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Photocatalytic upgrading of renewable biomass is a promising way to relieve energy crisis and environmental pollution. However, low photocatalytic efficiency and uncontrollable selectivity still limit its development. Herein, ultrathin SnNb2O6 nanosheets with high dispersed Pt nanoparticles (Pt/SN) were successfully developed as an efficient photocatalyst for the precise hydrogenation of furfural (FUR) to furfuryl alcohol (FOL) under visible light irradiation and exhibited the high conversion of FUR (99.9%) with the high selectivity for FOL (99.9%). It was revealed that SN with only 4.1 nm thickness possess good separation ability of photo-generated carriers and abundant surface Lewis acid sites (Nb5+) which would selectively chemisorb and activate FUR molecules via the Nb···O = C coordination. Meanwhile, Pt nanoparticles would gather photo-generated electrons for greatly promoting the generation of active H species to support the hydrogenation of FUR to FOL. The synergistic effects between SnNb2O6 nanosheets and Pt nanoparticles remarkably facilitate the photocatalytic performance for hydrogenation. This work not only confirms the great potential of ultrathin nanosheet photocatalyst with functional metal sites for precise upgrading of biomass but also provides an in-depth view to understand the surface/interface interaction between reactant molecules and surface sites of a photocatalyst.

Rationally constructing functionalized cocatalysts for removing chemically inert polychlorinated biphenyls is significant and challenging. In this study, we have synthesized uniform Pd nanocrystals (Pd NCs) with cube (CUB) and octahedron (OCT) geometries, corresponding to the exposed (100) and (111) facets, and they were incorporated with ultrathin TiO2(B) nanosheets (TBs) for the photocatalytic dechlorination of polychlorinated biphenyls under visible light illumination (λ ≥ 400 nm). Photocatalytic performance experiments revealed that CUB/TBs is more efficient with a 200% enhancement higher than OCT/TBs. Physicochemical characterizations reveal that the CUB possesses higher surface charge density than OCT, which promotes the activation of the C–Cl bond of polychlorinated biphenyls, leading to higher dechlorination performances of CUB/TBs than OCT/TBs. This study not only fundamentally elucidates the effect of facet-engineering palladium nanocrystals on the photocatalytic dechlorination of polychlorinated biphenyls, but also paves the way for rationally fabricating superior photocatalysts for other advanced applications.

In this paper, the synthesis of 2,4,6-trinitrophenol from phenol was improved in the range of 0–65°C, and the yield was 79.4%. The effectiveness of the synthesis process was confirmed by Nuclear Ma...

α-Formamidinium lead iodide (α-FAPbI3) has become one of the most promising candidate materials for high-efficiency and thermally stable perovskite solar cells (PSCs) owing to their outstanding optoelectrical properties and high thermal stability. However, achieving a stable form of α-FAPbI3 where both the composition and the phase are pure is very challenging. Herein, we first report on a combined strategy of precursor engineering and grain anchoring to successfully prepare MA-free and phase-pure stable α-FAPbI3 films. Engineering the precursor solutions by incorporating volatile FA-based additives completely suppresses the formation of non-perovskite δ-FAPbI3 during film crystallization. Grains of the desired α-phase are anchored together and stabilized by permeating 4-tert-butyl-benzylammonium iodide into the α-FAPbI3 film interior via grain boundaries. This cooperative scheme leads to a significantly increased efficiency close to 21% for FAPbI3 perovskite solar cells (PSCs), which is among one of the highest values to date. Moreover, the stabilized PSCs exhibit improved thermal stability and maintained ~90% of their initial efficiency after storing at 50 °C for over 1600 hours. These findings should open new routes towards fabrication of high-quality perovskite films and optoelectronic devices.

