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The W18O49 nanoparticles were synthesized by solvothermal method with tungsten chloride as raw material and n-propanol as solvent. Polyethylene glycol 400 (PEG-400) was modified for W18O49 nanoparticles (W18O49@PEG). The structure and morphology of W18O49 and W18O49@PEG were characterized by XRD and SEM. Methylene blue aqueous solution was used as wastewater adsorption model. And the comparative experiments with other absorbent materials, such as artificial zeolite and activated carbon were also conducted. The results revealed that after modifying by PEG-400, W18O49 has a better adsorption performance than other materials due to its large specific surface area and high surface energy. Finally adsorption circulation experiment was performed，the results indicate that the W18O49@PEG nanoparticles show great potential in the treatment of colored wastewater.

The electrochemical production of green and low-cost ammonia requests the development of high-performance electrocatalysts. In this work, the ampoule method was applied to modulate the surface of the zinc electrode by implanting defects and low-valent active sites. The N-doped ZnS electrocatalyst was thus generated by sulfurization with thiourea and applied for electrocatalytic nitrogen reduction reaction (ENRR). Given the rich sulfur vacancies and abundant Zn-N active sites on the surface, excellent catalytic activity and selectivity were obtained, with an NH3 yield rate of 2.42 × 10–10 mol s−1 cm−2 and a Faradaic efficiency of 7.92% at − 0.6 V vs. RHE in 0.1 M KOH solution. Moreover, the as-synthesized zinc electrode exhibits high stability after five recycling tests and a 24 h potentiostatic test. The comparison with Zn foil, non-doping ZnS/Zn and recent metal sulfide electrocatalysts further demonstrated advanced catalytic performance of N@ZnS/Zn for ENRR. By simple synthesis, S vacancies, and N-doping defects, this promising electrocatalyst would represent a good addition to the arena of transition-metal-based catalysts with superior performance in ENRR. Graphic abstract

A polymer based bag filter with high temperature resistance plays a key role in dust and acid gas treatment in the power industry. Currently, the polymers used for preparing filters with improved heat resistance include those with a high content of aromatic units. But the aromatic structure inevitably leads to a high melting point, which is disadvantageous for melt spinning. Here, we report a polyamide 66 and polyamide 6T copolymer (PA66-co-PA6T) fiber with both high thermal stability and good spinnability. The retention rates of heat resistance of fibers after heat treatment at 185 °C and 200 °C were higher than 97.8% and 88.4%, respectively. This high thermal stability is ascribed to the high thermal degradation activation energy (E), which was confirmed by DSC, TG, and XRD characterization studies and fitting of kinetic data. PA66-co-PA6T with good melt spinnability, high heat resistance strength and low cost is expected to be applied in high-temperature resistance filtration equipment such as bag filters, expanding the application range of PA66 materials.

Effective transfer and utilization of the photogenerated electrons are a key factor for achieving highly efficient H2 generation by photocatalytic water splitting. Apart from the activity of the co-catalyst, the interface between the co-catalyst and semiconductor is of particular importance. Guided by DFT calculations, single-atom (SA) Pt doped carbon nitride (CN) is successfully synthesized for use as the co-catalyst to the semiconducting CuS. The catalyst system (Pt1-CN@CuS) exhibits an enhanced photocatalytic performance for water splitting with a H2 production rate of 25.4 μmol h-1 and an apparent quantum yield (AQY) of 50.3 % under the illumination of LED-530. Solar-to-hydrogen (STH) conversion efficiency is calculated to be 0.5 % under AM 1.5 illumination. This is the very first investigation of SA as the co-catalyst, which decreases the overpotential of CN during the water splitting and lowers interfacial resistance of the catalyst/co-catalyst and co-catalyst/electrolyte.

We present an experimental investigation on photocarrier dynamics in a TlGaS2 bulk crystal and its heterostructures with hexagonal BN and WS2. The samples were obtained by mechanical exfoliation an...

Developing hydrogen evolution reaction (HER) electrocatalysts with high activity, durability and moderate price is essential for sustainable hydrogen energy utilization. Here, the facile coupling of carbon dots (CDs, 0D carbon materials) and carbon fibres (CFs, 1D carbon materials) for enhanced electrochemical hydrogen production was demonstrated. Electrochemical tests revealed that the CD/CF catalysts showed outstanding catalytic activity with a small overpotential of 280 mV at the current density of 10 mA cm-2 , a small Tafel slope of 87 mV dec-1 and prominent durability. Percolation theory was for the first time introduced to interpret the catalytic mechanism of the CD/CF catalysts. The special morphology assembled by the 0D carbons constituted the percolating clusters and promoted electron transport throughout the 1D carbons. The strategy and theory can be adapted to general electrocatalytic applications for achieving and interpreting precise tuning on highly efficient electron transfer in electrocatalysts.

The gas generation features of coals at different maturities were studied by the anhydrous pyrolysis of Jurassic coal from the Minhe Basin in sealed gold tubes at 50 MPa. The gas component yields (C1, C2, C3, i-C4, n-C4, i-C5, n-C5, and CO2); the δ13C of C1, C2, C3, and CO2; and the mass of the liquid hydrocarbons (C6+) were measured. On the basis of these data, the stage changes of δ13C1, δ13C2, δ13C3, and δ13CO2 were calculated. The diagrams of δ13C1–δ13C2 vs ln (C1/C2) and δ13C2–δ13C1 vs δ13C3–δ13C2 were used to evaluate the gas generation features of the coal maturity stages. At the high maturity evolution stage (T > 527.6 °C at 2 °C/h), the stage change of δ13C1 and the CH4 yield are much higher than that of CO2, suggesting that high maturity coal could still generate methane. When T 2 is generated by breaking bonds between carbons and heteroatoms. The reaction between different sources of coke and water may be the reason for the complicated stage change in $$\delta^{{{13}}} {\text{C}}_{{{\text{CO}}_{{2}} }}$$ δ 13 C CO 2 when the temperature was higher than 455 °C. With increasing pyrolysis temperature, δ13C1–δ13C2 vs ln (C1/C2) has four evolution stages corresponding to the early stage of breaking bonds between carbon and hetero atoms, the later stage of breaking bonds between carbon and hetero atoms, the cracking of C6+ and coal demethylation, and the cracking of C2–5. The δ13C2–δ13C1 vs δ13C3–δ13C2 has three evolution stages corresponding to the breaking bonds between carbon and hetero atoms, demethylation and cracking of C6+, and cracking of C2–5.

