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A free-standing covalently bonded CNTs/graphene foam (LPM-3D rebar GF) is developed by using an in-situ loose powder metallurgy templates method for high-performance dendrite-free Li metal anodes. The LPM-3D rebar GF possesses a macroporous structure with interconnected porous pipelines. The homogeneously dispersed CNTs can induce an in-situ growth for covalently bridging graphene sheets, resulting in the increase of electrical conductivity, structural stability, and active Li nucleation sites. With the guidance of CNTs, Li metal deposit preferentially on the junctions of CNTs and graphene to achieve a uniform deposition and avoid the formation of Li dendrites effectively, which is verified by both experiments and first-principle calculations. As the anode of Li metal battery, the LPM-3D rebar GF shows outstanding cycling stability even at 20 mA cm−2 for 20 mA h cm−2. Notably, this anode can still operate 90 cycles at 30 mA h cm−2 with a Coulombic efficiency (CE) of >98%. These properties indicate promising prospects of LPM-3D rebar GF as a new and dendrite-free anode with large areal capacity for high-performance Li metal batteries, and in other fields requiring 3D carbon monoliths including fuel cells and sodium-ion batteries. Image 1 • Covalently bonded CNTs/graphene foam (LPM-3D rebar GF) wasdeveloped through an in-situ loose powder metallurgy approach. • Li was uniformly deposited under the guidance of CNTs by nucleating preferentially at the covalent junctions. • The LPM-3D rebar GF shows excellent performance at high current density of 20 mA cm−2 for areal capacity of 20 mA h cm−2. [ABSTRACT FROM AUTHOR]

Laser powder bed fusion (L -PBF) technique, as the mainstream technology in metal additive manufacturing, enables the fabrication of aluminum alloys and their composite components with high precision and design freedom, thereby advancing structural lightweighting in various application domains, such as aerospace and transportation. Nevertheless, aluminum powders present challenges including high laser reflectivity, high thermal conductivity, low melting point, and susceptibility to oxidation. Consequently, defects such as pores, solidification cracks, orientation anisotropy, and surface roughness commonly exist in L -PBFed aluminum alloy and composite parts. These defects severely compromise the mechanical performance and dimensional accuracy of L -PBFed parts. Thus, extensive research efforts have been focused on defect control in the L -PBFed aluminum alloys and their composites. However, a systematic summary and in-depth analysis of the formation mechanism and controlling strategy of various defects is still absent, which is the key to develop high performance aluminum alloys and their composites via L -PBF. In this review, a thorough analysis and summary of the causes of defects are provided, followed by an in-depth analysis and conclusion of defect control strategies and mechanism in L -PBF. Furthermore, we also present an outlook on the challenges and research opportunities in L -PBFed aluminum alloys and their composites in the last section, which we hope could inspire more new development of high-performance aluminum alloys and their composites via L -PBF. [ABSTRACT FROM AUTHOR]

Abstract Traditional laminated metal matrix composites are confined to two-component system of pure metal matrix and its reinforcement. To achieve further improvement of the applied mechanical properties, in this work, the soft phase of laminated composites was enhanced by alloying with Cu. The synergistic effect of Cu on phases of both soft and hard including in-situ catalyzing and precipitation hardening was firstly explored. The laminated graphene nanosheets (GNSs) /AlCu composites of 2 vol% GNSs, were fabricated by ball milling and hot-rolling processes with much higher mechanical properties. The multi-pass hot rolling provided the solution-precipitation process of Cu transforming into Al 2 Cu and significantly increased the dislocation density of the original soft Al matrix. In addition, the fracture mechanism and fracture model of the laminated GNSs/AlCu composites were also investigated. [ABSTRACT FROM AUTHOR]

With the rise of flexible electronics, the demand for advanced power sources has grown. Developing high-performance energy storage devices requires comprehensive consideration of various factors such as electrodes, electrolytes, and service conditions. Herein, a data-driven research framework is proposed to optimize the electrode-electrolyte system in supercapacitors. With the help of machine learning, we reveal the key factors affecting the capacitance performance of carbon-based materials. According to the algorithm analysis, a kind of 3D carbon network is prepared with controlled composition and structure, which is incorporated with a high-safety ionic liquid to obtain a supercapacitor device. This device with high energy density and impressive flexibility can maintain operational stability under extreme conditions such as humidity, shock, and localized damage. Overall, this work presents a typical pipeline for accelerating the design of energy-related devices. [Display omitted] • A data-driven design framework for energy storage devices is proposed. • Machine learning is used to investigate the key features of electrode materials. • An ultra-thin flexible supercapacitor device with high safety is fabricated. [ABSTRACT FROM AUTHOR]

Three-dimensional (3D) reduced graphene oxide (rGO) anchored carbon-coated Fe 2 O 3 core-shell nanoparticles (Fe 2 O 3 @C-rGO) has been developed successfully through a simple one-pot hydrothermal process followed by a further annealing treatment. The 3D Fe 2 O 3 @C-rGO nanocomposite consists of carbon-coated Fe 2 O 3 nanoparticle clusters (Fe 2 O 3 @C) and rGO nanosheets. The homogenously distributed and intercalated Fe 2 O 3 @C nanoparticles between rGO nanosheets form a highly conductive 3D carbon network with rGO, and present a hierarchical pore size structure, enabling fast ion and electron transport, as well as remarkable specific surface area. The electrochemical performance in supercapacitor has been characterized, and the as-prepared Fe 2 O 3 @C-rGO electrode shows a significant high specific capacitance of 211.4 F/g at 0.5 A/g and 177.2 F/g at 20 A/g with no visible performance decay even after 2500 cycles testing. These properties indicate a good potential to achieve high performance electrochemical devices. [ABSTRACT FROM AUTHOR]

Abstract: Two kinds of TiO2 with novel structures, interpenetrating anatase TiO2 tablets (IP-TiO2), and overlapping anatase TiO2 nanosheets (OL-TiO2) with exposed {001} facets, are synthesized. The graphene oxide (GO) supported ultrathin TiO2 nanosheets (OL-TiO2/GO) is also prepared by one-pot hydrothermal method. The microscopic feature, morphology, phase, and nitrogen adsorption–desorption isotherms are characterized. The performance of photocatalytic degradation of methyl blue is also measured. Compared with IP-TiO2, the OL-TiO2 with GO possess higher photocatalytic efficiency. The GO can improve the photocatalytic property by increasing specific surface area, accelerating the separation of electron–hole pairs, as well as extending the electron life. The growth process of TiO2 nanosheets on graphene oxide layers probably follows a step-growth mechanism with F− as morphology controlling agent. The steps on the surface can improve the photocatalytic activity further due to the increase of dangling bonds of 5-coordinated Ti (Ti5c) which are considered to be the active sites in the photocatalytic reaction. [Copyright &y& Elsevier]

Three-dimensional bi-functional modular graphene network (3D bmG) is developed by using metal powder assisted soluble salt templates method. The 3D bmG contains two kinds of modules with different functions: the 3D graphene catalyzed by Ni powder (3D bmG-n) and the 3D graphene grown on NaCl crystals (3D bmG-s). The 3D bmG-n with high crystallization degree ensures the high electrical conductivity and structural stability and protects the 3D bmG-s from etching in electrolyte. The 3D bmG-s with more defects and pores provides high capacity and rate properties. Thus, the synergistic effects of the two modules endow the 3D bmG excellent electrochemical performance as both cathode and anode of lithium-ion capacitors (LICs). The as-prepared "all-carbon" bmG//bmG full LIC with a high voltage window of 4.5 V presents high energy densities of 278 Wh kg−1 and 52.2 Wh kg−1 at power densities of 405 W kg−1 and 16200 W kg−1, respectively, and excellent cycling stability with a capacity retention ratio of 88.57% after 3000 cycles, which is superior compared with LICs reported previously. These properties indicate promising application of 3D bmG in high performance energy storage devices, and the modular design in this work will inspire more designs and types of 3D materials. [Display omitted] • 3D bi-functional modular graphene network was successfully developed. • Two modules with specific structures ensure synergistic improvement of properties. • 4.5 V symmetrical LIC achieved high energy and power density and long cycle life. [ABSTRACT FROM AUTHOR]

