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Lithium metal batteries (LMBs) are well recognized as promising next-generation high energy density batteries, but the uncontrollable Li dendrites growth and the volatilization/gas production of electrolytes, which become extremely worse at low and high temperatures, restrict their practical utilizations. In this work, a hierarchically structured polymerized gel electrolyte (HGE), which was composed of an inorganic (LixGa86In14 alloy and LiCl salt)/organic (polymerized tetrahydrofuran (THF)) hybrid layer and the bulk polymerized THF electrolyte, was proposed to achieve a steady performance of LMBs over a wide temperature range of -20-55 °C. The HGE fabrication can be completed within assembled cells with a simultaneously occurring replacement-polymerization-alloying reaction, which helps decrease the interfacial resistance and enhance the stability and ion diffusion under both low and high temperatures. The use of THF with low polarity also ensures high ion conductivity under low temperatures. With such HGE, the Li symmetric cells showed low overpotential under 10 mA/cm2 with a capacity of 10 mAh/cm2 over a 1200 h cycling, and the full cell coupled with Li4Ti5O12 demonstrated high capacity retention over 5000 cycles at room temperature. Besides, the symmetric cells showed low overpotentials of 12 mV at 55 °C and 80 mV at -20 °C at 2 mA/cm2 after a 1000 h cycling, and the full cell revealed the high capacity retention of 93.5% at 55 °C and 88.8% at -20 °C after 1500 cycles under a high current density of 1000 mA/g. This work shows a hierarchically structured polymerized electrolyte design for advanced Li batteries workable under broad temperatures.

Stable organic radicals are promising materials for information storage, molecular magnetism, electronic devices, and biological probes. Many organic radicals have been prepared, but most are non- ...

Ferroelectric tunnel junctions (FTJs) as the artificial synaptic devices have been considered promising for constructing brain-inspired neuromorphic computing systems. However, the memristive synapses based on the flexible FTJs have been rarely studied. Here, we report a flexible FTJ memristor grown on a mica substrate, which consists of an ultrathin ferroelectric barrier of BiFeO3, a semiconducting layer of ZnO, and an electrode of SrRuO3. The obtained flexible FTJ memristor exhibits stable voltage-tuned multi-states, and the resistive switchings are robust after 103 bending cycles. The capability of the FTJ as a flexible synaptic device is demonstrated by the functionality of the spike-timing-dependent plasticity with bending, and the accurate conductance manipulation with small nonlinearity (−0.24) and low cycle-to-cycle variation (1.77%) is also realized. Especially, artificial neural network simulations based on experimental device behaviors reveal that the high recognition accuracies up to 92.8% and 86.2% are obtained for handwritten digits and images, respectively, which are close to the performances for ideal memristors. This work highlights the potential applications of FTJ as flexible electronics for data storage and processing.

This paper reports a new approach to density improvement in ceramic binder jetting additive manufacturing: combining powder bed compaction and nanopowders. Samples were printed on a commercially available binder jetting 3D printer using an alumina nanopowder. Compaction thickness was varied across 0, 5, 10, 15, 20, and 60 μm at a layer thickness of 5 μm, and across 0, 100, and 200 μm at a layer thickness of 30 μm. Sintered density, as well as powder bed density, was measured. Furthermore, microstructure of sintered samples, with a focus on number and size of pores, was investigated to substantiate the density results. It was shown that at the same layer thickness, higher compaction thickness resulted in higher powder bed density, higher sintered density, and smaller number and size of pores in sintered samples. The highest sintered density (72.0%) achieved in this study was on par with the highest density reported in the literature on binder jetting of alumina without involving unusual liquid feedstocks or special post-processing techniques, demonstrating the effectiveness of this new approach to density improvement.

(Ti0.25V0.25Nb0.25Ta0.25)(C1-xNx) high-entropy ceramics with various N contents (x = 0, 0.1, 0.2, 0.3) were successfully produced by spark plasma sintering to investigate the influence of N element on their microstructure and properties. The mixed carbide and nitride powders were sintered to form a single-phase face-centered cubic structure ceramic with a uniform composition at 2100 °C for 10 min. The introduction of slight nitrides in high-entropy ceramics refined the grain size and enhanced the hardness of ceramics. The (Ti0.25V0.25Nb0.25Ta0.25) (C0.8N0.2) ceramic demonstrated a fine grain size of 5.29 μm, a high relative density of 96.7% and an excellent hardness values of 20.6 GPa at 9.8 N and 29.3 GPa at 50 mN. With increasing contents of nitrides, the wear resistance and thermal conductivity of high-entropy ceramics increased firstly and then decreased. The ceramic with 30 at.% nitrides showed a relatively low thermal conductivity of 11.27 W m−1 K−1 at room temperature. The high-entropy carbonitride ceramics had a potential application in high temperature structure parts and machining tools.

A sandwich-like melamine/phytic acid/silicon nitride hybrid (SW-Si3N4) sheets were prepared by supramolecular wrapping as the hybrid flame retardants for thermoplastic polyurethane (TPU). The introduction of Si3N4 sheets as a template could not only induce the generation of two-dimensional phytic/melamine (PAMA) capping layers, but also produce the synergistic flame-retardant effect on TPU composites. Cone test showed that heat release rate (HRR), smoke production rate (SPR) and total smoke production (TSP) values of TPU were decreased obviously by adding SW-Si3N4. TG-IR test indicated the dramatic inhibition of aromatic compound, hydrocarbons, CO and HCN release. Besides, the thermal conductivity of composites was obviously improved by adding SW-Si3N4. This work may provide better reference for developing multi-functional TPU composites for diverse application.

