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The electrocatalytic oxygen evolution reaction is a crucial means to support the conversion and storage of the sustainable renewable energy. Low-crystallinity can offer short-range structural ordering and high active site density. In this work, an efficient self-supported oxygen evolution reaction (OER) electrocatalyst, cobalt iron layered double hydroxide (LDH) grown on Ti 3 C 2 modified nickel foam (NF) heterostructure anode (CoFe-LDH/Ti 3 C 2 /NF) was prepared using electrodeposition. The exceptional electrocatalytic OER performance is ensured by in situ decorating monolayer Ti 3 C 2 /NF (s-Ti 3 C 2 /NF) with low-crystallinity CoFe nanospheres. By harnessing the low crystallinity, well-chosen composition and reasonable heterostructure, the overpotential of CoFe-LDH/Ti 3 C 2 /NF decreases to 246 mV at a current density of 10 mA·cm−2 in alkaline media. After 3000 cyclic voltammograms cycles, the ignorable increase in overpotential of 14 mV suggest the excellent long circular stability. Moreover, an accelerated reaction kinetics is implied by the smaller Tafel slope (28.76 mV·dec−1) and higher double-layer specific capacitance (2.33 mF·cm−2), which surpassed the counterparts CoFe-LDH grown on NF (CoFe-LDH/NF) and s-Ti 3 C 2 /NF. This work paves a new way to fabricate the low-crystallinity materials for electrocatalysis and energy storage. [Display omitted] • Low-crystallinity CoFe nanospheres grow on the s-Ti 3 C 2 by directly electrodepositing. • Low-crystallinity enhances the OER activity and stability for CoFe-LDH/Ti 3 C 2 /NF. • Catalyst yields a low overpotential of 246 mV and Tafel slope of 28.76 mV·dec−1. • Catalyst delivers a high C dl of 2.33 mF·cm−2 and desirable long-term stability. [ABSTRACT FROM AUTHOR]

Constructing hydroxide precursors with radially oriented primary grains is the key factor for fabricating Ni-rich cathodes with sufficient cycle life. Herein, hydroxide precursors with composition of Ni 0.92 Co 0.04 Mn 0.04 (OH) 2 were synthesized to study the effects of pH and ammonia concentration on the phase, morphology, and orientation of grains, as well as the evolution of primary grains and secondary particles during industrial-scale continuous precipitation process. Results show that the preferential growth of primary grains varies significantly with change of pH, ammonia concentration and the growth of secondary particles. Meanwhile, the variation of grain size along direction parallel to [001] is more obvious than that perpendicular to [001] after decreasing pH or increasing ammonia concentration. Moreover, the size distribution of secondary particle varies with the increase of feeding time or the change of reaction condition in a regular manner. Although a steady state could be reached for continuous precipitation, the different residence times endow the size of secondary particles with normal distribution. The results disclosed in this work may provide a guiding significance for designing precipitation procedure for hydroxide precursor of high-end Ni-rich cathodes. [Display omitted] • Synthesis of Ni 0.92 Co 0.04 Mn 0.04 (OH) 2 via industrial-scale continuous precipitation. • Effects of pH and ammonia concentration on orientation of grains. • Evolution of grain orientation during growth of secondary particle. • Variation of secondary particle with change of condition and feeding time. [ABSTRACT FROM AUTHOR]

Abstract RuO 2 -doped IrO 2 -ZrO 2 ternary oxide coatings with different Ru/Ir/Zr mole ratios were synthesized using a sol-gel route. The surface morphology was determined by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM), atomic force microscopy (AFM) and energy dispersive spectroscopy (EDS) analysis. The electrochemical behavior was investigated using linear sweep voltammetry (LSV), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and accelerated life test (ALT). The results showed that the compositions of the coatings are rutile IrO 2 and RuO 2. ZrO 2 is present as an amorphous phase in the coatings. The coating with Ru content of 21 mol% shows a compact structure with needle-like crystals dispersed. With the increase in Ru content, the porous and cracked structure of the ternary oxide coating of increased active surface area is obtained. Increasing Ru content improves the electrocatalytic activity, but worsens the stability of the coating in OER. The coating with Ru content of 21 mol% shows good electrocatalytic activity and the longest service lifetime in OER. Highlights • RuO 2 -doped Ti/IrO 2 -ZrO 2 anodes were prepared using a sol-gel route. • Compositions and nanostructured morphology of coatings were detected. • Effects of Ru content on crystallization and microstructure were determined. • Effects of Ru content on electrocatalytic properties were investigated. [ABSTRACT FROM AUTHOR]

Magnesium titanates (including three main phases, Mg 2 TiO 4 , MgTiO 3 and MgTi 2 O 5 ) and Mn 4+ doped magnesium titanates were successfully prepared in a simple route. Mn 4+ occupied octahedral positions to substitute Ti 4+ in the magnesium titanates host lattice. The absorption bands at 400–600 nm assigned to the d-d band transition of Mn 4+ had difference in three systems, which were strongly influenced by local crystal field environments. In this work, the samples doped Mn 4+ showed the difference in emission peak positions, attributing to the 2 E g → 4 A 2g emission process of Mn 4+ . Crystal field strength of host material and Mn O nephelauxetic nature of the Mn 4+ -doped magnesium titanates (Mg 2 TiO 4 :Mn 4+ , MgTiO 3 :Mn 4+ and MgTi 2 O 5 :Mn 4+ ) influenced on the photoluminescent properties, which was demonstrated through the combination with density functional theory (DFT) and experimental method. These results suggested that Mn 4+ doped Mg 2 TiO 4 material had high color purity, which was a promising material for red phosphor in attractive white-light LEDs application. This research is very useful because it could rapidly predicted the luminescent property of new Mn 4+ doped materials through DFT calculation. [ABSTRACT FROM AUTHOR]

