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P2-type layered transition metal oxides are considered one of the ideal cathode materials for sodium ion batteries because of its high working voltage and excellent theoretical specific capacity. P2-Na 0.67 Ni 0.33 Mn 0.67 O 2 electrodes deliver a theoretical specific capacity of 173 mAh g-1, which is dependent on Ni2+/Ni3+/Ni4+ charge compensation. High operating voltage leads to higher specific capacity and energy density, which are better adapted to practical development needs, but at the same time it causes the material to undergo a destructive P2-O2 phase transition, which greatly affect cycle stability and Na+ diffusion kinetics. In this study, we propose Zn2+ doping and spherical morphology modification strategy. The spherical morphology not only reduces the distance of Na+ diffusion and improves the rate performance, but also the spherical structure can alleviate the volume change during Na+ intercalation/extraction. Furthermore, the doping of Zn2+ changes the valence distribution of Mn, suppressing the phase transition at high voltage and further improving the cycling stability. At a high cut-off voltage of 4.4 V, the cathode material with Zn2+ doping and spherical shaped possesses an average operating voltage of up to 3.6 V and exhibits 90% capacity retention after 30 cycles (compared to only 56% for the pristine material). Above that, the rate performance is also greatly improved, with the modified material contributing an excellent specific capacity of 95 mAh g-1, even at a high current density of 5 C (1 C = 170 mA g-1). • A P2 layered Na 0.67 Ni 0.23 Zn 0.1 Mn 0.67 O 2 is successfully synthesized by a urea-assisted hydrothermal method. • Zn2+ doping enables layered oxide to optimize the ratio of Mn3+ and lattice oxygen to achieve excellent cycling stability. • Improved rate performance due to larger lattice spacing. • Zn2+ doping can reduce the involvement of lattice oxygen in the reaction at high operating voltages [ABSTRACT FROM AUTHOR]

The three-dimensional reduced graphene oxide (RGO)/CoFe 2 O 4 composites have been synthesized by one-pot hydrothermal method. Different quantities of lithium-aluminum-silicate (LAS) glass-ceramics have been introduced to coat the RGO/CoFe 2 O 4 sheets. The stacked LAS and CoFe 2 O 4 nanoparticles are evenly distributed on the surface of RGO films and the microwave absorbing properties of LAS@RGO/CoFe 2 O 4 composites are greatly enhanced owing to the introduction of LAS. With the thickness of only 2.3 mm, the corresponding reflection loss (RL) value of the absorber reaches −50.0 dB. Moreover, it should be noted that the effective bandwidth can be up to 6.16 GHz for only 2.0 mm absorbing layer. The outstanding microwave absorption performance is mainly attributed to excellent impedance matching and multi-dipole polarization. This research is expected to provide a new direction to the design of high-performance microwave absorbing materials. Image 1 • The three-dimensional RGO/CoFe 2 O 4 composites are prepared by a facile route. • The wave absorption properties of RGO/CoFe 2 O 4 coated by LAS are greatly enhanced. • The impedance matching of LAS@RGO/CoFe 2 O 4 composites are remarkably improved. [ABSTRACT FROM AUTHOR]

Abstract To improve the efficiency of traditional advanced oxidation processes (AOPs), a novel photo-assisted heterogeneous Fenton-like process was proposed and verified by experiments. Under visible light, NaHSO 3 and transition metal composite oxide MnO 2 /NiO were tested together for degradation of orange II (OII). MnO 2 /NiO nanocomposites were prepared by a hydrothermal method using different nickel oxide to manganese oxide ratios and characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, Ultraviolet–vis (UV–vis) diffuse reflectance spectroscopy (DRS) and scanning electron microscopy (SEM). The best MnO 2 /NiO nanocomposite (Ni:Mn = 1:2) which was designated as Ni-Mn-3 showed the best OII removal efficiency of about 92.8% among the various MnO 2 /NiO nanocomposites of different Ni:Mn ratios. Moreover, the best catalyst, Ni-Mn-3 also showed good stability and recovery performance for degrading OII. The degradation ability of Ni-Mn-3 decreased no more than 10% after three times of repeated tests, which makes it more competitive in practical industrial applications than other heterogeneous Fenton-like catalysts. Graphical abstract Image 1 Highlights • New photo-assisted heterogeneous Fenton-like process was used with MnO 2 /NiO catalysts. • Key novelty was the use of NaHSO 3 to activate MnO 2 /NiO under visible light. • The MnO 2 /NiO (Ni:Mn = 1:2) showed the best Orange II removal efficiency of about 92.8%. • 1Ni:2Mn oxide showed good stability and recycling performance for degrading Orang II. [ABSTRACT FROM AUTHOR]

Abstract Even small amounts of oxygen can profoundly affect the mechanical behavior of α-Zr, thereby controlling the oxygen concentration of Zr-O system plays a crucial role in its industrial application. In this work, we first conclude the oxygen solubility of α-Zr lying in the range of 33–38 at.%. Then, the mechanical and dynamical stability for all Zr-O compounds are confirmed by the analysis of elastic modulus and phonon dispersion. Furthermore, the stress responses of Zr-O system under the tensile and shear loadings have been systematically investigated by using first-principles calculations. The results reveal that ideal-strength depends on the O concentration strongly. Oxygen addition significantly enhances the ideal-strength compared with pure α-Zr, which provides direct evidence that α-Zr can notably harden by oxygen. Specifically, the alloy with 33 at.% oxygen contents exhibits the highest tension strength whereas 38 at.% oxygen content confers the alloy relatively excellent shear strength. Finally, the stress response and bonding nature of Zr-O system under loading are examined by the electronic structures. Graphical abstract Image 1 Highlights • The tension and shear strength of Zr-O system were systematically investigated. • Oxygen additions to α-Zr lattice produced a significant strengthening effect. • The 33 at.% oxygen content exhibits the highest tension strength. • The 38 at.% oxygen content possesses relatively excellent shear strength. [ABSTRACT FROM AUTHOR]