In powder bed additive manufacturing, feedstock powder can be dispensed onto powder bed through a hopper. The hopper dispensing system assisted by ultrasonic vibration is effective, especially for powder with small particle sizes (e.g.

Flexible microscopic pressure sensors are important to the emerging fields of intelligent robots and advanced healthcare. However, common microstructured pressure sensors often require sophisticated mould and/or material preparation, and yield limited pressure sensing performances. In this letter, we report a facile approach to design a scalable and stretchable mould-free sensitive layer with a unique hierarchical microstructure. Inspired by natural skin, a sensitive layer with interdigitated electrodes is utilized to constructed into resistive pressure sensors, which are able to robustly detect the pressure variations with high sensitivity in a wide dynamic range (about $33\,\,kPa^{-1}$ below 5 kPa, more than $0.6\,\,kPa^{-1}$ under 108 kPa), also deliver low hysteresis (within 8%), rapid response (less than 48 ms), and ultralow operation voltage ( $10~{\mu }V$ ). We illustrate that such self-patterned high-performance pressure sensors can be applied to convert the pressure stimulus into spike-like signals in both low- and medium-pressure regimes, and are being able to clearly reveal the details of human pulse wave.

This study demonstrates the feasibility of fabricating copper/diamond (Cu/Dia) composite samples using binder jetting additive manufacturing for the first time. Binder jetting fabricates parts in two steps: forming green parts with a binder at a low temperature and consolidating the green parts by sintering. The low processing temperature makes binder jetting an excellent candidate to create complex-shaped Cu/Dia parts without causing diamond graphitization. In this study, mixtures of copper-coated diamond powder and pure copper powder were used to print Cu/Dia samples on a binder jetting printer. The printed samples were then sintered under a medium vacuum environment with flowing forming gas (95% nitrogen and 5% hydrogen). The effects of diamond volume fraction (10 vol% and 50 vol%) and sintering temperature (800 °C and 900 °C) on density and porosity, phase composition, and microstructure of Cu/Dia samples were investigated. As the diamond volume fraction increased from 10 vol% to 50 vol%, the sinterability of the powder mixture decreased. Increasing sintering temperature from 800 °C to 900 °C significantly improved sintered bulk density for samples from each powder mixture. When sintering temperature increased from 800 °C to 900 °C, the microstructure evolved from a granular structure to a network structure. In all sintered samples, the distribution of diamond was uniform and there was no sign of diamond graphitization.

Optimization of mathematical model of flow field in slab continuous casting mold was performed by means of industrial measurement and mathematical modeling. The rod deflection method was used to quantitatively measure the velocities near the mold surface at high temperature. The measurement results were compared with the simulation results of three mathematical models at different argon gas flow rates of 6, 10 and 14 L min−1. The model 1 neglects the mold powder layer, thermal effect and solidified shell. The model 2 only considers the influence of mold powder layer. The model 3 considers the influence of mold powder layer, thermal effect and solidified shell on the flow field. In all three models, the diameter of argon bubbles obeys Rosin–Rammler distribution fitted according to the experimental data of others’ previous work. With increasing the argon gas flow rate, the velocity of liquid steel near the mold surface decreases. The model 1 seriously underestimates the shear stress of liquid steel near the mold surface, and its calculation results show higher velocity near the mold surface, lower turbulent kinetic energy and wider distribution of argon gas bubbles in the mold. The simulation results of model 2 only considering the viscous resistance of the mold powder layer to liquid steel makes the velocity near the surface lower than the measurement results obviously. The calculated velocities near the mold surface with model 3 are in best agreement with the measured results, showing the reasonable spatial distribution range of argon bubbles in the mold and the moderate turbulent kinetic energy. In the present conditions, the best argon gas flow rate is 10 L min−1 due to the moderate velocity near the mold surface, the appropriate distribution of argon gas bubbles in the mold and the smallest fluctuation amplitude on the mold surface.

The development of pressure sensor arrays capable of distinguishing the shape and texture details of objects is of considerable interest in the emerging fields of smart robots, prostheses, human-machine interfaces, and artificial intelligence (AI). Here we report an integrated pressure sensor array, by combining solution-processed two-dimensional (2D) MoS2 van der Waals (vdW) thin film transistor (TFT) active matrix and conductive micropyramidal pressure-sensitive rubber (PSR) electrodes made of polydimethylsiloxane/carbon nanotube composites, to achieve spatially revolved pressure mapping with excellent contrast and low power consumption. We demonstrate a 10 × 10 active matrix by using the 2D MoS2 vdW-TFTs with high on-off ratio > 106, minimal hysteresis, and excellent device-to-device uniformity. The combination of the vdW-TFT active matrix with the highly uniform micropyramidal PSR electrodes creates an integrated pressure sensing array for spatially resolved pressure mapping. This study demonstrates that the solution-processed 2D vdW-TFTs offer a solution for active-matrix control of pressure sensor arrays, and could be extended for other active-matrix arrays of electronic or optoelectronic devices.