Charge-transfer excitons are formed by photoexcited electrons and holes following charge transfer across a heterojunction. They are important quasiparticles for optoelectronic applications of semiconducting heterostructures. The newly developed two-dimensional heterostructures provide a new platform to study these excitons. We report spatially and temporally resolved transient absorption measurements on the dynamics of charge-transfer excitons in a MoS2/WS2/MoSe2 trilayer heterostructure. We observed a non-classical lateral diffusion process of charge-transfer excitons with a decreasing diffusion coefficient. This feature suggests that hot charge-transfer excitons with large kinetic energies are formed and their cooling process persists for about 100 ps. The long energy relaxation time of excitons in the trilayer compared to its monolayer components is attributed to the reduced carrier and phonon scattering due to the dielectric screening effect in the trilayer. Our results help develop an in-depth understanding of the dynamics of charge-transfer excitons in two-dimensional heterostructures.

The key to photocatalytic efficient decomposition of VOCs is to significantly improve carrier separation-efficiency of the photocatalyst. Herein, we synthesized a novel photocatalytic composite material of I-deficient BiO1.2I0.6/WO3 by solvothermal method coupling with thermal decomposition. The PL spectrum and photoelectrochemical tests found that WO3 compounded by 40 wt% BiO1.2I0.6 greatly promoted its separation efficiency of carriers. This was mainly caused by the potential difference of band edge between the 40 wt% BiO1.2I0.6 and WO3 driving reverse shift of carriers in their space charge-layer. The 40 wt% BiO1.2I0.6/WO3 achieved 58.8% mineralization ratio in the process of degrading typical VOCs, toluene after 8 h irradiation, which was 15.9 and 2 times those of BiO1.2I0.6 and WO3, respectively. Gaussian calculation and ESR investigation demonstrated that toluene was decomposed by h+ and hydroxyl radical (·OH) under irradiation.

Ceramic TiB2, a layered metal diboride with remarkable conductivity and chemical stability, are potential electrocatalyst towards hydrogen evolution reaction (HER). However, high overpotential (>1 V) is required for pristine TiB2 to drive water splitting, which is less than satisfactory in future hydrogen economy. Herein, conductive polypyrrole (PPy) encapsulating TiB2 (TiB2@PPy) has been developed via vapor phase polymerization, as the electrocatalyst for HER. Theoretically, the PPy shell serves both as electron-transfer channels to accelerate electron migration, and as Mott-Schottky centre to modify the electronic structure of TiB2. Beneficially, more improved HER performance has been achieved with the overpotential of 432 mV at 10 mA cm−2, superior to that of pristine TiB2 (848 mV at 10 mA cm−2). Moreover, excellent stability is presented during 1000 CV cycles and 10 h constant evaluation. Our study provides a new avenue to create efficient HER electrocatalyst via conductive PPy engineering.

Despite many years of research, the current-carrying friction interface still strongly depends on the lubricating film between the friction pairs, because this film can reduce the probability of arc occurrence. However, this film has poor conductivity, cannot self-heal, and is prone to be greasy, which reduces the efficiency of current conduction, which seriously affects the contact status. In order to solve this problem, graphite materials with excellent lubricating properties and electrical conductivity are used to make current-carrying friction materials. Graphite and graphite-based composite materials are the most widely used current-carrying friction materials in various industries. Graphite has excellent lubricity, conductivity, and high temperature resistance to steel and many other metal materials. However, with the passage of time, due to the continuous deterioration of the application conditions and the environment, such as arc under high current density, spark phenomenon, severe mechanical wear under high load, etc., the lubricating film is destroyed, which greatly weakened the performance of protecting friction pairs. Therefore, improving the working stability of the current-carrying friction pair is the key to ensuring that the contact pair does not spark. In this review, we mainly discuss how to improve the stability of the current-carrying friction system, reduce the wear of the current-carrying friction system, and thereby extend the service life of the current-carrying friction material. At first, we discussed the latest research progress of current-carrying friction from the electrical properties, contact resistance, thermal effect, and arc of current-carrying friction materials to tribological characteristics. Secondly, the influence of contact resistance parameters and structural function parameters on the wear life of current-carrying friction pairs is discussed. The current research status of current-carrying performance and tribological performance of current-carrying friction pairs under the coupled effects of temperature field and current field is discussed. It is necessary to combine experiment, theory, and simulation to study the temperature field of the current-carrying friction pair, especially the influence of complicated conditions such as oil and dust on the friction performance of the current-carrying. Thirdly, the influence of arcing, sparking, and dynamic characteristics on the friction performance of the current-carrying friction system is reviewed. At the same time, the prediction model of current-carrying friction and wear should be studied systematically to detect current-carrying friction and wear online. Finally, it introduces in detail that new current-carrying friction materials are developing in the direction of tissue functionalization and structural composite.

