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The regulation of interface electron-transfer and catalytic kinetics is very important to design the efficient electrocatalyst for alkaline hydrogen oxidation reaction (HOR). Here, we show the Pt-Ni alloy nanoparticles (PtNi2) have an enhanced HOR activity compared with single component Pt catalyst. While, the interface electron-transfer kinetics of PtNi2 catalyst exhibits a very wide electron-transfer speed distribution. When combined with carbon dots (CDs), the interface charge transfer of PtNi2-CDs composite is optimized, and then the PtNi2-5 mg CDs exhibits about 2.67 times and 4.04 times higher mass and specific activity in 0.1 M KOH than that of 20% commercial Pt/C. In this system, CDs also contribute to trapping H+ and H2O generated during HOR, tuning hydrogen binding energy (HBE), and regulating interface electron transfer. This work provides a deep understanding of the interface catalytic kinetics of Pt-based alloys towards highly efficient HOR catalysts design.

Development of low-cost electrode materials with long cycle life and high volumetric capacity is important for large-scale applications of lithium-ion batteries (LIBs). Here, an electrode made from Fe2O3 encapsulated with N-doped carbon (Fe2O3@N-C) via ZIF-8 coating and carbonization process is reported. A cavity was generated between the Fe2O3 and N-C material during the carbonization process that is conducive to alleviating the volume expansion of Fe2O3. As a result, the Fe2O3@N-C composite exhibits a high specific capacity (1064 mAh/g at 0.1 A/g) and cycle stability (803.6 mAh/g at 1.0 A/g after 1100 cycles) when used as the LIB anode. In addition, the influence of carbonization under air on the LIB performance was investigated by controllably changing the crystal phase of Fe2O3 and the thickness of the carbon layer. This work provides a new method for the design and fabrication of yolk-shell composite electrodes for LIBs and other applications.

The dynamic behavior of electron-hole pairs at the interface of the nanocomposites is important for photoelectrochemical catalysis, but it is difficult to characterize. Here we construct a ternary titanium dioxide/nitrogen-doped carbon dot/gold (TiO2/NCD/Au) complex as the model catalyst to investigate the kinetic indexes at their interfaces. Under irradiation (200 mW cm−2), the photocurrent density of TiO2/NCD/Au is 10.26 mA cm−2, which is higher than those of TiO2/Au (4.34 mA cm−2), TiO2/NCD (7.55 mA cm−2) and TiO2 (3.34 mA cm−2). The evolved oxygen of TiO2/NCD/Au reaches 125.8 μmol after 5000 s test. The energy bands of complexes are very similar to that of the unmodified TiO2 catalyst due to the low content modification of NCDs and Au. In addition, the transient photovoltage (TPV) tests with a series of control samples show differences about the carriers’ separation and transfer process, which verify that Au can increase the separation quantity of electron-hole pairs while NCDs play a more important role on the increase of the separation quantity and separation rate simultaneously. This work quantifies the function of each component in a composite catalyst and deepens the understanding of the catalyst interface design.

The fault devices induced by device breakdown (BD) are unavoidable due to defect formation during fabrication or along with device cycling stress. The BD cells not only deteriorate device yield, but they also introduce sneak current and result in cell-to-cell interference in the high density crossbar array, which further produces severe array yield loss. Although the BD interference is important, methods of alleviation is less discussed. In this work, we evaluate the strategy of mitigating the strong interference between normal cells and leaky BD cells. We show that while a sufficiently high device yield is the prerequisite, optimizing cell parameters such as resistance of the BD cell and line resistance are proven crucial. However, the yield loss induced by BD interference is not easily compensated using naive redundancy designs. Therefore, a careful optimization on array partition is thus required. We show that with a device yield of 99% and a total memory capacity of megabits, partitioning into a smaller array size (

This paper reports a comprehensive investigation on the tensile behavior of FRP bar butt joints built with new FRP sleeves. The simplified bond-slip constitutive relationship between FRP bars and bonding medium was firstly established by using the existing research results. Based on five proposed assumptions, the stress–strain analysis of the FRP bar butt joint was performed on the FRP bar, bonding medium and sleeve under tensile load. The bond-slip behavior and the shear force between FRP bars and bonding medium were discussed in detail. According to the stress–strain analysis, the key design parameters of the FRP sleeve and the anchor length of FRP bars were determined, which is also verified by comparing test data. According to the design parameter and anchor length, two types of FRP sleeves with two different internal structures and lengths were designed, and then these FRP sleeves were made of GFRP by professional manufacturers. In addition, the axial tensile tests were conducted on a total of 10 BFRP bar butt joints, GFRP bar butt joints and CFRP bar butt joints which are connected by the proposed GFRP sleeves. Based on the test results, the failure modes of various FRP bar butt joints built with GFRP sleeves were observed, and the corresponding tensile load–displacement curves, maximum tensile load and strain were analyzed. Finally, it is found that all fractures occur on the connected FRP bars instead of the GFRP sleeves, which indicates that various FRP bars can be effectively connected by the two types of GFRP sleeves. The load–displacement curves of the GFRP sleeves exhibit a small linear elastic deformation before the FRP bars rupture. The maximum elongated length of the GFRP sleeves is only 13% of the maximum tensile displacement of FRP bar butt joints uner tensile load, while the maximum circumferential strain of GFRP sleeves is about 41.72% of their corresponding longitudinal strain.