Emerging high entropy compounds (HECs) have attracted huge attention in electrochemical energy‐related applications. The features of ultrafine size and carbon incorporation show great potential to boost the ion‐storage kinetics of HECs. However, they are rarely reported because high‐temperature calcination tends to result in larger crystallites, phase separation, and carbon reduction. Herein, using the NaCl self‐assembly template method, by introducing a high‐pressure field in the calcination process, the atom diffusion and phase separation are inhibited for the general formation of HECs, and the HEC aggregation is inhibited for obtaining ultrafine size. The general preparation of ultrafine‐sized (<10 nm) HECs (nitrides, oxides, sulfides, and phosphates) anchored on porous carbon composites is realized. They are demonstrated by combining advanced characterization technologies with theoretical computations. Ultrafine‐sized high entropy sulfides‐MnFeCoCuSnMo/porous carbon (HES‐MnFeCoCuSnMo/PC) as representative anodes exhibit excellent sodium‐ion storage kinetics and capacities (a high rating capacity of 278 mAh g−1 at 10 A g−1 for full cell and a high cycling capacity of 281 mAh g−1 at 20 A g−1 after 6000 cycles for half cell) due to the combining advantages of high entropy effect, ultrafine size, and PC incorporation. Our work provides a new opportunity for designing and fabricating ultrafine‐sized HECs. [ABSTRACT FROM AUTHOR]

Emerging high entropy compounds (HECs) have attracted huge attention in electrochemical energy‐related applications. The features of ultrafine size and carbon incorporation show great potential to boost the ion‐storage kinetics of HECs. However, they are rarely reported because high‐temperature calcination tends to result in larger crystallites, phase separation, and carbon reduction. Herein, using the NaCl self‐assembly template method, by introducing a high‐pressure field in the calcination process, the atom diffusion and phase separation are inhibited for the general formation of HECs, and the HEC aggregation is inhibited for obtaining ultrafine size. The general preparation of ultrafine‐sized (<10 nm) HECs (nitrides, oxides, sulfides, and phosphates) anchored on porous carbon composites is realized. They are demonstrated by combining advanced characterization technologies with theoretical computations. Ultrafine‐sized high entropy sulfides‐MnFeCoCuSnMo/porous carbon (HES‐MnFeCoCuSnMo/PC) as representative anodes exhibit excellent sodium‐ion storage kinetics and capacities (a high rating capacity of 278 mAh g−1 at 10 A g−1 for full cell and a high cycling capacity of 281 mAh g−1 at 20 A g−1 after 6000 cycles for half cell) due to the combining advantages of high entropy effect, ultrafine size, and PC incorporation. Our work provides a new opportunity for designing and fabricating ultrafine‐sized HECs. [ABSTRACT FROM AUTHOR]

Metal oxide/carbon materials composites (MOx/C) are broadly used as electrodes in energy storage devices. However, their capacity under high rates is limited due to the sluggish ion/electron transportation during faradaic reactions. In this work, carbon nanotube carpets (CC)/Fe 2 O 3 nanoparticles covered with bud-liked carbon layer (CC/Fe 2 O 3 @b-C) is developed as an electrode by interfaces design. It is found that the bud-liked carbon wrapper enlarges interface area and provides an accelerated conducting network between CC and Fe 2 O 3 nanoparticles through "seamless" connection. With boosted charge transfer efficiency, this composite demonstrates an excellent rate capability. The CC/Fe 2 O 3 @b-C electrode shows a high capacity of 246.15 mC cm−2 under 5 mV s−1 and can maintain ~95% when the scan rate is increased to 100 mV s−1. Moreover, the hybrid device paired with carbon fiber cloth (CFC)/Co(OH) 2 cathode exhibits simultaneous high energy density and power density, showing good potential application in high-power devices. Image 1 • Bud-liked CNT carpets/Fe 2 O 3 @C were seamlessly connected through interfaces control. • Boosted charge transfer efficiency was obtained by perfectly matching R s and R ct. • Principles of designing MOx/C composites for energy storage devices were concluded. [ABSTRACT FROM AUTHOR]

The co-segregation of Cu and Mg solutes at grain boundaries (GBs) in Al alloys is widely observed in experiments, but this segregation pattern is much less understood. Herein, the Cu, Mg co-segregation behaviors and their effects on Al Σ5 (210) GB properties were systematically studied via first-principles calculations. The segregation order of Cu and Mg atoms was firstly determined wherein the segregation tendency of Cu is comparatively stronger than Mg. Calculations demonstrate that Cu and Mg atoms exhibit attractive interaction, which would promote synergistic co-segregation of both dopants at the GB. It is revealed that Cu, Mg co-segregation not only improves GB thermodynamic stability, but also enhances the GB fracture strength. Detailed analysis of charge density, bonding characteristics, etc., suggests that the newly formed Al–Cu bonds upon Cu segregation are the primary contribution to the increased GB cohesion. The further Mg doping at the Al GB with Cu segregation results in charge depletion and meanwhile decreases Al–Cu bonding length, the net results of which increase GB cohesion, suggesting a synergistically enhanced GB strength with Mg and Cu co-segregation. This work is supposed to provide fundamental insights into the effect of Cu, Mg co-segregation on the strength of Al GBs. [ABSTRACT FROM AUTHOR]

Introduction of magnetism in large-area monolayer graphene has captured much attention in the graphene community, owing to the potential applications in transistors, magnetic memory, spintronic devices, and so on. Here, we use graphene nanoribbons (GNRs) as reinforcing rebar to in situ reinforce large-area graphene, where the edges of graphene nanoribbons are found to be seamlessly welded with graphene sheet. Based on the GNR-reinforced graphene, Fe nanoparticles encapsulated by carbon nano-onions (CNOs) with controllable shell thickness are in situ grown on the surface to introduce efficient ferromagnetic phase to graphene by a facile and scalable method. When core-shell Fe@CNOs with thick shells are anchored, the hybrid film shows a strong p -doping electric behavior and an intriguing ferromagnetic property with remarkable remanence and coercivity in applied magnetic fields. The in situ growth of nanoscale Fe@CNOs on large-area GNR reinforced graphene will provide an additional avenue for the application of graphene-based films in flexible and transparent spintronic or magnetic electronics. Image 1 [ABSTRACT FROM AUTHOR]

Graphene nanosheets (GNS) have attracted lots of attention as an ideal reinforcement in Al matrix composites. However, there are still challenges limiting the performance of the composites, such as the homogenous distribution of GNS in Al matrices, the structural integrity of GNS after ball-milling, and the interfacial bonding between GNS and Al matrices. This work presents a new approach to grow GNS on Al powders at 600 °C by in-situ chemical vapor deposition (CVD) process, using methane as the carbon source, and Cu as the catalyst. The GNS coated Cu reinforced Al matrix bulk composites (Cu@GNS/Al) from the composite powders was fabricated by powder metallurgy (PM) technique. It was found that Cu 2+ from CuCl 2 can easily anchor onto the surfaces of Al particles uniformly though a nanoscale-disperse-method in alcohol, enabling the homogenously dispersion of Cu particles in Al matrices after being reduced from Cu 2+ in hydrogen. With the assistance of Cu particles, network-liked GNS was successfully synthesized in-situ and strongly bonded with Al, resulting in a good mechanical performance of the composites. It is indicated that the tensile strength of the composites was improved by ~ 200% compared to the unreinforced pure Al. The strengthening mechanism was mainly ascribed to the load transfer of GNS, precipitation strengthening of Al 2 Cu compounds after 400 °C annealing and dislocation strengthening. [ABSTRACT FROM AUTHOR]

