRD. The results show that the damping performance decreases at first and then increases when the pre-deformation amount is higher than 10%, and the valley value is reached at about 12%. When the pre-deformation amount is more than 12%, the content of ε phase decreases, while the amount of γ austenite and α′ martensite increases, the ε martensite phase of the alloy is divided and appears finer, ε martensitic phase and γ austenite have better parallelism, the phase interfaces of γ/ε significantly increase, and more damping sources with better slippage are provided, resulting in gradually increasing of damping properties of Fe-Mn binary alloy. When the strain amplitude is greater than 1 × 10−3, the damping properties and strain amplitudes of the pre-deformation alloys do not always maintain an approximately linear relationship, which closely related to different characteristics of damping sources due to stress-induced phase transition and formation of different alloy microstructures. Highlights • The relationship between large pre-deformation (maximum 15%) and damping property of Fe-17%Mn alloy was established. • Effect of large pre-deformation on the microstructural evolution was studied for Fe-17%Mn alloy. • The dependence of high strain amplitude (maximum 1.6 × 10−3) on the damping property of Fe-17%Mn was presented. [ABSTRACT FROM AUTHOR]

To meet the electrolyte requirements for high-voltage cathode materials, lithium difluorophosphate (LiDFP) is evaluated as a lithium salt additive for the conventional carbonate-based electrolyte system. The LiNi 0.5 Co 0.2 Mn 0.3 O 2 /graphite pouch cells containing 1 wt% LiDFP delivers a discharge capacity retention of 93.8% over 100 cycles operated at a cut-off voltage of 4.5 V, which is higher than the 43.2% of that without additive; and its average discharge capacity can reach around 118.9 mAh g −1 at 5 C, while the reference cell only achieves 93.4 mAh g −1 . Herein, the electrochemical impedance spectroscopy results obtained from the two- and three-electrode pouch cells indicate that LiDFP can respectively suppress impedance growth of two electrodes during cycling. The spectroscopic analysis demonstrates that the cathode surface can be modified by the additive and a stable solid electrolyte interface (SEI) is also formed on the anode surface by the presence of LiDFP in the electrolyte. Additionally, the capacity retention for the LiNi 0.5 Co 0.2 Mn 0.3 O 2 /Si-C pouch cell is also noticeably enhanced from ∼3.5% to 67.2% by adding 1 wt% LiDFP into the electrolyte over 200 cycles operated at 4.5 V. [ABSTRACT FROM AUTHOR]

The corrosion and discharging behavior of Al-Zn-In-Mg-Ti alloy were studied at a series pressures ranged from 0.1 MPa to 13.0 MPa using weigh loss experiments, electrochemical techniques, and imaging measurements et al. Results reveal that the self-corrosion and self-discharging process of Al-Zn-In-Mg-Ti alloy live through the same three stages, which are all accelerated by hydrostatic pressure. The discharging performance of Al-Zn-In-Mg-Ti drops with increasing pressure, which is caused by the acceleration of cathodic process and severer intergranular corrosion. The corresponding cathodic protection design based on Al-Zn-In-Mg-Ti sacrificial anode with the changing pressure has been set up, which follows exponential function. • The working performance of Al-Zn-In-Mg-Ti alloy as sacrificial anode decreases with increasing pressure. • Study unveiled the effect of hydrostatic pressure on the corrosion and self-discharging behavior of Al-Zn-In-Mg-Ti alloy. • The cathodic protection design based on the Al-Zn-In-Mg-Ti sacrificial anode with changing pressure was firstly set up. [ABSTRACT FROM AUTHOR]

A novel Ni(OH) 2 /ZnO hydrangea-like structure is prepared via a facile electrodeposition strategy with the Ni(OH) 2 flower-like particles growing on the ZnO layered carrier. This flower-like structure can take advantage of both ZnO and Ni(OH) 2 , leading to a fast ion/electron transport speed and structural stability, finally, attaining an outstanding specific capacitance (2264.55 F g−1 at 0.5 A g−1), excellent rate performance (601.09 F g−1 at 30 A g−1) and cycle stability (maintain 94.9% specific capacitance after 5000 cycles). The Ni-OH/ZnO//AC asymmetric supercapacitor device achieves a high energy density of 68.44 Wh kg−1 at a power density of 400 W kg−1, demonstrating great potential as an electrode material for energy storage devices. The mechanism of synergistic effect of Ni(OH) 2 and ZnO mutually supporting composite structure to improve electrochemical properties is innovatively proposed. • A novel Ni(OH) 2 /ZnO hydrangea-like structure is prepared via electrodeposition. • Outstanding cyclic and rate performance is achieved due to the supporting of ZnO. • The composite fulfills an outstanding capacitance of 2264.55 F g−1 at 0.5 A g−1. • The synergistic effect of mutually supporting structure is discussed in detail. [ABSTRACT FROM AUTHOR]