High-resolution transmission electron microscopy (HRTEM) was used to observe the soot particles emitted from gasoline direct injection (GDI) engine equipped with metallic particulate filter (GPF). The changes of microscopic morphology and structure of the soot particles at pre-GPF and post-GPF were studied at a fixed speed of 1500 r/min and 25 %, 50 % 75 % and 100 % load, respectively. Furthermore, the micro-parameters of the primary particles that make up the soot particles were analyzed. The results show that the primary particles are approximately spherical, and agglomerate to form irregular shapes such as chains, branches and rings. The load and GPF have no significant influence on the microscopic morphology of the soot particles, the fractal dimension of soot particles at both ends of the GPF increases with the increase of load. Under the experimental conditions of the engine, most primary particles consisting of the soot particles are “shell-core” structure; The fringe length, tortuosity and interlayer spacing of the primary particles at pre- and post-GPF are monomodal. Among them, the average fringe length increases with the increase of load, while both the average tortuosity and average interlayer spacing change the opposite. These indicated that the degree of graphitization of the soot particle increases with the increasing load. Load and GPF only affect the micro-structure parameters of the primary particles and have no effect on its distribution.

This work highlights a new process for direct manufacturing of ductile iron that is based on the innovative combined technology of quenching and partitioning, and low-temperature-transformation of nano bainite as used for high strength steels. In this process, a commercial unalloyed ductile iron is austenitized at 890 °C for 20 min, then rapidly quenched to 180 °C for 5 s, and finally partitioned at 220 °C for 240 min. A maximum tensile strength of more than 1600 MPa, a hardness of 55 HRC at an elongation in excess of 5%, and the number of repeat tensile fatigue failure of 2.5 × 104 cycles at a stress amplitude of 600 MPa, are achieved. This is comparable to those of a high strength carbon alloy steel. These properties are due to the synergistic strengthening and toughening effects of a multiphase structure comprising tempered martensite, bainitic ferrite and retained austenite in the matrix, and a spherical graphite morphology. This work provides a guidance on how to produce unique steel-like ductile iron with a high level of strength and acceptable toughness.

Background A considerable amount of azo dye wastewater is generated from textile industry every day, which jeopardizes human health and environment. To treat azo dye-containing wastewater in visible-light environment, a perovskite YFeO3/carbon fiber (CF) electrode was developed. Methods A sol-gel process combined with calcination was adopted to synthesize YFeO3 catalysts, and the composite electrode was fabricated using a facile dip-coating method. Significant findings The YFeO3 powder that was calcined at 700 °C consisted of mixed hexagonal and orthorhombic phases with crystallite sizes of 15–30 nm. The particles tended to aggregate, forming a porous structure, and they exhibited a photocatalytic degradation capability for Reactive Black 5 (RB5) dyes. Notably, the YFeO3/CF composite electrode enabled significant photoelectrocatalytic activity over RB5 under visible light irradiation, with a removal efficiency of 99% in a 60 min treatment. In addition, the composite electrode demonstrated its high stability during the repeated treatments. The synergetic effect of photo- and electrocatalysis accounted for breaking the N=N bonds, as well as the benzene and naphthalene structures of RB5, resulting in a favorable pollutant degradation. Moreover, the photoelectrocatalytic treatment system kinetics followed a pseudo-first-order rate equation, corresponding to a single-molecule reaction. The improved photoelectrocatalytic activity of the composite electrode can be attributed to the reduced surface and charge transfer resistances during the photoelectrocatalysis process.

Aluminum-ion batteries (AIBs) are recognized as one of the promising candidates for future energy storage devices due to their merits of cost-effectiveness, high voltage, and high-power operation. Many efforts have been devoted to the development of cathode materials, and the progress has been well summarized in this review paper. Moreover, in addition to materials, the intercalation mechanism also plays a key role in determining cell performance. Here, the research progress of cathode materials and corresponding ion intercalation mechanism in AIBs are summarized, including intercalation of AlCl4−, intercalation of Al3+, and coordination of AlCl2+/AlCl2+. This minireview provides comprehensive guidance on the design of cathode materials for the development of high-performance AIBs.