Recharging batteries operate at sub‐zero temperature is usually limited by the slow ion diffusion and uneven charge distribution at low temperature. Here, we report a strategy to regulate electric field and thermal field simultaneously, creating a fast and uniform deposition surroundings for potassium ion in potassium metal batteries (PMBs). This regulation is achieved by using a highly ordered 1D nanoarray electrode which provides a dense and flat surface for uniforming the electric field and high thermal conductivity for reducing the temperature fluctuation. Consequently, this electrode could achieve high‐areal capacity of 10 mAh cm−2. Besides, the dependence of potassium nucleation on temperature is unveiled. Furthermore, a full‐cell could steady operate with over 80 % of its room‐temperature capacity at −20 °C. Those respectable performances demonstrate that this strategy is valid, potentially providing guidelines for the rational design of advanced electrodes toward PMBs. [ABSTRACT FROM AUTHOR]

Recharging batteries operate at sub‐zero temperature is usually limited by the slow ion diffusion and uneven charge distribution at low temperature. Here, we report a strategy to regulate electric field and thermal field simultaneously, creating a fast and uniform deposition surroundings for potassium ion in potassium metal batteries (PMBs). This regulation is achieved by using a highly ordered 1D nanoarray electrode which provides a dense and flat surface for uniforming the electric field and high thermal conductivity for reducing the temperature fluctuation. Consequently, this electrode could achieve high‐areal capacity of 10 mAh cm−2. Besides, the dependence of potassium nucleation on temperature is unveiled. Furthermore, a full‐cell could steady operate with over 80 % of its room‐temperature capacity at −20 °C. Those respectable performances demonstrate that this strategy is valid, potentially providing guidelines for the rational design of advanced electrodes toward PMBs. [ABSTRACT FROM AUTHOR]

The marked Mg segregation at grain boundaries (GBs) in nanocrystalline Al alloys usually contributes additional GB segregation strengthening. To gain a further understanding of this phenomenon, molecular dynamics simulations were conducted to reveal the Mg segregation behavior at Al Σ9 (221)[ 1 1 ¯ 0 ] symmetric tilt grain boundary (STGB) and its effects on the GB stability and strength. Results reveal that Mg dopants have a large driving force to segregate at Al GBs. Such Mg segregation not only enhances the strength of Σ9 (221) STGB but also improves GB stability. It is found that the Mg segregation turns to enlarge and narrow the strain intervals of stable and thickening stages of Σ9 (221) STGB during tensile test, indicative of the Mg-induced stabilizing effect on the GB structural integrity. Calculations further elucidate that the segregated Mg dopants increase the critical stress for dislocation nucleation, which accounts for the remarkably increased tensile strength of Σ9 (221) STGB with Mg segregation. Such retarded dislocation nucleation is ascribed to the decrement in boundary free volume by Mg segregation. This work will provide important atomic-scale insights into the extra GB strengthening in Al alloys deriving from Mg segregation. [ABSTRACT FROM AUTHOR]

Bimetallic doping is widely used to enhance the oxygen evolution reaction (OER) activity of layered transition metal oxyhydroxides. However, the synergistic enhancement effect of different doping elements on the intrinsic OER activity is still obscure. In this study, the FeNi-codoped cobalt oxyhydroxide (CoOOH) as OER electrocatalyst was prepared successfully by simple electrodeposition and anodic oxidation methods, which exhibits superior OER activity to the single-metal doped CoOOH systems. Based on both experiments and first-principles calculations, the results show that the reaction kinetics enhance due to the codoping of Fe and Ni. Fe-doping changes the active site from Co to Fe and enhances the hydroxyl group adsorption. Ni doping benefits the electron transfer between Fe and intermediates, thereby enhancing the Fe–O covalent component to further balance the two steps of hydroxyl group adsorption and the deprotonation step. The essential mechanism of bimetal-doping in CoOOH provides theoretical support for the design and development of bimetal-doped Co-based OER catalysts. [Display omitted] • The FeNi-codoped CoOOH as OER electrocatalyst is prepared successfully, which has high OER activity and good stability. • Fe doping decreases the adsorption energies of intermediates and benefits adsorption between Fe and intermediates. • The increased covalent components between active sites and intermediates after Ni doping result in the enhanced OER activity. [ABSTRACT FROM AUTHOR]

A free-standing Fe 3 O 4 /rebar graphene (FRG) composite film was obtained through solvothermal method. The microstructure, phases, electrochemical performance of the composite used as anode in lithium ion battery have been characterized by SEM, TEM, XRD, Raman, FT-IR and electrochemical measurements. In rebar graphene (RG), the single-wall carbon nanotubes (SWCNTs) and graphene are interconnected via π–π stacking and covalent bonding. SWCNTs can keep the graphene in RG from fracture and maintain the integrity of the composite electrodes during lithiation/delithiation. The absence of additive and conductive agent can enhance electrochemical performance of FRG composite by losing redundant weight. The FRG composite exhibits an outstanding rate capability with an excellent cycling performance (1038 mAh g −1 after 100 cycles at 100 mA g −1 ). [ABSTRACT FROM AUTHOR]

The Li–CO2 battery often suffers from high overpotential and limited capacity due to the challenges associated with the adsorption of Li+ and CO2 and the decomposition of Li2CO3. Herein, hexagonal rich-stepped NiSe crystals are in situ achieved on a three-dimensional (3D) free-standing porous Ni skeleton with double continuous channel architecture (namely p-Ni@NiSe-50) through an in situ selenization process. Structural characterization and theoretical calculation are applied to demonstrate the synergistic effects of marco/microstructural design and electronic band structure regulation. As a result, the adsorption/desorption of Li+ and CO2 and the formation/decomposition of Li2CO3 are effectively promoted, simultaneously, enabling an enhanced capacity and reversibility of p-Ni@NiSe-50 as the cathode of Li–CO2 battery. An ultra-low overpotential of 0.46 V and a remarkably high energy efficiency of 83.8% (20 μA cm−2) are achieved, along with a high full discharge specific capacity of 8844 μAh cm−2. Excellent long-term cycling stability (cycles up to 1000 h at a voltage gap of 1.14 V) of p-Ni@NiSe-50 is also obtained. The results of this work would provide a new insight and strategy to develop high-performance alkali metal-air batteries.Multi-scale synergistic effect of combining the cathode macroscopic structure design and the microscopic band structure design of NiSe was demonstrated to promote the adsorption of Li+ and CO2, as well as the decomposition of Li2CO3, so as to achieve ultra-low voltage gap and high capacity of Li-CO2 batteries.Graphical abstract: The Li–CO2 battery often suffers from high overpotential and limited capacity due to the challenges associated with the adsorption of Li+ and CO2 and the decomposition of Li2CO3. Herein, hexagonal rich-stepped NiSe crystals are in situ achieved on a three-dimensional (3D) free-standing porous Ni skeleton with double continuous channel architecture (namely p-Ni@NiSe-50) through an in situ selenization process. Structural characterization and theoretical calculation are applied to demonstrate the synergistic effects of marco/microstructural design and electronic band structure regulation. As a result, the adsorption/desorption of Li+ and CO2 and the formation/decomposition of Li2CO3 are effectively promoted, simultaneously, enabling an enhanced capacity and reversibility of p-Ni@NiSe-50 as the cathode of Li–CO2 battery. An ultra-low overpotential of 0.46 V and a remarkably high energy efficiency of 83.8% (20 μA cm−2) are achieved, along with a high full discharge specific capacity of 8844 μAh cm−2. Excellent long-term cycling stability (cycles up to 1000 h at a voltage gap of 1.14 V) of p-Ni@NiSe-50 is also obtained. The results of this work would provide a new insight and strategy to develop high-performance alkali metal-air batteries.Multi-scale synergistic effect of combining the cathode macroscopic structure design and the microscopic band structure design of NiSe was demonstrated to promote the adsorption of Li+ and CO2, as well as the decomposition of Li2CO3, so as to achieve ultra-low voltage gap and high capacity of Li-CO2 batteries. [ABSTRACT FROM AUTHOR]