Spherical particles of (Y 1- x Eu x )BO 3 ( x = 0–0.20, ∼0.8–1.5 μm in diameter) have been converted from (Y 1- x Eu x )(B(OH) 4 )CO 3 precursors synthesized via homogenous precipitation processing. Detailed characterizations of the samples were achieved by combined techniques of XRD, Raman, FE-SEM, HR-TEM, PLE/PL, and fluorescence decay analysis. Through homogenous precipitation processing in the absence of EG, orthorhombic (Y,Eu)(B(OH) 4 )CO 3 cubic particles were obtained owing to their crystal habit. Proper EG addition leads to the formation of spherical particles, but nano-sized amorphous particles were resulted from the excessive EG content. Longing reaction time or elevating the reaction temperature induced the appearance of cubic ones. Calcining (Y,Eu)(B(OH) 4 )CO 3 at 700 °C yielded hexagonal structured (Y,Eu)BO 3 phase with the space group of P 6 3 / m , but another hexagonal structured (Y,Eu)BO 3 phase (space group: P 6 3 / mmc ) was obtained with the calcination temperatures of 800–1000 °C. The spherical shape and excellent dispersion of the original particles can be well retained up to 800 °C. Upon UV excitation, the (Y 1- x Eu x )BO 3 ( x = 0–0.20) spheres exhibited a typical Eu 3+ emission with the orange emission at 592 nm from the 5 D 0 - 7 F 1 magnetic dipole transitions of Eu 3+ ions taking the dominant role. Space-group vibrations between in 700 °C-phase and 800–1000 °C phase resulted in the blue shift of CTB center, but they did not significantly affect the lifetimes. A higher Eu content ( x = 0.01–0.10) leaded more Eu 3+ ions occupying the non-centrosymmetric site instead of S 6 one, thus inducing enhanced emission of 5 D 0 → 7 F 2 transition, larger asymmetry factor, and red shift of the CIE chromaticity coordinates. However, the asymmetry factor remains nearly constant with the x value up to 0.20. The fluorescence lifetime is similar (5.3 ± 0.3 ms) up to 8 at% of Eu 3+ , followed by decreases at higher Eu 3+ contents. [ABSTRACT FROM AUTHOR]

GaN:Dy films were prepared by implanting Dy ions into c-plane (0001) GaN films and a subsequent rapid thermal annealing process. The structural and magnetic properties of samples were investigated by means of X-ray diffraction (XRD), Raman and Physical Property Measurement System (PPMS). The XRD and Raman studies showed that lattice damage and dislocation caused by ion implantation can be effectively recovered by rapid thermal annealing. The PPMS results showed ferromagnetism at room temperature. The average value of the moment per Dy ion (M s /Dy) is increased after thermal annealing. The available vacancies and formation of bound magnetic poloron as a result of implantation and thermal annealing are assigned responsible for observed ferromagnetism. [ABSTRACT FROM AUTHOR]

Local-ordering MoO 2 nanostructures within porous N-doped carbon nanotubes (MoO 2 @NCNTs) is achieved by a facile method for high-performance anode material for Li-ion battery. The inner MoO 2 material is divided into many separated nanoribbons with a length of ca. 200 nm and a thickness of ca. 15 nm, which can decrease the diffusion length of lithium ions and facilitate mass transport. The outside walls of the NCNTs also exhibit a porous feature, which not only can ensure rapid lithium ion diffusion during charging/discharging processes but preserve the structural stability of the active materials at a high current density. As a consequence, MoO 2 @NCNTs exhibit excellent electrochemical performance with a reversible capacity of 868.3 mA h g −1 at a high current density of 2 A g −1 after 100 cycles, superior to most recently reported MoO 2 -based nanostructures. Thus, the present facile strategy may open a way to development of cost-efficient anode material with high-performance for large-scale energy conversion and storage systems. [ABSTRACT FROM AUTHOR]

A facile and efficient approach was proposed for the direct utilization of mixed cathode (LiNi 1/3 Co 1/3 Mn 1/3 O 2) and anode materials (Graphite) from the spent lithium-ion battery (LIBs) to prepare high-stability oxygen evolution reaction (OER) electrode. Benefitting from the high catalytic activity of LiNi 1/3 Co 1/3 Mn 1/3 O 2 cathode and excellent electrical conductivity of graphite anode, the composite electrode exhibited a low overpotential of 320 mV at 10 mA cm−2 in KOH solution, close to that of the benchmark RuO 2 catalyst for OER. The effects of operating temperatures and substrates on the electrocatalytic activity of composite electrodes toward OER were investigated. More importantly, the electrode showed superior long-term stability and the potential retains at almost the same value at 10 mA cm−2 for 680 h, demonstrating its great potential for practical applications. This work opens a novel and convenient route for the fabrication of efficient and stable electrocatalysts, offering a new perspective on the recycling and reutilization of spent LIBs. [Display omitted] • Mixed cathode and anode from the spent LIBs were directly employed as OER electrode. • The electrode makes full use of complementary properties of the cathode and anode. • The electrode exhibited a low overpotential and superior long-term stability. • This work offers a new perspective on the recycling and reutilization of spent LIBs. [ABSTRACT FROM AUTHOR]