Fluid inhomogeneous distribution affects heat transfer efficiency in the plate-fin heat exchanger (PFHE). In order to improve fluid uniform distribution in the exchanger, the irregular-shaped hole leading flow structure (IHLFS) was proposed for solving fluid inhomogeneous distribution among different layers of PFHE. The inlet distributor with irregular-shaped holes was designed according to different inlet flow velocities aiming at improving fluid uniform distribution. The results on fluid flow and heat transfer characteristics were carried out by the methods of CFD and experimental analysis, and finally, the fluid flow characteristics in inlet section of PFHE with IHLFS were achieved. Comparing with round hole leading flow structure (RHLFS), it can be observed that fluid distribution in PFHE with IHLFS is more uniform than that with round hole, however, the dynamic pressure increases accordingly and finally, increases the ratio of heat transfer and dynamic pressure. The comparison results also demonstrate that the IHLFS can improve fluid distribution, decrease fluid impact in inlet section of PFHE and finally, improve heat transfer enhancement.

Supplementary cementitious materials (SCMs) are usually employed to replace partial cement and the pore-solution chemistry of blended cements is extremely essential for their cement hydration and d...

This paper describes a novel process, hematite involved roasting − alkaline leaching − Bayer digestion, to extract silica and alumina from high-alumina coal gangue (HACG). The phase transformations during roasting were investigated through X-ray diffraction, X-ray photoelectron spectroscopy, scanning electronic microscope, and energy-dispersive spectrometer. The silica and alumina extraction were carried out through alkaline leaching. Results shown that, by reductively roasting with hematite, kaolinite converted into hercynite (FeAl2O4), and cristobalite solid solution (SiO2), which dispersed as the form of fine grain dissemination. During cooling in oxidizing atmosphere, the cristobalite solid solution showed insignificant change. In contrast, the hercynite oxidized into α-Fe2O3 and α-Al2O3 through the conversion of intermediate products of Fe3O4, γ-Fe2O3, and γ-Al2O3. The migration of iron oxides to hercynite surface during cooling process prevented the formation of Al–Si compounds. > 96% of silica and > 97% of alumina were extracted by alkaline leaching at 110 °C and Bayer digestion at 260 °C, respectively. This work demonstrates a new process to treat and recover the high-value components in HACG and decrease the red mud output through recycling the hematite.

Aqueous zinc ion batteries (ZIBs) are widely researched due to the low-cost and intrinsic safety. However, the rate capability and specific capacity of ZIBs is limited due to the dissolution and structural collapse of cathode materials. It is crucial to construct stable cathode materials to promote rate capability and cycle stability of ZIBs. In this paper, The V3O7 was tightly attached to the surface of graphene oxide (GO) by a hydrothermal reaction and a V3O7/GO heterostructure was successfully achieved. The GO could increase structural stability, enhance electrical conductivity, and expand specific surface area of V3O7. Therefore, the V3O7/GO with a heterostructure exhibits an improved cycle stability and rate capability compared with V3O7. It displayed a specific capacity of 275.6 mA h g−1 at a current density of 1.0 A g−1. The study paves the way for promoting the Zn2+ storage performance of vanadium oxide and developing stable cathode materials of ZIBs.

Mg(1-x)ZnxTa2O6 (x = 0.00−0.08) dielectric ceramics were synthesized via the traditional solid-state reaction method. We used XRD and Rietveld refinement to demonstrate that a pure Mg(1-x)ZnxTa2O6 phase with trirutile structure was formed. Zn2+ substitution helped to decrease the Raman full width at half width of the A1g mode at 703 cm−1, which resulted in an increase in the order and rigidity of the TaO6 octahedron, this in turn contributed to improving the Q×f values. Additionally, the introduction of Zn2+ significantly promoted grain growth and increased the dense, and the molecular polarizability, these factors lead to a higher permittivity. Moreover, enhanced Ta-O bond energy resulted in a more stable TaO6 octahedron in the Mg(1−x)ZnxTa2O6 system, which contributed to enhanced τf values via substitution of Zn2+ doped on the A-site. Correspondingly, the microwave dielectric properties were significantly improved for 0.04-doped samples, obtaining: er = 27, Q × f = 185,000 GHz (at 7.47 GHz), τf =32 ppm/°C.