• The 5% Cu-NCS@FG exhibits mesoporous structure for electrolyte ions diffusion. • A small amount of Cu doping can completely maintain the 3D structure of NCS. • An outstanding rate capability of 86% at 20 times current density can be achieved. • The synergy effect of Cu and FG significantly enhances the electrochemical property. Cu-doped NiCo 2 S 4 /flake graphite nanosheet arrays were prepared by multi-step hydrothermal calcination. Three-dimensional structure provides a wealth of active sites and structure stability to improve the charging/discharging rate. Moreover, 5% Cu-doped NiCo 2 S 4 /flake graphite composite fulfills an excellent specific capacitance of 3080 F·g−1 at 1 A·g−1 and remains 2600 F·g−1 at 20 A·g−1 with an outstanding capacitance retention rate of 86% at 20 times current density. The all-solid supercapacitor with 5% Cu-doped NiCo 2 S 4 /flake graphite electrode and activated carbon electrode exhibits an excellent energy density of 79.4 Wh·g−1 at a power density of 400 W·kg−1 with an outstanding cycling stability of 94% retention after 10000 cycles，suggesting its great potential for the development of high-performance energy storage devices. [ABSTRACT FROM AUTHOR]

• There are multiple types nodal line semimetals in Pm 3 ̅ m space group. • Nodal line fermions show strong robustness. • Nodal lines clearly show the Fermi arc edge states. • Nodal lines have good regulation properties with dispersion and energy levels. Nodal line semimetals (NLSMs) have been widely studied in condensed matter physics, due to interesting electronic behaviors and wide application in electronic devices. Generally, based on band dispersion, the linear nodal lines (NLs) can be classified into four types, namely type-I, type-II, critical-type, and hybrid-type. In particular, realistic critical-type NLs are relatively rare. Here, we systematically report a series of NLSMs (thirty-one NLSMs) with critical-type and type-I one-dimensional (1D) crossings, namely intermetallic XY (X = Ca, Rare earth; Y = Ni, PGE, Ag, Cu). Specifically, in Pm 3 ̅ m space group with the time (T) and spatial (P) reversal invariances, we find thirty-one synthesized NLSMs, which contain five critical-type NLSMs and twenty-six type-I NLSMs. It is worth noting that these non-trivial NLs show clear drumhead surface states. Also, these NLs are protected by PT and M z symmetries, showing strong robustness. Besides, these NL fermions possess excellent regulation properties for band dispersion and energy level. Also, these NLs open tiny energy gaps (<100 meV) under SOC, very closing to previous typical NLSMs. The above results indicate we provide a number of excellent candidate materials for the future research on NL fermions and their potential applications in electronic devices. [ABSTRACT FROM AUTHOR]

An innovative and convenient method has been performed to stabilize the surface of O3-type NaNi 0.45 Mn 0.3 Ti 0.2 Zr 0.05 O 2 composited electrode by ultrathin MgO film. There are few reports on the modification on the fabricated electrode instead of the active material powder, especially by radio frequency magnetron sputtering. Besides, the surface stability and capacity retention of MgO coated cathode are superior compared to the bare one under the high rate. The protective effect could physically enhance electrochemical performance because the MgO coating has been identified strictly. Three main reasons are discovered by investigating the mechanisms. Firstly, the MgO layer suppresses the dissolution of the active material into electrolyte; this might be the origin for more stable electrode structure. Secondly, the MgO layer boosts sodium-ion and electron transport owing to its location of the deposition. Finally, the appropriate thickness of MgO can minimize transmission resistance and SEI formation. Particularly, the half-cell constructed with NaNi 0.45 Mn 0.3 Ti 0.2 Zr 0.05 O 2 –MgO cathode delivers a good rate performance (80.3 and 70.3 mA h g−1 at 1200 and 1920 mA g−1) and a long cycle life (71.6 mA h g−1 at 240 mA g−1 for 300 cycles) when sputtering time is 10 s; meanwhile, the reversible discharge capacity (140.7 mA h g−1 at 12 mA g−1) with a cut-off voltage of 2–4 V is also a considerable achievement. The work provides a broad idea to apply MgO as a protective coating. • MgO film is performed via magnetron sputtering on NaNi 0.45 Mn 0.3 Ti 0.2 Zr 0.05 O 2 electrode. • The surface stability and capacity retention of MgO coated cathode are superior at high rate. • MgO layer boosts sodium-ion and electron transport owing to its location of deposition. • The appropriate thickness of MgO can minimize transmission resistance and SEI formation. • The NaNi 0.45 Mn 0.3 Ti 0.2 Zr 0.05 O 2 –MgO cell delivers 80.3 and 70.3 mA h g−1 at 1200 and 1920 mA g−1. [ABSTRACT FROM AUTHOR]