As an attractive cathode material, the layered sodium chromium oxide NaCrO 2 (NCO) can provide a reversible capacity of around 120 mAh g−1 between 2.0 and 3.6 V, which corresponds to about 0.5 Na per formula is extracted/inserted. However, irreversible phase transition happens in Na x CrO 2 when x is less than 0.4 and the potential is exceeding 3.6 V vs. Na+/Na. To improve its high-potential structural stability, Nb5+ is introduced to Cr3+ site by a sol-gel method successfully in this study. The influences of Nb5+ doping on the crystal structure and electrochemical properties are explored. As a result, a more stable structure as well as a higher ionic conductivity are achieved in Na 0.94 Cr 0.97 Nb 0.03 O 2 (NCO-Nb3), exhibiting better rate performance and cycling stability between 2.0 and 3.6 V and 2.0–3.7 V. When elevating the charging cut-off voltage to 3.8 V, 4.0 V, 4.4 V, the initial coulombic efficiencies of NCO-Nb3 are still significantly higher than those of pristine NCO. • Pentavalent Nb5+ is substituted in Cr3+ site successfully, and the lattice spacing is enlarged. • The structure stability and ionic conductivity are improved with the doping of Nb5+. • Enhanced rate performances and stable cycle performances are achieved in different voltage ranges. • When tested between 2.0 and 3.7 V, NCO-Nb3 can achieve 1000 cycles at 10 C. [ABSTRACT FROM AUTHOR]

Cation-Disordered Li-Excess cathode material with an initial capacity over 300 mAh/g have drawn great attention as cathode materials for lithium batteries. In this work, Li 1.3 Mn 0.4 Ti 0.3 O 2 cathode material with superior capacity was synthesized through the effective content adjustment of Li and Ti by ball milling combined with a high-temperature solid-state method. The synthesized Li 1.3 Mn 0.4 Ti 0.3 O 2 possessed high crystallinity with a uniform particle size. The initial capacity reached 334.9, 230.5 and 127.3 mAh/g at current densities of 10, 50, and 100 mA/g, respectively. The oxidation-reduction of Mn3+/Mn4+, Mn2+/Mn3+ and O2-/O-, contributed to the ultrahigh capacity of Li 1.3 Mn 0.4 Ti 0.3 O 2 was investigated by electrochemical characterization. The density of states in Li 1.3 Mn 0.4 Ti 0.3 O 2 was studied by density functional theory based calculations. The experimental results show that Li 1.3 Mn 0.4 Ti 0.3 O 2 could be promising cathode material for high-energy-density lithium batteries. • Li 1.3 Mn 0.4 Ti 0.3 O 2 cathode material with superior capacity was synthesized through easy method. • The initial capacity reached 334.9 mAh/g at current densities of 10 mA/g at room temperature. • The oxidation-reduction of Mn3+/Mn4+, Mn2+/Mn3+ and O2-/O-, contributed to the ultrahigh capacity of Li 1.3 Mn 0.4 Ti 0.3 O 2 was investigated by electrochemical characterization. • The Mn-O hybridization states dominated the electronic states in the vicinity of the Fermi level. [ABSTRACT FROM AUTHOR]

Sodium and potassium ion storage have received more attention over the last several years due to their fascinating properties, such as competitive cost-benefit and sustainable resource supply. It is challenging to maintain a stable electrode structure during the electrochemical process for the larger radius ions of Na+ and K+. One-dimensional (1D) materials can be an ideal model for developing insight into relationships between physical-chemical properties and dimension when used as electrodes. Furthermore, it can serve as a convenient migration pathway for electrons or ions, enhancing charge transfer and reducing contact resistance. As a controllable and facile synthesis approach, electrospun can be applied to design 1D nanofibers with tunable compositions and morphologies to supply the required high electrochemical activity and stability. In this review, we will discuss current electrospun techniques used to make stable electrodes for larger radius ions and enhance electrochemical stability. Some approaches to promote the thermal stability and mechanical strength of separators through electrospun strategies are also included. The insights presented in this article can serve as a guide for fabricating electrospun-based nanofiber electrodes for larger radius ion storage. [Display omitted] [ABSTRACT FROM AUTHOR]

• Two continuous precipitate modes of the δ′ phase are proposed which uncovers the structural ordering in Al-Li solid solutions. • Precipitation thermodynamic and kinetics have been calculated to identify the continuous precipitate modes. • Crystallographic structural differences at these intermediate paths have been identified for guilding processing by design. [Display omitted] Owing to the fast kinetics of the precipitation, the formation mechanism of the δ′ phase in Al-Li alloys is still open to question. Using ab initio calculations, here, we reported two continuous precipitate modes (Bulk and Planar modes based on Li atoms arrangements) to complete the ordered δ′ phase through progressive Al-Li solid solutions. Under the vacancy-dependent solid-state precipitation mechanism, we found that these intermediate solid solutions were dominated by sequent Al-Li-vacancy complex structures that exhibit strong binding effects from Li atoms to vacancies. In turn, vacancies located in different sub-lattices exert short- and long-range effects to tailor the bonding strength of the constituted atoms. Based on the diffusion activation energy calculations, we suggested that the ordering transition of the δ′ phase prefers the Planar mode. In later stages of precipitation, the kinetics of precipitation accelerates, resulting in great difficulties in capturing this structural performance in experiments. Our findings are informative for understanding the energetic and phase transformation mechanism behind continuous precipitate for the precipitated phases with fast kinetics. [ABSTRACT FROM AUTHOR]

Abstract: We investigated the effect of Ge additions (0.1–0.5at.%) on properties of Sn84Zn13Bi3 solder-alloys, specifically the anti-oxidation capability, electrical resistance, thermal expansion behavior, and mechanical strength. The Sn–Zn–Bi–Ge alloys have a melting point around 197°C, and are not noticeably oxidized after soaking at 250°C for 180min under ambient air flow 100ml/min. Coefficient of thermal expansion, tunable between 10 and 17ppm/°C by the Ge addition, matches those of various metals such as Cu, Ni or lead-frames, leading to low thermal stress. Electrical resistivity of Sn–Zn–Bi–Ge solder-alloys, 10–15μΩcm, is much lower than that of Sn–37Pb solder. The micro-Vickers hardness, up to 400MPa with 0.5at.% Ge addition, is 150% that of Ge-free Sn84Zn13Bi3, or 300% that of Sn–37Pb solder. Moreover, it possesses better tensile strength, being 127% that of Ge-free Sn84Zn13Bi3, and 190% that of Sn–37Pb solder. [Copyright &y& Elsevier]