The segregation of alien solute atoms at grain boundaries (GBs) in nanocrystalline materials can dramatically affect their macroscopic properties. As important solutes in Al alloys, Mg and Cu atoms have been experimentally observed to segregate at GBs, which would render a significant impact on the material. In this work, first-principles calculations were used to conduct a systematic and comprehensive investigation to reveal the segregation behavior of Mg and Cu atoms at Al Σ5 (310) and Σ9 (221) GBs and its effect on GB properties. The negative segregation energy demonstrates that both Mg and Cu have a strong tendency to segregate to the Al GBs. Moreover, the segregation of Mg and Cu atoms can reduce the GB energy, indicating an increased thermodynamic stability of the GBs. Mechanical properties are explored by a combination of canonical Griffith fracture model with ab-initio tensile test method. Results reveal that the doped Mg will embrittle both GBs due to the elongation of interatomic bonds and depletion of charge density across the GBs. Contrarily, the segregated Cu contributes greatly to enhancing the GB strength by creating strong Cu-Al bonds with surrounding Al at GBs. Besides, the increased tensile separation displacement of GBs with Cu segregation also suggests an improved resistance to fracture, especially the Σ9 (221) GB. This work provides a theoretical understanding for the changes in microscopic properties of Al GBs caused by Mg and Cu segregation from an atomic and electronic level. [Display omitted] • Mg/Cu solutes have strong segregation tendency toward Ʃ5 (310) and Ʃ9 (221) GBs in Al alloys. • Mg/Cu segregation thermodynamically stabilizes the Ʃ5 (310) and Ʃ9 (221) GBs. • Mg doping causes embrittlement of Al GBs while Cu segregation will enhance the GB cohesion. [ABSTRACT FROM AUTHOR]

• The carbon nanotubes (CNTs) reinforced closed-cell Al-Si composite foams (C-ASCFs) with CNTs content of 0.50 wt% have fatigue strength of 0.697 σ s (7.40 MPa), showing a superior improvement of the fatigue properties. • The appropriate incorporation of CNTs can change the fatigue failure mode, reduce the crack growth rate, and delay the fracture, hence raising the fatigue life. • The microstructure optimization of C-ASCFs influenced by CNT and its content was deeply investigated to interpret the influences on the fatigue properties of C-ASCFs. • The load transfer effect of CNTs in composite foams was firstly revealed, the contribution of which exhibits the largest of 2.07 MPa in 0.50 wt% C-ASCFs accounting for 22.5 % of its yield strength. As the requirement of compressive fatigue loading on the mechanical properties of aluminium foams increase rapidly, the limited fatigue performance of them significantly restricts their engineering applications. In this study, the compression-compression fatigue properties of carbon nanotubes (CNTs) reinforced closed-cell Al-Si composite foams (C-ASCFs) were investigated. The fatigue strength of C-ASCFs with 0.50 wt% CNTs increased by 54% than that of Al-Si foams, where the CNTs contributed to decrease the crack expansion rate, transfer the fatigue load and hence change the fatigue failure mode, causing a combination of plastic and brittle deformation in them. Meanwhile, the appropriate incorporation of CNTs decreased pore nucleation threshold, optimized the pore morphology, and promoted the formation and refinement of eutectic Si. Such inhibited the probability of fatigue cracks initiation, resulting in the enhancement of fatigue life. This work provides theoretical and practical basis of design strategy of Al-Si composite foams and broadens their application prospect. [ABSTRACT FROM AUTHOR]

Constructing sodium‐ion battery anodes with efficient ion/electron transport and high cycling stability is significantly promising for applications but still remains challenging. Here, "three‐in‐one" multi‐level design is performed to develop a carbon‐coated phosphorous‐doped MoS2 anchored on carbon nanotube paper (P‐MoS2@C/CNTP). The Na+ diffusion and electron transport, as well as the structural stability of the whole anode are simultaneously enhanced through the synergistically optimization of P‐MoS2@C/CNTP at atomic, nanoscopic, and macroscopic levels. Resulted from the multi‐level modification, the synergetic mechanism has been demonstrated by electrochemical measurement and theoretical calculation. As a result, the free‐standing P‐MoS2@C/CNTP anode presents a high rate performance (150 mA h g−1 at 5 A g−1) and a long cycling life (1 A g−1, 1200 cycles, 249 mA h g−1). This work provides a new approach to the design and fabrication of high‐performance conversion‐type electrode materials for rechargeable batteries application. [ABSTRACT FROM AUTHOR]

The incorporation of nano carbon reinforcement is a useful strategy to broaden the engineering applications of metal foams. In this work, carbon nanotubes (CNTs) reinforced aluminum (Al) matrix composite foams (CNTs/Al composite foams) with different CNTs content are prepared by combining ball-milling technique with powder metallurgy method. The result shows that the appropriate content of CNTs can reduce the pore size, improve the circularity, and enhance the compressive properties. Especially, the 1.0 wt% CNTs/Al composite foams possess the optimal compressive properties of yield stress (7.90 MPa), plateau stress (8.75 MPa) and energy absorption capacity (5.19 MJ/m3), which have an enhancement of 23.24%, 98.41% and 84.70%, respectively. Composite foams undergo shear deformation throughout the quasi-static compression process, and the failure mode performs as the brittle mode combined with ductile mode. Meanwhile, the incorporation of CNTs can contribute to the inhomogeneous distribution of the Si phase, provide more nucleation sites, and significantly refine the pore size. It is confirmed that the CNTs in composite foams contribute the grain refinement and the formation of micro stacking faults, making the mechanical properties of CNTs/Al composite foams outperform the counterpart of Al-Si foams. Moreover, due to the weak interfacial reaction, the low content of aluminum carbide is formed, which can promote the load transfer between CNTs and Al. The present finding provides a theoretical and practical design strategy to the future preparation of CNTs/Al composite foams. • The CNTs/Al composite foams with CNTs content of 1.0 wt% show a superior improvement of the compressive properties. • The incorporation of CNTs can contribute to the inhomogeneous distribution of the Si phase and refine the grain size. • The deformation and failure mode of CNTs/Al composite foams are affected by the content of CNTs. • The formation of aluminum carbides and micro stacking faults benefit to promote the compressive properties of composite foams. [ABSTRACT FROM AUTHOR]

The unique electronic structure and diverse elemental composition of high-entropy materials (HEMs) have already showcased remarkable properties in the realm of oxygen evolution reaction (OER). Despite this, the active sites and reaction pathways of HEMs have yet to be fully understood. Our findings indicate that the addition of Fe in HEMs results in a more positive valence state of metals, leading to the enhancement of the covalent characteristic of the M-O bond. Additionally, the predominant oxygen 2p orbitals near the Fermi level enables lattice oxygen to function as an OER center. Guided by theoretical calculations, we synthesized a nanoporous NiFeCoMnOOH (np-NiFeCoMnOOH) electrocatalyst exhibited a low overpotential of 194 mV at 10 mA cm−2 and long-term stability of 120 h at 100 mA cm−2. These results offer insights into the reaction mechanisms of HEM electrocatalysts and may guide future studies in designing high-entropy electrocatalysts with superior activity. Theoretical calculations guided the synthesis of np-NiFeCoMnOOH free-standing composite electrodes exhibiting strong LOM pathway selectivity in the OER process and scrutinizes the reaction pathway transition mechanism, which from AEM to LOM, and the source of excellent OER activity. [Display omitted] • Calculations validate the possibility and causes of pathway transformations of high-entropy OER catalysts. • Multiple active sites and two reaction pathways have been investigated. • np-NiFeCoMnOOH electrode exhibits a low overpotential of 194 mV at 10 mA cm−2 and long-term stability of 120 h at 100 mA cm−2. [ABSTRACT FROM AUTHOR]