The Niutitang Formation at the Huijunba syncline south of Hanzhong, China, has large shale gas resource potential. The development characteristics of shale nanoscale pores are key factors affecting the storage capacity of shale gas. To study the development mechanism, the shale pores in the area were systematically observed using scanning electron microscopy combined with argon ion polishing and low-pressure gas adsorption. The determination of structural parameters (e.g., the pore specific surface area, pore volume, and pore size distribution) of the mineral components provided an in-depth analysis of the development characteristics and mechanisms of organic-inorganic composite pores. Morphological analysis revealed that the development of organic-inorganic composite pores is dominated by the sedimentary action of organic matter and mineral components due to differences in physical properties, the fracture of brittle minerals, the plastic deformation of organic matter, structural effects, and other factors. Syndeposition forms a symbiotic relationship between organic matter and mineral components in the shale that leads to specific surface area and pore volume parameters that are smaller than the individual components. Because the mineral and organic particles in shale have diameters primarily larger than 2 nm, the abovementioned factor primarily affects mesopores and macropores and has a relatively limited impact on micropores.

Using polarization-resolved Raman spectroscopy, we investigate layer number, temperature, and magnetic field dependence of Raman spectra in one- to four-layer $\mathrm{CrI_{3}}$. Layer-number-dependent Raman spectra show that in the paramagnetic phase a doubly degenerated $E_{g}$ mode of monolayer $\mathrm{CrI_{3}}$ splits into one $A_{g}$ and one $B_{g}$ mode in N-layer (N > 1) $\mathrm{CrI_{3}}$ due to the monoclinic stacking. Their energy separation increases in thicker samples until an eventual saturation. Temperature-dependent measurements further show that the split modes tend to merge upon cooling but remain separated until 10 K, indicating a failed attempt of the monoclinic-to-rhombohedral structural phase transition that is present in the bulk crystal. Magnetic-field-dependent measurements reveal an additional monoclinic distortion across the magnetic-field-induced layered antiferromagnetism-to-ferromagnetism phase transition. We propose a structural change that consists of both a lateral sliding toward the rhombohedral stacking and a decrease in the interlayer distance to explain our experimental observations., The article was published in ACS Nano on June 2

To improve the safety of orthotropic steel bridge decks and the construction efficiency of bridge deck pavement by enhancing the performance of pavement materials, a new-generation, high-performance cold-mix resin was prepared by carrying out the combination of micro-characteristic analysis and performance test. Meanwhile, the pavement performance and fatigue performance of high-performance cold-mix resin mixtures and hot-mix epoxy saphalt mixtures as a control group were studied experimentally. The results show that different kinds of epoxy resins show bisphenol structure in essence. The curing exothermic peak temperature of the cold-mix resin increases with the heating rate. Both the specific heat capacity (△CP) of cold-mix resin and cold-mix resin asphalts exhibit a sudden change between −20 °C and 40 °C. In resin asphalt mixtures, cold-mix resin forms the network structure skeleton whereas the asphalt distributed in the form of tiny particles. The dosage of respective component has a significant effect on the tensile strength and elongation at break of cold-mix resin. Compared with hot-mix epoxy asphalt mixtures, cold-mix resin mixtures exhibit comparable water stability and high and low-temperature performance, as well as greater fatigue life.

We report a daytime passive radiative cooler using chemically fabricated porous anodic aluminum oxide (AAO) membranes. Effective medium theory (EMT) has been applied to analyzing the optical properties of the air-doped porous medium. The composite structure is specifically optimized so that it has a high absorbance (emittance) in the far-infrared atmospheric window and nearly no loss in the solar spectrum. The calculated emittance is well reproduced in the experiment by our AAO sample. The fabricated porous membrane shows a potential cooling power density of 64 W/m2 at ambient (humidity = 75%) under direct sunlight irradiance (AM1.5). Experimentally, the sample is cooled by a 2.6C temperature reduction below the ambient air temperature in the sunlight. This performance shows little variance at night. The AAO approach proposed here may provide a promising way to produce low-cost and efficient radiative cooler in large scales for feasible energy conservation., 4

Pseudocapacitive Bi2O3 is considered as a promising negative material on account of the advantage of high theoretical specific capacitance, but its capacitance is still limited by poor intrinsic electrical conductivity and poor ionic diffusion. Therefore, rationally engineering the surface and the structure are essential to decorate Bi2O3 with high capacitance. Here, we reported conductive PEDOT-engineered Bi2O3 nanosheet arrays (CC/Bi2O3@PEDOT NAs) constructed via a combined solvothermal and electrodeposition approach as high-performance negative electrodes. As-achieved CC/Bi2O3@PEDOT NAs present vertical and interconnected network architecture, which provid a huge surface to connect with the electrolyte and shorten the penetration pathways. Benefiting from the PEDOT-engineered surface, superior electrical conductivity and accelerated charge transport are obtained and thus, the electrode exhibits optimal areal capacitance of 1.7 F cm−2 at 10 mV s−1. Remarkably, maximum energy density of 1.2 mW h cm−3 (123 W h kg−1) is delivered at power density of 9.4 mW cm−3 for the constructed ASC device. This study provides a novel strategy to engineer Bi2O3 towards high capacitance; also, it may be applied to design other high-performance electrodes in the future.

Various renewable energy systems, such as water splitting cells and metal–air batteries, are based on the oxygen evolution reaction (OER). The replacement of common noble-metal platinum catalysts with highly efficient, cheap, and operationally stable electrocatalysts opens huge potential applications for OER; thus, there have been increasing efforts to develop alternative efficient OER catalysts via low-cost fabrication processes. Herein, we report a facile self-templated method to synthesize ZnCo–Fe core–shell nanocages derived from metal–organic frameworks (MOFs) as an efficient catalyst for OER. The unique structure of ZnCo–Fe core–shell nanocages offers a large active surface area with abundant active sites and efficient charge transfer capability as the hollow structure facilitates the active direct contact of materials with electrolytes. We introduced these catalysts at different ratios of Fe, which had a significant effect on the electrocatalytic performance of OER. In other words, the introduction of Fe not only changed the composition but also changed the morphology to expose numerous active sites for OER. Owing to the synergistic effect between the element composition and abundant active sites, the optimized ZnCo–Fe-20 sample presented a superior electrocatalytic OER performance with a very low overpotential (η = 176 mV at 10 mA cm−2) and a small Tafel slope (69.3 mV dec−1). This developed strategy can be easily extended to synthesize other MOF-derived polymetallic oxide-based hybrid electrodes for OER as a practical route for the design of cheap and efficient electrocatalysts.