AlSn20Cu alloy is currently one of the most widely used bearing materials, and its microstructure is the most important indicator in application. In this paper, AlSn20Cu alloy ingots were prepared by two methods: ordinary casting and semi-continuous casting, and deformation and annealing process of the two ingots were studied. Scanning electron microscope (SEM) and Image Pro Plus software were used to observe and analyze the evolution of the microstructure, and the morphological information such as the average grain size and area fraction of the Sn phase was quantitatively characterized. The effects of casting method, deformation temperature, deformation amount and annealing temperature on the morphology of Sn phase were studied in this paper. Compared with ordinary casting, the cooling rate of semi-continuous casting is higher, so the Sn phase is smaller, the casting defects are less, and the deformability of the alloy is better. The AlSn20Cu alloy prepared by ordinary casting has better deformability at about 140 °C, while the AlSn20Cu alloy prepared by semi-continuous casting can be rolled and deformed at room temperature. When the deformation is greater than 40%, after annealing at 250 °C, the average grain size of the Sn phase in the AlSn20Cu alloy prepared by semi-continuous casting is around one hundred square microns and the area fraction is more than 10%, and the Sn phase morphology is better than ordinary casting alloy under any processing conditions.

Silicon is considered as an ideal anode material for the next generation of lithium-ion batteries (LIBs) owing to its high specific capacity, low lithiation potential, and high natural abundance. H...

Al-Mg-Mn-Er-Zr alloy, produced through a combination of cold rolling and heat treatment process conditions, has been studied on its microstructure evolution, strengthening mechanism, and corrosion properties. The results demonstrated that, the dispersion of coherent Al3 (Er, Zr) nanoscale particles effectively pinned dislocations and increased the strength. The dislocation strengthening was considered as the primary strengthening method for Al-Mg-Mn-Er-Zr alloy. The β phase was preferentially precipitated at the grain boundary and the tip of the Al6Mn phase during annealing. The corrosion resistance of stabilized alloys was degraded after cold rolling, which can be attributed to the increase in the proportion of sub-grain stripe and high-angle grain boundaries. The alloy prepared by the process (50% deformation + 270 ˚C/4 h annealing + 10% deformation) exhibited a UTS of 434 MPa and a YS of 323 MPa; the degree of sensitization was quantified by the ASTM G67 test and the susceptibility to intergranular corrosion was in unsusceptible categories; this alloy thus achieves excellent mechanical properties and presents sufficient corrosion resistance.

Yb3+/Tb3+/Ho3+ tri-doped phosphate glasses with a chemical composition (in mol %) of 20Na2O–42ZnO–28P2O5–10B2O3 were combined by the conventional melt quenching technique. The physical properties, glass network structure, transmittance spectrum, up-conversion (UC) emission spectra, energy transfer mechanism, and chromaticity change of the prepared glasses were systematically studied. The UC emission spectra results show that the strongest UC luminescence is observed for 2.0Yb3+/1.0Tb3+/0.15Ho3+ (mol %) composition. When Yb3+ ions as sensitizer, the energy transfer of Ho3+ → Tb3+ ions happens. The physical properties indicate that the Yb3+, Tb3+, and Ho3+ ions are beneficial for a compact glass structure. It can be observed that the glasses have a strong light transmittance in the visible range, and its light transmittance is about 90%. Furthermore, Yb3+/Tb3+/Ho3+ tri-doped phosphate glass materials have better thermostability and chroma stability, these findings have significant implications for the use of advanced solid-state lighting.

The low power loss Mn-Zn ferrites with fine grains were developed by the low-temperature-sintering ceramic process for power applications at a high frequency of 1 MHz. The LiBO2 sintering aid was added to promote the low temperature sintering and densification. The effects of LiBO2 on micromorphology and magnetic properties of the sintered Mn-Zn ferrites were investigated. With the aid of LiBO2, sintering temperature could be reduced as low as 990 °C. The optimum sample was obtained by the addition of 500 ppm LiBO2 sintered at 1020 °C. The average grain size of this sample is 2.78 μm, the density reaches 4.82 g/cm3, and the minimum power loss is 310 kW/m3 at 1 MHz/30 m T and 25 °C. This sample shows good wide-temperature stability of power loss. The mechanism of power loss affected by the LiBO2 addition was also discussed. The ceramic sintering process combining the low temperature sintering and the sintering aid offers a new way to develop high-frequency Mn-Zn ferrites.

To understand the overpressure transient and flame behavior of CH4/air premixed gas explosion venting in the presence of porous materials, a series of explosion venting tests is conducted in a sphe...