Achieving uniform reinforcement dispersion and strong interfacial bonding remains challenging to increase the strengthening efficiency in advanced metal matrix composites (MMCs). In this work, we report the prominent strengthening efficiency in graphene nanosheet reinforced Al matrix (GNS/Al) composites fabricated via hybrid deformation combining hot extrusion and multi-pass hot rolling (MPHR). Results show that most GNS-rich zones in extruded GNS/Al composites were eliminated by MPHR, leading to an even layer-distribution of GNSs aligning along the Al grains, which initiates grain recrystallization and promotes dislocation accumulation for a high strain hardening of the composites. Moreover, the shear stress induced by MPHR was revealed to exfoliate overlapped GNSs to attach with Al and enhance the formation of boundary-like defects/disorders at the edge of GNSs, which promotes Al–C interdiffusion and generates the typically infiltrated Al-GNS interfaces featured by transition zones. Such unique interface structure exhibits a high interfacial shear strength, enabling the effective load transfer between GNSs and Al. It is confirmed that the fine distribution of GNS and robust Al-GNS interfacial cohesion contribute to the remarkable strengthening efficiency of GNSs. The present work paves a new way to disperse GNSs and tune interface structures for enhancing mechanical performance of Al matrix composites. [Display omitted] [ABSTRACT FROM AUTHOR]

Doping second phase particles tends to improve the strength of additively manufactured nickel-based superalloys fabricated via laser powder bed fusion (LPBF). However, the stress concentration caused by the second phase particles inevitably deteriorates their ductility. In this study, Hastelloy X (HX) composites with single (1 wt% Y 2 O 3) and multiple (0.5 wt% Y 2 O 3 and 0.5 wt% La 2 O 3) oxide particles are successfully prepared via in-situ chemical doping method together with LPBF. The results show that co-doping Y 2 O 3 and La 2 O 3 refines oxide particles from 35 nm to 26 nm in the LPBF fabricated HX. The finer oxide particles can more effectively increase the Zener force and block the grain boundary migration, thus weakening the preferred (001) texture and inhibiting the grain growth. As a result, the Y-HX and Y–La-HX samples possess an ultimate tensile strength of 1091 ± 10 MPa and 975 ± 6 MPa, respectively, representing an increase of 26.8% and 13.3% compared to the HX sample (860 ± 5 MPa). The strengthening mechanisms are mainly attributed to Orowan strengthening, dislocation strengthening and grain refinement. Moreover, the Y–La-HX sample exhibits the highest elongation, increasing by 9% compared to the HX sample. The high elongation is associated with excellent strain hardening behavior caused by finer oxide particles within grains. Our work can provide guidance for the preparation of additively manufactured nickel-based superalloys with superior mechanical properties. [ABSTRACT FROM AUTHOR]

This work applies machine learning tools to achieve the early prediction of commercial battery life. We compared the prediction accuracy of different machine learning algorithms to the battery database. Among various algorithms, the decision tree (DT) method exhibits the highest accuracy of 95.2% to predict whether the battery can maintain above 80% initial capacity after 550 cycles. Using the initial two cycles of data, DT proposes that the change of discharge capacity is the main feature to estimate the lifetime type of batteries. Given the first 100 cycles, the factor with the maximum weight turns to the internal resistance for estimating the battery lifetime. [ABSTRACT FROM AUTHOR]

Performance of a mechanical buffer can be significantly improved by strengthening the materials and optimizing its structure. Manufacturing of high-strength and light-weight foam-filled tubes (FFTs) has been proved to be an ingenious strategy. In this work, the in situ grown carbon nanotubes (CNTs) were used to reinforce aluminum (Al) foams. The FFTs were prepared by inserting CNT/Al composite foams (CFs) into 6061 Al alloy empty tubes (ETs). The crushing behavior and energy absorption property of the as-prepared CNT/Al FFTs (C-FFTs) were evaluated using uniaxial compressive tests. The results show that the adopted CFs can effectively interact with outside tubes in C-FFTs. The C-FFTs significantly improve the compressive performance and energy absorption property, but only slightly increase the structure weight compared to single ETs. The plateau stress and energy absorption capacity of C-FFTs are nearly 3.5 and 3.7 times higher than those of ETs, respectively. This phenomenon is ascribed to the stable support of CFs and the excellent load transfer ability of CNTs. [ABSTRACT FROM AUTHOR]

The compression‐compression fatigue performance of carbon nanotube (CNT) reinforced aluminium matrix composite foams (AMCFs) were investigated. The ε‐N curves of AMCFs are composed of three stages (the elastic, strain hardening, and rapid accumulation stages), while the fatigue strain of AMCFs accumulates very rapidly in stage III compared with Al foams. The fatigue strength of AMCFs with CNT contents of 2.0, 2.5, and 3.0 wt% increases by 6%, 44%, and 102% than Al foams, respectively. Different from Al foams' deformation of layer‐by‐layer, the main failure modes of AMCFs are the brittle fracture and collapse of pores within significant shear deformation bands under fatigue loading. The uniform distribution of CNTs and good interfacial bonding of CNTs and Al matrix is the important factor for the improvement of fatigue properties of AMCFs. [ABSTRACT FROM AUTHOR]

• Since Te can tune bandgap of WS 2 with a wide range and the electronegativity between S and Te differ greatly, the HER activities of WS 2 nanosheets was highly improved via Te doping. • Compared with sulfide and selenide, little research has been done on the electrocatalytic HER performance of Telluride. Hydrogen evolution reaction (HER) activities of WS 2 can be improved by doping exotic atom to increase active sites on base plane and narrow the bandgap. However, most of these catalysts of exotic atom doped WS 2 are composed of semiconductor and the electronegativity between atoms is similar, which do harm to tuning bandgap with a wide range and decreasing the value of free Gibbs energy (Δ G H) for hydrogen adsorption. Given that Te can tune bandgap with a wide range and the electronegativity between S and Te differ greatly, a vertically arranged WS 2 nanoelectrode is prepared by doping Te on WS 2. According to experimental studies and the density functional theory calculations (DFT), the bandgap of WS 2 nanosheets is successfully narrowed after doping Te. This lowers the Schottky barrier which benefits the transfer of charges and improves electrocatalytic performance in turn. Meanwhile, the presence of Te atoms with much lower electronegativity than S increases the electron density of the adjacent region, thereby the S edges of basal plane around Te atoms and hollow sites of WS 2 nanosheet become active to drive HER, which has been verified by the reduced Δ G H of S edges of basal plane from 2.27 to 2.08 eV and hollow sites from 2.28 to 1.85 eV after the doping in DFT. Te-doped WS 2 nanosheets used as excellent HER catalysts with an overpotential of 213 mV to drive a current density of 10 mA/cm2, a small Tafel slope of 94 mV/dec, along with a superior stability in acid media. [ABSTRACT FROM AUTHOR]