The metallic dopants in palladium (Pd) sensing materials enable modification of the d-band center of Pd, which is expected to tune the α–β phase transitions of the PdHx intermediate, thus improve the sensing stability to hydrogen. Here, the boosted hydrogen-sensing stability at ultra-low temperatures has been achieved with palladium/cobalt nanowires (PdCo NWs) as the sensing material. The various Co contents in PdCo NWs were modulated via AAO-template-confined electrodeposition. The temperature-dependent sensing evaluations were performed in 0.1–3 v/v% hydrogen. Such sensors integrated with PdCo NWs are able to stably detect hydrogen as low as 0.1 v/v%, even when the temperature is lowered to 273 K. In addition, the critical temperatures of “reverse sensing behavior” of the PdCo NWs (Pd82Co18: Tc = 194 K; Pd63Co37: Tc = 180 K; Pd33Co67: Tc = 184 K) are observed much lower than that of pristine Pd NWs (Tc = 287 K). Specifically, the Pd63Co37 NWs (∼37 at% Co content) sensor shows outstanding stability of sensing hydrogen against α–β phase transitions within the wide temperature range of 180–388 K, which is attributed to both the electronic interactions between Pd and Co and the lattice compression strain caused by Co dopants. Moreover, the “reverse sensing behavior” of the PdCo NWs is explicitly interpreted using the α–β phase transition model.

A novel electrochemical strategy for simple and facile synthesis of semicarbazide functionalized nitrogen-doped graphene quantum dots (N-GQDs) was reported, based on direct exfoliation and oxidation from graphite rods. The average diameter of the as-synthesized N-GQDs is about 20 nm, and their dispersion is bright yellow due to the rich nitrogen and oxygen functional groups on their surface. The N-GQD dispersion was further applied in the selective detection of ferric ions (Fe3+) based on the photoluminescence (PL) quenching of N-GQDs after adding Fe3+. The fluorescent sensor has a wide linear range of 0–200 μM and a detection limit of 0.87 μM, which is much lower than the maximum level (0.3 mg L−1, equivalent to 5.4 μM) of Fe3+ permitted in drinking water by the U.S. Environmental Protection Agency (EPA). Moreover, these novel N-GQDs exhibit much wider emission bands, which extend into the entire visible region, and emit three primary color fluorescence independently. This distinctive behavior of the as-prepared GQDs not only breaks the limitation that traditional reported GQDs only exhibit blue emission in the short-wavelength region, but may also provide a new research platform for further applications of GQDs in real environmental detection and biological imaging systems.

A superamphiphobic coating is usually prepared via a reduction reaction and then deposited onto the surface of the substrate. This technology is difficult to control and achieve high bond strength, which easily leads to powder shedding. To overcome this issue, electroplating technology is usually preferred for preparing adhesion coatings. However, the coating prepared using this method is usually suitable only for hard steel substrates, and not for soft substrates such as carbon brushes. Herein, we demonstrate an air spray technology for preparing anti-greasy and conductive superamphiphobic graphite-1H,1H,2H,2H-perfluorooctyltrichlorosilane–SiO2 (GPS) coatings suitable for both soft substrates (carbon brushes) and hard substrates (collector rings). The sheet resistance of the coating with 10% graphite content is 4.8 × 10−3 Ω □−1 for a 10 μm thin coating, corresponding to a resistivity of 4.8 μΩ cm. More importantly, the prepared coating has excellent liquid repellency, such as water, rapeseed oil and n-hexane. In addition, the coating has excellent anti-greasy and mechanical properties, which provide a brand-new solution for the greasy pollution in the engineering field. These advantages will enhance the application of superamphiphobic GPS coating in the fields of hydropower, wind power and transportation, and so on.

New solid polymer electrolytes are of particular interest for next-generation high-energy batteries since they can overcome the limited voltage window of conventional polyether-based electrolytes. Herein, a flame-retardant phosphorus-containing polymer, poly(dimethyl(methacryloyloxy)methyl phosphonate) (PMAPC1) is introduced as a promising polymer matrix. Free-standing membranes are easily obtained by mixing PMAPC1 with lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and a small amount of acetonitrile (AN). LiTFSI/AN mixed aggregates are formed that act as plasticizers and enable ionic conductivities up to 1.6 × 10-3 S cm-1 at 100 °C. The high content of LiTFSI used in our electrolytes leads to the formation of a stable LiF solid-electrolyte interphase, which can effectively suppress Li dendrites and the chemical degradation of AN in contact with Li. Accordingly the electrolyte membranes exhibit a wide electrochemical stability window above 4.7 V versus Li+/Li and fire-retardant properties due to the presence of the phosphorus-containing polymer. Atomistic molecular modeling simulations have been performed to determine the structure of the electrolytes on the microscopic scale and to rationalize the trends in ionic conductivity and the transport regime as a function of the electrolyte composition. Finally, our electrolyte membranes enable stable cycling performance for LiFePO4|PMAPC1 + LiTFSI + AN|Li batteries.