The photocatalytic conversion of organic wastewater into value-added chemicals is a promising strategy to solve the environmental issue and energy crisis. Herein, Co/In2O3 nanotubes with a double-shell structure, as a highly efficient photocatalyst, are synthesized by a one-step calcination method. The Co/In2O3 heterostructure shows an outstanding photocatalytic CO2 reduction performance of 4902 μmol h-1 g-1. Notably, these Co/In2O3 photocatalysts also achieve CO2 self-generation and in situ reduction conversion in acid organic wastewater (phenol solution), in which the high CO2 (47.5 μmol h-1 g-1) and CO (0.9 μmol h-1 g-1) evolution rates are demonstrated under solar irradiation. Transient photovoltage (TPV) tests demonstrate that Co nanoparticles on Co/In2O3 double-shell heterostructure serve as the CO2 reduction sites for the effective capture and stabilization of the photogenerated electrons.

Based on the free volume theory, lattice model, the Scatchard–Hildebrand theory, novel expressions of configuration partition function and excessive Gibbs free energy and component activity coefficients of solid solutions were developed using configuration partition function and statistical thermodynamics of molecular interaction volume model (MIVM). Herein, the separation of the volume and energy parameters was achieved. The proposed model can reflect the contributions from both the molecular configuration micro-state number (entropy) and molecular interactions (enthalpy) toward excessive Gibbs free energy. The proposed equations are more consistent with the practical solid solutions. This model can use either the relevant binary infinite dilution activity coefficients or binary activity to describe and predict the thermodynamic properties of the multi-component solid solutions. Applications of the proposed model in some typical binary and ternary solid solution alloys revealed that the thermodynamic properties predicted by the proposed model were consistent with the experimental data and the proposed model was found to be superior to MIVM in terms of the prediction performance. Hence, it can be concluded that the proposed model exhibits good physical basis, applicability, stability and reliability.

Silver selenide, Ag2Se, is a promising low-temperature thermoelectric material which can be used to harvest the low-quality waste heat for electrical power generation or cool the microelectronics. Currently, the investigation on Ag2Se and its derivatives has become a hot topic in the thermoelectric community, but the thermoelectric properties of Ag2Se below 300 K have been rarely investigated. In this study, we prepared Ag2Se by using the zone-melting method. The electrical and thermal transport properties of zone-melted Ag2Se from 5 to 380 K were systematically investigated and compared with the previously reported data of Ag2Se and other typical low-temperature thermoelectric materials, such as Mg3Bi2, Bi2Te3, and BiSb. Ag2Se shows intrinsic semiconductor features, ultrahigh carrier mobility, small density-of-state effective mass, and ultralow lattice thermal conductivity. At 300 K, the zT of zone-melted Ag2Se is 0.75. This study will shed light on the further investigation of Ag2Se.

Photocatalytic hydrogen production by overall water solar-splitting is a prospective strategy to solve energy crisis. However, the rapid recombination of photogenerated electron-hole pairs deeply restricts photocatalytic activity of catalysts. Here, the in-situ transient photovoltage (TPV) technique was developed to investigate the interfacial photogenerated carrier extraction, photogenerated carrier recombination and the interfacial electron delivery kinetics of the photocatalyst. The carbon dots/NiCo2O4 (CDs/NiCo2O4) composite shows weakened recombination rate of photogenerated carriers due to charge storage of CDs, which enhances the photocatalytic water decomposition activity without any scavenger. CDs can accelerate the interface electron extraction about 0.09 ms, while the maximum electron storage time by CDs is up to 0.7 ms. The optimal CDs/NiCo2O4 composite (5 wt.% CDs) displays the hydrogen production of 62 µmol·h−1g−1 and oxygen production of 29 µmol·h−1g−1 at normal atmosphere, which is about 4 times greater than that of pristine NiCo2O4. This work provides sufficient evidence on the charge storage of CDs and the interfacial charge kinetics of photocatalysts on the basis of in-situ TPV tests.

Purpose The corrosion of buried steel pipelines is becoming more serious because of stress corrosion, stray current corrosion and other reasons. This paper aims to study the various alternating current (AC) interference densities on the stress corrosion cracking behaviors of X80 steel samples under cathodic protection (CP) in the simulated soil electrolyte environment by using an electrochemical method. Design/methodology/approach The change of corrosion rate and surface morphology of the X80 steel samples at various AC current densities from 0 to 150 A/m2 or CP potential between −750 and −1,200 mV in the soil-simulating environment was revealed by the electrochemical methods and slow strain rate testing methods. Findings The results revealed that with the increase of interference density, the corrosion potential of the X80 steel samples shifted to the negative side, and the corrosion pitting was observed on the surface of the sample, this may cause a danger of energy leak. Moreover, the corrosion rate was found to follow a corresponding change with the stress–strain curve. Besides, with the introduction of the CP system, the corrosion rate of the X80 steel working electrode decreased at a low cathodic potential, while showed an opposite behavior at high cathodic potential. In this study, the correlation between AC stray current, cathodic potential and stress was established, which is beneficial to the protection of oil and gas pipeline. Originality/value Investigation results are of benefit to provide a new CP strategy under the interference of AC stray current corrosion and stress corrosion to reduce the corrosion rate of buried pipelines and improve the safety of pipeline transportation.