The SiC nanowires have been in situ grown on the carbon fabric by thermal evaporation. Furthermore, to reduce the reflection of electromagnetic (EM) wave on the surface of EM wave absorbents and to improve the impedance matching, the laminated SiC NW -C f /lithium-aluminum-silicate (LAS) composites were prepared through slurry impregnation and hot-pressing sintering methods using the fabrics as reinforced body. The as-prepared samples were characterized by X-ray diffraction (XRD), Raman spectra, field emission scanning electron microscope (FESEM) and high-resolution transmission electron microscope (HRTEM). The formation mechanism of SiC nanowires was specified. The SiC NW -C f /LAS composites in this study exhibited superior EM wave absorption abilities and good impedance match in the frequency range of 2–18 GHz compared with SiC NW -C f . A minimum reflection loss (RL) value of −37.8 dB was observed at 7.2 GHz with absorber thickness of only 3 mm. Moreover, the absorption bandwidth for RL less than −10 dB was 4.6 GHz (13.4 GHz - 18 GHz) when the absorber thickness decreased to 1.5 mm. A possible wave absorbing mechanism was discussed. This study proposed a facile method to fabricate a lightweight and broadband material with enhanced EM wave absorption performance. [ABSTRACT FROM AUTHOR]

Omega (ω) phase plays a crucial role in determining performance of numerous Zr- or Ti-based alloys, which necessitates a sound knowledge of its fundamental properties. Through first-principles calculations, the present study gives a detailed comparison of structural, elastic and electronic properties of two closely related omega phases, ω-Zr and Zr 2 Al. Despite the structural similarity, their elastic properties turn out to be remarkably different. Zr 2 Al possesses considerably higher elastic stiffness constants (except C 33 ), single crystal Young's modulus (except along directions near those in the xy -plane and near the z axis), polycrystalline bulk and shear moduli, Vickers hardness and lower elastic anisotropy, demonstrating a pronounced strengthening effect of the ordered Al substitution for Zr. In addition, they have distinct 3D plots for crystal orientation dependence of Young's modulus, shear modulus and Poisson's ratio. We demonstrate that these 3D plots are not artificial results or technical mistakes and can be rationalized by simple mathematics. For example, whether the 3D plot of Young's modulus is ellipsoidal or not is determined by a proposed factor of ( S 11 − S 13 − S 44 / 2 ) / ( S 11 + S 33 − 2 S 13 − S 44 ) . Based on Bader's theory of atoms in molecules, subsequent electron density topological analysis uncovers a clear electron density origin for the different elastic properties. The ordered Al substitution for Zr is found to not only change the overall electron density topology but also increase the bond directionality and decrease the bond anisotropy. Additionally, intriguing “banana bonds” are found in both phases. The present study is of significant importance for design of advanced Zr-based alloys associated with ω phase. [ABSTRACT FROM AUTHOR]

The structural, elastic, electronic and thermodynamic properties of Cu 5 Zr and Cu 5 Hf compounds are investigated by first-principles calculations combined with the quasi-harmonic Debye model. The calculated lattice parameters of cubic AuBe 5 -type Cu 5 Zr and Cu 5 Hf agree well with available experimental and other theoretical results and the formation enthalpy calculations show that AuBe 5 -type Cu 5 Hf is more energetically stable than the competing hexagonal CaCu 5 -type phase. The mechanical properties such as mechanical stabilities, anisotropy character, ductility (estimated from the value of B / G , Poisson’s ratio υ and Cauchy pressures C 12 – C 44 ) and thermodynamic properties such as volume change under temperature and pressure ( V / V 0 ), heat capacity ( C v ), Debye temperature ( Θ ), thermal expansion coefficient ( α ) of AuBe 5 -type Cu 5 Zr and Cu 5 Hf are calculated together. Cu 5 Hf has better performances than Cu 5 Zr with higher hardness and better resistance to fracture which are rationalized from the calculated electronic structure (including density of states, charge density distributions, Mulliken’s population analysis) and we find that all ionic, covalent and metallic components exist in bonding of Cu 5 Zr and Cu 5 Hf but the covalent bonding in Cu 5 Hf is stronger. [ABSTRACT FROM AUTHOR]

Phase competition between C11 b , C16 and E9 3 phases under pressure (0–60 GPa) in Zr 2 Cu 1− x Ni x ( x = 0, 0.125, 0.25, 0.50, 0.75, 0.875 and 1) alloys has been investigated by first-principles pseudopotential calculations. The whole picture of phase competition mediated by both external pressure and composition has been unambiguously established by modeling using both supercell (SC) method and virtual crystal approximation (VCA) method, which sheds light on the pressure dependent glass stability and crystallization behavior of related alloy systems. It is revealed that both pressure and increasing Ni content stabilize the C16 phase over the other two. The underlying mechanism of external pressure and composition stabilizing the C16 phase is also analyzed. A feasible procedure for achieving metallic glass composites with tunable precipitated phases is proposed. [ABSTRACT FROM AUTHOR]

The stress-induced martensitic transformation of CuZr-based alloy takes an indispensable part in its shape memory effect and plasticity improving. CuZr–B19' phase as an unstable martensite product of CuZr–B2 austenite has been widely reported by experimental and DFT methods. However, the instability of B19' structure ignored in theoretical calculation drives it transform into B33 phase after structural relaxation, which makes computational properties of B19' phase untrusted. Therefore, in this work, we prevented B19' phase from relaxation phase transition by applying external force to supply a reliable structure for its subsequent properties calculations. In addition, a reversible phase transition between phases B19' and B33 was found and the theoretical value of transformation stress was determined. The changes of elastic modulus, formation enthalpy and electronic property of two phases (B33 and B19') under various pressures were compared and analyzed. The results aforementioned justify that CuZr–B33 is an indirect martensite product of CuZr–B2 phase, which explains why some peoples observed B33 phase in experiments, while others did not. • Metastable CuZr B19' structure can be stabilized by external pressure of 0.87 Gpa in DFT structural relaxation. • Reversible phase transition exists between phases B19' and B33. • Thermodynamic and mechanical performances of B33 phase are generally superior than B19' phase. [ABSTRACT FROM AUTHOR]