Herein, the influence of annealing current intensities on magnetic properties of Gd-based microfibers was systematically investigated. The experimental results indicated that the as-prepared microfibers have amorphous structure and excellent thermal-stability, and the Curie temperature T C of which slightly change before and after annealing. The general magnetic physical magnitudes (M s , M r , μ 0 H c and μ m) of microfibers increase firstly and then decrease with the rising of annealing current intensities, and those of the microfibers annealed at 90 mA microfibers are more obvious (M s = 255 A m2/kg and μ m = 0.38 ± 0.01). Similarly, the magnetocaloric parameters of microfibers also increase firstly and then decrease with the rising of current intensities. At 5 T of magnetic field change μ 0 Δ H , the maximum magnetic entropy change Δ S m max and refrigerant capacity RC of 90 mA annealed metallic microfibers are 12.77 J/(kg·K) and 906 J/kg, respectively, and which remarkably increased in compared with the as-prepared state, respectively. From the microstructural evolution perspective, a certain intensity current annealing induces the tendency of micro-regional clusters and nanocrystals, forming atomic ordered regions, and the internal residual stress release with a reduction of magnetic anisotropy. Meanwhile, the magnetic ordering and the critical magnetic-moment rotational driving-force were changed after Fe-doping, resulting in effective improvement of refrigerant capacity. Accordingly, the current-annealed Gd-Al-Co-Fe microfibers can be adopted as low-temperature magnetic refrigeration working-medium, which also provides a theoretical foundation for magnetic refrigeration technology application. Magnetocaloric properties of Gd-Al-Co-Fe metallic microfibers current-annealed at 90 mA are significantly improved according to the microstructural evolution and magnetic ordering modulation. Image 1 • Effects of current annealing intensities on the magnetic properties were investigated in detail. • MCE characteristics of Gd-Al-Co-Fe microfibers could be obviously improved at 90 mA. • Magnetocaloric mechanism is illustrated by the perspective of structural evolution and magnetic ordering transformation. [ABSTRACT FROM AUTHOR]

Lithium-sulfur (Li–S) batteries have attracted more and more attention in recent years, as their theoretical capacity is several times larger than conventional lithium-ion batteries and they have a high energy density in secondary battery systems. In our work, a titanium carbide - titanium dioxide/single-walled carbon nanotube/sulfur (TiC–TiO 2 /SWCNT/S) cathode with high conductivity and effective polysulfides adsorption is prepared by a facile method for fabricating Li–S batteries. The batteries with this composite cathode show a good performance at 0.1 C due to relatively high utilization of sulfur, reaching 1338.6 mAh·g−1 specific capacity at first cycle and retaining 802.5 mAh·g−1 after 100 cycles. Meanwhile, it presents an excellent rate performance with 711.2 mAh·g−1 at 4 C, and recovers to 1006.9 mAh·g−1 when the current returns to 0.1 C. Also a slow capacity decay (0.045% decay rate per cycle) is observed at 1 C. These results suggest that a small amount of SWCNT can increase the conductivity of the whole composite to a great extent, and the strong adsorption ability of TiO 2 increases the cycle life. This work offers an efficient and low-cost strategy to obtain high performance batteries with great potential for commercial applications. • A high conductive composite with effective polysulfides adsorption for high performance Li-S batteries cathode is prepared by a facile method. • It presents an excellent rate performance and a slow capacity decay at 1 C. • With addition of a small amount of SWCNT, the cathode achieve higher conductivity and need less conductive agent in slurry. [ABSTRACT FROM AUTHOR]