• P-doped Ni 3 S 2 nanosheet arrays were controlled preparation successfully. • The water dissociation kinetics of P-doped Ni 3 S 2 were tuned by electronic modulation. • The mechanism of HER performance improvement were revealed by DFT calculations. Developing efficient and low-cost electrocatalysts for hydrogen evolution reaction (HER) is important in clean energy systems. Non-noble transition metals are the most promising candidates for the replacement of conventional Pt group catalysts of HER. However, most non-noble metals show poor HER activity due to the intrinsic electronic structures. Herein, P atoms doped Ni 3 S 2 (P-doped Ni 3 S 2) nanosheets array grown on Ni foam has been successfully synthesized and further applied as the efficient electrocatalysts for HER in alkaline media. P-doped Ni 3 S 2 shows higher catalytic activity for HER compared with pristine Ni 3 S 2 , which affords the current densities of 10 mA cm−2 at an overpotential of 139 mV and long-term stability over 110 h. Density functional theory (DFT) calculations reveal that the introduction of P atoms modify the electronic structure of Ni 3 S 2 , enhance the electrical conductivity, optimize the HER Gibbs free-energy (Δ G H*) and the change of water adsorption energy (Δ G H2O*), and reduce the barrier of water dissociation optimize the HER Gibbs free-energy (Δ G H*), change water adsorption energy (Δ G H2O *) and reduce the barrier of water dissociation. Remarkably, energy integral of a crystal orbital Hamilton population (ICOHP) gives access to the contribution of an atom or a chemical bond to the distribution of one-particle bonding within the transistion state of water dissociation and reveals the reduced essence of water dissociation barrier. [ABSTRACT FROM AUTHOR]

The controllable design of composition and structure makes incorporating reinforcements to be a promising way to fabricate aluminum (Al) composite foams. In this work, graphene nanosheets (GNSs) decorated with copper (Cu) nanoparticles reinforced Al composite foams are successfully synthesized via shift-speed ball-milling and space-holder method. The compressive properties and energy absorption capacity of composite foams increase first and then decrease with the increase of the GNSs@Cu content. Unexpectedly, the introduction of the GNSs@Cu has not changed the ductile failure mode of pure Al foams. The strengthening mechanisms of composite foams include load transfer strengthening and dispersion strengthening, and the toughening mechanism of composite foams is considered as crack bridging. The 0.75 wt% GNSs@Cu/Al composite foams possess the optimal yield stress (24.7 MPa), plateau stress (41.3 MPa) and energy absorption capacity (22.8 MJ/m3), which has an improvement of 104.7%, 113.7% and 115.1% in comparison with that of pure Al foams. Image 1 [ABSTRACT FROM AUTHOR]

Developing high-capacity anodes with fast kinetics and stable structure is critical for the effective implementation of sodium ion capacitors (SICs). In this study, Fe 2 O 3 @C nanoparticles modified vertically aligned carbon nanotubes (VACNTs) composites are designed and employed as SIC anodes through a two-step chemical vapor deposition (CVD) process with the aid of a refined Fe 3 O 4 /AlO x dispersion catalyst. With nano-sized Fe 2 O 3 coated with defected carbon layers sufficiently loading onto the VACNTs substrates, the resulting composites demonstrate remarkable sodium storage properties, with a high areal specific capacity (1.26 mAh cm−2 at 0.2 mA cm−2) and rate performance (0.19 mAh cm−2 at 5.0 mA cm−2). Moreover, continuous capacity promotion is observed over 1000 cycles, leading to superior cycling performance (0.444 mAh cm−2 at 1 mA cm−2), with 178% retention after 1000 cycles. This improved cycling performance is attributed to the defective structure and high specific surface area of the VACNTs, which accommodates the volume change of the Fe 2 O 3 particles. In addition, the induced locally graphitization and rearrangement of the carbon layers are demonstrated, which results in better kinetics for Na+ transfer, further enhancing capacity retention over long cycles. [Display omitted] • Fe 2 O 3 @C/VACNTs composites realized superior synergistic effect. • Sustained increasing for capacities were obtained by modifying nano-sized Fe 2 O 3 @C. • Refined Fe 2 O 3 paritcles and Na + insertion inducing graphtization was investigated. [ABSTRACT FROM AUTHOR]

Highlights • The fatigue mechanism was analyzed from macroscopic to microscopic scales. • Effect of porosity on fatigue performance of Al foams was investigated. • The deformation process under quasi-static and cyclic compression was comparatively analyzed. Abstract The compression-compression fatigue properties of open-cell Al foams fabricated by space-holder method with different porosities were investigated. The ε–N curves of the Al foams show two types based on the stress levels (k). The first type shows a three-stages for low stress level (k < 0.9), while the second type only presents stage I and stage III for high stress level (k ≥ 0.9). The quasi-static compression tests were performed to determine the yield strength (σ s) of Al foams. The fatigue strengths of Al foams with porosities of 50%, 60% and 70% are 12.77 MPa (0.75 σ s), 7.61 MPa (0.68 σ s) and 3.02 MPa (0.66 σ s) respectively, showing a linear decrease with the increment of porosity. The macroscopic deformation observation shows that the local deformation regions during fatigue tests emerge earlier than those during quasi-static compression tests. The initiation and propagation of fatigue cracks are the main failure mechanism of Al foams subjected to compression fatigue loading. [ABSTRACT FROM AUTHOR]

Highlights • A novel and efficient method to fabricate CNTs reinforced Al alloy matrix composite foams is put forward. • CNTs are homogeneously dispersed in the matrix. • The effects of CNTs on pore structure during foaming process is discussed. Abstract Uniformly dispersed carbon nanotubes (CNTs) reinforced aluminum (Al) alloy matrix composite foams were successfully fabricated by the combination of in-situ chemical vapor deposition and powder metallurgy using titanium hydride as a blowing agent. The effects of CNTs on the pore structure were systematically studied. The results showed that compared to the Al alloy foam, the introduction of CNTs could significantly improve the pore uniformity and reduce the pore size. As a result, the compressive property of composite foam had an obvious increase. The reasons for the enhanced pore structure mainly lie in that the CNTs increased nucleation sites for the decomposed hydrogen and the limited the movements of bubbles in the melt during foaming process. [ABSTRACT FROM AUTHOR]

• The hierarchical porous CuMn current collector with lithiophilic layer is synthesized. • Hierarchical porous framework shows uniform current distribution and geometric constraints. • The epitaxially grown MnO effectively enhance the interfacial bonding and lithiophilicity. • The electrode can store Li of 14.45 mAh cm−2 by molten lithium injection. • Full cells with LiFePO 4 display ultrahigh capacity retention ratio after 600 cycles at 2 C. Lithium metal faces serious problems such as dendrite growth and volume expansion, which make lithium metal batteries lose the opportunity in commercialization. Herein, we report a simple route to prepare a hierarchical porous CuMn (hp-CuMn) current collector (CC) with an epitaxially grown lithiophilic layer to solve these problems. The hp-CuMn with industrialization potential can achieve uniform current distribution and geometric constraints. Meanwhile, the epitaxially grown MnO by annealing the hp-CuMn with surface absorbed oxygen in reductive atmosphere effectively improves the interfacial bonding force and lithiophilicity. Consequently, the hp-CuMn@MnO with thickness about 85 μm (can store Li of 14.45 mAh cm−2 by molten lithium injection, 5 times of the graphite anode) have a small hysteresis voltage and can be stable for up to 1500 h. Full cells with LiFePO 4 display ultrahigh capacity retention ratio (96.8 %) after 600 cycles at 2 C, and has good compatibility with the current industry, which verifies the application value. [ABSTRACT FROM AUTHOR]