Two novel low-er gallates MGa2O4 (M = Ca, Sr) have been synthesized via a standard solid-state reaction method. According to the X-ray diffraction results, CaGa2O4 crystallizes in space group Pna21 with an orthorhombic symmetry, while SrGa2O4 belongs to the monoclinic P21/c system. Both ceramics show ever-improving microstructures with the increasing sintering temperature. The optimal microwave dielectric properties (er = 9.2, Qf = 66,000 GHz, τf =–85 ppm/°C for SrGa2O4 and er = 10.6, Qf = 15,400 GHz, τf =–58 ppm/°C for CaGa2O4) are obtained when sintered at 1275 °C. A patch antenna is fabricated using SrGa2O4 ceramics as the substrate, which realizes a return loss of –19.94 dB and total efficiency of –1.38 dB (72.8 % in power ratio) at 4.84 GHz. The exceptional performances indicate that SrGa2O4 ceramics are promising candidates for antenna applications at the Sub-6 GHz band.

The large-scale application of Zn-air battery requires the development of efficient, low-cost, and stable bifunctional electrocatalysts for the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR). Herein, an electrocatalyst of a Co/MoC-nanoparticles embedded N-doped carbon (Co/MoC@N-C) was prepared via the in-situ encapsulation of Co2(CO)8 and Mo(CO)6 in ZIF-8 using ball-milling, followed by pyrolysis under an Ar atmosphere. When used as a bifunctional electrocatalyst, the as-prepared Co/MoC@N-C showed an ORR half-wave potential of 0.824 V in an alkaline medium and an overpotential of only 290 mV for the OER at 10 mA cm−2, which was 70 mV lower than RuO2. The Co/MoC@N-C was also evaluated as a cathode in a solid-state Zn-air battery and delivered a higher peak discharge power density and better cycling stability (over 1600 min) than Pt/C-RuO2. Most importantly, our work provides a new strategy to prepare bifunctional catalysts and promotes their applications in the energy conversion field.

The rapid development of electronic devices such as organic field-effect transistors (OFETs) and solar cells makes the research and development of electronic transport materials imminent. The acceptor–acceptor-type (A−A-type) conjugated n-type polymer semiconductors have caught much attention due to the outstanding advantages on excellent electron-accepting capabilities, the precise adjustment of energy levels and the mass production at low fabrication cost. This article systematically reviews the polymerization methods of A−A-type polymers and the recent advancements applied in OFETs and polymer solar cells (PSCs). The analyses of the synthesis and the relationship between device performances and polymer molecular structures may provide a constructive guidance for the further development of high-performance n-type polymer materials.

In this study, the critical condition of serrated chip formation of 42CrMo quenched and tempered steel considering thermal-mechanical coupled material behavior was studied. It was found that the balance of the strain strengthening and temperature softening of the materials dominated the mechanism of different types of chip formation. Thus, the material constitutive model of 42CrMo quenched and tempered steel considering the items of strain strengthening and temperature softening was established by the Split Hopkinson Pressure Bar (SHPB) tests. The initial condition and final condition for the tooth generation of serrated chips were derived by using the material constitutive model, combining with slip line theory which was used to calculate the local stress. It was found that the critical plastic strain of the serrated chip formation under the different cutting speeds was almost constant. The final strain of the serrated chip formation gradually increased with the increase of cutting speeds. Therefore, the chip types under different cutting conditions could be predicted according to the proposed mathematical model in this study.

Cold sintering is adopted to pre-densify LiF ceramics, where the relative density increases significantly from 72.1 % at 125 MPa to 88.9 % at 500 MPa. The following post-annealings at 800 °C lead to further optimizations of densification, and near-full densifications with relative densities of 95.6 % and 97.6 % are achieved at 375 and 500 MPa, respectively. Qf value increased with increasing uniaxial pressure until it reaches the maximum value of 134,050 GHz at 375 MPa, which is 1.82 times higher than that via conventional sintering (73,800 GHz). er and τf are mainly determined by the relative density, and the optimum microwave dielectric properties are obtained as follows: er = 8.45, Qf = 134,050 GHz, τf =–135 ppm/°C. A microstrip patch antenna is designed and fabricated using the LiF ceramic as the substrate, which gives an S11 of –20.3 dB, a simulated high efficiency of 90.5 %, and a gain of 4.25 dB at the resonant frequency of 6.81 GHz.

Solid-state refrigeration which is environmentally benign has attracted considerable attention. Mechanocaloric (mC) materials, in which the phase transitions can be induced by mechanical stresses, represent one of the most promising types of solid-state caloric materials. Herein, we have developed a thermodynamic phenomenological model and predicted extraordinarily large elastocaloric (eC) strengths for the (111)-oriented metal-free perovskite ferroelectric [MDABCO](NH4)I3 thin-films. The predicted room temperature isothermal eC ΔSeC/Δσ (eC entropy change under unit stress change) and adiabatic eC ΔTeC/Δσ (eC temperature change under unit stress change) for [MDABCO](NH4)I3 are −60.0 J K−1 kg−1 GPa−1 and 17.9 K GPa−1, respectively, which are 20 times higher than the traditional ferroelectric oxides such as BaTiO3 thin films. We have also demonstrated that the eC performance can be improved by reducing the Young’s modulus or enhancing the thermal expansion coefficient (which could be realized through chemical doping, etc.). We expect these discoveries to spur further interest in the potential applications of metal-free organic ferroelectrics materials towards next-generation eC refrigeration devices.