Metal chalcogenides undergoing alloying and conversion mechanism can give high capacity as anode for lithium-ion batteries. However, large volume change and phase segregation lead to poor cycle performance. In this study, we focus on Sb 2 Se 3 and develop methods to enhance its long-term stability and reversibility. In particular, we find that carbon encapsulation reduces volume change during lithiation/delithiation and facilitates the recombination process of Sb and Se even after long cycling. With an addition of 20 wt% acetylene black, the Sb 2 Se 3 /C nanocomposite material exhibits an excellent cycle performance with a charge capacity of 545 mAh g−1 at 250 mA g−1 after 1000 cycles, corresponding to a capacity retention of 99.3%. We also demonstrate a full cell with LiFePO 4 cathode and Sb 2 Se 3 /C anode that is capable of delivering a stable capacity of 340 mAh g−1 at 1 A g−1 (about 3 C rate) after 300 cycles. • Sb 2 Se 3 nanoparticles encapsulated with carbon matrix is synthesized via mechanical ball-milling. • Carbon matrix enhances the mechanical stability of the electrode and suppresses phase segregation. • Sb 2 Se 3 @20%AB delivers a stable capacity of 545 mAh g−1 over 1000 cycles. • Sb 2 Se 3 @20%AB/LiFeO 4 full cell shows good rate capability and cycle stability. [ABSTRACT FROM AUTHOR]

A study of Fe-ion intercalation in Bi 2 Te 3 probed by the x-ray diffraction, magnetization, Hall measurement, and spectra of synchrotron x-ray photoemission spectroscopy is reported, in which a large positive magnetoresistance (MR) and a high carrier mobility for applications have been achieved and probed in the quenched Fe x Bi 2 Te 3 single crystals with x = 0.01 and 0.15. Large positive MR of ∼470% with a Hall mobility of ∼44000 cm2/Vs at 5 K and 6 T has been observed on a quenched Fe 0.01 Bi 2 Te 3 sample with a quenching temperature T q of 400 °C, where the electrical parameters can be tuned by T q. Larger c -axis lattice constants and electron-dominant carriers in the quenched samples lead to the inference that the doped Fe atoms are mostly located at the intercalated van der Waals gap positions and exist as a metallic state of Fe0, which is confirmed by the synchrotron x-ray photoemission spectroscopy (XPS) spectra. Combining the x-ray diffraction, magnetization, and Hall-coefficient studies, here we pave a simple way for probing into the location of Fe dopants in Bi 2 Te 3. In addition, novel magnetotransports of Fe-doped Bi 2 Te 3 associated with the absence of ferromagnetism have been presented, and satisfy the scenario that the topological surface state persists without the loss of topological insulating characteristics of the linear band dispersion, and the large MR may originate from the surface magnetism, even in the presence of Fe impurities. This study also discusses the huge enhancement of Hall mobility arising from the surface Dirac electrons that are accompanied with a modified band structure in quenched Fe 0.01 Bi 2 Te 3. • This paper reports on the c-axis crystalline structure, magnetization, and magnetotransport properties of quenched Fe-doped Bi 2 Te 3 single crystals, which have been at the center of debate over magnetically doped topological insulators. • Stable magnetoresistance of ∼470% with a Hall mobility of ∼44000 cm2/Vs at 5 K and 6 T has been observed on the quenched sample, leading to the conclusion that this material is suitable for applications in next-generation photoelectrical devices and spintronics. • In the quenched samples, it can be inferred that the doped Fe atoms are mostly located at the intercalated van der Waals gap positions and exist within metallic state of Fe0. • Here a simple way is presented, for the first time, to probe into the location of impurity atoms in Bi 2 Te 3. [ABSTRACT FROM AUTHOR]

The volumetric capacity plays a critical role in lithium-ion batteries (LIBs) on account of the restrictive electrode material. Herein we report a novel electrode material of Co 0.85 Se@C/Ti 3 C 2 T x MXene hybrids (CSTCs) with high volumetric capacities are prepared by ultrasonication of Ti 3 C 2 T x MXene and Co 0.85 Se@C nanoparticles. These samples are systematically characterized by X-ray diffraction, scanning and transmission electron microscopy, X-ray photoelectron spectroscopy, and energy dispersive spectroscopy. The electrochemical performance of these samples as anode materials for LIBs are also studied. Owing to the opened two-dimensional structure, good electrochemical property, and weak Li+ diffusion resistance, these materials exhibit good electrochemical properties. The CSTC3 sample delivers the maximum reversible capacity, up to 700 mA h g−1 at 0.1 A g−1, corresponding to a very high volumetric capacity of 2044 mA h cm−3 due to its high compact density. This hybrid is considered to be a promising anode material in small-size wearable or portable electronic devices. Co 0.85 Se@C/Ti 3 C 2 T x MXene hybrids with high volumetric capacities are prepared as anode materials for lithium-ion batteries. Image 1 • Co 0.85 Se@C/Ti 3 C 2 T x MXene hybrids is used as a new anode materials. • The hybrids complement the advantages of Co 0.85 Se@C and Ti 3 C 2 T x MXene. • The specific capacity of CSTC3 reaches to 700 mA h g−1 at 0.1 A g−1. • The anode electrode exhibits very high volumetric capacities. [ABSTRACT FROM AUTHOR]