Nano-whiskers based 3D Si3N4 porous ceramics (3D-NWSNPC) with high-porosity (about 91–93 %), low density (0.17–0.25 g/cm3), low thermal conductivity, and a certain degree of recoverability under cyclic compressive loading and reasonably strengths were prepared at 1423–1523 K via a one-pot foam-gelcasting/nitridation route using inexpensive commercial Si powders as starting materials and hexadecyl trimethyl ammonium bromide as foaming agent. After nitridation at 1523 K, the sample with an original solid loading of 12.5 wt% exhibited the highest compressive strength of 1.9 MPa, even though its density was lowered to 0.25 g/cm3. The sample nitrided at 1473 K had a relative density of 7.3 %. Its compressive and specific strength were respectively 1.1 MPa and 5.5 MPa·cm3 g−1, and its thermal conductivity was as low as 0.074 W/(m K) (measured at 323 K). These outstanding properties would make the as-prepared 3D-NWSNPC a promising candidate for applications in catalysis, filtration, thermal insulation and many other important areas.

High-performance lithium ion capacitors (LICs) have been seriously hindered by the very low capacity and unclear capacitive mechanism of carbon cathode. Herein, after the combination of experimental results and theoretical calculations, it is found that the critical pore size of 0.8 nm for PF6− ion adsorption decreases strong interactive repulsion of electrons and largely reduces adsorption energy barrier, which greatly improves the charge accommodation capacity in electrical double-layer behavior. Most importantly, the chemical-bond evolution process of C=O group has been firstly revealed by X-ray photoelectron spectroscopy (XPS), indicating that the introduction of C=O group can provide abundant redox active sites for PF6− ion adsorption accompanied with enhanced pseudocapacitive capacity. Attributed to the synergistic effect of dual capacitive mechanism, porous carbon sheet (PCS) cathode shows a reversible specific capacity of 53.6 mAh g−1 even at a high current density of 50 A g−1. Significantly, the quasi-solid-state LIC manifests state-of-the-art electrochemical performances with an integrated maximum energy density of 163 Wh kg−1 and an outstanding power density of 15,000 W kg−1. This elaborate work promotes better fundamental understanding about capacitive mechanism of PF6− ion and offers a rational dual-capacitive strategy for the design of advanced carbon cathodes.

Attracted by the capability of light to heat and electricity conversion, the photothermoelectric (PTE) effect has drawn great attention in the field of energy conversion and self-powered electronics. However, it still requires effective strategies to convert electricity from light based on the corresponding photothermoelectric generator. Herein, considering the broad photoresponse and large Seebeck effect of tellurium nanowires (Te NWs) as well as the high electrical conductivity of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS), PEDOT:PSS/Te NW hybrid thin films were fabricated to enhance the conversion efficiency by the photothermoelectric effect with respect to single thermoelectric performance. A detailed comparison has been achieved between the photothermoelectric and thermoelectric properties induced by light illumination and heating plates through current-voltage (I-V) transport, respectively. PEDOT:PSS/Te NW hybrid films also show an enhanced photothermal harvesting compared to pure PEDOT:PSS. A photothermoelectric device was assembled based on the as-fabricated PEDOT:PSS/Te NW hybrid films with 90 wt% Te NWs and achieved a competitive output power density with good stability, which may provide insights into improving solar energy harvesting-based photothermoelectric conversion by organic/inorganic hybrids.

Herein, silver wire is synthesized electrochemically within a nanopipette using the nanopipette-liquid/liquid interface. The i-t curve characterizes the growth state of the silver wire. The higher rate of current increase indicates the faster electron transfer and the faster growth of the silver wire; conversely, when the current does not increase significantly with time, i.e., the rate of increase of the current is small, the growth rate of the silver wire is slow. The main driving force for the growth of silver into a linear structure is the theoretical current differential between the water and oil, caused by the concentration difference between the silver nitrate and ferrocene. The growth of the silver wire is also influenced by the shape of the nanopipette. If the diameter of the pipet increases quickly, silver wire tends to produce multibranched structures, while a smaller diameter makes it easier to obtain silver wire with fewer branches due to the confinement effect. This method is also applicable to the synthesis of gold within a nanopipette. The combination of nanopipette and metallic material using a liquid-liquid interface results in a broader application of nanopipettes for nanopore sensors, nanopore electrodes, bipolar electrodes, etc.