Solute atoms segregation can drastically change the cohesive properties of grain boundaries (GBs), eventually leads to the intergranular embrittlement of materials. Selecting solute atoms and evaluating their effects on the GB are of considerable importance to analysis and design of Zr-based alloys. In this work, first-principles calculations were performed to explore the effects of thirty solute atoms segregation on the strength of Zr { 10 1 ¯ 1 }. After a comprehensive analysis, we conclude that Cr, Mn, Fe, W and Mo atoms easily segregate at Zr { 10 1 ¯ 1 } GB. Furthermore, the strengthening/embrittlement potency of solute atoms on Zr { 10 1 ¯ 1 } was estimated using both the Rice-Wang model and ab-initio tensile test calculations. It is demonstrated that the segregation of Ag, Bi, Au and Sn at site1 presents a significant embrittling effect on the GB. In contrast, V, Cr, Nb, Mo, Ta and W elements have a remarkable strengthening effect on the GB. Our results may provide a valuable reference to analysis and design of Zr-based alloys. Image 1 • The thirty solute atoms segregation and their effects on the strength of Zr (10 1 ¯ 1) GB were systematically investigated. • The strengthening/embrittlement potency of solute atoms on the GB was estimated using both the Rice-Wang model and ab-initio tensile test calculations. • Solute atoms: Ti, V, Cr, Mn, Fe, Co, Ni, Nb, Mo, Tc, Ru, Rh, Pd, W, Re, Os, Ir, and Pt prefer to segregate at the GB, while the other atoms prefer to locate in the bulk site. • The segregation of Ti, V, Cr, Nb, Mo and W has a remarkable strengthening effect on strength of the GB, whereas Ni, Pd and Pt weaken the GB. [ABSTRACT FROM AUTHOR]

A novel carbon quantum dots- (CDs) modified 2D heterojunction photocatalyst was successfully fabricated by a facile impregnation and calcination approach. The results of photocatalytic experiments showed that the photocatalyst CDs/g-C 3 N 4 /MoS 2 exhibited tremendously enhanced photocatalytic activity. The rates for hydrogen evolution and degradation of rhodamine B (RhB) under simulated sunlight irradiation were about 5 and 7 times higher than those of pristine g-C 3 N 4. Moreover, its photocatalytic activity was higher than those of g-C 3 N 4 /MoS 2 , the benchmark reagent P25, and other heterojunctions reported previously. Heterojunctins loaded with different percentages of CDs by weight were synthesized and it was found that the heterojunctin with 2% of CDs showed the highest efficiency. The possible mechanism for enhanced activity was proposed. The great enhancement of photocatalytic activity could be ascribed to the CDs modification and the formation of the 2D heterojunction, which greatly facilitate the charge transfer at interfaces, reduce the recombination rates of photoinduced electron-hole pairs, and increase the light absorption. The results reveal that the construction of CDs-modified 2D heterojunction is a facile strategy to boost the sunlight-driven photocatalytic activity for semiconductor photocatalysts, facilitating their practical applications in environmental protection. Image 1 • A novel carbon quantum dots (CDs) modified 2D heterojunction was successfully fabricated. • The product was prepared by a facile impregnation and calcination approach. • The prepared product exhibited tremendously enhanced photocatalytic activity. • The enhanced activity can be ascribed to the CDs modification and formation of 2D heterojunction. [ABSTRACT FROM AUTHOR]

In this study, we investigated the morphology evolution of deformation-induced α' , α ″ martensite and retained β phase with increasing deformation strain in metastable β-Zr-43.2Ti-4.5Al-4.2V (wt. %) alloy by ex-situ and regular compression tests. Three types of deformation-induced α' martensite have been observed for the first time during deformation, namely, twinned α' martensite, untwinned α' martensite and paired α' martensite. Transitions in morphology of twinned α' martensite from thin plate to twinned plate and to widened twinned plate, eventually to { 10 1 ¯ 2 } twin-related domains and of untwinned α' martensite from thin plate to widened plate to domain have been observed with increasing deformation strains. The paired α' martensite is undergone a process in which the α' martensite impacted grain boundaries stimulating the nucleation of new α' martensite in neighboring grains, and then leading to martensite growth on both sides grow simultaneously. With progressive deformation, the nano-size deformation-induced α ″ martensite changes from long thin plate to ladder-shaped plate to 90° rotation domains. The morphology evolution of untwinned α' martensite, paired α' martensite and α ″ martensite are mainly related to the self-accommodation mechanism, while the morphology evolution of twinned α' martensite is mainly related to the plastic accommodation mechanism. The average hardness increased with increase in deformation strains, owing to the martensitic transformation strengthening along with dislocation multiplication strengthening. • Morphology evolution of α′, α′′ martensite and retained β phase were investigated. • Three types α′ have been observed for the first time during deformation. • Twinned α′, untwinned α′ and paired α′ martensite were observed. • α′′ changes from long thin plate to ladder-shaped plate to 90° rotation domains. • Morphology evolution mechanisms and hardening mechanisms are discussed. [ABSTRACT FROM AUTHOR]

NH 3 photosynthesis from nitrogen remains a big challenge due to the extreme difficulty for the activation of N N bond. In this work, Ag-modified MoO 3 ·0.55 H 2 O nanorods (named as Ag@Mo) are prepared by a simple photoreduction method. Under visible light (λ ≥ 420 nm) for 60 min, the NH 3 yield over 2%Ag@Mo (molar ratio of Ag to MoO 3 ·0.55 H 2 O) reaches 242.0 μmol·gcat −1 , which is about 2.8 times higher than MoO 3 ·0.55 H 2 O under the same conditions. The effect of Ag modification on photocatalytic ammonia synthesis is explored through experiments and theoretical calculations. The excellent photocatalytic performance is mainly attributed to the localized surface plasmon resonance effect of Ag and the successful construction of Mott-Schottky junction, which improves light utilization efficiency and reduces carrier recombination efficiency, respectively. Moreover, density functional theory calculations theoretically prove that over Ag@Mo, Ag provides new adsorption sites, and the N N tri-bond length is elongated by about 16.2%, confirming that Ag modification obviously promotes the activation of N N tri-bond. The ammonia generation rate is obviously higher than the previously reported results. [Display omitted] • Ag@Mo Mott-Schottky junctions are designed by a simple photoreduction method. • Ag provides new active sites for N 2 , promoting the activation of N N tri-bond. • Ag@Mo Mott-Schottky junction greatly reduces charge recombination efficiency. • The plasmon resonance effect of Ag enhances light absorption. • The NH 3 yield over 2%Ag@Mo increases by 2.8 times under visible light irradiation. [ABSTRACT FROM AUTHOR]