The development of supercapacitors generally suffers from the used anodes with insufficient energy density. In this paper, nitrogen-doped monolayered Ti 3 C 2 (N-Ti 3 C 2) is synthesized via a facile urea assisted solvothermal route and then abundant MnCo 2 S 4 curved nanosheets are directly in-situ grown on their surface to form a novel 3D porous anode material (N-Ti 3 C 2 /MnCo 2 S 4). The expanded interlayer spacing of nitrogen-doped Ti 3 C 2 can effectively facilitate ion diffusion as well as regulate the growth of MnCo 2 S 4 nanosheets. Subsequently, the highly conductive 3D MnCo 2 S 4 porous network further gives a rapid pathway for ions and electrolyte transfer. Hence, N-Ti 3 C 2 /MnCo 2 S 4 electrode delivers an ultra-high mass capacitance of 1243.1 F g−1 at 5 mV s−1. Furthermore, the asymmetric supercapacitors (ASCs) based on N-Ti 3 C 2 /MnCo 2 S 4 not only acquires a higher energy density of 162.8 Wh kg−1 at the power density of 2700.0 W kg−1 under a wide potential window of 0–1.5 V, but also exhibits an outstanding cycling durability with a minor loss of 6.20 % after 10,000 charge and discharge cycles. [Display omitted] • MnCo 2 S 4 nanoplates grew on N-doped monolayered Ti 3 C 2 and self-assembled a distinct 3D porous network. • N-Ti 3 C 2 /MnCo 2 S 4 showed an outstanding specific capacitance of 1243.1 F g−1 at 5 mV s−1. • N-Ti 3 C 2 /MnCo 2 S 4 //AC delivered an enhanced energy density of 168.2 Wh kg−1 and a stable cycle life. [ABSTRACT FROM AUTHOR]

One of the major obstacles restricting the wide applications of Mg alloys is their low Young's modulus at ∼45 GPa, which is uncompetitive to Al alloy over 60 GPa. To resolve this issue, we proposed a new strategy of designing ultra-light Mg-Li alloys by employing the microscale compounds in both HCP and BCC grains to achieve high Young's modulus. HCP or BCC alone cannot achieve a high modulus due to the segregation of solutes at the grain boundaries and the formation of brittle intermetallics in the interdendritic region. We designed chemistry that is so perfect to arrest the excess solutes inside the BCC matrix during solidification and engulf pre-solidified rare earth particles by HCP primary grains which have such a lean chemical composition that has almost no segregation. During solution heat treatment, the dissolution of solutes pushes the BCC boundary towards HCP grains by Ostwald ripening (BCC structures are interconnected but the HCP structures are isolated). During low-temperature aging heat treatment, nucleation of HCP structure on the rare earth particles inside the BCC grain is found, degrading the strength. Therefore, a novel Mg-Li-Al-Zn-Y-Mn-Gd (LAZWMV) alloy with a very high modulus was designed which reaches Young's modulus as high as 61.4 GPa. Micro-compounds (AlLi and Al-X) with average equivalent diameters of 3.76 µm and 6.55 µm were quantified in 3D using X-ray computed tomography and nanoindentation tests for establishing the microstructure-modulus correlation. The influence of Li addition on Mg-Mg was calculated by DFT calculations and the mechanism of modulus improvements has been proposed. [Display omitted] • Ultra-light Mg-Li alloy was designed with high strength and high modulus. • Super-high Young's Modulus of 61.4 GPa was first reported for a novel Mg alloy. • Nanoindentation uncovers the principles of modulus increase in Mg-Li alloys. • Quantitative 3D characterization of high modulus phase using XCT prectict alloy properties. • DFT calculation of Mg-Mg bonds explores the effects of heat treatments. [ABSTRACT FROM AUTHOR]

Monoclinic (M1) VO 2 film has potential applications in thermochromic modulators owing to the particular optical performance caused by phase transition. However, its controllable preparation is very difficult due to the multivalence of V element. Here, we studied a sol-gel process followed by annealing in a closed vaccum furnace containing NH 3 atmosphere, and discussed the formation mechanism of M1-phase VO 2 films. Thermochromic M1-phase VO 2 thin films can be fabricated under the base pressure of 600–2000 Pa with the annealing temperature at 470–590 °C for more than 0.5 h, and the optimal condition is at 1000–2000 Pa and 500–530 °C for 0.5 h, by synthetically considering their luminous transmittance ( T lum ), solar modulation efficiency ( ΔT sol ), and modulation efficiency at 2000 nm ( ΔT 2000nm ). The M1-phase VO 2 thin film generally exhibits the optical properties with T lum ≈ 39–41%, ΔT sol ≈ 7.7% and ΔT 2000nm ≈ 50%. A higher base pressure introduces more oxygen to remove polymers in precursors, enhancing the transparency of films. Improving the temperature or the duration promotes the growth of VO 2 crystallite with limits. However, inappropriate base pressure, temperature or duration will reduce or oxidize the VO 2 films, resulting in the inferior thermochromic properties. According to thermal and XPS analysis, NH 3 can act as a reductant to prevent oxidation of VO 2 films during the annealing process. This convenient heat treatment method to synthesize M1-VO 2 films may provide a useful and practical technique for the production of VO 2 -based smart window and optical devices. [ABSTRACT FROM AUTHOR]

In this study, solute X (X = Li, Al, Mn, Zn, Y, Zr, Nd, and Gd) solution strengthening in Mg alloys have been screened by ab initio density functional theory calculations to quantify not only the substitutional stacking-fault configurations but also the solute ordering sequence as a function of local segregation. Interestingly, it has been found that the strengthening effects of single atom addition to a supercell made of 64 atoms can be mostly attributed to lattice distortions (Mn>Nd>Gd>Y>Zn>Al>Zr>Li), while the local ordering arrangements of Mg-X complex actually contribute most to the strengthening when the solute concentration rises. For example, Nd can induce a large local atomic ordering and significantly increase the basal critical-resolved shear stress (CRSS). A linear relationship between solute concentrations and ideal strength, and the quasi-quadratic relationship between solute atomic radii and ideal strength have been observed. Simultaneously, the higher the solute concentration, the higher degree of the solid solution strengthening, resulting in a smaller quasi-quadratic function curve opening. Based on the screening of the chemical (including stacking fault energy and atomic bonds) and strain (lattice distortion energy) energy calculations, we have discovered that the solute strengthening follows the ordering sequence of Nd> Mn> Gd> Y> Zn> Al> Zr> Li. [Display omitted] • Local ordering of Mg-X alloys was found by thermodynamic evaluations using DFT. • Both chemical and strain energy contribute to the solute strengthening ordering. • Local ordering configuration in solid solution strengthening guide the alloy by design. [ABSTRACT FROM AUTHOR]