Microchannel plate (MCP) is an important compact signal multiplier. The dynamic range of MCP is the key index influencing the detection quality of high flux, high energy and wide output linearity signals, but limited on the bulk resistance of MCP multiplier. Therefore, the problem of the bulk resistance-dependent of dynamic range transition in these devices needs to further continues to be investigated. In this paper, lead silicate glass microchannel plates in three different bismuth contents (0at%, 1at%, 2at%) were present. The bulk resistance decreased exponentially (from 6000MΩ into 15MΩ) with the increase of the content of bismuth in the lead silicate glass from 0at% to 2at%, meanwhile, the dynamic range was increased from 3.3×102 to 2.3×103 . As the bulk resistance of MCP multipliers dropped from 150MΩ into 15 MΩ (dropped about 90%), while the dynamic range of that just extended by seven times, meanwhile, the dark current of that boosted almost ten times (from 1pA to 10pA). It implicated that the dynamic range of MCP multiplier was influenced not only by the charge replenishment abilities involved in the bulk resistance, but also by the joule heating effect-depended dark current variation concerned with the bulk resistance.

The lubricity and anti-wear ability of ionic liquids (ILs) were studied by a current-carrying friction test on IL-lubricated carbon brushes. The results indicated that the conductivity and wear resistance of different ILs are different, and may vary for different carbon brushes. The E468e carbon brush was found to be more sensitive to IL lubrication than D172 carbon brush. Importantly, an analysis of the wear surfaces of the D172 and E468e carbon brushes revealed that, due to the different materials of the two carbon brushes and the composition of the IL, the lubrication effect on the carbon brushes was different. The viscosity of the IL will affect its wettability on the carbon brush surface. The better the wettability, the easier the movement of ions on the surface, which makes it easier to form a conductive physical adsorption film. Therefore, in practice, a better IL must be selected by considering the wettability of IL and carbon brushes.

Unbonded flexible pipe is widely used in the oil and gas industry for its good flexibility, especially in deepwater oil and gas transportation. And the fiber reinforced unbonded flexible pipe has excellent corrosion resistance and wear resistance. However, they are subjected to internal pressure, external pressure and tensile loads during the service process, which are important factors affecting the integrity and security of the flexible pipe. In this paper, the mechanical behaviors of an 8-inchs fiber reinforced unbonded flexible pipe used in offshore gas development which consists of internal layer, internal pressure reinforcement layers, anti-wear layers, external pressure armor, tensile reinforcement layers and outer sheath is investigated by numerical methods. A rigorous three-dimensional solid finite element model of flexible pipe that considers the real material parameters, structural nonlinearity as well as the nonlinear contact behavior was created. ABAQUS/Explicit quasi-static simulation is adopted to study the mechanical behaviors of the flexible pipe under combined load. And the accuracy of the simulation method for the fiber reinforced layers such as internal pressure layer is verified by comparing with the small-scale internal pressure burst test of 1-inch flexible pipe. The mechanical behavior of flexible pipe subjected to internal pressure, external pressure and tensile load was investigated in detail. Based on the contrastive analysis, some practical conclusions have been obtained which may be used for the practical design and production of flexible pipe. This study can be referenced for the applications of unbonded flexible pipe in marine oil and gas production.

Electrochemical ammonia synthesis that utilizes renewable electricity in the nitrogen reduction reaction (NRR) has recently been remarkably considered. Of particular importance is to develop efficient electrocatalysts at low costs. Herein, highly selective nitrogen capture using porous aluminum-based metal-organic frameworks (MOFs) materials, MIL-100 (Al), is first designed for the electrochemical nitrogen fixation in alkaline media under ambient conditions. Owing to the unique structure, MIL-100 (Al) exhibits remarkable NRR properties (NH3 yield: 10.6 µg h-1 cm-2 mgcat.-1, Faradaic efficiency: 22.6%) at a low overpotential (177 mV). Investigation indicates that the catalyst shows excellent N2-selective captures due to the unsaturated metal sites binding with N2. More specifically, as Al 3p band can strongly interact with N 2p orbitals, Al as a main-group metal presents a high and selective affinity to N2. The utilization of multifunctional MOF catalysts delivers both high N2 selectivity and abundant catalytic sites, resulting in remarkable efficiency for NH3 production.

We report core@satellite Janus mesoporous silica-Pt@Au (JMPA) nanomotors with pH-responsive multi-phoretic propulsion. The JMPA nanomotors first undergo self-diffusiophoretic propulsion in 3.0 % H2 O2 due to the isolation of the Au nanoparticles (AuNPs) from the PtNPs layer. Then the weak acidity of H2 O2 can trigger the disassembly and reassembly of the AuNPs, resulting in the Janus distribution of large AuNPs aggregates. Such reconstruction of JMPA leads to the contact between PtNPs and AuNPs aggregates, thus changing the propulsion mechanism to self-electrophoresis. The asymmetric and aggregated AuNPs also enable the generation of a thermal gradient under laser irradiation, which propels the JMPA nanomotors by self-thermophoresis. Such multi-phoretic propulsion offers considerable promise for developing advanced nanomachines with a stimuli-responsive switch of propulsion modes in biomedical applications.

The hot deformation of 18Cr-5Ni-4Cu nitrogen-alloyed austenitic stainless steel was tested with a Gleeble-1500D simulator in the temperature range of 1273&ndash, 1473 K and in the strain rate range of 0.01&ndash, 10 s&minus, 1. The Zener-Hollomon parameter method was used to construct a constitutive equation for high-temperature plastic deformation. The energy dissipation diagram of the material was calculated based on dynamic material modelling (DMM). The microstructural variations were characterized via X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) with energy dispersive spectroscopy (EDS) and transmission electron microscopy (TEM). The thermodynamic calculation results showed that the addition of nitrogen to 18Cr-5Ni-4Cu steel promoted the formation of Cr2N and gas phases and expanded the austenite phase region, these results were consistent with the XRD test results of the solid solution sample. The hot deformation activation energy after nitrogen addition was 556.46 kJ∙mol&minus, 1. The processing map predicted that the optimum hot working regimes were in the temperature range of 1416&ndash, 1461 K, where ln &epsilon, ˙ was 0.75&ndash, 1 on the power dissipation map. At high temperatures and a small strain rate, dynamic recrystallization easily occurred. The TEM analyses showed that nano-scale M23C6 and Cr2N precipitated at the grain boundary, and NbC with a diameter of approximately 150 nm appeared along the grain boundary, resulting in grain boundary strengthening. The phase precipitation results were consistent with the Thermo-Calc calculation results. The nitrogen solid solution in the steel promoted the precipitation of nitrides, which caused grain boundary strengthening. Thus, the grain boundary stress increased and wedge-shaped grain boundary cracks formed.