• Flexible membrane was used as free-standing anode for LIBs without additive. • Ultrathin MoS 2 nanosheets composed of less than 5 layers enhance lithium storage performance. • MoS 2 nanosheets on carbon nanofibers is formed, showing flower-like coaxial architecture. • Flexible hybrid material has stable reversible capacity and excellent rate capability in LIBs. [Display omitted] Lithium-ion batteries have high potential to be used as energy storage devices for wearable electronics due to their high energy density, high output voltage and environmental benignity. The increasing demand to develop wearable electronics has aroused great interests for flexible anode of lithium-ion batteries. However, the traditional rigid anode severely hiders further development of lithium-ion batteries in flexible wearable devices. Herein, we demonstrated a flower-like architecture material, in which the layered MoS 2 nanosheets are anchoring on 3D porous carbon nanofibers (CNFs), serving as free-standing anode for LIBs, and this material can be wound at will. The free-standing CNFs were prepared through a facile electrospinning and carbonization process, the MoS 2 nanosheets consist of few MoS 2 ≤ 5 layers and were prepared through a hydrothermal process. Time-dependent experiment illustrated that the flower-like architecture was transformed from bare fibers and tiny particles. Although the polymers were stretched, shrank and covered by MoS 2 nanosheets in the fabrication proess, the membrane still retained excellent flexible from beginning to end. Benefiting from the coaxial structure and synergistic effect, the flexible anode delivered an initial high discharge capacity (938.8 mAh g−1, 0.2 A g−1) and outstanding capacity retention rate at high current density (457.2 mAh g−1, 2 A g−1, 276.3 mAh g−1 after 1000 cycles). Its stability can surpass other flexible MoS 2 -based anodes. Furthermore, the hybrid electrode can maintain superior flexibility and mechanical stability after experiments, guaranteeing a promising future in wearable electronics. This work indicates that the flexible MoS 2 @CNFs can be used as anode for flexible batteries, flexible capacitors and other wearable applications. [ABSTRACT FROM AUTHOR]

Highlights: [•] MgO nanoflakes with different morphologies were synthesized by a simple low-temperature hydrothermal process. [•] EDTA and KCl additives have a great effect on the morphology of the products. [•] Quasi-circular MgO nanoflakes exhibited higher catalytic activity on the thermal decomposition of ammonium perchlorate. [ABSTRACT FROM AUTHOR]

Severe charge recombination and poor light absorbance are the limiting factors for TiO 2 to access efficient photocathodic protection (PCP) towards metals. Engineering the TiO 2 with Bi 2 S 3 to form the heterojunction is proposed to overcome these limitations. Impressively, the optimal Bi 2 S 3 -12 h@TiO 2 photoanode coupled with 304SS displays an open circuit potential that negatively shifts to −480 mV vs Ag/AgCl, accompanied by a photoinduced current of 18.5μA/cm2. Comprehensively, characterizations discover that a tight interface between TiO 2 and Bi 2 S 3 exhibits strong electron interaction. The resulting enhanced PCP performance is attributed to extending the photoresponse range, increasing the carrier density, and improving the photocarrier separation. This work proves and validates the effectiveness of Bi 2 S 3 @TiO 2 in enhancing the PCP performance and provides the instruction to construct a high-performance photoanode. [Display omitted] • The tight interface between Bi 2 S 3 and TiO 2 is formed in the heterojunction. • The strong electron interaction between Bi 2 S 3 and TiO 2 favors the charge separation. • Light-harvesting properties are extended from ultraviolet to visible light. • The heterojunction effectively suppresses the photocarrier suppression. [ABSTRACT FROM AUTHOR]

The effects of Zr addition on mechanical properties and corrosion properties of hot-rolled Ti-6Al-7 Nb- x Zr (x = 0, 5, 10, 15, 20 wt%) (TANZ) alloys were investigated. As the Zr content increases, the phase evolution of alloy is α phase → α + α″ phase → α + metastable β + α″ phase. The results show that the simultaneous existence of initial α phase and metastable phase was beneficial to increase the uniform elongation and work hardening ability of the alloy. Ti-6Al-7 Nb-20Zr alloy exhibit the best combined mechanical properties, including tensile strength of 862 MPa, uniform elongation of 9.1%, and total elongation of 16.8%. Compared with Ti-6Al-7 Nb alloy, the improvement is 96%, 98%, and 65%, respectively. At the same time, the addition of Zr improves the passivation ability of the alloy and the corrosion resistance of the alloy. This study illustrates the broad application potential of titanium alloys in the field of medical device manufacturing. • The addition of Zr significantly enhances the mechanical properties of Ti-6Al-7Nb alloy. • The addition of Zr significantly reduces the elastic modulus of the alloy. • The addition of Zr significantly enhances the corrosion resistance of the alloy. [ABSTRACT FROM AUTHOR]

Sodium-ion batteries (SIBs) have shown great potential as energy storage devices due to their low price and abundant sodium content. In terms of current research, cathode materials remain the bottleneck for improving the performance of SIBs. Ti-doped O3-type Na(Ni 0.3 Fe 0.2 Mn 0.5) 1−x Ti x O 2 (x = 0, 0.05, 0.1, 0.15) are investigated as the cathode material for sodium-ion batteries, and the results show that Ti doping can widen the layer spacing and suppress the ordering of Na+/vacancy and O3-P3 phase transition. The structurally stable Na(Ni 0.3 Fe 0.2 Mn 0.5) 0.9 Ti 0.1 O 2 cathode material, in particular, demonstrates enhanced rate capacity (93 mAh g−1, 2.0–4.0 V vs Na+/Na, 10 C, and 115 mAh g−1, 2.0–4.2 V vs Na+/Na, 10 C) and excellent cycling stability (87.5% capacity retention, 2.0–4.0 V vs Na+/Na, after 300 cycles, 1 C, and 82.1% capacity retention, 2.0–4.2 V vs Na+/Na, after 100 cycles, 1 C). In addition, Ti doping can effectively suppress the O3-P3 phase transition of the cathode materials and reduce the formation of the P3 phase at high voltage, which effectively suppresses the capacity decay during the charge/discharge process and reduces the irreversible capacity. As a result, the Ti doping strategy provides a simple and effective method for designing and developing high-performance layered oxide cathode materials for sodium-ion batteries. [Display omitted] • Ti-doped O3-type layered oxides were synthesized by the solid-phase method. • Ti doping can suppress the ordering of Na+/vacancy and the O3-P3 phase transition. • Ti doping increases the Na+ diffusion rate and increases the smoothness of the particle surface. • The structurally stable Na(Ni 0.3 Fe 0.2 Mn 0.5) 0.9 Ti 0.1 O 2 showed enhanced electrochemical performance. [ABSTRACT FROM AUTHOR]