In this work, a novel lightweight AlCrTiNbMo refractory high-entropy alloy (RHEA) coating has been developed to overcome the surface damage defects in Ti-6Al-4V alloys under wear and erosion conditions. A crack-free in-situ nitride (AlCrTiNbMo)N x RHEA coating were successfully prepared by the gas assisted laser nitriding. According to XRD, SEM and TEM analysis, AlCrTiNbMo coating was composed of single BCC phase, while (AlCrTiNbMo)N x coating was constituted by BCC and TiN phases. The average microhardness of AlCrTiNbMo and (AlCrTiNbMo)N x RHEA coatings were 591.2 HV 0.3 and 1070.1 HV 0.3 respectively. (AlCrTiNbMo)N x RHEA coating has lower friction coefficient and wear rate than AlCrTiNbMo RHEA coating and the substrate from room temperature to 600 °C. At 600 °C, (AlCrTiNbMo)N x RHEA coating showed a rare self-lubricating behavior, the friction coefficient decreased to 0.275 (61.9 % of the substrate), and the wear rate was 0.06 mm3/N m× 10−4 (1.24 % of the substrate). The erosion rates of (AlCrTiNbMo)N x RHEA coating at erosion angle of 30°, 60° and 90° were 11.0 %, 22.3 %, and 36.8 % of those of the substrate, respectively. The homogeneous and hard TiN array-BCC structure generated by in-situ self-reaction was the main factor for the excellent wear and erosion resistance of (AlCrTiNbMo)N x RHEA coating. Thus, (AlCrTiNbMo)N x RHEA coating and corresponding laser nitride technique were expected to be applied in the severe working environment of high temperature, wear, and erosion. • In-situ nitride (AlCrTiNbMo)N x refractory high-entropy alloy coating by gas assisted laser nitriding was first proposed. • The wear and erosion performance of Ti-6Al-4V alloy was improved significantly and the effect mechanism was investigated. • The homogeneous and hard TiN array-BCC structure generated was the main factor for the excellent performance. [ABSTRACT FROM AUTHOR]

Compared to alternative materials (aluminum alloys and steel), magnesium alloys have low strength and modulus which restricts further applications in critical structural components. To overcome this limitation, we have successfully designed a strong and stiff magnesium-lithium alloy (LAZWMGT) by using Sn and RE (Gd, Y) nuclei to refine HCP α-Mg grains and forming secondary Mg 2 Sn inside primary Mg grains. Although the bulk Gibbs free energy favors the dissolution of HCP α-Mg and growth of BCC β-Li grains, the dispersion of thermally stable Mg 2 Sn, Al 2 Gd, and Al 2 Y particles inside the BCC β-Li grains can actually template the nucleation of HCP α-Mg heterogeneously. Because the Mg 2 Sn, Al 2 Gd, and Al 2 Y phases are hard (E > 76 GPa) and have an entropy of melting greater than 16.6 J/mol·K, they are faceted crystals and semi-coherency exists between the HCP α-Mg and Mg 2 Sn, Al 2 Gd, and Al 2 Y particles, leading to limited growth orientations at slow rate. As a result, new HCP α-Mg grains inside BCC β-Li do not coarsen. Therefore, both strength and stiffness are increased significantly up to YS: 319 MPa, UTS: 365 MPa, and E: 64.5 GPa. To quantify each phase's contribution to Young's modulus, nanoindentation has been used to measure the stiff particles as well as the soft BCC β-Li. It has been found by XPS experiments and DFT calculations that strong covalent Mg-Mg and Mg-X bonds in BCC β-Li enhances when Sn or RE presents either in solution heat treatment or as Mg 2 Sn precipitates, justifying the rigidity and directionality bonds as a result of Sn and RE. In addition, the effects of Sn and RE on grain boundary, solid solution, and precipitation strengthening have been predicted. [Display omitted] • An ultra-high elastic modulus(64.5 GPa) Mg-Li alloy was successfully designed. • Effects of heat treatment on elastic modulus was measured by nanoindentation. • Contribution of various nano-sized particles to the the alloy's strength and modulus was quantified. • XPS and DFT identified the effects of Sn on covalent bonding to be the critical factor of elevating Young's modulus. [ABSTRACT FROM AUTHOR]

Optimizing photocatalyst structure at the atomic level is a crucial challenge in improving photocatalytic performance. Herein, a series of TiO 2 /P-doped C 3 N 4 -pinned composites have been synthesized to optimize photocatalyst structure at the atomic level. Among the nonmetals (P, C, and N) in P-doped C 3 N 4 (CN-P), TiO 2 preferentially bonds with P to form stable P-O-Ti chemical bonds that can act as efficient carrier transfer channels. Comprehensive correlations between P-O-Ti bond features, defects, carrier kinetics, and photocatalytic activity have been studied theoretically and experimentally. Photocurrent-time curves and distribution of relaxation times analysis reveals that preferentially bonded P-O-Ti improves carrier separation and transfer. The special P-O-Ti interface bonds endows composites TiO 2 /P-doped C 3 N 4 with multifunctional photocatalysis properties, i.e., hydrogen production (815 µmol g−1 h−1), and completely reducing heavy metal ions Cr (VI) (10 min) under visible light (λ > 400 nm) irradiations, which outperforms most of existing CN-P and TiO 2 composite catalysts, as well as excellent degradation performance for organic contaminants. More importantly, the composite with optimal composition shows a superior stability and repeatability in ten cycles of testing. These findings provide valuable hints in optimizing photocatalyst structure at the atomic level for enhancing carrier dynamics and improving photocatalytic performance necessary for applications under visible light. [Display omitted] • TiO 2 nanoparticles pinned in P-doped C 3 N 4 have been synthesized. • TiO 2 preferentially bonds with P to form stable P-O-Ti chemical bonds. • The P-O-Ti bonds act as transport channels for photogenerated carriers. • Composite 0.33 A-TO/CN-P exhibits excellent photocatalytic performances. [ABSTRACT FROM AUTHOR]