The effects of trace Fe-doping on the magnetic and magnetocaloric performances of Gd-based metallic microfibers were systematically and detailedly investigated in this article. Experimental results indicated that the Gd-based microfibers prepared by the rotated-dipping process are uniform and continuous, with typically amorphous structure characteristics and favorable thermal stability. Curie temperature T C of Gd-based amorphous microfibers increases with the rising of Fe content, and the T C of GdAlCoFe3 microfibers is the highest at 128.7 K (relatively increased by 15.3 K than before doping). Among the general magnetic performance indicators, the saturation magnetization M s of GdAlCoFe2 microfibers reaches a peak at 264.04 emu/g. Furthermore, the values of magnetocaloric performance indexes of Gd-based amorphous microfibers increase firstly and then decrease with the rising of Fe-doping amount. When the external magnetic field H ex = 50,000 Oe, the maximum magnetic entropy change -Δ S m max, refrigeration capacity RC and relative cooling power RCP of GdAlCoFe1 microfibers are 10.33 J/kg·K, 748.22 J/kg and 1006.90 J/kg, which increased by 0.07 times, 0.13 times and 0.16 times, respectively than before Fe-doping (namely -Δ S m max = 9.68 J/kg·K, RC = 663.79 J/kg, RCP = 871.73 J/kg). From the perspective of microstructural changes, Fe-doping results in the formation tendency of atomic clusters and nanocrystals in micro-regions, the orderly orientation of atoms appears, and the magnetic anisotropy increases accordingly. In addition, the 3d electron layer of the doped Fe element in Gd-Al-Co-Fe quaternary alloy system enhances the RKKY indirectly exchange coupling interaction and changes the state of magnetic entropy, which in turn leads to an increase in Curie temperature and an improvement in magnetocaloric performance. Since RC and RCP are the main indicators in engineering applications, the GdAlCoFe1 amorphous microfibers can be selected as a low-temperature magnetic refrigeration working medium to provide technical guarantee for the application of magnetic refrigeration technology. In comparison to Fe-doped Gd-based amorphous microfibers, # GdAlCoFe1 microfibers have enhanced magnetocaloric properties by coactions of atomic arrangement ordering transformation (AAOT) and magnetic moment ordering transformation (MMOT). Image 1 • Influence of Fe-doping amounts on the magnetocaloric properties was investigated systematically. • MCE properties of # GdAlCoFe1 amorphous fibers were enhanced effectively. • Interaction mechanism was illustrated from the perspective of atomic arrangement and magnetic moment ordering transformation. [ABSTRACT FROM AUTHOR]

The fully dense Ni–Al energetic structural material (ESM) was successfully fabricated by using shock consolidation, with no reaction between the constituents. The microstructure, quasi-static and dynamic compressive behavior and energetic characteristics were investigated. The results revealed a uniform microstructure along the cross-section and both phases were continuously distributed. No intermetallic was detected by the XRD and a 5 nm thick interlayer composed of amorphous phase and crystalline phase was observed at the Ni–Al interface by TEM. The interfacial strength was shown to have a strong effect on the ductility and the strength of Ni–Al ESM, and could be significantly improved by solid-state diffusion during the shock loading and the following heat-treatment. After heat-treatment the samples showed a high quasi-static compressive strength of 300 MPa and a ductility of 14.5%. At impact velocity above 671 m/s, the Ni–Al ESM was initiated and released a large amount of rising the shock temperature or energy. Its reaction efficiency strongly depends on the impact velocity. The good mechanical properties and energetic characteristics of the Ni–Al ESM shows a great potential for the shock consolidation in fabrication of metallic energetic structural materials. • The fully dense Ni–Al energetic structural material (ESM) was successfully fabricated by shock consolidation. • The composites show continuous distribution of both Ni and Al. • The Ni–Al bonding is crucial to its mechanical properties and could be improved through heat treatment. • A 5 nm thick interlayer composed of amorphous phase and crystalline phase was observed at the Ni–Al interface. [ABSTRACT FROM AUTHOR]

