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Inspired by the hierarchical structure of the pearl shell and its related multi-scale toughening mechanism, based on the combination of powder metallurgy technology and spark plasma sintering, a layered graphene and carbon nanotubes hybrid reinforced Cu matrix composite material was successfully prepared. Compared with other conventional Cu matrix composite materials, the compressive elongation of the bionic materials is significantly improved, and all of them are above 20%, which is attributed to the effective crack deflection and the pull-out of the reinforcing phase. In terms of overall strength and toughness, (0.8 wt% MWCNTs+0.2 wt% GNPs)/Cu has the best performance. Its tensile strength, compressive strength and compressive elongation are 103.63 MPa, 202.32 MPa and 33.49% respectively. The large grain size in the laminates is conducive to the movement of dislocations, while the interlayer interface and nanocrystalline grains hinder the movement of dislocations in the direction perpendicular to the laminates.

The ability to detect multidimensional forces is highly desired for electronic skin (E-skin) sensors. Here, based on single-electrode-mode triboelectric nanogenerators (S-TENGs), fully elastic E-skin that can simultaneously sense normal pressure and shear force has been proposed. With the hemispherical curve-structure design and further structural optimization, the pressure sensor exhibits a high linearity and sensitivity of 144.8 mV/kPa in the low-pressure region. By partitioning the lower tribolayer into two symmetric parts, a multidimensional force sensor has been fabricated in which the output voltage sum and ratio of the two S-TENGs can be used for normal pressure and shear force sensing, respectively. When the multidimensional force sensors are mounted at a two-fingered robotic manipulator, the change of the grabbing state can be recognized, indicating that the sensor may have great application potential in tactile sensing for robotic manipulation, human-robot interactions, environmental awareness, and object recognition.

In this paper, the hot deformation behavior of Fe–30Mn–10Al–1C low-density steel was investigated by Gleeble-1500D thermomechanical simulator at a temperature range of 850–1100 °C and a strain rate range of 0.01–10 s–1. The constitutive equation and dynamic recrystallization (DRX) kinetic model of the experimental steel were established. Processing maps under different strains were drawn to explore the optimum hot working parameters of the steel. The results show that the flow stress decreases with increasing deformation temperature and increases with increasing strain rate. The average activation energy of hot deformation (Q) was calculated to be 391.57 kJ/mol. The volume fraction of DRX grains increases with the increase in strain with a sigmoid-shape curve. Dislocation slip is the predominant deformation mechanism of the experimental steel with increasing hot compression temperature. The optimum hot working parameters of the experimental steel are: a deformation temperature of 975–1100 °C, a strain rate in the range 0.01–1 s–1, and the efficiency of power dissipation of 36–64%.

Lithium–air batteries possess ultrahigh energy density compared to lithium-ion batteries because oxygen is applied as the reacting matter of the cathode without restrictions. However, they cannot b...

Cu–Al–Mn–Ti–xTa alloys (x = 0, 1, 2, 3, wt.%) prepared by spark plasma sintering were investigated for the effect of Ta content on the microstructure, mechanical and damping properties. The microstructure and phase composition indicate that the alloy is mainly composed of β′1 martensite, γ′1 martensite, Ti-rich and Ta-rich phase. As the Ta content increases, the grain size of the alloy first decreases and then increases. The reverse trend was observed for hardness, tensile and compressive strength. The hardness, tensile strength and compressive strength increased by 18.2%, 44.9% and 28%, respectively, when the Ta content was 1 wt.% compared to the alloy without Ta element. The presence of martensite provides the alloy with promising damping properties. Meanwhile, the formation of the second phase has a two-sided effect on the damping characteristics. That is, the increase in grain boundaries provides more interfaces for energy dissipation, but the increased compressive stress between the interfaces also hinders the movement of the interfaces. Excellent damping performance is demonstrated with the addition of 1 wt.% of Ta element. The peak values of damping capacity at room temperature and at about 580 °C reached 0.026 and 0.19, respectively. The results confirm that the addition of Ta elements is achievable to obtain Cu–Al–Mn–Ti alloys with both high mechanical and damping properties.

In this work, Ag or/and Cu doped BiVO 4 samples has been prepared successfully via hydrothermal and photoreduction method. Ag/Cu co-doped BiVO 4 exhibited high photocatalytic degradation efficiency in the degradation of methylene blue (MB) and displayed a significantly superior property compared to pure BiVO 4, as well as only Ag or Cu doped BiVO 4 upon exposure to visible light source. Interestingly, we found that enhanced photocatalytic activity of Ag/Cu co-doped BiVO 4 arises from the synergistic effect between the Ag and Cu co-doped BiVO 4 with smaller crystalline size, improved photocatalytic reaction sites, improved life-time and enhanced separation of photogenerated charge carriers which are confirmed using different characterization techniques. The degradation of MB was mainly indicated by superoxide radical species as confirmed by the trapping experiment. Based on the collective results obtained an excellent photocatalytic activity in Ag/Cu co-doped BiVO 4 has been confirmed.

To study the mechanical behavior of 5052 aluminum alloy at different strain rates, uniaxial tensile tests at quasi-static, medium, and high strain rates were carried out using a CMT5305 MTS hydraulic servo universal testing machine, Zwick HTM5020 high-speed tensile testing machine, and Split Hopkinson tensile bar device, and the stress-strain curves of the material were obtained. Then, the fracture morphology and microstructure of the samples were studied and analyzed using macroscopic and microscopic analysis methods to obtain the material’s fracture and deformation mechanism. The results show that 5052 aluminum alloy exhibits strain rate sensitivity, and its yield strength and strength limit increase with the increase in strain rate. At different strain rates, the forming properties of the materials are similar. The plastic deformation mechanism is all dislocation slip, and the fracture mechanism is all ductile fracture. However, with the increase in strain rate, the necking phenomenon becomes more remarkable, the dislocation density increases continuously, and the distribution becomes more uniform. The dimples on fracture surface became deeper, and the number of dimples increased, indicating that the plastic deformation of the material increases continuously.