This short communication reports an experimental investigation on the relationships among powder properties (i.e., apparent density, tap density, and Hausner ratio), feed region density, and powder bed density in ceramic binder jetting additive manufacturing. Seven differently sized alumina powders (from 0.05 μm to 70 μm) were used for this experimental investigation. Simple linear regression was applied to analyze the experimental data. It was found that powder bed density matched well with feed region density under all conditions of this investigation. The results also showed that apparent density was a stronger predictor than tap density and Hausner ratio for powder bed density.

We demonstrated a novel long-period fiber grating (LPFG) written in a tri-hole fiber (THF). The LPFG was fabricated by periodically collapsed micro holes utilizing CO2 laser irradiation integrated with pressure-assisted technology. The mode coupling between the fundamental mode and higher mode of the proposed grating is mainly caused by geometric deformation along the fiber axis. Compared with conventional LPFGs, such a grating has strong refractive index modulation due to periodic collapsed structure. We have established an approximate hypothesis to simulate the transmission spectrum of the grating. The measured spectrum is basically consistent with the simulated transmission spectrum at the resonant peak position. We investigated the sensing characteristics of the proposed LPFG, including axial strain, bending, torsion, and temperature. The sensitivity of bending, temperature and torsion are −9.56 nm/m−1, 162.8 pm/(rad/m) in clockwise and −346.9 pm/(rad/m) in counterclockwise and 86.8 pm/°C, respectively. The experimental data shows that the fabricated LPFG has potential applications in the field of external high-sensitivity strain sensing with a sensitivity of −26 pm/μϵ.

Soy protein (SP)-based adhesives can replace traditional aldehyde-based adhesives for the manufacturing of wood-based panels. However, developing a SP-based adhesive with excellent prepressing bonding strength, flame retardancy, and mildew resistance remains a challenge. Herein, an inorganic crystal cross-linked hybrid SP adhesive was developed inspired by the "secreting-hardening" process of the mussel adhesive protein and the organic-inorganic hybrid adhesive system of the oyster. Calcium sulfoaluminate (CSA) was introduced into the adhesive mixture of SP and acrylic acid to induce the in situ polymerization of acrylic acid to achieve adhesive gelation. The generation of the inorganic crystals by hydration of CSA not only contributed to the formation of a stable cross-linked hybrid adhesive system for strong cohesion but also provided strong interfacial adhesion between the adhesive layers and the plywood veneers. As anticipated, the prepared plywood sample bonded with the hybrid adhesive gel had an excellent prepressing bonding strength of 544 kPa, representing a significant increase compared to that of the pure SP adhesive (19 kPa). Moreover, the generated inorganic crystals endowed the adhesive with excellent mildew resistance and flame retardancy. This study provides a novel and effective strategy for the preparation of high-performance SP-based adhesives.

Hybrid solid/gel electrolytes (SGEs) have generated much research attentions because of their capability to suppress Li dendrite growth and improve battery safety. However, the interfacial compatibility of the electrode/electrolyte or polymer/inorganic ceramics within hybrid electrolytes remains challenging for practical applications. Herein, an SGE is fabricated by confining ceramic particles (Li7La3Zr2O12; LLZO) into in situ formed tetraethylene glycol dimethyl ether (G4)-based gel electrolytes within assembled cells. A hierarchical layered structure is formed when LLZO settles near the Li anode within the liquid electrolyte during the gradual gelatinization process. Good interfacial compatibility is obtained from good contact with the liquid G4 component. The LLZO layer also serves as an ionic sieve to redistribute the Li deposition. This SGE endows stable Li stripping/plating cycling over 800 h at 0.5 mA/cm2 (60 °C). Moreover, Li-metal batteries with an SGE coupled with LiFePO4 and an air cathode both exhibit superior cycling performance. This work presents a promising strategy for hierarchically layered SGEs for high-performance Li-metal batteries.

Precisely manipulating the built-in electric fields of heterojunctions is an effective way to promote photogenerated charge separation. In this work, BiPO4 nanorods/graphene (GA) hydrogels were prepared by hydrothermal methods. The BiPO4 nanorods were evenly embedded in the graphene hydrogel, forming a stable three-dimensional (3D) network structure. The 70% BiPO4/GA hydrogel shows the highest tetracycline hydrochloride degradation activity, which is 3.2 times that of pure BiPO4. The formation of the built-in electric field of the BiPO4/GA hydrogel is demonstrated by experimental investigation (especially in situ atomic force microscopy (AFM) surface potential investigation) and theoretical calculation. The reasons for the enhanced photocatalytic activity are the optimal built-in electric field of the interface induced by precisely manipulating the interfacial contact of the BiPO4/GA hydrogel, as well as the synergistic effect of in situ photocatalytic degradation and adsorption enrichment induced by the 3D network structure. This work provides technical approach and research ideas for the photocatalytic degradation of antibiotics through the manipulation of interlaminar built-in electric field and heterojunction.