We use a combination of polarized Raman spectroscopy experiment and model magnetism-phonon coupling calculations to study the rich magneto-Raman effect in the two-dimensional (2D) magnet $\mathrm{CrI_3}$. We reveal a novel layered-magnetism-assisted phonon scattering mechanism below the magnetic onset temperature, whose Raman excitation breaks time-reversal symmetry, has an antisymmetric Raman tensor, and follows the magnetic phase transitions across critical magnetic fields, on top of the presence of the conventional phonon scattering with symmetric Raman tensors in $N$-layer $\mathrm{CrI_3}$. We resolve in data and by calculations that the 1st-order $A_g$ phonon of monolayer splits into a $N$-fold multiplet in $N$-layer $\mathrm{CrI_3}$ due to the interlayer coupling ($N$>=2) and that the phonons with the multiple show distinct magnetic field dependence because of their different layered-magnetism-phonon coupling. We further find that such a layered-magnetism-phonon coupled Raman scattering mechanism extends beyond 1st-order to higher-order multi-phonon scattering processes. Our results on magneto-Raman effect of the 1st-order phonons in the multiplet and the higher-order multi-phonons in $N$-layer $\mathrm{CrI_3}$ demonstrate the rich and strong behavior of emergent magneto-optical effects in 2D magnets and underlines the unique opportunities of new spin-phonon physics in van der Waals layered magnets., 16 pages, 4 figures + supplementary material

The prediction of the morphology of ternary polymer blends requires a good knowledge of the values of the three interfacial tensions. We selected three polymers, either biobased or biodegradable, PA, PBAT and PLA and we accurately measured their interfacial tensions using the retraction method, varying the molar mass or inverting the phases. The following values of interfacial tensions were obtained: = 3.3±0.7mN/m, = 5.6±0.3mN/m and = 3.0±0.4 mN/m. These values were used to calculate the spreading coefficients giving rise to two negative coefficients and one coefficient close to zero. Ternary blends with various compositions, two different levels of viscosity for the PBAT, different processing conditions were prepared. There was a very good agreement between the predictions of the spreading theory, when using the values of interfacial tensions in the right order of magnitude, and the observed morphologies, whatever the polymer serving as a matrix. When the PLA or PBAT was chosen as the matrix, the ternary blend morphology was composed of composite droplets, presenting a partial wetting morphology, dispersed in the polymer matrix. This morphology was observed whatever the composition, the viscosity level of the PBAT phase and the processing conditions. A further calculation of the free energy confirmed this 2 morphology. The formation process of this semi-encapsulated morphology was observed during blending.

Spinel-structured Li x Mn 2 O 4 (x = 1.0, 1.02, 1.04, and 1.06) cathode materials have been synthesized by a solid-state method using Mn 3 O 4 and Li 2 CO 3 as raw materials. The Mn 4+ content gradually decreases from 84.80% to 82.62% and then increases from 82.62% to 88.98%, when the Li content increases from 1.00 to 1.06. The rate capability of the LiMn 2 O 4 samples evidently increases as the lithium content increases from 1.00 to 1.06. Electrochemical impedance spectroscopy results indicate that the R ct values gradually increase from 58.33 Ω to 133.1 Ω and then decrease from 133.1 Ω to 68.79 Ω when the Li concentration increases from 1.00 to 1.06. The R sf values also increase from 25.67 Ω to 37.84 Ω and then decrease from 37.84 Ω to 16.69 Ω, when the Li concentration increases from 1.00 to 1.06. These changes in Mn 4+ content, R sf , and R ct with the increase in Li content are related to changes in the second phase in LiMn 2 O 4 .

An improved time-varying mesh stiffness (TVMS) model of a helical gear pair is proposed, in which the total mesh stiffness contains not only the common transverse tooth bending stiffness, transverse tooth shear stiffness, transverse tooth radial compressive stiffness, transverse gear foundation stiffness and Hertzian contact stiffness, but also the axial tooth bending stiffness, axial tooth torsional stiffness and axial gear foundation stiffness proposed in this paper. In addition, a rapid TVMS calculation method is proposed. Considering each stiffness component, the TVMS can be calculated by the integration along the tooth width direction. Then, three cases are applied to validate the developed model. The results demonstrate that the proposed analytical method is accurate, effective and efficient for helical gear pairs and the axial mesh stiffness should be taken into consideration in the TVMS of a helical gear pair. Finally, influences of the helix angle on TVMS are studied. The results show that the improved TVMS model is effective for any helix angle and the traditional TVMS model is only effective under a small helix angle.

Polyethylene glycol (PEG) based graphene aerogel (GA) confined shaped-stabilized phase change materials (PCMs) are simply prepared by a one-step hydrothermal method. Three-dimensional GA inserted by PEG molecule chains, as a supporting material, obtained by reducing graphene oxide sheets, is used to keep their stabilized shape during a phase change process. The volume of GA is obviously expended after adding PEG, and only 9.8 wt% of GA make the composite achieve high energy efficiency without leakage during their phase change because of hydrogen bonding widely existing in the GA/PEG composites (GA-PCMs). The heat storage energy of GA-PCMs is 164.9 J/g, which is 90.2% of the phase change enthalpy of pure PEG. In addition, this composite inherits the natural thermal properties of graphene and thus shows enhanced thermal conductivity compared with pure PEG. This novel study provides an efficient way to fabricate shape-stabilized PCMs with a high content of PEG for thermal energy storage.