Engineering lattice defects in two-dimensional (2D) sulfide semiconductors has been accepted as an effective strategy to enhance the efficiency of the solar-to-fuels conversion. Although many researches have proven the lattice defect-mediated photocatalytic activity of ZnIn2S4, the artificial control of S-defects for optimizing the charge-carrier kinetics process in ZnIn2S4 has long been a challenging task. Herein, we report a facile one-step method to modulate the lattice S-content of ZnIn2S4 microflowers (MFs) only through adjusting the used amount of S-precursor in the hydrothermal solution that contains the metal precursors with a fixed Zn/In stoichiometric ratio at 1:2. We also demonstrated that the S-vacancies at the In facets were the main type of lattice defects in the formed ZnIn2S4 MFs, which could enhance both the separation and migration processes of the photoinduced charge-carriers due to the existence of discrete defect energy-levels (DELs) and the reduced effective mass of electrons, as evidenced by the first-principles calculations and the electron spectra analyses. The ZnIn2S4 MFs with the optimal content of S-vacancy obtained by a hydrothermal treatment of the precursors with the Zn/In/S stoichiometric ratio of 1:2:8 possessed the long-lived photoinduced electron (~94.64 ns) for contributing to the photo-physical and -chemical processes. Thus, upon visible light irradiation, the H2-evolution rate of this sample reached ~ 2.40 mmol h−1 g−1 with an apparent quantum efficiency of ~ 0.16% at 420 nm even though only using 5 mg of photocatalysts without any cocatalysts.

As an ideal reinforcing phase, nano-carbon has been widely used to improve the properties of composites. In this paper, Mo–Cu–Zr ternary composites were reinforced with various types and contents of nano-carbon to find the optimal composition and the microstructure and mechanical properties of the composites were systematically characterized and analyzed. The composites were fabricated via a powder metallurgy method to achieve high compactness and structural uniformity. The analysis results show that the increase of nano-carbon may cause a serious agglomeration and subsequent decrease of the composite compactness, while the synergetic effect of carbon nanotubes (CNTs) and graphene nanoplatelets (GNPs) can improve their dispersion. The 0.8C + 0.2G-MCZ3 composite showed the best comprehensive properties, which achieved a relative density, hardness and compressive strength of 99.7%, 343.6 HV and 953.5 MPa, respectively. Moreover, the component Zr mainly formed solid solution and compound particles with Cu or C through in-situ chemical reactions. It played an important role in solid solution strengthening and dispersion strengthening, and the in-situ synthesized ZrC nanoparticles on nano-carbon surfaces can pin interfaces and improve the effect of load transfer. The synergetic effects and multiple strengthening mechanisms result in the improvement of the microstructure and properties of the composites.

A Mach–Zehnder interferometer (MZI) sensor based on a four-core sapphire-derived fiber (FSDF) for bending sensing is proposed and demonstrated. The MZI is formed by splicing a coupled FSDF between two single-mode fibers, delivering supermode interference among four LP01-like supermodes (LP01s modes) and eight LP11-like supermodes (LP11s modes). Benefiting from the different response of the field distribution of each supermode to curvature changes, MZI sensors with a variety of bending properties can be fabricated based on the interference of different supermodes in the FSDF. The experimental results show that the sensitivity of the FSDF-MZI sensor I based on the interference between the LP01s and the LP11s modes is about 4.5 dB/m−1 in the curvature range from 0.4 to 2.5 m−1. The FSDF-MZI sensor II based on the interference of two LP11s modes can realize bending sensing in ± Y directions. The sensitivity of FSDF-MZI sensor II in the curvature range of −10.0–5.0 m−1 is about −24.526 nm/m−1. It suggests that the proposed FSDF-MZI sensor has potential application in the field of structure health detection.

An all-silica Fabry-Perot interferometer (FPI) is demonstrated for high-temperature pressure monitoring. The pressure sensor is fabricated with single mode fiber and silica capillary by CO2 laser. Owing to slight mismatch of thermal expansion coefficient in all-silica structure, it can work stably under 600°C atmosphere. The influence of the temperature on the pressure sensor was investigated within a temperature range from 25°C to 700°C and a pressure range from standard atmosphere pressure to 4 MPa. The experimental results show that the wavelength shift versus the pressure at each temperature is linear, which indicates the proposed FPI pressure sensor has potential applications in industrial reactors, oil and gas wells, and so on.