Interfacial magnetism in functional oxide heterostructures not only exhibits intriguing physical phenomena but also implies great potential for device applications. In these systems, interfacial structural and electronic reconstructions are essential for improving the stability and tunability of the magnetic properties. In this work, we constructed ultra-thin La0.67Ca0.33MnO3 (LCMO) and SrRuO3 (SRO) layers into superlattices, which exhibited a robust ferromagnetic phase. The high Curie temperature (TC) reaches 291 K, more than 30 K higher than that of bulk LCMO. We found that the LCMO/SRO superlattices consisted of atomically-sharp and asymmetric heterointerfaces. Such a unique interface structure can trigger a sizable charge transfer as well as a ferroelectric-like polar distortion. These two interfacial effects cooperatively stabilized the high-TC ferromagnetic phase. Our results could pave a promising approach towards effective control of interfacial magnetism and new designs of oxide-based spintronic devices.

The present study mixed twelve kinds of n-heptadecane, n-octadecane, and n-eicosane composite phase transition materials to prepare two-component mixtures. The phase transition temperature and pote...

With the increasing demand of rare earth metals in functional materials, recovery of rare earth elements (REEs) from secondary resources has become important for the green economy transition. Molten salt electrolysis has the advantages of low water consumption and low hazardous waste during REE recovery. This review systematically summarizes the separation and electroextraction of REEs on various reactive electrodes in different molten salts. It also highlights the relationship between the formed alloy phases and electrodeposition parameters, including applied potential, current, and ion concentration. Moreover, the feasibility of using LiF-NaF-KF electrolyte to recover REEs is evaluated through thermodynamic analysis. Problems related to REE separation/recovery the choice of electrolyte are discussed in detail to realize the low-energy and high current efficiency of practical applications.

During continuous extrusion, the welds were formed at the confluence of two billets. Influences of extrusion wheel rotational speed on micromorphology and properties of welds of 6063 Al alloy were investigated through microstructure observation, tensile test, and SEM analyses. Welding parameters were analyzed using finite element simulation. Results indicated that metal welding was remarkably affected by oxide on outer surface of the double billets during continuous extrusion. Degree of oxide breakage on the welding surface increased due to the evident increase in effective strain rate with increasing extrusion speed. The high temperature induced by increased extrusion speed accelerated the formation of metallurgical bonding. A portion of weld seam lines slowly disappeared, and the proportion of the welding interface that failed to reach metallurgical bonding was also gradually reduced. Tensile strength and elongation of the weld specimen increased with the increase of extrusion speed.

Proteinaceous fibers based on spidroins have attracted widespread attention due to their lightweight and mechanically strong properties. Presently, mechanical modulation is mainly dependent on the ...

Hydrogen has become a versatile and clean alternative to meet increasingly urgent energy demands since its high heating value and renewability. However, considering the hazards of hydrogen storage and transport, in-situ production processes are drawing more attention. Among all the hydrogen carriers, methanol has become one of the research focuses due to its high H/C ratio, flexibility and sustainability. Regarded as the core of hydrogen supply system, catalysts with higher activity, selectivity and stability are continuously developed for improved efficiency. In this review, two groups of catalysts were investigated namely copper-based and group VIII metal-based catalysts. Not only macro indicators such as feedstock conversion and product selectivity, but also micro interaction and reaction mechanism were elaborated, with respect to the effects of promoters, supports, synthesis methods and binary metal components. Notably, several reaction pathways and catalysts deactivation mechanisms were suggested based on this series of inspection of the structure-reactivity relationship, along with a general perception that large surface area, well dispersed metals, small particle size and synergy effects significantly improve the catalytic performance. Accordingly, a novel concept of single-atom catalysts (SACs) was introduced aimed at efficient hydrogen production under more moderate conditions, by combining the advantages of heterogeneous and homogeneous catalysis. Additionally, an efficient reforming process is required by properly regulating the feed flow and heat flow through a coupled system. Conclusively, a thorough supply and demand network of hydrogen based on methanol was presented, giving an overview for on-board applications of hydrogen energy.

As the technology development, the future advanced combustion engines must be designed to perform at a low temperature. Thus, it is a great challenge to synthesize high active and stable catalysts to resolve exhaust below 100 °C. Here, we report that bismuth as a dopant is added to form platinum-bismuth cluster on silica for CO oxidation. The highly reducible oxygen species provided by surface metal-oxide (M-O) interface could be activated by CO at low temperature (~50 °C) with a high CO2 production rate of 487 μmolCO2·gPt−1·s−1 at 110 °C. Experiment data combined with density functional calculation (DFT) results demonstrate that Pt cluster with surface Pt−O−Bi structure is the active site for CO oxidation via providing moderate CO adsorption and activating CO molecules with electron transformation between platinum atom and carbon monoxide. These findings provide a unique and general approach towards design of potential excellent performance catalysts for redox reaction., The technological development requires the future advanced combustion engines be designed to operate at low temperature. Here, the authors show that partially oxide Pt-[O]x-Bi interface catalyzes CO oxidation at ~ 50 °C via providing moderate CO adsorption and activating CO molecules with electron transformation.