Overall water photo-splitting is a prospective ideal pathway to produce ultra-clean H2 energy by semiconductors. However, the band structure of many semiconductors cannot satisfy the requirement of H2 and O2 production at the same time. Herein, we illustrate that carbon dots (CDs)/Bi2WO6 photocatalyst with compensatory photo-electronic effect has enhanced activity for overall water photo-splitting without any sacrificial agent. In this complex photocatalytic system, the photo-potential provided by CDs makes the CDs/Bi2WO6 (C-BWO) composite could satisfy the band structure conditions for overall water photo-splitting. The C-BWO composite (3 wt% CDs content) exhibits optimized hydrogen evolution (oxygen evolution) of 0.28 μmol/h (0.12 μmol/h) with an approximate 2:1 (H2:O2) stoichiometry at normal pressure. We further employed the in-situ transient photovoltage (TPV) technique to study the photoelectron extraction and the interface charge transfer kinetics of this composite catalyst.

Side-chain engineering is an effective strategy to regulate the solubility and packing behavior of organic materials. Recently, a unique strategy, so-called terminal side-chain (T-SC) engineering, has attracted much attention in the field of organic solar cells (OSCs), but there is a lack of deep understanding of the mechanism. Herein, a new noncovalently fused-ring electron acceptor (NFREA) containing two T-SCs (NoCA-5) was designed and synthesized. Introduction of T-SCs can enhance molecular rigidity and intermolecular π-π stacking, which is confirmed by the smaller Stokes shift value, lower reorganization free energy, and shorter π-π stacking distance in comparison to NoCA-1. Hence, the NoCA-5-based device exhibits a record power conversion efficiency (PCE) of 14.82 % in labs and a certified PCE of 14.5 %, resulting from a high electron mobility, a short charge-extraction time, a small Urbach energy (Eu ), and a favorable phase separation.

The wall-slip effect is observed in areas with magnetorheological fluids (MRFs). A slip layer is formed, which reduces the friction between the solid particles and working surface that causes relative movement of the particles. This leads to errors in the measurement of rheological parameters and an inaccurate braking torque model. Thus, here, a rheometer with a sandpaper on the rotor is used to change the working surface roughness to analyze the wall-slip effect of the MRFs. Based on the experimental results, the influence patterns of wall-slip effect on fluid viscosity and yield stress are obtained. Furthermore, a MRF model is established that considers wall-slip effect, which is different from the conventional models. The model is employed to establish a magnetorheological (MR) braking torque model. To verify the braking torque model, a prototype was manufactured, and its mechanical properties were tested. When compared with a smooth rotor, the braking torque of MR brakes with rectangular grooves is increased. This confirms the existence of the wall-slip effect and shows that the wall-slip effect of MRF can be effectively suppressed by incorporating grooves on the rotor surface.

Methanol aqueous phase reforming (MAPR) reaction under mild conditions is one of the most practical ways to generate hydrogen (H2), in which the liquid vaporization unit could be removed by the water phase reforming, making the structure of an in situ H2 production reactor more compact. In this work, the H2 production performances of the metal-free catalyst, N-doped carbon dots/g-C3N4 (NCDs/g-C3N4; CN-x) composites, was investigated for the MAPR reaction under low temperature and normal pressure. The optimized metal-free catalyst (NCDs/g-C3N4; CN-0.7) displays a H2 yield of 19.5 μmol g-1 h-1 at 80 °C. More importantly, a clear understanding on the effective MAPR reaction at low temperature and normal pressure was acquired from in situ diffuse reflectance FTIR spectroscopy and the transient photovoltage test. The introduction of NCDs leads to the localization of surface charge, which is beneficial to the selective adsorption and polarization activation of polar molecules on the catalyst surface. This work provides a new strategy for the carbon-based catalyst design of the MAPR reaction at low temperatures.

Photoassisted electrocatalytic (P-EC) water splitting for H2 production has received much attention. Here, we report a metal-free bifunctional photoassisted catalyst of a polyaniline/carbon dots (PANI/CDs) composite for overall water splitting. In a neutral electrolyte, under visible light, the overpotentials of the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) for PANI/CDs/NF are reduced by 150 and 65 mV to reach the current densities of 30 and 20 mA cm-2, respectively. In a full water-splitting cell, under visible light, the current density is 13.27 mA cm-2 at 2.0 V, which increases by 62.8% compared with that under the dark conditions (8.15 mA cm-2). The in situ transient photovoltage (TPV) tests were used to study the light-induced effects on half-reactions of water splitting, as well as the charge-transfer kinetic characteristics at the catalyst interface.

Noncovalently fused-ring electron acceptors (NFREAs) have attracted much attention in recent years owing to their advantages of simple synthetic routes, high yields and low costs. However, the efficiencies of NFREAs based organic solar cells (OSCs) are still far behind those of fused-ring electron acceptors (FREAs). Herein, a series of NFREAs with S⋅⋅⋅O noncovalent intramolecular interactions were designed and synthesized with a two-step synthetic route. Upon introducing π-extended end-groups into the backbones, the electronic properties, charge transport, film morphology, and energy loss were precisely tuned by fine-tuning the degree of multi-fluorination. As a result, a record PCE of 14.53 % in labs and a certified PCE of 13.8 % for NFREAs based devices were obtained. This contribution demonstrated that combining the strategies of noncovalent conformational locks and π-extended end-group engineering is a simple and effective way to explore high-performance NFREAs.