Membranes with high permeance and high rejection for di- and multivalent cation removal are highly desired for efficient brackish water and industrial water treatment. In this work, we report a facile strategy for constructing ultrathin nanofiltration (NF) membranes by in situ cross-linking of amine which is confined in a network film. The network made of single-walled carbon nanotubes (SWCNTs) serves as a framework for poly(ethylene imine) (PEI) to attach and stay, facilitating the formation of a polyamine (PA) layer with high quality and controlled thickness. Benefiting from the ultrathin thickness of the SWCNT network (∼31 nm), an active layer (∼34 nm thick) comes with a high permeance of 27 L m

Developing a multifunctional theranostic nanoplatform is vital for dealing with challenging matters correlated with cancers. In this paper, we report an improved facile and relatively green fabrication of highly monodisperse CoFe2O4 nanoparticles with tunable size and morphology. Furthermore, a multifunctional cancer theranostic nanoplatform (CoFe2O4 nanoparticles@dopamine@DOX) was successfully developed for magnetic-responsive on-demand hyperthermia and chemotherapy synergistic theranostics. The proposed nanoplatform exhibits outstanding magneto-triggered hyperthermia efficiency, magnetic-responsive controlled drug delivery capability, enhanced MRI T2-weighted signal, and good biocompatibility. More importantly, the in vivo tumor-bearing mouse model experiments indicated that the CoFe2O4 nanoparticles@dopamine@DOX nanomedicine could realize the functions of magnetic-responsive on-demand hyperthermia and DOX release, which significantly promoted the inactive condition of cancer cells and resulted in obvious tumor regression without evident toxic side effects. According to its facile and green fabrication approach, magneto-triggered high hyperthermia efficiency, magnetic-responsive on-demand cancer therapy, and noninvasive imaging mode, this multifunctional nanoplatform holds great advantages over traditional monotherapy techniques and provides an alternative for the precise clinical treatment of cancer. A multifunctional cancer theranostic nanoplatform (CoFe2O4 nanoparticles@dopamine@DOX) was successfully developed for magnetic-responsive on-demand hyperthermia and chemotherapy synergistic theranostics.

Raman optical activity (ROA) is effective for studying the conformational structure and behavior of chiral molecules in aqueous solutions and is advantageous over X-ray crystallography and nuclear magnetic resonance spectroscopy in sample preparation and cost performance. However, ROA signals are inherently minuscule; 3–5 orders of magnitude weaker than spontaneous Raman scattering due to the weak chiral light–matter interaction. Localized surface plasmon resonance on metallic nanoparticles has been employed to enhance ROA signals, but suffers from detrimental spectral artifacts due to its photothermal heat generation and inability to efficiently transfer and enhance optical chirality from the far field to the near field. Here we demonstrate all-dielectric chiral-field-enhanced ROA by devising a silicon nanodisk array and exploiting its dark mode to overcome these limitations. Specifically, we use it with pairs of chemical and biological enantiomers to show >100x enhanced chiral light–molecule interaction with negligible artifacts for ROA measurements., Raman optical activity (ROA) is useful for studying conformational structure and behavior of chiral molecules, but is limited by the weak signals. Here, the authors demonstrate 100x signal enhancement via an all-dielectric approach, using a silicon nanodisk array and exploiting its dark mode.

One of the severe plastic deformation techniques, elliptical cross-sectioned spiral equal-channel extrusion (ECSEE) was successfully applied to the pure Mg processed at 200°C and the microstructure...

A low defect density in metal halide perovskite single crystals is critical to achieve high performance optoelectronic devices. Here we show the reduction of defect density in perovskite single crystals grown by a ligand-assisted solution process with 3‐(decyldimethylammonio)‐propane‐sulfonate inner salt (DPSI) as an additive. DPSI ligands anchoring with lead ions on perovskite crystal surfaces not only suppress nucleation in solution, but also regulate the addition of proper ions to the growing surface, which greatly enhances the crystal quality. The grown CH3NH3PbI3 crystals show better crystallinity and a 23-fold smaller trap density of 7 × 1010 cm−3 than the optimized control crystals. The enhanced material properties result in significantly suppressed ion migration and superior X-ray detection sensitivity of CH3NH3PbI3 detectors of (2.6 ± 0.4) × 106 µC Gy−1air cm−2 for 60 kVp X-ray and the lowest detectable dose rate reaches (5.0 ± 0.7) nGy s−1, which enables reduced radiation dose to patients in medical X-ray diagnostics., The performance of a metal halide perovskite single crystal is governed by the defect density. Here, the authors report a high quality single crystal perovskite grown by a ligand-assisted solution process with DPSI achieving 23-fold smaller trap density than that without DPSI.

Transition-metal aluminium nitrides widely used as protective tool coatings are a class of materials with a combination of high hardness, outstanding wear resistance as well as good chemical stability. In this work, through a well developed structure searching method, the ground-state phase of V0.5Al0.5N is verified and systematically studied on its mechanical and electronic properties by comparing with Ti0.5Al0.5N and W0.5Al0.5N via first-principles calculations. Our results show that the ground-state phase of V0.5Al0.5N adopts a hexagonal structure of P63/mmc symmetry. Mechanical property studies demonstrate the hexagonal phase has a surprisingly improved hardness of about 38 GPa and enhanced ideal strengths relative to its well-known metastable cubic B1 phase whose hardness is only about 20 GPa. This mechanical enhancement greatly expands the upper limit of the strength and hardness for this type of Al-containing ternary systems. Meanwhile, detailed analysis on strength and elastic anisotropy indicates it also exhibits much better mechanical isotropy. Underlying mechanism of the mechanical enhancement is explored by the electronic analysis in-depth. The position of the EF is tuned by the introduction of the Al element and this electronic tuning leads to a metallic-to-semiconductor transformation from B1 to the hexagonal phase and the strengthening of the bonds between the metal elements and the N atoms.

Coal seam water injection, as an indispensable process in underground mining, is of great significance to the treatment of dust hazard in working face. However, the permeability of water in the coal seam is unsatisfactory due to hydrophobic properties of coal and many other factors. Here we synthesized a water injection additive with stellate structure by modified β-cyclodextrin. The molecular structure characteristics of the product were analyzed by FTIR, XRD and TG-DTG-DSC. The permeability and wettability of materials, which are closely related to water injection were tested. The contact angle of 0.1% product solution was only 25°. Moreover, combined with the characteristics of molecular structure and the effects, the principle of action was explained. And the optimum reaction conditions were determined. After performance testing, the synthesized material has stronger penetrating and pre-wetting ability than common surfactants, and the mechanism of its action was explained based on the molecular characteristics of the material.