Aiming to improve the rate capability and cycling stability, cesium doped Li-rich cathode materials Li 1.2-x Cs x Ni 0.13 Co 0.13 Mn 0.54 O 2 (x = 0, 0.012, 0.036, 0.060, 0.096) are synthesized by a sol-gel method and a subsequent calcination process. The optimal Cs+ content is found to be x = 0.060. After Cesium doping to Li+ sites, the enlarged interplanar spacing of (003) plane, which is confirmed by high resolution transmission electron microscopy, can accelerate the Li+ diffusion during the lithiation/delithiation process at the interface of electrode/electrolyte. The obtained Cs-doped Li-rich sample with x = 0.060 exhibits much improved electrochemical performance compared with the bare, especially the rate capability (148 mAh g−1 compared to 50 mAh g−1 at 10 C). The first discharge capacity is much enhanced from 250 to 281 mAh g−1 at 0.1 C with a heightened coulombic efficiency from 72% to 81%. XRD, SEM, TEM, elemental mapping, EDS and ICP-AES are adopted to characterize the morphologies and structures. • Cesium is successfully doped to Li+ sites in Li-rich cathode material. • Both rate and cycling properties are enhanced for Li 1.14 Cs 0.06 Ni 0.13 Co 0.13 Mn 0.54 O 2. • A variety of techniques are adopted to elucidate the improvement mechanism. [ABSTRACT FROM AUTHOR]

Abstract Controlling hierarchical structure assembled by nanoplates with exposed {010} active planes is essential to optimize the electrochemical performance of nickel-rich layered oxide cathode materials. In this work, nickel-rich layered oxide cathodes with various degrees of packing and surface area of exposed {010} facets were synthesized via a simple continuous co-precipitation method and a stepwise calcination process. The effects of structure and morphology on the Li+ transport kinetics of LiNi 0.58 Co 0.25 Mn 0.17 O 2 were systematically evaluated by physical and electrochemical characterizations. The results show that the enhanced growth of {010} active facets, namely, the lateral plane of the primary nanoplates can facilitate the Li+ intercalation/deintercalation and thus improve the rate capability. Meanwhile, the compact micro-sized secondary particle guarantees the structural stability of the Ni-rich cathodes. The LiNi 0.58 Co 0.25 Mn 0.17 O 2 material with optimized structure manifests high discharge capacities (185 mAh g−1 at 0.1 C), outstanding high-rate capability (106 mAh g−1 at 50 C) and excellent long cycle life (capacity retention of 78% after 500 cycles at 5 C). Highlights • Ni rich cathode with preferentially exposed {010} active facets is synthesized. • The enhanced growth of {010} active facets can facilitate Li+ diffusion. • The cathode with preferentially exposed active facets shows excellent performance. [ABSTRACT FROM AUTHOR]

In this paper, samples were prepared by co-implanting Dy and carbon ions into c-plane (0001) GaN films and a subsequent rapid thermal annealing at 800 °C. The room temperature magnetic properties of Dy and C co-implanted GaN samples were investigated by experiments and theoretical calculations. Dy and C co-implanted GaN samples had the larger room temperature magnetic moment than that of the Dy-implanted GaN. The calculated results showed that the spin polarization of C-2p electrons leads to the local magnetic moment due to the hybridization between Dy-4f electron states and C-2p electron, which explains the enhancement of magnetic moment in co-implanted GaN samples. Our results suggest that co-implantation is a potential approach to enhance the room temperature ferromagnetism. [ABSTRACT FROM AUTHOR]

Traditionally, Mg alloys suffer from the low Young's modulus, making it uncompetitive to Al alloys in such applications as aerospace components where high stiffness is necessary. In this study, a new Mg-Li-Al-Dy-Nd-Y-Ag-Zn-Er-Zr alloy was performed, which has an ultra-high modulus of 61.73 GPa and excellent ductility of 19.3% after cast, homogenization, cold rolling, and heat treatment. The origin of such a significant increase in modulus is due to the formation of micro- and nano- AlX particles. The increase in plasticity can be explained by the activation of non-basal slips in the α-Mg matrix and dislocation slips in the β-Li phase. In addition, the relationship between the grain orientation (obtained from the EBSD results) and hardness were discovered by using nanoindentation experiments and crystal plasticity finite elements modeling (CPFEM). The high hardness of the alloy is due to the fact that the Schmid factor (SF) range of the slip system is mostly between 0.3 and 0.5. [Display omitted] • A new Mg-Li alloy with an ultra-high modulus of 61.73 GPa and excellent ductility of 19.3% was invented. • The significant increase in modulus is due to the formation of micro- and nano- AlX particles. • A large amount of dislocation slips in the β-Li and non-basal slips in the α-Mg matrix contributed to high ductility. • The quantitative relationship between the grain orientation and hardness has been established. [ABSTRACT FROM AUTHOR]