Systematic first-principles calculations based on density functional theory have been performed to determine the self-diffusion mechanism of Zr 3 Al. The formation energies of four intrinsic point defects were calculated and the relationship between concentration of different point defects and temperature was determined. Then, the effect of defect types on the stability of the system was explored after analyzing the electronic density of different supercells. In addition, the minimum energy pathways (MEPs) and the saddle point configurations during Zr or Al atom migration were calculated using the climbing image nudged elastic band method (CI-NEB). The energetic results show that the V Zr -mediated nearest neighbor (NN) jump mechanism is the feasible migration mechanism for Zr atom and dominant Al atom diffusion mechanism is the antisite assisted (AS) mechanism because of the lowest diffusion activation energy barrier. The present study lays the foundation for further investigation, including solute-diffusion in Zr 3 Al and quantitative calculation of diffusion coefficients, and provides theoretical guideline for further design and improvement of the crucial diffusion-mediated properties of Zr 3 Al. • The point defects formation energies are determined in Zr 3 Al. • The concentration of the four intrinsic point defects increases with the increasing of temperature. • The nearest-neighbor jump mechanism induced by V Zr is the most feasible diffusion mechanism for Zr atom. • Al mainly diffuses by the antisite assisted mechanism. [ABSTRACT FROM AUTHOR]

A metastable β-51.1Zr-40.2Ti-4.5Al-4.2V (wt.%) alloy with both TRIP and TWIP effects, exhibiting high yield strength of 800 MPa, high work hardening rate and good total elongation close to 17.5% was reported. The solid solution strengthening of high content of Ti and the special initial deformation mechanisms result in the outstanding yield strength. Microstructural analyses show that the dominant deformation mechanisms transformed from deformation-induced β→α′ martensitic transformation and kinking band at low strain to deformation-induced β→α′ martensitic transformation, widening and merging of α′ martensite, and { 10 1 ‾ 1 } α′ twinning at high strain. Changes in the dominant deformation mechanisms at different deformation stages lead to changes in special boundaries, resulting in a substantial high work hardening rate (2000–5440 MPa) until 10% strain. In addition, the reason for the TWIP effect in present alloy is internal { 10 1 ‾ 1 } α′ twin, which is different from that of the previously reported twins. • A new metastable β-ZrTiAlV alloy with both TRIP and TWIP effects was reported. • The alloy shows high yield strength, high work hardening rate and good elongation. • Solid solution strengthening and special initial deformation mechanisms result in the high yield strength. • Combination of α′, { 10 1 ‾ 1 } twin and kink band contribute to a high work hardening rate. • The reason for the TWIP effect in present alloy is internal { 10 1 ‾ 1 } α′ twin. [ABSTRACT FROM AUTHOR]

Zinc-ion batteries (ZIBs) are promising energy storage system owing to the low cost and high safety features. As the most-used anode material, zinc metal always encounters poor coulombic efficiency (CE) and cycling stability, because of the serious zinc dendrite and harmful side reactions on Zn surface. Here, a solid-phase non-adhesive homogeneous Nano-Si layer has been embedded on the Zn surface (Zn-Si) via an ultra-facile grinding method. The Nano-Si layer can regulate an even electric field distribution to achieve a homogeneous zinc deposition, and it also can greatly lower the charge transfer resistance and nucleation energy barrier of Zn2+ to facilitate the zinc deposition, thus achieving a dendrites-free and long-life Zn anode. Encouragingly, the zinc symmetrical battery with Zn-Si anode delivers a superior CE of 99.6 % in 1000 cycles under 5 mA cm−2, and a stable cycle lifespan of 3600 h under 1 mA cm−2 with much lower polarization potential (42 mV), outperforming the symmetrical battery with pure Zn anode (455 h, 59 mV) and various previously reported strategies. Additionally, the effectiveness of Nano-Si layer is further proved in the Zn-Si/MnO 2 battery, which presents a greatly improved capacity retention and cycling performance. [Display omitted] • Zn-Si anode has been prepared via a facile grinding process with sandpaper and Nano-Si powder. • Zn-Si anode shows lower the charge transfer resistance and nucleation energy overpotential. • Zn-Si can prevent the formation of zinc dendrites and by-products. • Zn-Si anode can further improve the electrochemical performance of full battery. [ABSTRACT FROM AUTHOR]

The metal-organic frameworks (MOFs)/derivates emerged as promising catalysts for hydrogen generation from electrolyzing water, however, further improvements in the activities are still awaited. Herein, bimetallic MOFs and the derivates were developed for catalyzing the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) by regulating the morphology, and activity of the intermediates. We demonstrated the activity and morphology of the catalysts strongly correlated with the atomic ratio of Ni and Co in bimetallic MOFs. The hierarchical Ni 0.1 Co 0.9 -MOF delivered a relatively low overpotential of 384 mV to afford 100 mA/cm2 for OER, but a high overpotential of 512 mV for HER. While the phosphide Ni 0.1 Co 0.9 P only needed an overpotential of 276 mV to deliver 100 mA/cm2 for HER. And we discussed the roles of bimetallic sites and phosphorous in OER and HER in depth. More importantly the Ni 0.1 Co 0.9 -MOF and Ni 0.1 Co 0.9 P were integrated to drive the overall water splitting, at a current density of 10 mA/cm2, the overpotential value is 500 mV. This work provided insights into the exploration of efficient MOFs/derivates catalysts and shed new light on the novel combination for water electrolysis. [Display omitted] • The hierarchical nanoflower morphology is elaborately fabricated. • The OER activity highly depends on the metallic atomic ratio in NiCo-MOF. • Ni 0.1 Co 0.9 -MOF performs the most superior OER performance. • Boosted HER performance is achieved by phosphorization (Ni 0.1 Co 0.9 P). • Paring Ni 0.1 Co 0.9 -MOF and Ni 0.1 Co 0.9 P generate excellent water electrolysis. [ABSTRACT FROM AUTHOR]