Aiming at the “light wind start, light wind power generation” of vertical axis wind turbine, a new T-shaped radial passive magnetic bearing with high suspension characteristics is proposed. Passive magnetic bearings used in vertical axis wind turbines usually have small bearing capacity and difficult magnetization. The new T-shaped radial PMB can improve the radial bearing capacity, and the three magnetic rings all adopt simple axial magnetization. The new T-shaped radial PMB is combined with mechanical auxiliary bearing to form the suspension system of wind turbine. In the stable state, the suspension system can realize radial and axial stable suspension. The structure and working principle of the suspension system are briefly described. Through the finite element simulation, the characteristics of the new T-shaped radial PMB, the traditional double-ring PMB and the T-shaped PMBs are compared. Taking the high bearing capacity and high stiffness of the new T-shaped radial PMB as the optimization objective, the multi-objective optimization of the new T-shaped radial PMB was carried out by changing its geometric parameters (inner diameter, magnetization length and air gap). The research results show that: Under the same bearing capacity, the volume of the new T-shaped radial PMB is reduced by about 78.64%. Under the same volume, its bearing capacity increased by about 30.7%, and its stiffness increased by about 96.1%. After optimization, its radial bearing capacity increased to 101.38 N, and its stiffness increased to 202.76 N/mm.

In recent years, high-performance half-Heusler compounds have been developed as promising thermoelectric materials for power generation. Aiming at practical device applications, one key step is to seek suitable metal electrodes so that low interfacial resistivity is guaranteed under long-term thermal aging. In the previous work, the fresh Mo/Nb

Our theoretical research indicate that the electric field are generated in the direction of (C doped) TiO2 (101) surface to (B-doped) g-C3N4 monolayer for the pristine, C and B doped g-C3N4/TiO2, and higher band-edge potential on the (C doped) TiO2 (101) surface are observed compared to (B-doped) g-C3N4 monolayer. Thus, the pristine (2.591 eV), C-doped (2.663 eV) and B-doped (2.339 eV) g-C3N4/TiO2 are Z-scheme heterostructures, which promotes charge separation and retains a prominent redox ability. After C doping, the C 2p energy level is introduced which facilitate the separation of photoexcited carriers. The B-doped g-C3N4/TiO2 has a reduced bandgap and the mixing of B 2p and N 2p energy levels, promoting the red-shift of the optical absorption edge. The C&B codoped g-C3N4/TiO2 follows type-II charge transfer mode because of their synergistic effect in C and B atoms, which changes the direction of the built-in electric field. It also has a narrow bandgap (1.309 eV) and effectively separate electron-hole pairs leading to strong optical absorption ability in the range of 360 nm–460 nm. The band-edges matching of the semiconductor photocatalyst and the direction of the built-in electric field jointly determine whether the charges are selected to be Z-scheme or II-type transfer mode. Based on g-C3N4/TiO2 for C or/and B (co)doping, their different charge transfer modes have been established and they are expected to show promising photocatalytic water splitting performance.

Cu–Al-based alloys are a kind of new functional material. Due to their unique thermoelastic martensite structure, they have excellent damping performance, which has become a research hotspot in the field of materials science and engineering in recent years. However, the elastic anisotropy and large grain size easily cause a brittle fracture, which is harmful to the mechanical properties of the material. In order to meet the practical needs of engineering, it is an important choice to design Cu–Al-based alloys with excellent mechanical properties and damping performances from the perspective of refining the grain size. When the grain size is small, the effect of fine grain strengthening and interfacial damping can play a role simultaneously to obtain Cu–Al-based alloys with excellent comprehensive properties. In this paper, several common preparation methods of Cu–Al-based alloy are introduced firstly. Then the contributions of researchers in refining grain size from alloying and heat treatment are summarized. Meanwhile, nanomaterials can be used as the reinforcing phase of Cu–Al based alloy, and play a superb role in mechanical properties and damping performances. The purpose of this study is to provide a reference for the further research of structure-function integrated materials with high strength and high damping simultaneously. Finally, the development of Cu–Al-based alloy from the aspects of 3D printing and numerical simulation is prospected.

Pd/CeO2 catalysts show superior catalytic performance owing to their optimal cycling activity and stability. In this study, single-atom Pd and eight-atom Pd nanoparticle clusters were supported on the surface of CeO2(110) to investigate the effect of loaded-metal size on the catalytic performance of the Pd–CeO2 system for CO2 reduction. We investigated the CO2 reduction reaction (CRR) that produces C1 products (CO, HCOOH, CH3OH, and CH4) on Pd8/CeO2 and Pd/CeO2 by density functional theory. The structures, CO2 adsorption configurations, and CO2 reduction mechanisms of these two electrocatalysts were systematically studied. Subsequently, different reduction pathways on Pd8/CeO2 and Pd/CeO2 were investigated to identify the optimal reaction pathway for further assessment. The results showed that both of these catalysts are more selective towards the production of CH3OH than CH4. Moreover, compared to Pd/CeO2 and Pd4/CeO2 (from a previously reported study) the production of CH3OH via the CRR on Pd8/CeO2 exhibited the lowest limiting potential. These results demonstrate the superiority of Pd8/CeO2 as an electrocatalyst for the electrochemical reduction of CO2 to CH3OH.