Transition metal sulfides (TMSs) are widely used in energy storage and energy conversion systems because of their excellent electrochemical properties. However, their application is restricted by a low electron transfer efficiency, few active sites and poor stability. In this paper, CoNi bimetallic sulfides supported by carbon skeleton (CoNi-SP/NPC) were prepared using bimetallic organic frameworks (MOFs) as templates and modified with phosphorus doping. Compared with single metal sulfides, the bimetallic sulfides are more favorable for electron transfer in the catalytic process. Meanwhile, the carbon skeleton support gives the catalyst higher mechanical stability, and the P-doping brings more active sites into to contact with the aqueous solution. The overpotential of CoNi-SP/NPC catalyst is only 105 mV at 10 mA cm−2 for hydrogen evolution reaction (HER) and 313 mV at 100 mA cm−2 for oxygen evolution reaction (OER). In addition, CoNi-SP/NPC also displays remarkable performance in the course of overall water splitting, which can achieve 50 mA cm−2 at only 1.8 V and remains good stability for 12 h. This work proposes a feasible strategy to synthesize highly efficient water splitting electrocatalysts. • CoNi-SP/NPC exhibits synergy between bimetallic sulfides. • P-doping increases the active sites of bimetallic sulfides. • Metal-organic frameworks enhance electrical conductivity of materials. • Composite exhibits high-efficient OER and HER catalytic capacities and good stability. [ABSTRACT FROM AUTHOR]

• A KVP 2 O 7 powder with a wrinkled pea-shaped morphology is fabricated. • A room temperature capacity of 60 mA h g−1 is achieved for this KVP 2 O 7 cathode. • A KVP 2 O 7 @C//hard carbon full cell exhibits an energy density up to 184 W h kg−1. Searching for advanced cathode materials is indispensable for the eventual practical applications of potassium-ion batteries (KIBs). Herein, we design and synthesize a carbon-matrixed potassium vanadium pyrophosphate powder (KVP 2 O 7 @C) with a wrinkled pea-shaped particle morphology via a spray drying process. As a cathode material for KIBs, this KVP 2 O 7 @C exhibits a reversible capacity of 60 mA h g−1 with two discharge plateaus at 4.1 V and 4.5 V (vs. K+/K), leading to a high energy density of 250 W h kg−1 at 0.2 C in half cells. The potassium storage mechanism of KVP 2 O 7 is revealed by ex-situ X-ray diffraction technology as an intercalation/de-intercalation reaction during electrochemical cycling, i.e. KVP 2 O 7 (P2 1 /c + P 1 ¯) ↔ K x VP 2 O 7 (x ≈ 0.4, P 1 ¯). A full cell constructed by coupling KVP 2 O 7 @C cathode with a hard carbon anode can achieve a high operating voltage (3.55 V), high energy density (184 W h kg−1) and superior cycling stability (89% capacity retention after 400 cycles). [ABSTRACT FROM AUTHOR]

Developing high-efficient and Earth-abundant electrocatalysts toward hydrogen evolution reaction (HER) is strongly desired for electrochemical water splitting but remains a considerable challenge. Herein, we propose a 3D hierarchical Fe(PO 3) 2 @Cu 3 P heterostructure nanotube arrays on Cu foams for promising HER catalysts. The HER performance can be tuned by changing FeCl 3 concentrations and the optimized cathode exhibits excellent HER activity in 1 M KOH with a low overpotentials of 108 mV @ 10 mA cm−2 and a small Tafel slope of 84 mV dec−1. Furthermore, this electrode delivers high electrochemical durability with stable operation for 24 h. Such high performance can be ascribed to the unique hierarchical heterostructure with large electrochemical surface area, synergistic effect and fast electron transport. Our study can provide new inspiration for rational construction of copper-based hierarchical nanomaterials for HER electrodes and other energy-related applications. Hierarchical Fe(PO 3) 2 @Cu 3 P nanotube hybrids on 3D copper foam were synthesized, which demonstrate excellent activity toward hydrogen evolution in alkaline solution with robust stability. Image 1 • Hierarchical Fe(PO 3) 2 @Cu 3 P nanotube arrays were successfully synthesized on Cu foam. • The hybrid catalysts exhibit excellent activities for HER in alkaline media. • Synergistic effect between Fe(PO 3) 2 and Cu 3 P was found by XPS. • The hybrid catalyst exhibits considerable stability for HER. [ABSTRACT FROM AUTHOR]

A novel coral-like Au 1 Pt 3 alloy nanoparticles (ANPs) with multiple surface defects are prepared on the basis of co-/surfactant (n-octanoic acid and PVP) via one-pot method at room temperature. The coral-like Au 1 Pt 3 ANPs are characterized by XRD, HRTEM, SAED, EDS, and HAADF-STEM, respectively. Then, l -methionine (L-Met) is one-step electropolymerized on the surface of the glassy carbon electrode (GCE) decorated by Au 1 Pt 3 ANPs. The morphology and element mapping of the poly(L-Met)/Au 1 Pt 3 /GCE are observed by FE-SEM. The poly(L-Met)/Au 1 Pt 3 /GCE sensor exhibits higher electrochemical sensibility, wider linear range, lower detection limit, better selectivity, reproducibility and stability to dopamine (DA) under the optimized conditions. The limit of detection (S/N = 3) is found to be 0.07 μM with the linear variation over 0.5–200 μM, and the sensitivity is calculated as 4.07 μA μM−1 cm−2. The sensor shows excellent determination results towards spiked human urine samples with recoveries ranging from 93.8 to 104.2%. Image 1 • Coral-like Au 1 Pt 3 alloy nanoparticles with multiple surface defects are synthesized by a one-pot method at room temperature. • An advanced dopamine sensor is established based on the synergic effects from Au 1 Pt 3 alloy nanoparticles and the electropolymerization membrane of l -methionine (L-Met). • The poly(L-Met)/Au 1 Pt 3 /GCE shows satisfactory detection limit, selectivity, stability, and practical application performance. [ABSTRACT FROM AUTHOR]