The top-performing perovskite solar cells (efficiency > 20%) generally rely on the use of a nanocrystal TiO2 electron transport layer (ETL). However, the efficacies and stability of the current stereotypically prepared TiO2 ETLs employing commercially available TiO2 nanocrystal paste are far from their maximum values. As revealed herein, the long-hidden reason for this discrepancy is that acidic protons (∼0.11 wt %) always remain in TiO2 ETLs after high-temperature sintering due to the decomposition of the organic proton solvent (mostly alcohol). These protons readily lead to the formation of Ti–H species upon light irradiation, which act to block the electron transfer at the perovskite/TiO2 interface. Affront this challenge, we introduced a simple deprotonation protocol by adding a small amount of strong proton acceptors (sodium ethoxide or NaOH) into the common TiO2 nanocrystal paste precursor and replicated the high-temperature sintering process, which wiped out nearly all protons in TiO2 ETLs during the sintering process. The use of deprotonated TiO2 ETLs not only promotes the PCE of both MAPbI3-based and FA0.85MA0.15PbI2.55Br0.45-based devices over 20% but also significantly improves the long-term photostability of the target devices upon 1000 h of continuous operation.

Polarity often refers to the charge carrier type of a semiconductor or the charging state of a functional group, generally dominating their functionality and performance. Herein we uncover a spontaneous and stochastic polarity-flipping phenomenon in monolayer WSe2, which randomly switches between the n-type and p-type states and is essentially triggered by fluctuating carrier flows from or to the adjacent WS2 monolayer. We have traced such fluctuating carrier flows by interfacial photocurrent measurements in a zero-bias two-terminal device. Such polarity flipping results in switching between the negative and positive correlations between the emission intensities of WS2 and WSe2 in the heterobilayer, which is further well-controlled by the electrostatic gate-tuning experiments in a capacitor-structure device. Our work not only demonstrates giant and intermittent carrier flows through long-range coupling in 2D heterostructures and a consequent spontaneous polarity flipping phenomenon but also provides a two-emitter system with a switchable correlation sign that could project future applications in optical logic devices.

Ni2+ modified MgTa2O6 ceramics with a trirutile phase and space group P42/mnm were obtained. The correlations between crystallographic characteristics and microwave dielectric performance of MgTa2O6 ceramics were systematically studied based on the chemistry bond theory (PVL theory) for the first time. The results indicate that the introduction of Ni2+ causes a change in polarizability and the Mg–O bond ionicity, which contributes to the variation of dielectric constant. Moreover, the lattice energy, and packing fraction, full width at half maximum of the Raman peak of Ta–O bond, as the quantitative characterization of crystallographic parameters, regulate the dielectric loss of MgTa2O6 ceramics in GHz frequency band. In addition, the study of sintering behavior shows that the densification and micromorphology are the crucial factors affecting the microwave dielectric performance. Typically, Ni2+ doping on the A-site of MgTa2O6 can effectively promote the Q × f values to 173,000 GHz (at 7.43 GHz), which ensures its applicability in 5G communication technology.

With the decreasing size of the integrated circuits, developments of materials with low dielectric constant have become an important research to solve the problems of parasitic capacitance. Thus in this study, low-cost SiO2 and polylactic acid (PLA) were used for the fabrication of SiO2/PLA hybrid films targeting capacitor applications. SiO2 nanoparticles with porous structure were prepared via spray pyrolysis with non-ionic surfactant F-127 as a pore-forming agent. In addition, surface morphology, porous structure, specific surface area, and particle porosity were examined via X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and nitrogen adsorption/desorption isotherms, respectively. Then, the SiO2/PLA hybrid films were fabricated and the resulting dielectric constants were measured. Finally, the resulting morphologies and properties and the corresponding mechanisms were discussed.

The porous morphology and secondary phase originated from lithium evaporation have deteriorated dielectric properties of Li2Mg3SnO6 ceramic. To solve this issue, a set of non-stoichiometric Li2Mg3-2xSn1-xO6 (x = −0.04, −0.02, 0.00, 0.02, 0.04, 0.06) samples were prepared by the solid-state method. Subsequently, the effects of non-stoichiometry on the structural evolution, microstructure and dielectric properties of rock salt-type Li2Mg3-2xSn1-xO6 ceramics were investigated. The Rietveld refinement and SEM results confirmed that moderate non-stoichiometry could eliminate secondary phase and promote densification. For −0.04 ≤ x ≤ 0.04, the upward tendency of dielectric constant (er) and quality factor (Q×f) was dominated by the improved phase purity and densification. As 0.04 ≤ x, the deterioration of dielectric characteristics was explained by the dielectric polarizability, lattice energy and packing fraction. The temperature coefficient of resonance frequency (τf) shifted from −36.41 to −27.23 ppm/°C, which could be attributed to the poor thermostability of Mg2SnO4 (τf = −64 ppm/°C) and enhanced octahedra bond energy.