Metal–organic framework (MOF) materials have been extensively incorporated with inorganic semiconductor photocatalysts to improve their photocatalytic activity through an efficient charge transfer process across their heterointerface. In this work, octahedral UiO-66-NH2 MOFs with edge-lengths of 110–330 nm are uniformly decorated on the surface of TiO2 electrospun nanofibers by a traditional solvothermal method combined with activation pretreatment. Before the solvothermal growth of UiO-66-NH2, the TiO2 electrospun nanofibers were activated in NaOH solution to etch the TiO2 surface for allowing the exposure of lattice oxygen. The exposed lattice oxygen on the TiO2 surface could interact with the MOF precursor of Zr4+ ions, thus enabling octahedral UiO-66-NH2 to grow uniformly on the surface of TiO2 nanofibers with an intimate Ti–O–Zr hetero-interface. Such an intimate hetero-interface provides an effective channel for boosting the electron transfer between UiO-66-NH2 and TiO2 in their heterostructure. Thus, the UiO-66-NH2/TiO2(anatase) heterostructures exhibited enhanced photocatalytic activity for H2 production as compared to either TiO2(anatase) nanofibers or UiO-66-NH2 nanooctahedra in the presence of Rhodamine B (RhB) as a sensitizer under visible light irradiation. In particular, the decoration of UiO-66-NH2 nanooctahedra on anatase/rutile mixed TiO2 nanofibers could induce further enhancement of the photocatalytic H2 production. The enhanced photocatalytic activity is attributed to the multi-step continuous interfacial transfer of photoinduced electrons with the way of RhB → UiO-66-NH2 → TiO2(anatase) → TiO2(rutile).

The instability of metal halide perovskites (MHPs) remains to be one major obstacle for the commercialization of perovskite solar cells. Here we report the observation of nanocrystals and some amorphous phases at the surface of apparent single crystalline grains in polycrystalline films deposited by almost all known solution deposition methods, which accelerate the degradation of MHPs. By removing the defective surface layer through mechanical polishing, the stability of perovskite films is significantly enhanced. Encapsulated solar cells based on polished MHPs retain 93% of their initial efficiency after continuous illumination for 2180 hours at 1 sun intensity and with ultraviolet radiation at 65 °C. Removing the defective surface layers restores the mechanical hardness to be comparable to that of single crystals, which suppresses ion migration and permeation of detrimental species into perovskite grains. This study narrows down the stability gap between the MHP polycrystalline films and single crystal perovskites which represents the upper limit for the stability of MHPs.

A systematic theoretical research on the geometrical, electronic, optical, charge transfer, and photocatalytic mechanisms of pure, Cr-doped, B-doped, and (Cr, B) codoped g-C3N4/BiVO4 heterostructures using a hybrid density functional approach has been carried out. The face-to-face g-C3N4/BiVO4 composed of two-dimensional materials of g-C3N4 and BiVO4 (010) surface, can introduce a built-in electric field, which promotes interface charge transfer and prevents the electron-hole pair recombination, and causing g-C3N4 monolayer with negative charge and BiVO4 (010) surface with positive charge. Under visible light irradiation, electrons are excited to the conduction band minimum (CBM) of the BiVO4 (010) surface undergoing the hydrogen evolution reaction (HER), while the holes remain in the valence band maximum (VBM) of g-C3N4 monolayer aiding the oxygen evolution reaction (OER). The band edge potentials of BiVO4 (010) surface is higher than that of g-C3N4 monolayer, which ensures a stronger redox reaction potential and therefore belongs to a typical Z-scheme heterostructure. In addition, the Cr or/and B (co)doping introduces the Cr-3d or/and B-2p states to reduce the bandgap and generate impurity levels, thus enhancing solar energy utilization rate and expanding the optical absorption in the visible-light range. The optical absorption intensity of the (Cr, B) codoped g-C3N4/BiVO4 is superior to pure and Cr or B doped g-C3N4/BiVO4, confiriming the synergistic effect of Cr-3d and B-2p states. Thus, this research is helpful to design a novel and potential Z-scheme photocatalyst useful for the photocatalytic water splitting.

A small energy gap between charge transfer (CT) singlet and triplet states enables thermally activated delayed fluorescence (TADF). Nevertheless, the small oscillator strength associated with CT states and their long exciton lifetimes are detrimental to establishing a population inversion for stimulated emission (SE), hindering the application of a TADF material in organic lasers. Here, we demonstrated that a TADF molecule of sulfide-substituted difluoroboron derivatives can achieve stimulated emission in microcrystals by employing a new molecular design, in which an ultrafast reverse intersystem crossing (RISC) process was achieved between a hybrid locally excited CT (HLECT) singlet S1 and a high-lying triplet T2 (3HLECT) state. Femtosecond transient abaorption and time-reolved PL spectra reveal that the two states of S1 and T2 equilibrate within a time of 180 ps. In addition, the energetic spacing of ΔES1–T2 = 0.11 eV enables delayed fluorescence involving the T2 state at room temperature. Besides, the extremely fast exciton lifetime (0.31 μs) that decreases the probability of carrier annihilation, the HLECT singlet provides larger oscillator strength and therefore larger SE cross-section than those of the CT state. A multimode TADF laser was realized based on the good optical feedback (cavity quality factor Q ≈ 2000) provided by Fabry Perot (FP) microcrystal microcavity. Our results not only confirm that the high-lying Tn state plays a key role in the RISC process of TADF, but also provides a design of TADF gain materials.