The microstructure and mechanical properties of (Zr-Ti) 1- χ Ni χ (χ =0, 1, 3, and 5 wt.%) alloys were studied. With the addition of nickel (Ni), the phase composition of alloys changes from α phase to α phase + hexagonal close packed (hcp) C14 Laves-phase. The thickness of lamellar α phase decreases with increasing Ni content. Optical microscopy and transmission electron microscopy results indicated that C14 Laves-phase is formed on the boundary. The Zr-Ti-3wt.%Ni alloys exhibits better ultimate compressive strength and compressive plasticity (1715 MPa and 9.70%) than that of Zr-Ti alloys (1598 MPa and 12.40%). The decrease of the average thickness of the lamellar α-phases (from 0.183 μm to 0.065 μm) leads to the improvement of the strength of the alloy. Additionally, the solid solution strengthening and the second phase strengthening are also important reasons for the improvement of the strength. [ABSTRACT FROM AUTHOR]

Aqueous zinc−ion batteries have attracted wide attention because of their low cost and high safety advantages, whereas the cathode materials with stable internal structure and fast transfer channels are urgently needed. Herein, a Navajoite phase V 5 O 12 •6 H 2 O nanorods has been prepared via a facile hydrothermal method, and proved to be a good choice as the cathode of ZIBs because of the excellent structural stability and special Zn2+ ion transfer channel. Electrochemical measurements demonstrate that the as−fabricated V 5 O 12 •6 H 2 O nanorods can disclose a high rate performance (405 mA h g−1 under 0.1 A g−1), a long−term cyclability (81.2% maintained after 20,000 cycles under 10 A g−1) and an excellent energy output (338.04 Wh kg−1 at 227 W kg−1). In addition, various ex−situ characterizations have revealed the electrochemical mechanism in V 5 O 12 •6 H 2 O cathode during reversible Zn2+ ion intercalation/de−intercalation process. The impressive electrochemical performance of V 5 O 12 •6 H 2 O cathode shows its high potential in practical applications. [Display omitted] • Navajoite phase V 5 O 12 •6 H 2 O nanorods were prepared via a facile hydrothermal method. • V 5 O 12 •6 H 2 O nanorods were employed as an advanced cathode of ZIBs. • An excellent rate capacities and highly stable cycling performance were achieved. • The electrochemical mechanism of H+/Zn2+ co-insertion was well illustrated. [ABSTRACT FROM AUTHOR]

To compensate for the insufficiency of single doping and to exert the synergistic effect between the elements, further improving the electrochemical performance, a series of Mg and Cl co-doped Li 2 Fe 1−x Mg x SiO 4–2x Cl 2x /C (x = 0, 0.01, 0.02, 0.03) nanocomposites (LFS, LFS-1, LFS-2, and LFS-3) have been synthesized by solvothermal method. Experimentally, Mg and Cl co-doping in Li 2 Fe 1−x Mg x SiO 4–2x Cl 2x /C were confirmed by X-ray diffraction, X-ray photoelectron spectroscopy, high resolution transmission electron microscope, and field-emission gun scanning electron microscopy elemental mapping, while electrochemical cycling performance showed improved performance. According to the results, LFS-2 outperforms other nanocomposites in terms of electrochemical performance, rate capability, and initial discharge capacity, with a capacity of 238.3 mAh·g−1 after 100 cycles of charging and discharging at 0.05 C. This is because it has a stable monoclinic structure free of impurities, a lower charge transfer resistance, and a higher Li-ion diffusion coefficient. Our findings suggest that Mg and Cl co-doping might be a feasible low-cost technique to enhance the electrochemical performance of silicate-based cathode materials, taking into account potential and electronic conductivity advantages. • Co-doping can make up for the insufficiency of single doping to further improve the material properties. • Mg2+ doping can enhance the structural stability, reduce the potential polarization, and improve the initial discharge specific capacity. • Cl- doping can improves the intrinsic conductivity of the material. • Using the synergistic effect of co-doping to engineer magnesium and chlorine co-doping to improve the electrochemical performance of Li 2 FeSiO 4 /C cathodes. [ABSTRACT FROM AUTHOR]

Na 3 V 2 (PO 4) 3 has been widely studied due to its stable three-dimensional transmission channel structure as a cathode electrode of sodium ion batteries, but its micro particle size and low intrinsic electronic conductivity limit its further development. Therefore, hierarchical porous micro-nano NVP/C materials were successfully prepared using a metal-organic frameworks (MOFs) precursor. Because of the unique hierarchical porous micro-nano structure, 3D highly conductive network between surface and particles, and high specific surface area, M-NVP/C exhibits outstanding rate capability (95.0 mAh g−1 at a current density of 10 C) and extraordinary stable cycle life (the capacity decays from 111.2 mAh g−1 to 108.8 mAh g−1 after 500 cycles at 1 C, with a capacity retention rate of 97.8 %). This method provides a promising pathway for the application of MOFs in battery materials and promotes the development of SIBs in large-scale energy storage systems. • Hierarchical porous micro-nano Na 3 V 2 (PO 4) 3 /C derived from MOFs precursors. • Na 3 V 2 (PO 4) 3 /C has 3D highly conductive network and high specific surface area. • Na 3 V 2 (PO 4) 3 /C shows excellent electrochemical properties. [ABSTRACT FROM AUTHOR]