Owing to easy processability, ultralight weight, and low cost, carbon- and polymer-based composite materials are among emerging and promising electrothermal materials for high-performance flexible electric heaters. In this work, a sandwich-like structured electrothermal film composed of hybrid conductive fillers [Super-P (SP) and graphite], polymer blends matrix [thermoplastic polyurethane (TPU) and polyethersulfone (PES)], and alumina oxide (Al2O3) as a non-conductive filler has been fabricated by a facile slurry coating method. Hybrid conductive fillers of graphite and SP particles have a uniform spatial distribution in a TPU/PES polymer matrix, which construct a highly stable and continuous conductive network with a low percolation threshold of conductive filler content (14.8 wt.%) that allows electrothermal films to operate at a low applied dc voltage. As for the electrothermal film with 15 wt.% hybrid conductive fillers (SP/G-15 sample), it exhibits a superior response feature, high electrothermal conversion efficiency, stable structural stability and remarkable electrothermal reproducibility. More impressively, SP/G-15 composite electrothermal film as an integrated electric heater for heating water demonstrates a high potential in practical application scenarios.

Double‐loop Rogowski coils have become increasingly popular in the market because of their high sensitivity and flexible usage compared to their extended single‐loop coils. Due to the high number of turns (thousands) and its small turn diameter (

The bottleneck of electrochemical water splitting is the sluggish kinetics of oxygen evolution reaction (OER). Layered double hydroxides (LDHs) have been proposed as active and affordable electrocatalysts in OER. It has been reported that the activity of LDHs can be effectively tuned by doping of other metals. Despite previous experimental synthesis and improved catalytic performance, the in-depth OER mechanism on metal doped LDHs remains ambiguous. In the present work, transition metals (Cr, Mn and Co) doped NiFe LDHs were designed to investigate the doping effect in OER by both experimental analysis and density functional theory calculations. Based on experimental results, the intrinsic OER activity is Cr-NiFe LDHs > Co-NiFe LDHs > Mn-NiFe LDHs > NiFe LDHs, while the enhanced catalytic performance upon doping can be attributed to the interface effect, which results in the tuning of the binding energies of the intermediate states in OER.

Carbon dots (C-Dots) have many unique properties, which endow them with a promising platform from catalysis to biology applications. However, quantitative understanding of those properties of C-Dot...

The uniformity of temperature field distribution in creep aging process is very important to the forming accuracy of components. In this paper, the temperature field distribution of 2219 aluminum alloy tank cover during aging forming is simulated by using the finite element software FLUENT, and a two-stage heating process is proposed to reduce the temperature field distribution heterogeneity. The results show that the temperature difference of the tank cover is large in the single-stage heating process, and the maximum temperature difference is above 27°C,which seriously affects the forming accuracy of the tank cover. With two-stage heating process, the temperature difference in the first stage has almost no direct impact on the forming accuracy of the top cover. In the second stage, the temperature difference of the tank cover is controlled within 10°C, compared with the single-stage heating, the maximum temperature difference is reduced by more than 17°C. The two-stage heating effectively reduces the heterogeneity of the temperature field of the top cover. The research provides technical support for the precise thermal mechanical coupling of large-scale creep aging forming components.

2195 Al-Li alloy is famous for high strength, excellent fatigue strength and good stress corrosion resistance, which is widely used in the manufacture of high-performance aerospace components. The aim of this study is to validate how the stress relaxation aging behavior effect on the mechanical properties of 2195 Al-Li alloy. Through mechanical property test, the research was found that the performance after stress relaxation aging is higher than artificial aging (AA). In addition, the analysis of scanning electron microscopy SEM and TEM revealed that dislocations should be introduced by the stress relaxation aging process, which is more conducive to the precipitation of the T1 phase and strengthened the material with prolong ageing time. The results show that stress relaxation aging can significantly promote the precipitation of the T1. Therefore, this paper sheds new light on how SRA can improve mechanical properties and that SRA make better improve the distribution of precipitates in the grain boundary.

Based on the micro-hyperspectral imaging technique, spherical engineered microplastic (polyethylene, 10–45 μm) and microalgae (Isochrysis galbana) (4–7 μm) were identified. In transmittance mode of MHSI, micro image cubes from 400 to 1000 nm were obtained from slides containing MP and MA in thin seawater. Classifiers like Support Vector Machine (SVM(Radial Basis Function (RBF))), Least Squares Support Vector Machine (LSSVM(RBF)), k-Nearest Neighbors, etc. were adopted and compared to classify MP and MA. In order to expand the imaging range of micro imaging, image stitching technology was adopted. In allusion to the stitched image cube, SVM(RBF) is suggested for the identification of MA and MP, with recall and precision > 0.86. The above results demonstrate that the MHSI is a promising technique, which can detect MPs with particle size Limit of Detection of 10–45 μm, and it is potential to further expand this LOD.