The effect of Bi2O3 on ZnO-based varistor ceramic sintered around 800 °C is still not fully understood, because most of the ceramic cannot reach full densification at this low-temperature. Therefore, (balanced) ZnO–0.5 mol% V2O5–0.5 mol% MnCO3–0.5 mol% Co2O3–0.5 mol% TiO2–xmol% Bi2O3 (x = 0, 0.01, 0.05, 0.1 and 0.2) ceramic was designed and prepared by the solid-state sintering at 800 °C. The effect of Bi2O3 variation on the microstructure and electrical nonlinearity of the sample material was studied by using methods of XRD SEM, STEM, EDS and E–J test. Bi2O3 can further activate the reaction at the interface between the V-rich liquid phase and ZnO grains during sintering. This enhanced interface reaction is the key reason to the extremely low-temperature sintering of the ceramic at 800 °C. The variation of Bi2O3 in the 0–0.2 mol% range barely influences the constituents of the ceramic, which consists of ZnO main phase and two other secondary phases: Zn3(VO4)2 and Zn2TiO4. Most of Bi2O3 tends to segregate at grain boundaries. As a result, a soaking time longer than 4 h is needed to allow Bi ions diffusing into enough grain boundaries and improving the nonlinearity of ZnO based varistor ceramic. The sample containing 0.01 mol% Bi2O3 and sintered at 800 °C for 8 h has the best properties of a 43.3 nonlinear coefficient, a 2300 V/mm breakdown voltage and a 0.13 mA/cm2 leakage current density.

The high cost and platinum dissolution issues of counter electrodes (CEs) are two core problems for the development of dye-sensitized solar cells (DSSCs). In this work, different CEs based on binary alloy Ru81.09Co18.91, Ru80.55Se19.45 and Co20.85Se79.15 nanostructures for DSSCs were successfully synthesized and investigated by a facile and environmentally friendly approach. Here, we found that the Co20.85Se79.15 alloy CE-based device yields the higher photoelectric conversion efficiency of 7.08% compared with that (5.80%) of the DSSC using a pure Pt CE because of the larger number of active sites with improved charge transferability and reduced interface resistance by matching work function with the I3‒/I‒ redox electrolyte. The inexpensive synthesis method, cost-effectiveness and superior catalytic activity of the Co20.85Se79.15 alloy may open up a new avenue for the development of CEs for DSSCs in the near future.

High cost and instability of platinum (Pt) counter electrodes (CEs) are two persistent issues in dye-sensitized solar cells (DSSCs). Here, ternary selenide RuCoSe and NiCoSe-nanostructured CEs are ...

The microstructure，texture distribution and tensile property of 7xxx ultra-thick plate was investigated by optical microscopy (OM), scanning electron microscopy (SEM), electron back scattering diffraction (EBSD), transmission electron microscopy (TEM) and tensile tests. The results show that the microstructure, texture and tensile property were inhomogeneous along the thickness direction. A large number of sub-crystals remained on the surface of the thick plate and was accompanied by much recrystallization. Most of the structures were random texture, and the proportion of typical texture was low at the edge. For the center layer, there were also a lot of recrystallized grains and typical deformed texture along the β-fiber (Brass, S, and Copper) was observed. The 1/4 layer of the plate is a transition one, and had the lowest recrystallized fraction. From surface to center, precipitation phases within grains and grain boundaries gradually coarsen, mechanical properties reduced. At the same thickness, the tensile property showed appreciable anisotropy, the L direction was the highest and the S direction was the lowest.