Abstract: Electrochemical reduction of CO2 provides an opportunity to reach a carbon‐neutral energy recycling regime, in which CO2 emissions from fuel use are collected and converted back to fuels. The reduction of CO2 to CO is the first step toward the synthesis of more complex carbon‐based fuels and chemicals. Therefore, understanding this step is crucial for the development of high‐performance electrocatalyst for CO2 conversion to higher order products such as hydrocarbons. Here, atomic iron dispersed on nitrogen‐doped graphene (Fe/NG) is synthesized as an efficient electrocatalyst for CO2 reduction to CO. Fe/NG has a low reduction overpotential with high Faradic efficiency up to 80%. The existence of nitrogen‐confined atomic Fe moieties on the nitrogen‐doped graphene layer is confirmed by aberration‐corrected high‐angle annular dark‐field scanning transmission electron microscopy and X‐ray absorption fine structure analysis. The Fe/NG catalysts provide an ideal platform for comparative studies of the effect of the catalytic center on the electrocatalytic performance. The CO2 reduction reaction mechanism on atomic Fe surrounded by four N atoms (Fe–N4) embedded in nitrogen‐doped graphene is further investigated through density functional theory calculations, revealing a possible promotional effect of nitrogen doping on graphene. [ABSTRACT FROM AUTHOR]

A hybrid of graphene nanoribbons (GNRs) interlacing hollow NiCoO (G-HNCO) nanocages in a size range of 300~500 nm with rough surface is synthesized by a chemical etching CuO templates and followed by GNR interlacing process. The G-HNCO showed high electrochemical performance of oxygen evolution reaction (OER), which exhibited small onset potential of 1.50 V and achieved current densities of 10 mA cm at potentials of 1.62 V. Also, the hybrid delivered high capacitance of 937.8 F g at 1 A g in supercapacitor (SC) tests as well as stable cycling performance in both OER and SC measurements. The approach to synthesize the hybrid is simple and scalable for other graphene nanoribbon-based electrocatalysts. [ABSTRACT FROM AUTHOR]

Germanium is a promising anode for lithium ion batteries (LIB) because of its potential rate capability and high theoretical specific capacity. Here we demonstrate a seamlessly connected graphene and carbon nanotube (GCNT) hybrid that serves as an integral current collector for a Ge anode. A vertically aligned CNT (VA-CNT) forest grown on graphene provides a high surface area for Ge deposition. The seamless connection between graphene and VA-CNT facilitates electron transport from the Ge to the Cu current collector. Graphene serves to alleviate mechanical strain between the electrode and current collector. The mechanical resilience of the GCNT lessens Ge pulverization on charge/discharge of the LIB. As a result, the Ge/GCNT anode has a high specific capacity of 1315 mAh/g after 200 cycles at 0.5 A/g and a high rate performance of 803 mAh/g at 40 A/g. [ABSTRACT FROM AUTHOR]

[Display omitted] • FeS 2 nanodots were fabricated as the covalent linkages between SnS 2 nanosheets. • The covalent linkages facilitate the across-interlayer electron transfer. • The rich SnS 2 /FeS 2 heterostructures interfaces improve the ion diffusion rate. • SnS 2 /FeS 2 @rGO anode possesses a fast and ultra-stable Na+ storage capability. SnS 2 has been regarded as a promising anode material of sodium ion batteries (SIBs) due to the large interlayer spacing which favors to the reversible ion intercalation and extraction, and thus contributing to the high specific capacity. However, the intrinsic weak van der Waals interactions in the interlayers of SnS 2 nanosheets lead to the deficient electron transfer across interlayers and the poor stability of layered structure, which seriously deteriorates the electrochemical performance of SnS 2 anode in SIBs. Herein, the covalently-bonded SnS 2 /FeS 2 heterostructures anchored on reduced graphene oxide (rGO) (referred to as SnS 2 /FeS 2 @rGO) were prepared via the in-situ decomposition and subsequent sulfurization of FeSnO(OH) 5 nanoparticles. Based on the experimental characterizations and density functional theory (DFT) calculation, the covalently-bonded SnS 2 /FeS 2 interfaces could promote charge/electrons transfer and accelerate ion diffusion kinetics. When applied as the anode materials toward SIBs, SnS 2 /FeS 2 @rGO exhibits superior rate capability of 429.6 mA h g−1 at a high current density of 6 A/g along with excellent long cycle stability. This proposed in-situ synthesis strategy via FeSnO(OH) 5 nanoparticles may offer a new way toward effective electron transfer for metal ions storage and transport applications. [ABSTRACT FROM AUTHOR]

A three-dimensional (3D) interconnected graphene nanoribbons (GNRs) framework wrapping double nanoshells of SnO 2 @TiO 2 was synthesized by a simple but effective method. The nanoshell of TiO 2 anchored on the surface of SnO 2 nanoshell with hollow core to restrict large volume expansion, then GNRs wrapped and interlaced double nanoshells of SnO 2 @TiO 2 to construct a continuous 3D conducting network. The double protection strategy of active electrode materials can make full use of the function of the three components. The enhanced electrochemical performance can be attributed to the structural stability, excellent electronic conductivity and high electrochemical reaction activity. [ABSTRACT FROM AUTHOR]

The passivation effect of eight Lewis-base functional groups on perovskite was investigated, together with the molecular engineering of para-substitution by first principles calculations. The mechanism of work function shift of perovskite surface due to organic molecular adsorption was elucidated. [Display omitted] • The effect of organic molecular adsorption on the structural and electronic properties of perovskite was investigated via first-principles methods. • The Pyridine-N, –NH 2 and –COOH show the best coordination ability and passivation effects among the eight functional groups. • The interfacial dipole and intrinsic dipole of molecules can induce a remarkable change of work function. • The terminal group has little influence on the anchoring ability of molecule. • The direction and intensity of work function shift can be changed by employing different terminal groups. Organic molecules with various functional groups have been implemented to engineer the surface and grain boundary of perovskite, and improve the efficiency and stability of perovskite solar cells (PSCs). However, there is a lack of systematic comparison and comprehensive understanding about the intrinsic effect of various functional groups on the perovskite surface. Herein, we investigate the effect of molecular layer adsorption of eight different organic molecules on the structural and electronic properties of CH 3 CH 2 PbI 3 via first-principles methods. Our results show that the pyridine is the most effective passivation molecule which not only has the most anchoring ability, but also can mostly decrease the electron-hole interaction. And the carboxyl group can form hydrogen bond with the iodine on perovskite surface and suppress the migration of iodine consequently. Moreover, deriving from molecular adsorption, the work function of perovskite surface has undergone dramatic changes, mainly due to the contributions of the interfacial charge transfer and the intrinsic dipole moment of molecules. Based on molecular engineering method, we also decouple the para-substituted functional groups from the anchor group and emphasize the importance of it. This work provides a theoretical guidance for the selection and design of organic passivation molecules. [ABSTRACT FROM AUTHOR]

[Display omitted] • The predicted segregation energy ranging from −0.033 to −0.287 eV/atom suggests that Zn atom has a moderate driving force to segregate to Al GBs, being consistent with experiments. • The GB energy is decreased for most GBs with Zn segregation and the cohesive strength of Zn-doped GBs mostly reduces. • It is found that Zn exhibits a smaller effective atomic radius than Al when segregated at the GBs, which gives rise to its positive size effect on the GB strength. Contrarily, the charge depletion introduced by Zn segregation would contribute to the negative electronic effect. • Larger size than electronic effect renders the enhanced strength of Σ3 (1 1 1) and Σ7 (41 5 ¯ ) GBs with Zn segregation, while it is the opposite for other GBs, wherein the electronic effect surpasses the size counterpart. This work delivers an in-depth investigation about the effect of Zn segregation on the properties of Al GBs. The Zn segregation behavior at 11 representative GBs in Al and the resultant GB properties were systematically revealed in the atomic and electronic levels via first-principles calculations. It is found that Zn atom has a moderate driving force to segregate to the Al GBs, the segregation energy of which ranges from −0.033 to −0.287 eV/atom. GB energy is decreased for most GBs with Zn segregation. Additionally, the cohesive strength of Zn-doped GBs mostly reduces, which is ascribed to a combination of size and electronic effects. Calculations reveal that Zn exhibits a smaller effective atomic radius than Al when segregated at the GBs, which gives rise to its positive size effect on the GB strength. Contrarily, the negative electronic effect due to charge depletion introduced by Zn segregation would decrease the GB cohesion. Larger size than electronic effect renders the enhanced strength of Σ3 (1 1 1) and Σ7 (41 5 ¯ ) GBs with Zn segregation, while it is the opposite for other GBs, wherein the electronic effect surpasses the size counterpart. The present work is supposed to provide comprehensive insights into the Zn segregation at the GBs in Al alloys. [ABSTRACT FROM AUTHOR]