Electrocatalytic hydrogen production by water splitting is highly energy-intensive due to poor electrocatalysts and sluggish four-electron oxygen evolution reaction (OER) kinetics. Herein, MnO 2 and sulfur-doped MnO 2 (S-MnO 2) are prepared by a simple hydrothermal method. The results show that S-MnO 2 exhibits a higher OER activity than MnO 2 because the sulfur doping gives rise to more Mn3+ active sites, oxygen vacancies (V O) and electrochemically active surface areas. Density functional theory (DFT) calculation further confirms that the abundant V O leads to a higher surface energy of S-MnO 2 , which is conducive to the adsorptions of H 2 O and OH- on Mn3+ sites. Moreover, formaldehyde oxidation reaction (FOR) is employed to substitute for sluggish OER to improve hydrogen evolution reaction (HER). Compared to OER-based electrolyzer (3.354 V), the cell voltage of FOR-based electrolyzer (2.778 V) at 100 mA cm−2 has decreased by 17.17 %, and the Faradic efficiency of hydrogen production increases from 89.6 % to 98.6 %. The results indicates that to produce the same amount of hydrogen, 17.17 % of electric energy can be economized. Thus the cost of hydrogen production decreases greatly. The HER efficiency is greatly improved because FOR has faster kinetics than OER. Meanwhile, after running for 2 h at 1.75 V, 52 % of formaldehyde has been degraded. The results demonstrate that the innovative electrolyzer can not only greatly improve the HER efficiency, but also efficientl y degrade formaldehyde pollutants. Sulfur doping obviously improved the adsorptions of H 2 O and OH- on sulfur-doped MnO 2 , and hydrogen production efficiency is greatly enhanced by adding formaldehyde. Hydrogen production and pollutant degradation can be achieved synergistically at an ultra-low energy consumption. [Display omitted] • Sulfur doping improved the adsorptions of H 2 O and OH- on sulfur-doped MnO 2. • Hydrogen production efficiency is greatly enhanced by adding formaldehyde. • Whole cell voltage has decreased by more than 17 % while adding formaldehyde. • Hydrogen production cost greatly decreased due to an ultra-low energy consumption. • Hydrogen production and pollutant degradation can be achieved synergistically. [ABSTRACT FROM AUTHOR]

The effect of reduction on microstructure evolution and mechanical properties in a near α-Zr alloy (Zr0.5Be, wt%) has been studied in detail during cold rolling. The results indicate that the strength of (002)α texture increases gradually with the increase of reduction, which can be attributed to the activation of base slip of α phase under high stress concentration. In the process of cold rolling reduction from 0% to 70%, deformation mode of the α-laths changes from rigid rotation along the RD direction to plastic strain gradually. Microscopic analysis results show that the dislocation slip dominates the plastic behavior of the alloy and the evolution path of the microstructure can be described as: (I) the stage of increasing dislocation density, (II) the stage of dislocation wall and dislocation cell formation, (III) the stage of subgrain formation, and (IV) the stage of nanocrystalline formation. Also, as the reduction increases from 0% to 70%, the tensile strength increases while the fracture elongation decreases. The sample subjected to 70% reduction can display the highest ultimate tensile strength (~ 930 MPa) and retain a fracture elongation of 8.6%. The combined effects of fine grain strengthening, dislocation strengthening and strain hardening play a leading role in the increase of strength and decrease of fracture elongation. • High stress concentration leads to the enhancement of (002) α texture. • Deformation mode of the α-laths changes from rigid rotation to plastic deformation. • The formation process of nanoscale grains is analyzed in detail. • CR-70% sample has the highest σ b (~ 930 MPa) and good ε f (~ 8.6%). [ABSTRACT FROM AUTHOR]

Highlights: [•] The densification of nanocrystalline MgO powders was investigated by SPS. [•] We calculated the grain growth exponent and activation energy for grain growth. [•] The microhardess attained a maximum value of 7.62±0.38GPa at 1200°C. [•] The relation of microhardness and microstructure was discussed. [ABSTRACT FROM AUTHOR]

• CoSe 2 @NiSe 2 nanoflowers are synthesized via microwave method. • CoSe 2 @NiSe 2 electrode exhibits high capacitance value of 1434 F g−1 at 1 A g−1. • Good cycling stability of 87.5% retention after 20,000 cycles. [Display omitted] The work reports the fabrication of CoSe 2 @NiSe 2 nanoflowers on nickel foam substrates via one-step microwave method, in which the Ni foam serves as a skeleton and a nickel source. The as-prepared CoSe 2 @NiSe 2 nanoflowers display high capacitance value of 1434 F g−1 at the current density of 1 A g−1 and excellent cycling performance of 87.5% retention after 20,000 cycles at 10 A g−1. In addition, the supercapacitor device using CoSe 2 @NiSe 2 nanoflowers as the positive electrode and activated carbon (AC) as the negative electrode not only can exhibit wide voltage window of 1.6 V, but also deliver a maximum high energy density of 20.4 Wh Kg−1 at power density of 798 W Kg−1 and 86.6% of capacity retention after 20,000 cycles. [ABSTRACT FROM AUTHOR]

In this work, the effect of Ti content on the microstructure and mechanical properties of low-density Fe-30Mn-10Al-1.57C-2.3Cr-0.3Si-χTi (χ = 0, 0.3, 0.6, and 0.9 wt%) alloys was systematically investigated. The results reveal that hot deformation, followed by solid-solution treatment at 1050 °C (3 h) and thermal aging at 350 °C (6 h), ensures outstanding mechanical properties. The low-density alloys exhibit completely austenite microstructures with carbides. The original carbide phase, the so-called κ-carbide, is observed in the low-density Ti-free specimen. However, increase in the Ti content leads to the reduction of this phase and the emergence of a new type of carbide, i.e., TiC. Moreover, the grain size of austenite phase is refined with Ti addition, resulting in a superior yield strength. In addition, the low-density alloy with a Ti concentration of 0.6 wt% demonstrates optimal mechanical properties with the yield strength of 1031.75 MPa, the ultimate tensile strength of 1158.55 MPa, and the total elongation of 23.96%. It is worth noting that the novel low-density alloy exhibits a density of 6.65 g/cm3, which is ~14.74% lower than that of traditional steel (7.8 g/cm3) and can be ascribed to the incorporation of lightweight Al element. • The microstructure has been refined as the Ti content increased. • The mechanical properties of Fe-Mn-Al-C steels has been improved by Ti addition. • The 0.6Ti steel shows UTS of 1158.55 MPa at 23.96% elongation. • The density of low-density is 6.8 g/cm3. • Determined the contribution of different mechanisms to the yield strength. [ABSTRACT FROM AUTHOR]