Carbon materials have been widely applied in energy storage devices owing to the tunable morphology and microstructure. Herein, carbon materials with various morphologies and microstructures are sy...

The energy crisis has always been a widely concerned problem. It is an urgent need for green and renewable energy technologies to achieve sustainable development, and the photo-assisted charging energy storage devices provide a new way to realize the sustainable utilization of solar energy. Here, we fabricated a photo-assisted charging fibrous supercapacitor (NM2P1) with Ti3C2Tx-based hybrid fibre modified by nitrogen-doped carbon dots (NCDs). The NM2P1 fibre provides a volumetric capacitance of 1,445 F·cm−3 (630 F·g−1) at 10 A·cm−3 under photo-assisted charging, which increases by 35.9% than that of dark condition (1,063 F·cm−3/464 F·g−1). Furthermore, the NM2P1 fibrous supercapacitor device shows that the maximum volumetric energy density and volumetric power density are 18.75 mWh·cm−3 and 8,382 mW·cm−3. Notably, the transient photovoltage (TPV) test was used to further confirm that NCDs as a photosensitizer enhance the light absorption capacity and faster charge transfer kinetics of NM2P1 fibre. This work directly exploits solar energy to improve the overall performance of supercapacitor, which opens up opportunities for the utilization of renewable energy and the development of photosensitive energy equipment.

This paper presents the modelling and experimental evaluation of a semi-active vehicle suspension installed with a self-powered MR damper which is able to perform variable stiffness. Its variable stiffness feature as well as the self-powering capability was evaluated and verified using a hydraulic Instron test system. The testing results show that the stiffness of the damper is dependent on the current which can be generated by the self-powering component. A mathematic model was established to describe the dynamic properties of the MR damper and its power-generating capability. Finally, the self-powered MR suspension was installed on a quarter car test rig for its vibration isolation evaluation. A controller based on the short-time Fourier transform (STFT) was developed for the stiffness control. The evaluation result illustrates that the proposed MR damper can reduce the acceleration and displacement of the sprung mass by 16.8% and 21.4% respectively, compared with the passive system.

ZCS-C (ZnCdS/CdS) QDs were synthesized via low-temperature vulcanization using zeolitic imidazolate framework-8 (ZIF-8) nanoparticles as a precursor, cation exchange, and heterojunction construction. Without any precious metal as a cocatalyst, the photocatalytic hydrogen production rate of ZCS-C-3 QDs reached 2.7 mmol g−1 h−1 under visible light irradiation. The optimized sample exhibited an outstanding chemical stability and recyclability, which is superior to most of the reported Zn1−xCdxS-based photocatalysts.

The construction of organic solar cells with stacked structures by the sequential deposition (SD) of donor and acceptor films has great potential in industrial production, as it demonstrates little dependence on the ratio of donor and acceptor materials, solvents, and additives. Herein, we present an eco-friendly solvent protection (ESP) method for the fabrication of high-performance OSCs with stacked structures. Several non-aromatic and non-halogenated solvents are employed as protective agents to build SD devices with a configuration of indium tin oxide (ITO)/poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS Clevios P VP Al 4083)/donor/protective solvent/acceptor/perylene diimide functionalized with amino N-oxide (PDINO)/Al, which shows that n-octane is the optimal choice for SD devices. Nine different SD systems including the fullerene and nonfullerene ones present comparable photovoltaic performance to their BC counterparts, which proves the universality of this ESP method. Significantly, the device of ITO/PEDOT:PSS/D18/N3/PDINO/Al with n-octane as the protective solvent achieves a maximum PCE of 17.52%, which is the record efficiency of SD devices. Furthermore, a protective factor (δ) is proposed to demonstrate the quantitative relationship between δ and PCE after experimental and theoretical investigation, which presents an idea to understand the mechanism and provides a guideline for solvent choices.

To suppress the aggregation behavior caused by the high surface energy of quantum dots (QDs), ZnCdS QDs were grown in situ on a g-C3N4 support. During the growth process, the QDs tightly adhered to the support surface. The ZnCdS QDs were prepared by low-temperature sulfurization and cation exchange with a zeolitic imidazolate framework precursor under mild conditions. The heterojunction of g-C3N4/ZnCdS-2 (CN/ZCS-2, with a g-C3N4 to ZIF-8 ratio of 2.0) not only showed excellent optical absorption performance, abundant reactive sites, and a close contact interface but also effectively separated the photogenerated electrons and holes, which greatly improved its photocatalytic hydrogen production performance. Under visible light irradiation (wavelength > 420 nm) without a noble metal cocatalyst, the hydrogen evolution rate of the CN/ZCS-2 heterojunction reached 1467.23 μmol g−1 h−1, and the durability and chemical stability were extraordinarily high.