The interface doping with rare earth elements is a novel strategy to enhance the weak interface bonding of copper-graphene system (Cu-G). In this work, taking Sc, Y, La as representatives, we investigated the structural, electronic and mechanical properties of clean and doped Cu-G systems using first principles calculations. By the comparison of interface spacing and work of separation with clean system, the significantly improved interface interaction in rare earth elements doped systems has been verified. Besides, difference charge density, Bader charge and density of states were employed to reveal the microscopic modifying mechanism on the atomic scale. Then, the tensile stress-strain curves were obtained using a fitting function related with the element electronegativity, and thus the quantitative relationship between the interface bonding and mechanical properties was determined, which could provide theoretical guidance for the interface modification of Cu-G composites through doping rare earth elements. The introduction of rare earth elements could significantly enhance the interface bonding of copper-graphene system by promoting charge transfer and electron interaction at the interface, which could be demonstrated by the analysis of electronic properties. Then, the rigid stretching was implemented, and a fitting function containing electronegativity was employed to determine the quantitative relationship between interface bonding and tensile properties. [Display omitted] • Rare earth elements doping effects on copper-graphene system are studied. • The structural and electronic characteristic of doped systems are analyzed. • The rigid stretching is used to study the related mechanical properties. • Quantitative relationship between interface binding and mechanical property is explored. [ABSTRACT FROM AUTHOR]

{010}-Oriented flower-like Bi 2 WO 6 with high adsorptivity and photoactivity was prepared via a hydrothermal method without any additives under neutral environment. The anisotropic flower-like Bi 2 WO 6 shows greatly enhanced adsorptivity and photoactivity compared with isotropic particle Bi 2 WO 6 as well as most of other forms of Bi 2 WO 6 . The superior adsorptivity shows potential in suitability for majority of dyes. Detailed study on microstructure and morphology indicates that mesoporous structure and large surface area mainly contribute to the superior properties. Especially, {010} crystal planes of flower-like Bi 2 WO 6 terminated with [Bi 2 O 2 ] 2+ layers provide more adsorption sites for dyes than other facets. In combination with first-principles calculations, it is initially revealed that {010}-oriented facets preference benefits hole distribution at surface and provides the most reactive sites, thus enhances the photoactivity of the flower-like Bi 2 WO 6 . Moreover, the anisotropic flower-like Bi 2 WO 6 shows excellent recyclability and cycling stability with great potential in environmental applications. [ABSTRACT FROM AUTHOR]

The rare earth scandium (Sc) as a microalloying element has attracted an increasing interest in aluminum alloys for achieving excellent mechanical properties. Combining with zirconium, high strength and low price Al–Sc alloys are expected. The effects of Sc and Zr on the grain refinement, recrystallization resistance and precipitation hardening were investigated in new type of Al–Zn–Mg–Sc–Zr alloys by rolling, annealing and aging processes. Scandium addition into the Al–Zn–Mg alloys can efficiently refine the grain size and increase recrystallization resistance, especially together with zirconium addition. The maximum value of the yield-to-tensile strength (627 MPa/667 MPa) was obtained with 0.2Sc/0.4Zr ratio of the alloy after solution-aging treatment. The additional strengthening of the alloys is attributed to the grain refinement and the precipitation-strengthening effect of Al 3 Sc, Al 3 Zr or Al 3 (Sc, Zr) in the proper ratio of Sc/Zr during aging. [ABSTRACT FROM AUTHOR]

Designing heterogeneous structures is a promising pathway for overcoming the trade-off between strength and toughness in metal matrix composites (MMCs). Herein, we report an innovative strategy for fabricating graphene nanosheet-Cu reinforced Al matrix (GNS-Cu/Al) composites with heterogeneous structure. This strategy involves the consolidation of unique composite powders with core-shell grain structure, which are synthesized with the aid of in-situ GNS-Cu hybrids. Results reveal that the fabricated GNS-Cu/Al composite exhibits multiple microstructural heterogeneities, including both heterogeneous grain structure and reinforcement spatial distribution, which endow the composite with a prominent combination of tensile strength of ∼437 MPa, fracture elongation of ∼12.5% and toughness of ∼48.7 MJ m−3. It is confirmed that such microstructural heterogeneities in GNS-Cu/Al composite contribute significant hetero-deformation induced (HDI) stress strengthening and sustained strain hardening, making the key mechanical properties of GNS-Cu/Al considerably outperform the counterpart of Cu/Al composite. Moreover, the coordinated deformation and crack bridging/blunting behaviors are demonstrated to be responsible for the exceptional toughness of GNS-Cu/Al composite. This work offers a promising bottom-up tactic to fabricate Al matrix composites with heterogeneous structures and superior mechanical performances for structural applications. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • P-doped three dimensional (3D) network of MoS 2 was prepared. • P doping in MoS 2 accelerates the cleavage of S-S or Li-S bonds in LiPSs. • Li-S battery with 3D P-MoS 2 -G interlayer delivered 884.4 mAh g−1 after 100 cycles. • Li-S battery exhibited excellent rate performance under 3.7 mg cm−2 sulfur loading. To address the issues of "shuttle effect" of soluble polysulfides and sluggish redox kinetics in the cathodes of lithium-sulfur batteries, the acceleration of the polysulfides conversion via electrocatalysis is a promising solution. As a common electrocatalyst, the catalytic ability of two dimensional (2D) MoS 2 is considerably diminished due to agglomeration of nanosheets and insufficient active sites. In this work, a phosphorus-doped three dimensional (3D) network of MoS 2 -based interlayer sandwiched between the S cathode and the separator is developed. The 3D network could prevent 2D nanosheets from stacking and provide fast diffusion channels for Li ions transfer. Phosphorus doped MoS 2 forms stronger Mo-S and Li-P bonds to anchor polysulfides and to promote cleavage of S-S or Li-S bonds of lithium polysulfides to accelerate the polysulfides conversion. As a result, the cell exhibits a high specific capacity of 884.4 mAh g−1 after 100 cycles at 0.1C even under the high sulfur loading condition (3.7 mg cm−2). This work may encourage more efforts on heteroatom doping in electrocatalyst to realize a high performance in lithium–sulfur batteries. [ABSTRACT FROM AUTHOR]

This study presents the results of quasi-static compressive tests of aluminum (Al) foam-filled tubes (A-FFTs) and Carbon Nanotubes (CNTs)/Al composite foam-filled tubes (C-FFTs) prepared by in-situ filling space-holder method. The effects of processing parameters and interface interaction between foam fillers and tubes on mechanical properties and deformation behaviors of the C-FFTs are analyzed, through both the macro- and micro-scopic characterizations. The results show that both cold pressing and sintering can improve the interface connection between foam fillers and tubes. Besides, the addition of CNTs not only increases the strength of foam fillers, but also changes the deformation mode of foam fillers from layer-by-layer shear failure to overall shear failure, which in turn influences the mechanical properties of foam-filled tubes (FFTs). Meanwhile, the interface between foam fillers and tubes (macro interface) of the A-FFTs shows a metallurgical bonding because of the atom diffusion during cold pressing and sintering processes, and as a result, the energy absorption capability of the A-FFTs and 2.5 wt% C-FFTs are increased by 51.3% and 45.8%, respectively. Based on the current findings, a distinctive deformation behavior associated with the interaction effect is proposed. [ABSTRACT FROM AUTHOR]