Using optical absorption materials to heat localized water gaining water steam is a highly efficient way of solar energy utilization. Here, we introduced a new solar absorber of modified graphene aerogel (MGA) prepared by one-step hydrothermal method and oxygen plasma treatment for rapid and efficient solar steam generation. The obtained MGA possesses interconnected 3D porous networks formed by randomly construction of reduced graphene oxide (rGO) sheets and hydrophilic surface due to effective oxygen implant by oxygen plasma. Furthermore, under one sun illumination, MGA exhibited a high evaporation efficiency of 76.9%, which is not only due to the intrinsic property of rGO with excellent light absorption but also attributed to the particular structural merits of MGA—hydrophilic surface for water supplying and connected networks for steam escaping as well as porous matrix with low thermal conductivity. The cyclic tests confirmed that MGA still maintained a stable performance of solar steam generation even when it repeated multiple times. This new assembly demonstrated here is efficient and reusable for applications in rapid solar seawater desalination and wastewater treatment in remote area.

In this contribution, a novel type of piezoelectric tubular energy harvester based on fluctuating fluid pressure is investigated. Analytic model of the proposed energy harvester is built under the assumption of axisymmetric radial vibration. Exact solution of the piezoelectric vibrating tube is obtained with its output performances formulated. A series of numerical simulations are conducted to investigate the influences of geometrical parameters, input mechanical load parameters and output electrical load parameters upon the output performances of the proposed piezoelectric tubular energy harvester. The model and simulation results indicate the potential of the proposed piezoelectric tubular energy harvester. It is expected that the energy harvester be useful in powering wireless sensor network for the health monitoring of hydraulic systems, where fluid conveying pipe vibration is omnipresent.

The structural, electrical and magnetic properties of a new semiconductor material Co-Fe-Ta-B-O are investigated. The preparation of the material is a new try to make magnetic semiconductor, which ...

Constructing composite structure is an effective way to improve dielectric energy storage properties. However, ionic diffusion between composite members is generally inevitable, which mixes the effects of solid solution with composite structure on property to some extent. To exclude the ionic diffusion effect as much as possible, antiferroelectric (Pb0.97La0.02)(Zr0.5Sn0.4Ti0.1)O3 (PLZST) was sintered at a relatively high temperature to precipitate SnO2 particles, then more SnO2 were introduced to from (1-x)PLZST:xSnO2 (x = 0–0.25) composite. The results showed that composite structure had significant effects on microstructures and properties with changed lattice parameter, decreased grain size, increased Curie temperature, suppressed antiferroelectric property, and enhanced electric breakdown strength. The optimal composition of x = 0.2 showed high energy storage density of 2.38 J/cm3. This work provides a robust platform to investigate the effect of composite microstructure on electrical properties, which is helpful for further developing high performance composite materials.

Inspired by shallow-water sloshing in a moving tank, a novel type of vibration-based piezoelectric energy harvesting device composed of a piezoelectric bimorph beam and an extension tank is proposed in this paper. The structure and working principle of the proposed device are provided. Then, the effects of different heights of water filling in the tank on the performances of the harvester are studied and analyzed. Experiments are set up to investigate the actual device performance by changing the base excitation frequency and load resistance for different water heights. The results show that by modulating the water height, the resonant frequency and bandwidth can be adjusted, which can enhance the energy harvesting performance of the device at different ambient vibration frequencies. This study provides some clues to improve the performance of the vibration-based energy harvesting devices.

Modified WS2 by silane coupling agent were encapsulated in the dimples fabricated on the surface of cylinder liner samples by hot-pressing method. The tribological properties, anti-adhesion performance of the samples as well as the releasing behavior of modified WS2 in the dimples were tested by a reciprocating tribotester. Moreover, the anti-erosion performance of modified WS2 was examined by ultrasonic vibration test. The results indicate that the composite lubrication structure has good anti-friction and anti-adhesion effects. Furthermore, the release rate of WS2 in the dimples is decreased by 102.2% due to the introduction of silane coupling agent. Additionally, the synergistic effect among the dimples, the solid lubricant and the silane coupling agent can explain the anti-friction and sustained release mechanisms.

Solar steam generation driven by local hot spots is an efficient route to use solar energy. We introduce a novel photoreceiver composed of reduced graphene oxide (rGO) and polyurethane (PU) matrix for highly efficient solar steam generation. The rGO nanosheets covalently cross-linked to PU matrix provide excellent stability and broad optical absorption, together with the property of thermal insulation served by PU resulting in rapid increase of local thermal under illumination. Moreover, the hydrophilic segments and the interconnected pores of rGO/PU can be worked as water channels for replenishment of surface water evaporated. With excellent mechanical and chemical stability, the functional rGO/PU foam exhibited a solar photothermal efficiency of ∼81% at a light density of 10 kW/m2. The novel macro design demonstrated here is low cost, simple to prepare, and highly stable, being suitable for a series of practical applications in massive seawater desalination, solar steam generation, and sterilization of ...

Solar steam generation through heat localization is a new approach to efficiently utilize solar energy. Nanocomposites with noble metals and other porous materials have been employed to generate solar vapor at a high light intensity. However, large-scale applications of the nanocomposites based on noble metals are restricted due to their high cost, complex preparation, and low recycling stability. Herein, we report a simple method toward fabricating graphene aerogel (GA) from graphene oxides only by photoreduction, which is for the first time used to harvest solar energy. GA can not only convert almost the entire incident solar light to heat energy but can also self-float on the surface of water and pump the interface water forming a constant water steam. Solar steam generation efficiencies of 53.6 ± 2.5% and 82.7 ± 2.5% are achieved at light intensities of 1 and 10 kW m–2, respectively. Furthermore, this efficiency is still kept at a high value, and the morphology of GA is hardly broken after 10 cycles o...