Well-organized substrate materials are of considerable significance in the development of energy-efficient pseudocapacitor electrodes. Herein, functionalized three-dimensional (3D) carbon nanocoils on nickel foam (CNCs/NF) have been used as the substrate to grow faradaic nickel cobaltite (NiCo2O4) via a solvothermal method. The arrays of NiCo2O4 were assembled by interconnected ultrathin nanosheets with random inter-particle pores. The number of electroactive sites increased specifically because of the porous feature of NiCo2O4 nanosheets and the 3D structure of CNCs/NF. Moreover, the CNCs/NF network aided the electrolyte ions in diffusing deeply within the architecture. The NiCo2O4/CNCs/NF composite exhibited an outstanding specific capacitance of 2821 F g−1 at the current density of 1 A g−1, a remarkable rate capability (82.4%) and long cyclic stability (91.7% after 3000 cycles). Such encouraging electrochemical performance was attributed mainly to the synergistic interactions of NiCo2O4 arrays and CNCs/NF substrate that helped achieve efficient redox reactions, enhanced ion diffusivity and excellent electron conductivity. In summary, this binder-free NiCo2O4/CNCs/NF composite electrode paves a way towards the synthesis of highly efficacious electrodes for supercapacitors.

Environmentally benign synthesis of graphite at low temperatures is a great challenge in the absence of transition metal catalysts. Herein, we report a green and efficient approach of synthesizing graphite from carbon dioxide at ultralow temperatures in the absence of transition metal catalysts. Carbon dioxide is converted into graphite submicroflakes in the seconds timescale via reacting with lithium aluminum hydride as the mixture of carbon dioxide and lithium aluminum hydride is heated to as low as 126 °C. Gas pressure-dependent kinetic barriers for synthesizing graphite is demonstrated to be the major reason for our synthesis of graphite without the graphitization process of amorphous carbon. When serving as lithium storage materials, graphite submicroflakes exhibit excellent rate capability and cycling performance with a reversible capacity of ~320 mAh g–1 after 1500 cycles at 1.0 A g–1. This study provides an avenue to synthesize graphite from greenhouse gases at low temperatures. Green synthesis of graphite is a great challenge in the absence of the graphitization of amorphous carbon at high temperatures. Here, the authors report a green approach of synthesizing graphite from carbon dioxide at low temperature in seconds timescale.

The manufacture of blue light-emitting diodes (LEDs) has always been a tough problem to solve in the display and illumination fields. Inorganic/organic semiconductors and carbon dots (CDs) with a wide band gap still face obstacles such as a low external quantum efficiency (EQE) and poor stability. Herein, we synthesized highly stable and blue emission CDs with a chemically inert surface, and the photoluminescence (PL) peak (in ultra-pure water) of which is located at 446 nm with an absolute PL quantum yield (PLQY) of 26.4%. The LEDs based blue emission CDs exhibit an electroluminescence (EL) peak located at 456 nm and a high brightness of 223 cd m−2 with an EQE of 0.856%. The Commission Internationale del'Eclairage (CIE) coordinates are located at (0.21, 0.23) and the device lifetime with 65% brightness (T65) reaches over 217 h because of the chemically inert surface of the CDs. The results mean the devices are the most stable CDs-LEDs reported to date. This work represents a novel route for the preparation of low cost, highly stable and very bright CDs-LEDs with a short wavelength emission.

Solar-driven water splitting for hydrogen peroxide (H2O2) production is a sustainable and ultra-clean method. It is difficult for a single-component photocatalyst to meet all the requirements for efficient and stable photoproduction of H2O2. Meanwhile, for multiple-component catalysts, a huge and urgent challenge is to adjust the photo-charge between the multiple components and interfaces of catalysts. Herein, we report a metal-free photocatalyst CN1.8/ICT/CDs composed of CN1.8, organic small molecules (ICT) and N, S-doped carbon dots (CDs) to produce H2O2 efficiently and stably through a dual-channel process. In this catalyst system, CDs are first reported as the active site of water oxidation reaction (WOR) and ICT as the active site of oxygen reduction reaction (ORR), with greatly improved efficiency of the use of photo-charge, and the poisoning of CN1.8/ICT/CDs by H2O2 was prevented. In situ transient photovoltage measurements (TPV) further revealed the photo-charge regulation function of CDs in this multiple-component metal-free photocatalyst. As a result, the CN1.8/ICT/CDs catalyst exhibits a prominent H2O2 production rate of 2202.81 μmol h−1 g−1 (λ ≥ 420 nm), which represents the most efficient H2O2 production rate from a metal-free photocatalyst in air atmosphere without sacrificial agents. This work also provides a valid TPV-based method for a deep understanding of complex photocatalytic systems.

Introducing the effect of light into an electrocatalytic system is an effective method to improve electrocatalytic carbon dioxide reduction (CO2RR). Here, the composite catalyst (ZIF/Co-C3N4) was prepared for the electrocatalytic reduction of carbon dioxide. The Faraday efficiency of the catalytic reduction of CO2 to CO under light could reach 90.34% at −0.67 V vs. the RHE (reversible hydrogen electrode), which was 30% higher than that obtained under darkness, and the overpotential was reduced by 200 mV. Chemical kinetics experiments and in-situ transient photovoltage (TPV) tests show that the reason for highly efficient CO2RR is intermediate CO2− formed by activated CO2 in the electrocatalytic system under light. This work offers a deep insight into the photo-activated electrocatalytic reduction of carbon dioxide, and also opens a new way to devise efficient catalysts for CO2RR.