Morphology of transition metal oxide largely affects its electrochemical energy storage properties. This also applies to its composites. In this paper, NiFe 2 O 4 /Graphene nanosheets composites (NFO/GNSs) are successfully prepared by a facile hydrothermal method. NiFe 2 O 4 (NFO) in the sample exhibits a unique nanosheet morphology, vertically arranging on the graphene nanosheets (GNSs). Microscopically, NFO nanosheets interpenetrate on the surface of graphene to form a continuous network structure. The sample exhibits excellent specific capacitance and rate performance. It is worth mentioning that the specific capacitance increases to 140% after 5000 cycles, showing superior cycle stability. This may be due to the conductive network formed by NFO nanosheets and GNSs. Excellent electrochemical performance indicates excellent application prospects of materials in supercapacitor electrodes. Image 1 • Unique NiFe 2 O 4 nanosheets structure with graphene nanosheets was successfully prepared by a hydrothermal method. • NiFe 2 O 4 nanosheets/graphene performed a better specific capacitance, arriving at 464.15 F/g at current density of 1 A/g. • The network structure formed between NiFe 2 O 4 nanosheets and graphene nanosheets provides excellent cycle performance. [ABSTRACT FROM AUTHOR]

The oxygen evolution reaction (OER) is a cornerstone reaction for many renewable energy technologies. Developing low-cost and durable alternatives to precious-metal catalysts with high activity for OER are highly desirable to reduce the processing cost and complexity of renewable energy systems. Recently, metal phosphides based on earth-abundant transition metals, especially bimetallic phosphates have emerged as promising candidates for efficient OER catalysts. The rational design of nanostructured bimetallic phosphates is critical for the practical applications of these electrocatalysts, which requires a well understanding of the composition control and nanocrystal growth process. Herein, we report a facile strategy for the synthesis of novel iron-cobalt bimetallic phosphides (FeCoP) with hollow structures by phosphating Fe (Co)-centered metal-organic frameworks (MOFs). The resultant FeCoP hollow polyhedron, which have large specific surface area providing rich catalytic active sites, show excellent electrocatalytic activity towards OER with low overpotential, small Tafel slope, and remarkable stability. This work provides a new strategy for exploring efficient phosphide catalysts and opens up new avenues for the development of OER catalysts. Image 1 • A simple one-step MOF-derived strategy is reported for fabricating Fe x Co y P electrocatalysts. • The morphology of Fe x Co y P can be easily tuned by doping cobalt. • The OER properties of Fe x Co y P catalysts are strongly dependent on the amount of cobalt dopants in Fe 2 P. • The hollow-structured FeCo 2 P polyhedron exhibits remarkable electrocatalytic activity for OER. [ABSTRACT FROM AUTHOR]

Due to the low cost and abundance of sodium, sodium-ion batteries (SIBs) show great potential as energy storage devices. As far as the current research is concerned, cathode materials are still the bottleneck for boosting the performance of SIBs. O3-type layered NaNi 0.5 Mn 0.5 O 2 is considered as an important cathode material of SIBs, but its irreversible phase transition, poor stability in air, and sluggish kinetics usually lead to reduced capacity, poor rate performance and high cost for material storage, which largely limit the large-scale application. Herein, a remarkable O3-type layered material NaNi 0.5-x Mn 0.3 Ti 0.2 Zr x O 2 (NaNMTZ, x = 0.02, 0.05), with stable phase structure has been synthesized by the solid-phase method. The partial substitution of electrochemical inactive Ti/Zr brings about higher electronic delocalization and entropy of mixing leading to enhanced structural stability. In addition, the enlarged interlayer spacing and good conductivity contribute to better rate capability. The micro-nano structure leads to faster Na+ diffusion rates and shorter diffusion paths for both ions and electrons. Therefore, NaNi 0.45 Mn 0.3 Ti 0.2 Zr 0.05 O 2 exhibits an initial reversible capacity of 141.4 mAh g−1 with a coulombic efficiency of 98.8% and remarkable capacity retention of 70% after 200 cycles at 0.05C, presenting better electrochemistry performance than the conventional NaNi 0.5 Mn 0.5 O 2. This study provides a new angle to design high capacity cathode materials with high rate capability and cycling stability through crystal lattice modulation. Image 1 • A remarkable O3-type layered NaNi 0.45 Mn 0.3 Ti 0.2 Zr 0.05 O 2 is designed as cathode material for sodium ion batteries. • The structural stability and rate performance of NaNi 0.45 Mn 0.3 Ti 0.2 Zr 0.05 O 2 are superior. • The higher electronic delocalization and better conductivity of NaNi 0.45 Mn 0.3 Ti 0.2 Zr 0.05 O 2 are provided. • The difference value about entropy of mixing between NaNi 0.5 Mn 0.5 and NaNi 0.45 Mn 0.3 Ti 0.2 Zr 0.05 O 2 is calculated. • The enlarged interlayer spacing and micro-nano structure contribute to the high rate capability. [ABSTRACT FROM AUTHOR]