Welding properties of three alloys with different Cu contents (0.1, 0.4 and 0.9 wt.%) is studied by means of melt inert-gas welding (MIG). The results showed that, with the increase of Cu content from 0.1 wt.% to 0.9 wt.%, the strength and elongation increased obviously. When the Cu content was 0.9 wt.%, the strength and elongation reached 375MPa and 15%, respectively, which is a better match for bearing structure part of vehicles application. Besides, the adding of Cu element provided an increase limit for welding joint strength. Due to abundant coarse phases in fusion zone (FZ) and welding zone (WZ), the strength slightly increased and the failure fracture was different compared with that of 0.1Cu and 0.4Cu alloy. Present result was meaningful and valuable for pushing aluminum application automobile structural parts and other engineering components.

The poor stability and low catalytic activity of NH2-UiO-66 in basic solutions require the reactions to be conducted in acidic solutions, which seriously hinders its potential photocatalytic application. Herein, we report that NH2-UiO-66 coated with two-dimensional covalent organic frameworks (COFs) via imine bond connection presents not only high photocatalytic activity but also high stability and adaptability to the solution environment. The NH2-UiO-66/COF hybrid material was fabricated through the Schiff base reaction of NH2-UiO-66 with 4,4',4″-(1,3,5-triazine-2,4,6-triyl)trianiline (TAPT) and 2,4,6-triformylphloroglucinol (TP). The hybrid material showed high stability in an alkaline environment, with only 4.7% of NH2-UiO-66 decomposed after the photocatalytic reaction. The optimum photocatalytic H2 evolution rate was 8.44 mmol·h-1·g-1 when triethanolamine was used as an electron-donating agent. The results presented here illustrate the possibility for effectively improving both the photocatalytic performance and stability of NH2-UiO-66 by coupling with COFs.

International audience; A simple and readily applicable voltammetric approach is described to characterize and measure thesite-hopping surface diffusion of underpotential-deposited (UPD) metal adatoms at nanoelectrodes. UPD refers tothe deposition of atoms on foreign metal supports at potentials lower than those predicted by Nernst law for a bulkdeposition. Despite its importance in several fields of catalysis, advanced nanofabrication or even atomicnanoengineering by atomic layer epitaxy, diffusion of UPD adatoms is difficult to observe at micro- andmacroelectrodes. In fact, at electrodes of usual dimensions, UPD adatoms surface diffusion is masked by otherelectrochemical phenomena of greater relative amplitudes. Conversely, at nanowires electrodes sealed in glass,only an extremely small fraction of the surface of the wires is exposed to the electrolyte solution and is rapidlyloaded. This allows the spillage of UPD adatoms onto the much larger area of the nanowire rod which is immuneto Faradaic reactions due to its isolation from the electrochemical solution by the glass casing. Therefore,surprisingly for a UPD process, voltammetric peaks currents and integral desorption charges primarily reflect thesediffusional surface processes so that the integral charges vary linearly with the inverse of the square root of thescan rate. This is easily observable and measurable with usual bench-level electrochemical instrumentation. In thiswork, by using nanoelectrodes with diameters between 90 and 260 nm, we were able to establish the majorinvolvement of this site-hopping surface diffusion of UPD Pb adatoms on polycrystalline gold (Au) and characterizeit quantitatively. The equivalent surface diffusion coefficient of UPD Pb adatoms was determined to be ~4.4 × 10-11 cm2 s-1 at room temperature, corresponding to a Gibbs free energy activation barrier of ca. 18.72 kJ mol-1 (i.e.,0.19 eV per Pb adatom) for the reaction of inter-sites exchange of Pb adatoms on a polycrystalline Au surface.

Wolframite-structured Mg1-xCaxZrNb2O8 (0−0.1) ceramics were synthesized through a solid-state procedure. Crystal refinement indicates a pure Mg1-xCaxZrNb2O8 ceramic with a wolframite structure. Ca2+ substitution led to the redshift of the Ag mode at approximately 896 cm−1. Additionally, Ca2+ substitution could promote grain growth and contribute to microstructure evolution from a polyhedral shape to a rod shape. According to chemical bond theory, an appropriate Ca2+ concentration can increase Nb O bond iconicity and Nb O bond lattice energy, which contributed to the great improvement in the dielectric constant and Q × f value. Additionally, the τf value was affected by the bond valence and thermal expansion coefficient of the Mg O bond. The Mg1-xCaxZrNb2O8 (x = 0.04) ceramics exhibited great improvement in the Q × f value: er = 25.21, Q × f = 116,000 GHz (@7.17 GHz) and τf = −24.4 ppm/°C, which provides enormous potential for future millimeter-wave applications.