With the rapid development of world economy and an increasing use of portable electronic devices, energy storage systems are becoming more reliable on nano/micro supercapacitors. This work reports a fast and facile microwave-initiated synthesis approach of 2D-molybdenum ditelluride nanosheets supported on graphene substrate (MoTe 2 /graphene), which can be used as an efficient energy storage material. The physical characterizations, such as scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray diffraction analyses substantiate the successful synthesis of MoTe 2 /graphene nanocomposite. The electrochemical characterizations reveal their excellent supercapacitive behavior with specific capacitance of 434 ± 37.5 F g−1 at a current density of 1 A g−1 and a good cycling stability of 125% retention after 5000 cycles at 10 A g−1 in 1 M Na 2 SO 4 aqueous solution. In addition, the symmetric MoTe 2 /graphene//MoTe 2 /graphene configuration displays excellent cyclic stability up to 10,000 cycles with a maximum energy density of 43.2 Wh kg−1 at high power density of 3000 W kg−1 in 1 M Na 2 SO 4 electrolyte, which demonstrates the hybrid-capacitor behavior. Therefore, the microwave synthesized MoTe 2 /graphene reveals a great potential as advanced electrode materials for energy storage devices with high electrochemical performance through one-step facile synthesis approach. Image 1 • A solid-state, facile, ultra-fast (90 s) microwave-initiated synthesis of MoTe 2 /graphene nanocomposite. • Excellent energy storage performance of the resultant MoTe 2 /graphene nanocomposite with good cycling stability. • Symmetric MoTe 2 /graphene//MoTe 2 /graphene configuration exhibits hybrid capacitor behavior. [ABSTRACT FROM AUTHOR]

In the present work, nickel hydroxide modified delaminated-Ti 3 C 2 sheets (Ni(OH) 2 /d-Ti 3 C 2) were synthetized by the hydrothermal method in order to overcome the capacity degradation caused by the terminal functional groups of Ti 3 C 2 -MXenes. Due to synergetic effects, the obtained Ni(OH) 2 /d-Ti 3 C 2 displayed a capacity of 732.6 mA h g−1 at 0.1 A g−1, ∼6.0 times higher than that of d-Ti 3 C 2 (∼121.3 mA h g−1), and ∼6.2 times higher than that of Ni(OH) 2 (∼117.6 mA h g−1). Moreover, a higher reversible capacity of 372.0 mA h g−1 after 1000 cycles without apparent capacity decay at 1 A g−1 was obtained. This enhanced performance can be caused by the higher lithium ion diffusion coefficient in Ni(OH) 2 /d-Ti 3 C 2 (2.5 × 10−14 cm2 s−1), ∼284.1 times higher than that of Ni(OH) 2 (8.8 × 10−17 cm2 s−1) and ∼7.1 times higher than that of d-Ti 3 C 2 (3.5 × 10−15 cm2 s−1). DFT calculations further confirmed that the Ni(OH) 2 /d-Ti 3 C 2 can be a good candidate for the anode materials of lithium ion batteries. Image 1 • Ni(OH) 2 /d-Ti 3 C 2 composite was synthesized by one-step hydrothermal method. • The well-wrapped Ni(OH) 2 was grown on the d-Ti 3 C 2 MXene flakes. • This surface engineering improved capacity and cycle performance of d-Ti 3 C 2 MXene. [ABSTRACT FROM AUTHOR]

A series of hierarchical AgIO 3 /BiVO 4 -GO photocatalysts was synthesized using a solvothermal-precipitation method. The composition, structure, morphology, optical and photoelectrochemical performance of as-obtained photocatalysts were systematically characterized by XPS, XRD, TEM, SEM, EDS, PL, UV–Vis DRS, PT, and EIS, respectively. The photocatalytic activity was evaluated by the degradation of tetracycline hydrochloride (TC) and Rhodamine B (RhB) under visible light irradiation. Experimental results exhibited the photocatalytic degradation activity of AgIO 3 /BiVO 4 was significantly improved compared with pure AgIO 3 and BiVO 4. This may be due to the heterojunction formation of AgIO 3 and BiVO 4 and the introduction of GO, which accelerates the separation and migration of electron-hole pairs and reduce recombination. The h+ and •O 2 − was the key active species in the photocatalytic degradation process according to the trapping experiment. Furthermore, a potential photocatalytic mechanism was predicted based on experimental results. Image 1 • The AgIO 3 /BiVO 4 -GO photocatalysts was formed by self-assembly. • The AgIO 3 /BiVO 4 -GO composites show outstanding photocatalytic activity. • The mainly active species and the mechanism of charge separation and transfer was discussed. • The cycle-stability of the AgIO 3 /BiVO 4 -1% GO photocatalysts was examined. [ABSTRACT FROM AUTHOR]

The presence of L1 2 -Al 3 Zr, can drastically improve the strength of Al alloys, however, the L1 2 -Al 3 Zr is a metastable structure and prone to have phase transformation at the Al/Al 3 Zr (α/β′) interface. Therefore, it is very important to prevent the phase transformation and stabilize the metastable structure. In this work, the first-principles calculations method based on density functional theory was used to explore the intrinsic mechanism of adding solute atoms to effectively control the phase transition proposed in the experimental research. Based on the determination of the optimal doping sites of atoms, the calculation of the diffusion energy barrier proves that the introduction of alloying elements does hinder the diffusion of atoms, thus effectively suppressing the phase transition process at the interface. From the perspective of Griffith work of fracture (G), the effects of alloying element and vacancy on the interfacial bonding strength were considered. There is the best strength effect while the alloying atom replaces the β′-Al site at the interface with V Al or without V Al , and among the four elements studied, the alloying effect of Nb is the best, and Cu is relatively poor. In addition, the calculation results of the Griffith work of fracture were explained by the electronic local function. The introduction of alloying element makes the change of the degree of electron localization of Al atoms nearby is an important reason for the interfacial bonding strength. The obtained results in the present work instructive for the interfacial strengthening mechanisms and it may serve as a design tool for Al–Zr alloys with desired properties. • The occupation tendency of alloying elements (Nb, Ti, Cu and Sc) at Al/Al 3 Zr interface was investigated. • The vacancy diffusion energy barriers of Al and Zr atoms near the Al/Al 3 Zr interface were calculated. • The synergistic effect of alloying elements and vacancy on the interfacial bonding strength was comprehensively considered. • The calculated results of Griffith work of fracture are explained by the electronic local function. [ABSTRACT FROM AUTHOR]