van der Waals (vdW) vertical p-n junctions based on two-dimensional (2D) materials have shown great potential in flexible, self-driven, high-efficiency electronic and optoelectronic applications. However, due to the complex nucleation dynamics, the controllable synthesis of vertical heterostructures remains a daunting challenge. Here, we report the controlled growth of vertical GaSe/MoS2 p-n heterojunctions via a liquid gallium (Ga)-assisted chemical vapor deposition method. The growth mechanism can be interpreted by theoretical calculations based on the Burton-Cabrera-Frank theory. By analyzing the diffusion barriers and the Ehrlich-Schwoebel barriers of adatoms, we found that the growth modes between vertical and lateral can be precisely switched by means of adjusting the amount of Ga. Based on the achieved high-quality vertical GaSe/MoS2 p-n heterojunctions, photosensing devices are further designed and systematically investigated. Upon light illumination, prominent photovoltaic effects with large open-circuit voltage (0.61 V) and broadband detection capability from 375 to 633 nm are observed, which can further be employed for self-powered photodetection with high responsivity (900 mA/W) and fast response speed (5 ms). The developed liquid-metal-assisted strategy provides an effective method for controllable synthesis of vdW heterostructures and will give impetus to their applications in high-performance optoelectronic device.

Carbon-based matrix is known to exert a profound influence on the stability and activity of a supported molecular catalyst for electrochemical CO2 reduction reaction (eCO2RR), while regulating the interfacial π-π interaction by designing functional species on the carbon matrix has seldom been explored. Herein, promoted π electron transfer between a graphene substrate and cobalt phthalocyanine (CoPc) is achieved by introducing abundant intrinsic defects into graphene (DrGO), which not only generates more electrochemically active Co sites and leads to a positive shift of the Co2+/Co+ reduction potential but also enhances the CO2 chemical adsorption. Consequently, as compared to the defect-free counterpart rGO-CoPc, DrGO-CoPc could yield CO with a Faradaic efficiency (FECO) higher than 85% in a wide potential range from -0.53 to -0.88 V, and the largest FECO and partial CO current density (JCO) achieve 90.2% and 73.9 mA cm-2, respectively. More importantly, both FECO and JCO can be dramatically improved when conducting eCO2RR in an ionic liquid-based electrolyte, for which FECO is higher than 90.0% in a wide potential range of 600 mV, with the peak JCO of up to 113.6 mA cm-2 in an H-type cell. The excellent eCO2RR performance of DrGO-CoPc rates itself as one of the best immobilized molecular catalysts.

The heat transfer performance of steam and air flow in a rough rectangular channel with different inverted V-shaped ribs was investigated by infrared thermal imaging technology. Under the conditions that the Reynolds number is in the range of 4000–15,000, the effects of the rib angle on the heat transfer enhancement of the two coolants were obtained. The rib pitch ratio of the flow channel is 10, the ratio of the rib height to the channel hydraulic diameter is 0.078, and the inverted V-shaped rib angle varies from 45° to 90°. The results show that in the inverted V-shaped ribbed channel, the Nu number on both sides of the channel is greatly increased, while the Nu number in the middle of the channel is lower. The local Nu distribution on the surface of the ribbed channel is highly related to the shape of the rib. For different medium cooling, the value and unevenness of the heat transfer coefficient are different, but the shape of the high and low heat transfer coefficient distribution is hardly affected. The heat transfer of both coolants increases as the rib angle decreases from 90° to 45°. Compared with air flow, steam flow cooling shows higher convective heat transfer enhancement. For rib angles of 45°, 60°, 75°, and 90°, under the operating condition of the Reynolds number = 12,000, the area-averaged Nusselt numbers of the steam flow is 23.6%, 27.4% and 13.9% higher than that of the air flow, respectively. Based on the experimental heat transfer data, the correlation in terms of the Reynolds number and the rib angle was developed, which is used to estimate the Nu number for steam and air cooling in the inverted V-shaped rib-roughness channels.

High-index semiconductor nanoantennae represent a powerful platform for nonlinear photon generation. Devices with reduced footprints are pivotal for higher integration capacity and energy efficiency in photonic integrated circuitry (PIC). Here, we report on a deep subwavelength nonlinear antenna based on dilute nitride GaNP nanowires (NWs), whose second harmonic generation (SHG) shows a 5-fold increase by incorporating ∼0.45% of nitrogen (N), in comparison with GaP counterpart. Further integrating with a gold (Au) thin film-based hybrid cavity achieves a significantly boosted SHG output by a factor of ∼380, with a nonlinear conversion efficiency up to 9.4 × 10-6 W-1. In addition, high-density zinc blende (ZB) twin phases were found to tailor the nonlinear radiation profile via dipolar interference, resulting in a highly symmetric polarimetric pattern well-suited for coupling with polarization nano-optics. Our results manifest dilute nitride nanoantenna as promising building blocks for future chip-based nonlinear photonic technology.

Replacing conventional metal–N4 moieties with different coordination structures is a promising strategy to tailor the activity and selectivity of single-atom catalysts (SACs). However, for CO2 elec...

In view of the development status of high-reliability and low-cost cooling technology for radial turbine of micro-gas turbine or vehicle turbocharger, the impingement cooling technology of the radial turbine back disc was proposed, and the improvement of the cooling efficiency and thermal stress of the turbine back disc was numerically simulated. The results show that the impingement cooling technology can greatly improve the cooling efficiency of the turbine back disc and reduce the stress level. When the relative cooling flow is 1.0%–3.0%, the average cooling efficiency of the lower part of the turbine back disc is increased by 258%–486% compared with no cooling, which can reduce the thermal stress at the fillet of the back disc by 140–216 MPa. Both the average cooling efficiency and the fillet stress of the back disc increase slightly as the relative position of the jet hole moves outward. When the relative cooling flow is controlled within 2.0%, the effect of this cooling technology on the performance of the turbine can be ignored.