High-entropy alloys (HEAs) have become a research focus because of their easy access to nanostructures and the characteristics of high strength, hardness, wear resistance, and oxidation resistance, and have been applied in aerospace lightweight materials, ultrahigh temperature materials, high-performance materials, and biomimetic materials. At present, the study of HEAs mainly focuses on the microstructure and mechanical properties. HEAs of Mo, Ti, V, Nb, Hf, Ta, Cr, and W series have high strength, while HEAs of Fe, Co, Ni, Cr, Cu, and Mn series have good toughness. However, the emergence of medium-entropy alloys, metastable HEAs, dual-phase HEAs, and multiphase HEAs increased the complexity of the HEA system, and the phase transition mechanism and strengthening and toughening mechanisms were not fully established. In this article, the preparation, phase formation, phase transformation as well as strengthening and toughening mechanisms of the HEAs are reviewed. The inductive effects of alloying elements, temperature, magnetism, and pressure on the phase transformation were systematically analyzed. The strengthening mechanisms of HEAs are discussed, which provides a reference for the design and performance optimization of HEAs.

Porous polymeric support membranes with outstanding organic solvent resistance are highly required for fabricating thin-film composite (TFC) organic solvent nanofiltration (OSN) membranes. In this ...

Summary The presence of a defective layer composed of nanocrystals and amorphous regions at the surface of perovskite films has been shown to initialize the degradation of perovskites and cause nonradiative recombination. Here, we report the discovery that these defective surface layers are mechanically softer than the crystalline regions. The defective surface layer has a weaker bonding with the crystalline layer underneath it, which enables a facile approach to mechanically peel-off these defective layers using adhesive tapes. The chosen low-cost tape has an appropriate bonding force with perovskites, so the peeling does not damage the crystalline region and embedded interfaces underneath. The tape-treated devices retained 97.1% of the initial efficiency after operation at the near maximum power point under one sun illumination for 1,440 h at 65°C. This method is universally effective in enhancing the stability of various commonly used perovskite compositions and is compatible with the scaling up of perovskite solar modules.

Covalent organic framework (COF)-based membranes are burgeoning candidates for separation technologies owing to their well-ordered channel structures. The exponential interest in the stability of the COF membrane on exposure to harsh organic solvents is directed to develop a composite membrane for dye separations in polar aprotic solvents. Here, we reported a nanocomposite membrane composing of a single-walled carbon nanotube (SWCNT)/COF (an imine-based COF) hybrid on a commercial polytetrafluoroethylene (PTFE) substrate, with a thickness of ∼58 nm prepared in a diffusion cell. This membrane displayed high permeability and stability toward nonpolar and aprotic solvents. It exhibited high permeability for lower viscous organic solvents such as hexane (66 L m

In the pipeline transportation process for crude oil, the most important and popular maintenance method for perforated and ruptured oil pipelines is the replacement of the damaged pipeline segment. However, this method has several disadvantages, including a complex process, large time consumption, and excessively high costs. The present study reported the preparation of a strong cross-linking hydrogel that served as a temporary blocking material during the long-distance oil pipeline partial replacement process. The prepared product was characterized by infrared spectroscopy, X-ray diffraction analysis, and scanning electron microscopy to analyze the microscopic reactions and structures. Orthogonal experiments for shear stress were performed to determine the optimal synthesis condition. The relevant experiments indicated that the proposed product can effectively isolate oil and oil gas, and a 4.5 m long hydrogel can resist the force of a 0.57 MPa overpressure. The blocked pipeline turned to a dredged state on changing the pipeline pressure. The flame resistance experiment showed that the hydrogel exhibited excellent flame resistance and could therefore ensure the safety of the hot work. On the basis of this hydrogel material, a new method for replacing the partially damaged oil pipeline was proposed.

A visible light-driven Cu3SnS4/rGO (CTS/rGO) composite photocatalyst was prepared using ball milling (B) and solvothermal (S) method. CTS prepared by both the methods was preferentially oriented along the (1 1 2) plane exhibiting a tetragonal structure. The SEM image indicates an irregular structure and flower-like appearance in the morphology of CTS samples prepared by ball milling and solvothermal process, respectively. The impact on the morphological structure of CTS by incorporating rGO in both the methods of preparation has been analysed. UV–vis-DRS shows that the incorporation of rGO effectively influences the light response performance of the composite material in visible light. The photoluminescence (PL) spectra reveal that the composite photocatalyst can either effectually detach the electron–hole pairs and curtail their recombination or enhance the recombination based on the method of preparation owing to the phase purity of the prepared sample. Degradation of the model pollutant methylene blue (MB) was used to study the photocatalytic activity of the samples. The influence of rGO incorporation on the functioning of CTS as a photocatalyst has been studied. The species trapping experiments depicted the prominent role of h+ active species in the photocatalytic degradation of MB. The mechanism of photocatalysis in the presence of CTS/rGO has been discussed in detail.

Spark plasma sintering (SPS) is a powerful technique for consolidating metal powders at a remarkably shorter time with excellent quality. We used this technique for sintering nanocrystalline WC10Co powders and simultaneously bonding with high-strength steel. A series of experiments were conducted in order to find out the optimised set of SPS controlling parameters. The effects of temperatures (1000 to 1150 °C, with a 50 °C interval) in sintering nanocrystalline WC10Co powders and their bonding phenomena with AISI4340 steel were examined at a constant pressure of 80 MPa and a holding time of 5 min. The full density of the carbide powders was achieved at a lower temperature compared with that of conventional techniques. A number of techniques were employed to evaluate the microstructural characteristics of WC and steel bilayered composite and their mechanical properties. For determining the bonding strength of the joint, a novel micro-tensile testing system was adopted. Since such investigation is the first of its kind, to the best knowledge of the authors, where SPS is used to join the tungsten carbide with the steel, this research is expected to provide a valuable future reference for fabricating dissimilar bilayered composite materials.