Surface plasmon resonance effects of nanoparticles, generating local hot spots in a water-air interface under sunlight irradiation to drive water into steam, can realize the highly efficient conversion of solar energy. Here, we develop a novel solar steam generation system with double-layer structures, of which the top reduced graphene oxide (rGO) sheets as a light-to-heat conversion layer and the bottom mixed cellulose esters (MCE) membrane as a porous supporting layer. The double-layer system (rGO/MCE) connected by polyethylenimine can convert the absorbed solar energy to heat energy at a water-air interface to enable efficient evaporation (∼60%) under only 1 kW/m2 irradiation. Contrast experiments under a light density of 4 kW/m2 showed that the rGO/MCE membrane achieved the highest evaporation efficiency of 71.8 ± 3%, and its evaporation rate is 4.3 times higher than that of pure water. Cycling tests confirmed that the system still maintained a stable performance over 15 cycles under same illumination conditions. Excellent mechanical stability, low cost, simple preparation and reusability of the rGO/MCE membrane are suitable for a wide range of practical applications in large-scale solar steam generation, sterilization of waste, seawater desalination.

Solar vapor generation enabled by nanoparticles is a green, efficient and direct approach to utilize solar energy. In this work, nanocomposites of graphene oxide (GO) and gold (Au) nanoparticles were prepared to generate solar steam under sunlight irradiation. The changes on steam pressure, mass loss and temperature of water were used to study the solar photothermal properties of GO-Au nanocomposites in water, which demonstrated that the synergistic interaction between GO nanosheets and Au nanoparticles played an active role in the photothermal effect of the nanocomposites. Trace of Au nanoparticles (15.6 wt‰) in the GO nanofluids could significantly improve the efficiency of solar vapor generation. More interestingly, the morphology and color of GO-Au nanofluids varied with irradiation times under sunlight, and our results suggested that GO sheets were reduced to graphene sheets. This process of photothermal deoxygenation of GO provides an available solution for preparing graphene sheets under ambient conditions without any reductions, and the solar steam generation method can enable potential applications like sterilization of waste, seawater desalination, and disinfection.

Obtaining high strength hydrogels with good biocompatibility and identifiability is a challenging task. Herein, a new approach is presented that enables the simple one-pot synthesis of a high strength polymer hydrogel on the basis of silicone, poly(hydroxyethyl methacrylate) (PHEMA) and an Eu(III) organic complex. The composition and properties of the hydrogel could be easily tuned because of the good solubility of the monomers and non-interfering polymerization processes. The hydrogel exhibits an excellent integrated performance with toughness, high resilience, biocompatibility, and identifiability.

Photothermal conversion has shown great potential for the effective use of solar energy. Au nanoparticles (Au NPs) were a satisfactory material for photothermal conversion, mainly due to their surface plasmon resonance (SPR) effect. Herein, the diameter effect of Au NPs on photothermal conversion was explored for generating solar steam. The diameters varied from 3 to 40 nm, and the results showed that the photothermal conversion efficiency was enhanced by increasing the diameters of the Au NPs with constant total superficial areas under a xenon lamp. This study is important for the further exploration of the photothermal effect of Au NPs and their practical applications in large-scale solar steam generation, seawater desalination and sterilization of waste.

Argon stirring is one of the most widely used metallurgical methods in the secondary refining process as it is economical and easy, and also an important refining method in clean steel production. Aiming at the issue of poor homogeneity of composition and temperature of a bottom argon blowing ladle molten steel in a Chinese steel mill, a 1:5 water model for 110 t ladle was established, and the mixing time and interface slag entrainment under the different conditions of injection modes, flow rates and top slag thicknesses were investigated. The flow dynamics of argon plume in steel ladle was also discussed. The results show that, as the bottom blowing argon flow rate increases, the mixing time of ladle decreases, the depth of slag entrapment increases with the argon flow rate and slag thickness, the area of slag eyes decreases with the decrease of the argon flow rate and increase of slag thickness. The optimum argon flow rate is between 36&ndash, 42 m3/h, and the double porous plugs injection mode should be adopted at this time.

Hydrodynamically levitated rotary blood pumps (RBPs) with noncontact bearing are effective to enhance the blood compatibility. The spiral groove bearing (SGB) is one of the key components which offer the suspension force to the RBP. Current studies focus on the suspension performance of the SGB under continuous flow condition. However, the RBP shows pulsatile characteristics in the actual clinical application, which may affect the suspension performance of the SGB. In this paper, the impact of pulsatile flow upon the suspension force from the SGB is studied. A model of the SGB with a groove formed of wedge-shaped spirals is built. Then, the CFD calculation of the hydrodynamic force offered by designed SGB under simulated pulsatile flow is introduced to obtain the pulsatile performance of the suspension force. The proposed method was validated by experiments measuring the hydrodynamic force with different bearing gaps. The results show that the suspension force of the SGB under pulsate flow is the same as under steady flow with equivalent effective pressure. This paper provides a method for suspension performance test of the SGB.

Radiative thermal rectifiers capable of realizing asymmetric heat flux transfer have attracted a lot of research interests recently, mainly focusing on the engineering of the emissivity spectra. In this Letter, we propose a far-field radiative thermal rectifier utilizing the phase change material vanadium dioxide (VO2). The thermal rectifier consists of a metamaterial infrared absorber and a two-layer thin-film structure acting as the active and the passive components, respectively. Numerical optimization has been carried out to control the emissivity spectra of both parts and maximize the overall rectification effect. A large thermal rectification factor of 3.5 is predicted at a temperature bias of ΔT=100 K.