Low dielectric constant/low loss LTCC materials have drawn much attention with the emergence of 5G wireless telecommunications. LTCC offers unique properties in the millimeter wave frequency range. The low dielectric constant and dielectric loss enable low latency devices with enhanced performance. To meet the market demands of higher performance and lower cost, Ferro has developed a new M7 LTCC/Ag cofireable system suitable for antenna in 5G and other high frequency applications. M7 LTCC ceramic green tape and cofireable Ag conductors have been developed and tested. Properties of the LTCC/Ag system are included herein including high frequency dielectric properties.

In this paper, 15Cr-ODS steels containing 0, 1 wt%, 2 wt% and 3 wt% Al element were fabricated by combining wet-milling and spark plasma sintering (SPS) methods. The microstructure and mechanical properties of ODS steel were investigated by XRD, SEM, TEM, EBSD and tensile tests. The results demonstrate that the Al addition significantly refines the particle precipitates in the Fe−Cr matrix, leading to the obvious refinement in grain size of matrix and the improvement of mechanical properties. The dispersion particles in ODS steels with Al addition are identified as Al2O3 and Y2Ti2O7 nanoparticles, which has a heterogeneous size distribution in the range of 5 nm to 300 nm. Increasing Al addition causes an obvious increase in tensile strength and a decline in elongation. The tensile strength and elongation of 15Cr-ODS steel containing 3 wt% Al are 775.3 MPa and 15.1%, respectively. The existence of Al element improves the corrosion resistance of materials. The ODS steel containing 2 wt% Al shows corrosion potential of 0.39 V and passivation current density of 2.61×10−3 A/cm2(1.37 V). This work shows that Al-doped ODS steels prepared by wet-milling and SPS methods have a potential application in structural parts for nuclear system.

This paper, for the first time, reports observations of a type of powder bed surface defects (i.e., surface ridges) induced by forward-rotating roller compaction. Three compaction thicknesses, 0, 30, and 180 µm, were tested at a layer thickness of 120 µm. Surface ridges occurred on the powder bed surface when compaction thickness was 180 µm, but not when compaction thickness was 0 or 30 µm. The formation of surface ridges was a cumulative process where the number and height of surface ridges first increased and then reached a plateau as the number of spread and compacted layers increased.

Protein-based nanoparticles with tailored properties by using different functional proteins as building blocks have many actual and potential applications in biomedicine, biotechnology, and nanotechnology. In this study, we demonstrated a facile and efficient way to synthesize protein-based nanoparticles by taking advantage of photoinitiated reversible addition-fragmentation chain transfer (RAFT) polymerization-induced self-assembly by using multi-RAFT modified bovine serum albumin (BSA) as a macro-RAFT agent. The growth of the PHPMA chains results in the increase of the hydrophobicity of the star BSA-PHPMA conjugates, and when reaching the critical aggregation concentration in aqueous solution, they will aggregate into nanoparticles via the hydrophobic interaction of PHPMA. The generated nanoparticles also showed excellent encapsulation ability toward both hydrophobic and hydrophilic components, and as a proof of concept, after loading cancer drug DOX or biomacromolecule DNA, the protease-mediated release of the encapsulants was demonstrated. It is anticipated that the described method may open up new opportunities for designing a variety of protein-polymer self-assembled nanostructures tailored to specific applications.

The low-temperature hydrogenation of CO2 to methanol is of great significance for the recycling of this greenhouse gas to valuable products, however, it remains a great challenge due to the trade-off between catalytic activity and selectivity. Here, we report that CO2 can dissociate at sulfur vacancies in MoS2 nanosheets to yield surface-bound CO and O at room temperature, thus enabling a highly efficient low-temperature hydrogenation of CO2 to methanol. Multiple in situ spectroscopic and microscopic characterizations combined with theoretical calculations demonstrated that in-plane sulfur vacancies drive the selective hydrogenation of CO2 to methanol by inhibiting deep hydrogenolysis to methane, whereas edge vacancies facilitate excessive hydrogenation to methane. At 180 °C, the catalyst achieved a 94.3% methanol selectivity at a CO2 conversion of 12.5% over the in-plane sulfur vacancy-rich MoS2 nanosheets, which notably surpasses those of previously reported catalysts. This catalyst exhibited high stability for over 3,000 hours without any deactivation, rendering it a promising candidate for industrial application. The catalytic hydrogenation of CO2 to methanol is a crucial reaction for the recycling of this greenhouse gas, although the selection and related performance of commercial catalysts is still limited. Now, the authors introduce sulfur vacancy-rich MoS2 nanosheets as a superior catalyst for this process, rivalling the commercial benchmark system.