Summary Controlling of doping in semiconducting light absorber can minimize the charge recombination and maximizing power output from solar cells; however, it is challenging for perovskites due to lack of controlled doping. Here, we report that a short post-annealing of less than 3 min for facilitating high-throughput manufacturing of perovskite solar modules in an ambient environment maintains the stoichiometric composition of perovskites, encouraging a spontaneous de-doping of perovskites during aging. The reduced self-doping results in less charge recombination and, thus, higher device efficiency. The stabilized open-circuit voltage of sub-cells in the CH3NH3PbI3 minimodules with an area >20 cm2 reaches 1.19 V on average. The aperture efficiency reaches 17.8% under one sun and 18.7% under a quarter sun illumination, deriving an averaged efficiency >20.0% for each sub-cell with an area >3 cm2, demonstrating the excellent uniformity of the films by this scalable process. The minimodule also works as uniform light-emitting devices.

In this work, α-Al2O3 whisker reinforced Cu-graphite matrix composites were prepared by spark plasma sintering. Results show that the surface modification of α-Al2O3 whiskers with sodium dodecyl sulfate solution can improve its dispersibility, and the composites obtained are basically completely dense. The relative density of all composite materials is above 95%. The interface bonding mode in the composite is mainly mechanical bonding, and the formation of a diffusion layer is also observed from interfaces. With the increase of α-Al2O3 whisker content, mechanical properties of the composites increase first and then decrease. The composite with 1.0 wt% α-Al2O3 whisker has the best performance. The corresponding relative density, hardness and compressive strength are 96.35%, 56.20 HV, 139.12 MPa, respectively. By analyzing microstructure and fracture morphology of the composites, it is determined that the strengthening mechanisms are mainly fine grain strengthening, particle strengthening and load transfer. Simultaneously, the fracture type is brittle fracture., This work was supported by Key Laboratory of Infrared Imaging Materials and Detectors, Shanghai Institute of Technical Physics, Chinese Academy of Sciences (No.IIMDKFJJ-19-08) and China Postdoctoral Science Foundation (No. 2015M570794, No. 2018T110993).

The soft nature of metal halide perovskites makes them potentially applicable as flexible X-ray detectors. Here we report a structure of perovskite-filled membranes (PFMs) for highly sensitive, flexible and large-area X-ray detectors. PFMs with areas up to 400 cm2 are formed by infiltrating saturated perovskite solution through porous polymer membranes followed by hot lamination. The good connectivity and crystallization of perovskite crystals in the membranes enable a large mobility–lifetime product. The sensitivity of the X-ray detectors under a field of 0.05 V µm−1 reaches 8,696 ± 228 µC Gyair−1 cm−2 and shows no degradation after storage for over six months and exposure to a dose of 376.8 Gyair, equivalent to 1.88 million chest X-ray scans. The flexible PFMs can be bent at radii down to 2 mm without losing performance. The stand-alone detector array is curved and put inside metal pipes for the detection of material defects with imaging quality superior to flat-panel detectors. Perovskite-filled-membranes enable flexible, sensitive and large-area X-ray detectors. The structures are made by infiltrating perovskite solution into porous polymer membranes.

The efficiencies of all-perovskite tandem devices are improving quickly. However, their complex interconnection layer (ICL) structures—with typically four or more layers deposited by different processes—limit their prospects for applications. Here, we report an ICL in all-perovskite tandem cells consisting merely of a fullerene layer and a SnO2–x (0

© 2020, © 2020 Informa UK Limited, trading as Taylor & Francis Group. In this study we examined the effects of compaction pressure for bonding nanocrystalline cemented tungsten carbide (WC-10Co) and high-strength steel (AISI4340) and successfully fabricated a bilayered composite of ceramic and steel. The obtained results were compared with our previous studies, and then the optimised sintering conditions were suggested. The compaction pressure examined varied from 120–200 MPa at 1150°C for 20 min. The study shows that the change in experimental parameters has significant effects on both the sintering properties of nanocrystalline WC-10Co powders and their bonding with AISI4340 steel. The microstructure reveals a successful metallurgical bonding between ceramic and steel. Bonding temperature determines, to a great extent, the diffusion processes across the bonding interface and has found to be the most influential variable compared to sintering time and compaction pressure. The obtained average maximum bonding strength of the bimetal composite is 226 MPa, which is higher than that of previous studies.

In this study, nonequiatomic Co28.5Cr21.5Fe20Ni26Mo4 medium-entropy alloys (MEAs) were prepared using hot isostatic pressing. The effect of annealing heat treatment on microstructure and mechanical properties of MEAs was investigated. The results showed that the microstructure of as-sintered alloys was mainly composed of the face-centered cubic (FCC) phase and μ phase. The presence of the μ phase could improve the compressive strength of Co28.5Cr21.5Fe20Ni26Mo4 MEAs. Meanwhile, the ductile FCC phase matrix could effectively suppress the propagation of cracks to improve its ductility. Hence, as-sintered MEAs possessed excellent compression properties, and the average compressive strength value was 2,606 MPa when the strain was 50%. Compared with as-sintered MEAs, the phase composition of as-annealed MEAs did not change. The micro-hardness of annealed MEAs was stable compared to as-sintered MEAs (342 HV), and its fluctuation was about ±30 HV. The compressive strength of the annealed MEAs did not alter greatly, and the maximum fluctuation value was only about 6.5%. Hence, Co28.5Cr21.5Fe20Ni26Mo4 MEAs had excellent thermal stability.