Substitutional doping of two-dimensional (2D) transition metal dichalcogenides (TMDs) has been recognized as a promising strategy to tune their optoelectronic properties for a wide array of applications. However, controllable doping of TMDs remains a challenging issue due to the natural doping of these materials. Here, we demonstrate the controllable growth of indium-doped p-type WS2 monolayers with various doping concentrations via chemical vapor deposition (CVD) of a host tungsten (W) source and indium (In) dopant. Scanning transmission electron microscopy confirmed that In atoms successfully substitute the W atoms in the WS2 lattice. Intriguingly, the photoluminescence of the doped sample experiences strong intensity modulation by the doping concentration, which first increases remarkably with an enhancement factor up to ~35 and then decreases gradually when further increasing the doping concentration. Such a phenomenon is attributed to the progressive change of the exciton to trion ratio as well as the defect concentration in the doped samples. The assignment was further verified by the electric behavior of the fabricated In-doped WS2 field effect transistors, which changes regularly from n-type to bipolar and finally to p-type behavior with increasing doping concentration. The successful growth of p-type monolayer WS2 and the dual control of its optical and electrical properties by In doping may provide a promising method to engineer the opto-electronic properties of 2D materials.

The rechargeable Zn-air batteries as an environmentally friendly sustainable energy technology have been extensively studied. However, it is still a challenge to develop non-noble metal bifunctional catalysts with high oxygen reduction as well as oxygen evolution reaction (ORR and OER) activity and superior durability, which limit the large-scale application of rechargeable Zn-air batteries. Herein, we synthesized an ultrastable FeCo bifunctional oxygen electrocatalyst on Se-doped CNTs (FeCo/Se-CNT) via a gravity guided chemical vapor deposition (CVD) strategy. The catalyst exhibits excellent ORR (E1/2 = 0.9 V) and OER (overpotential at 10 mA cm-2 = 340 mV) properties simultaneously, surpassing commercial Pt/C and RuO2/C catalysts. More importantly, the catalyst shows an unordinary stability, that is, is no obvious decrease after 30K cycles accelerated durability test for ORR and OER processes. The small potential gap (0.75 V) represents superior bifunctional ORR and OER activities of the FeCo/Se-CNT catalyst. The FeCo/Se-CNT catalyst possesses outstanding electrochemical performance for the rechargeable liquid and flexible all-solid-state Zn-air batteries, for example, a high open circuit voltage (OCV) and peak power density of 1.543 and 1.405 V and 173.4 and 37.5 mW cm-2, respectively.

In accordance with hyperelastic transformation theory, a range of shear-wave manipulation devices can be designed with neo-Hookean materials pre-deformed properly. However, how such devices fit the background medium remains elusive. In this study, a systematic formula is developed in terms of elastic wave transmission and reflection between un-deformed and pre-deformed hyperelastic materials. By both theoretical analyses and numerical simulations, the shear-wave propagation from an un-deformed neo-Hookean material to the pre-deformed one is investigated. Among the three typical deformations, “constrained” uniaxial tension and simple-shear are found to be able to ensure total transmission, whereas ordinary uniaxial tension and hydrostatic compression could cause reflection. Thus, three embedded shear-wave manipulation devices are proposed, namely, a unidirectional cloak, a splicing beam bend and a concave lens; their performance is verified by numerical simulations. This study may underpin the design and realization of soft-matter-based wave control devices. Potential applications can be expected in nondestructive testing, impact protection, biomedical imaging, as well as soft robotics.

Current non-fullerene organic photovoltaics (OPVs) can achieve high photocurrent generation yields with small donor/acceptor energy offsets. However, the effect of varying energy offset on the char...

Synthesis of the unconventional phase of noble metal nanocrystals may create new opportunities in exploring intriguing physicochemical properties but remains challenging. In the research field of thin film growth, the interface strain offers a general driving force to stabilize the metastable phase of epitaxial film. Herein we extend this concept to the field of noble metal nanocrystals and report the solution synthesis of metastable face-centered tetragonal Au that has not been discovered before. The successful synthesis relies on the formation of intermetallic AuCu3@Au core-shell structure, where the interface strain stabilizes the metastable fct Au overlayer. Compared with the face-centered cubic Au counterpart, the metastable fct Au shows greatly improved catalytic activity toward CO2 reduction to CO. The density functional theory calculations and spectroscopic studies reveal that the metastable fct Au upshifts the d-band center, which lowers the energy barrier of key intermediate COOH* formation and thus facilitates the reaction kinetics.

Nanoscale materials have an irreplaceable advantage in solar energy utilization because of their perfect match with visible light wavelength on the length scale. Charge transfer (CT) between a meta...

A co-flow premixed flat flame is applied to form MoO3 nanobelts and nanoplatelets in the gas phase. An experimental study is conducted with a thermophoretic sampling particle diagnostic (TSPD) technique to reconstruct the evolution of nanostructure formation. In order to investigate the growth mechanism of the nanobelts and nanoplatelets, samples were directly taken along the centerline at different positions in the flame to represent the essential morphological variations of material. Based on the sample information collected by TEM, a growth mechanism of nanobelts and nanoplatelets is proposed. The results indicate that nanobelts and nanoplatelets with well-defined structure are successfully synthesized in premixed flame. The precursor temperature has a significant impact on the morphology by affecting the vapor concentration in the flame. For synthetic nanobelts, the intermediate particles tend to grow along a specific direction with small surface energy, and the final morphology is determined by particle attachment. In contrast, the initial growth of the nanoplatelets is mainly characterized by vapor surface deposition/growth, and the formation of the final morphology relies on the coalescence of large particles and small particles.