Low on/off ratio gravely hinders the application of magnetoresistance (MR) devices for the accurate and reliable data fetch. In this paper, a rectified tunnel MR (R-TMR) device is fabricated by integrating perpendicular-magnetic-anisotropy magnetic tunnel junction (PMA MTJ) and Schottky diode. High on/off ratio, intrinsic non-volatility and multi-dimensional regulation capabilities can be obtained, which makes this emerging spintronic device suitable for in-memory computing (IMC). By reversing the rectifying direction of the diode and tuning the proportions of alternating current (AC) and direct current (DC), reconfigurable logic operations have been achieved. Two proofs of concept, i.e. “NOR” and “NAND”, are experimentally performed.

Direct detection of drugs in the blood contributes to the study of pharmacokinetics, whereas low-concentration blood drug makes this goal challenging. Here, silver nanoparticles (AgNPs) are used fo...

The enhancement of the breakdown power during the spark discharge process has been proved to be beneficial for the flame kernel formation process under lean/diluted conditions. Such a strategy is realized by using a conventional transistor coil ignition system with an add-on capacitance in parallel to the spark plug gap in this paper. In practical application, the use of different ceramic material other than aluminum oxide can change the parasitic capacitance of the spark plug, achieving similar effect in terms of rescheduling the discharge energy released during the breakdown phase. Detailed research has been carried out to investigate the effect of the parallel capacitance and the cross flow velocity on the flame kernel formation and propagation process. With the increase in parallel capacitance, more spark energy is delivered during the breakdown phase, while less energy is released during the arc/glow phase. Shadowgraph images of the spark plasma reveal that the high-power spark discharge can generate a larger high-temperature area with enhanced electrically prompted turbulence under quiescent conditions, as compared with that using the conventional transistor coil ignition discharge strategy under the same condition. The breakdown enhanced turbulence of the high-power spark is proved to be beneficial for the flame kernel development, especially with the lean or exhaust gas recirculation diluted combustible mixtures, given that sufficient spark energy is available for the high-power spark strategy to successfully generate the breakdown event. The results of combustion tests under flow conditions reveal that the breakdown enhanced turbulence of the high-power spark tends to be overshadowed by the turbulence generated from the flow field, and both the increase in flow velocity and parallel capacitance contribute to the reduction in discharge duration of the arc/glow phase. Therefore, the benefits brought about by the high-power spark discharge tend to diminish with the intensification of flow velocity.

The influences of combined torsion-tension deformation on the microstructural evolution and corrosion resistance of 316L stainless steel were investigated. The microstructure and corrosion behavior of the deformation samples were studied in detail. The results showed that the grains were more significantly refined under combined deformation than under tensile deformation. However, further increase in pre-torsion led to little change in grain size. The results of transmission electron microscopy and corrosion tests results indicated that high-density dislocations were detrimental, whereas the corrosion resistance, grain refinement and deformation twins were beneficial to corrosion resistance. Furthermore, the effect of deformation twins on corrosion resistance was greater than that of dislocation density, which, in turn, was greater than the influence of grain size.

To address the low gas sensitivity of pristine graphene (Gr), chemical modification of Gr has been proved as a promising route. However, the existing chemical functionalization method imposes the u...

Summary Integrating perovskites onto textured silicon provides a pathway to 30% tandem solar cells. However, deposition of 0.5–1 μm thick perovskite layers from solution onto textured silicon with typical pyramid heights of 3–10 μm remains a challenge. We propose a new tandem architecture that enables scalable, solution-based blading of perovskites onto silicon wafers textured with pyramids less than 1 μm in height. These pyramids are rough enough to scatter light within the silicon nearly as efficiently as large pyramids but smooth enough to solution-process a perovskite film. A nitrogen-assisted blading process deposits both a conformal hole transport layer and a planarizing perovskite layer that fully covers the textured silicon, at a speed of 1.5 m/min. With a textured light-scattering layer added to the top of the tandem to reduce front-surface reflectance, we achieve a perovskite/silicon tandem cell with an efficiency of 26% on textured silicon.

Separating molecules or ions with sub-Angstrom scale precision is important but technically challenging. Achieving such a precise separation using membranes requires Angstrom scale pores with a high level of pore size uniformity. Herein, we demonstrate that precise solute-solute separation can be achieved using polyamide membranes formed via surfactant-assembly regulated interfacial polymerization (SARIP). The dynamic, self-assembled network of surfactants facilitates faster and more homogeneous diffusion of amine monomers across the water/hexane interface during interfacial polymerization, thereby forming a polyamide active layer with more uniform sub-nanometre pores compared to those formed via conventional interfacial polymerization. The polyamide membrane formed by SARIP exhibits highly size-dependent sieving of solutes, yielding a step-wise transition from low rejection to near-perfect rejection over a solute size range smaller than half Angstrom. SARIP represents an approach for the scalable fabrication of ultra-selective membranes with uniform nanopores for precise separation of ions and small solutes., Separating molecules or ions with sub-Angstrom scale precision is important but technically challenging. Here, the authors demonstrate that precise solute-solute separation can be achieved using polyamide membranes formed via surfactant-assembly regulated interfacial polymerization.

Mapping perovskite trap states The high efficiency of hybrid inorganic-organic perovskite solar cells is mainly limited by defects that trap the charge carriers and lead to unproductive recombination. Ni et al. used drive-level capacitance profiling to map the spatial and energetic distribution of trap states in both polycrystalline and single-crystal perovskite solar cells. The interface trap densities were up to five orders of magnitude higher than the bulk trap densities. Deep traps were mainly located at the interface of perovskites and hole-transport layers, where processing created a high density of nanocrystals. These results should aid efforts aimed at avoiding trap-state formation or passivating such defects. Science , this issue p. 1352