Metallic zinc is widely considered as the most promising anode candidate for next-generation rechargeable aqueous batteries owing to its high volumetric capacity and intrinsic safety. However, the inferior reversibility caused by uncontrolled dendrite growth and parasitic side reactions severely impedes the commercial application of rechargeable Zn-based batteries. Herein, a fast Zn-ion conductor, Zn-intercalated montmorillonite (Zn-Mont), is designed as an artificial solid/electrolyte interphase (SEI) film to tune the transfer and deposition behavior of Zn2+ ions on the surface of Zn anodes. Benefiting from the low Zn-ion migration energy barrier and Zn ion-selective pathway, the Zn-Mont coating could guarantee a homogeneous Zn-ion flux, and fast Zn2+ transfer kinetics, and avoid the ion/electron accumulation at the interface of the anode, thereby suppressing the growth of Zn dendrites. In addition, the Zn-Mont layer can prevent direct contact of the Zn metal with bulk electrolyte, alleviating the water/O2-induced side reactions. Consequently, high reversibility (coulombic efficiency > 99.6%), long-time stability (over 1000 cycles), and ultralow polarization (overpotential ≈ 28 mV) are achieved. When coupled with the MnO2 cathode, Zn@Zn-Mont||MnO2 full cells deliver outstanding cycling stability with 85.4% capacity retention (calculated based on the specific capacity of the 5th cycle) after 1000 cycles at 2C.

Organic compounds with high theoretical capacity, tunable redox potentials and rich structural chemistry are considered as promising electrode materials for sodium-ion batteries (SIBs). However, organic electrode materials suffer from low electronic conductivity and low structural stability, hindering their practical applications. Thiophene compounds have been well considered in the design of photoelectric materials with improved charge transfer properties. It is envisaged that electron-transfer capability is also essential in addressing the issues of organic electrode materials for SIBs. Herein, sodium thieno[3,2-b]thiophene-2,5-dicarboxylate (STTDC), an organic compound with high electron transfer capability is designed and synthesized. When employed as an electrode material for SIBs, remarkably high electrochemical performance, including large reversible capacity, high rate capability and excellent stability was achieved. A large specific discharge capacity of 430 mA h g−1 is delivered at a current density of 50 mA g−1. A high reversible capacity of approximately 288 mA h g−1 is retained after 4000 cycles at a high current density of 2.0 A g−1. The present work sheds new light on the design of high-performance organic electrode materials.

An experimental study was conducted on the effects of point distance and hatch distance on pore formation in selective laser melting of tungsten. The Archimedes’ method was used to measure the apparent and closed porosities. Apparent (open) porosity and closed porosity were found to follow different trends: the apparent porosity increased but the closed porosity decreased as hatch distance or point distance increased. The open pores are attributed to the lack of fusion at the large hatch distance or point distance while the closed pores are attributed to the possible spattering and keyhole formation at the smaller hatch distance or point distance. The results led to understanding the effects of hatch distance and point distance on the formation of open and closed pores and provided insight on the optimization of process parameters to further increase the relative bulk density.

Combining the advantages of the phase tunability provided by active frequency selective surfaces (FSSs) and the beam-steering scheme used in conventional 1-D Fresnel-zone-plate (FZP) antennas, we report in this communication a 2-D beam-steering FZP antenna that needs only 180° phase tunability. Compared with transmit arrays, while the substrate layers are reduced by a half, a phase compensation strategy is used to enhance antenna specifications. To verify the proposed approach, a radome implemented based on an active, reconfigurable FSS was designed, simulated, and experimentally implemented. With a simple three-layer structure, the implemented FZP antenna works within an ultrawide bandwidth ranging from 5 to 6.3 GHz, corresponding to a 21% relative bandwidth. With a gain up to 19.3 dBi, the scanning range reaches ±45° in both horizontal and vertical planes. This cost-effective, simple-structured antenna can be potentially used in diverse RF and microwave applications.

Developing a highly efficient, easy-to-fabricate and non-noble metal electrocatalyst is vital for the oxygen reduction reaction (ORR). Herein, we fabricate a single Fe site catalyst Fe1/d-CN by developing a double-layer MOF strategy. The Fe1/d-CN catalyst shows an excellent ORR activity in the pH-universal range, especially in alkaline electrolytes with a record-level half-wave potential of 0.950 V, exceeding those of almost all the reported non-noble electrocatalysts and the commercial Pt/C catalyst (0.863 V). Besides its exceptional ORR activity in alkaline electrolytes, it also exhibits comparable ORR activity to the commercial Pt/C catalyst in acidic and neutral electrolytes. We speculate that the sources of the excellent pH-universal ORR performance can be attributed to the regulation of the electronic structure of Fe centres and the excellent electron/proton transport capability that comes from the rich defects and hierarchical porous features of the Fe1/d-CN catalyst. More excitingly, the catalyst possesses remarkable durability, and exhibits a negligible decrease after 30k accelerated durability test (ADT) cycles in pH-universal media. The flexible quasi-solid-state alkaline rechargeable Zn–air batteries with the Fe1/d-CN catalyst as the cathode show superior performance such as a high OCV of 1.50 V and peak power density of 78.0 mW cm−2. Furthermore, the flexible quasi-solid-state neutral rechargeable Zn–air batteries also exhibited remarkable performance.