In this study, a method of surface texture is considered to improve the frictional performance of the ring-liner system (i.e. RLS) under the conditions of cylinder deactivation (i.e. CDA). To assess the effectiveness of the method, a lubrication model is developed with considerations of the liner deformation, the actual rheological properties of lubricant, and the lubricant transport. By solving the model numerically, the friction reduction effect of surface texture for the RLS under the CDA is investigated. The results show that the surface texture can improve the friction properties significantly. For a six-cylinder gasoline engine, 7.57% and 7.28% decreases in the total average friction loss and power loss are observed when the RLS under the CDA is surface textured.

Considering both the effect of the nonisothermal nature of the interface as well as the effect of forced convection, an extended free dendritic growth model for binary alloys was proposed. Comparative analysis indicates that the effect of convection on solute diffusion is more remarkable compared with the ignorable effect of convection on thermal diffusion at low bath undercooling, due to the fact that solute diffusion coefficient is usually three orders of magnitude less than thermal diffusion coefficient. At high bath undercooling, the effect of convection on the dendritic growth is very slight. Furthermore, a satisfying agreement between the model predictions with the available experiment data for the Cu70Ni30 alloy was obtained, especially at low bath undercoolings, profiting from the higher values of interfacial migration velocity predicted by the present model with nonideal fluid case than that predicted by the one ignoring the effect of convection.

To suppress the impurity phases and porous microstructure caused by lithium volatilization, the Li2Mg3ZrO6 and Zr-deficiency Li2Mg3Zr1-xO6 (x = 0.02, 0.04, 0.06, 0.08, 0.10) ceramics were successfully synthesized via the solid-state method assisted with atmosphere-controlled sintering. The influences of non-stoichiometric on structure characteristics, morphology and microwave dielectric properties of Li2Mg3Zr1-xO6 ceramics were investigated. The XRD and SEM results proved that the Zr-deficiency restrained the formation of impurity phases and remarkably improved the densification of Li2Mg3Zr1-xO6 samples. The variation trend of dielectric constant (er) was explained by the relative density and theoretical dielectric polarizability. The quality factor (Q × f) was strongly associated with the impurity phases and relative density. Additionally, the temperature coefficient of resonant frequency (τf) showed the same trend as the total bond energy Etotal, indicating the bond energy might play vital roles in thermal stability of Li2Mg3Zr1-xO6 samples. Typically, the Li2Mg3Zr1-xO6 sample obtained at x = 0.06 possessed remarkable dielectric performances: er = 13.13, Q × f = 116,400 GHz (10.14 GHz) and τf = −26.30 ppm/°C.

2D materials is a promising Na+ insertion-type material due to its unique layered structure, however, the long diffusion channels yielded by stacking limited the Na+ storage rate capability. Herein, a 3D MoS2–Ta4C3 heterostructure (M-Ta4C3) composite is designed by supported 2D MoS2 nanosheets on/in the surface/interlayers of 2D Ta4C3 matrix for achieving high rate Na+ storage. The 2D MoS2 nanosheets is confined in the interlayers of Ta4C3 matrix that can avoid the stacking and expand the interlayer spacing of Ta4C3 matrix, which enlarges the contact surface area between electrode and electrolyte, and exposes more electrochemical active sites for Na+ storage. The Ta4C3 matrix improves the conductivity, prevents the aggregation and confines the volume expansion of MoS2 nanosheets which optimizes the structure stability and provides short Na+ diffusion channels. The M-Ta4C3 exhibits a larger interlayer spacing of 1.69 nm, extraordinary electrochemical performance and outstanding rate capability which benefitted from the 3D heterostructure. The M-Ta4C3//AC SIC owns super energy and power densities of 87.6 Wh kg−1 and 3937.3 W kg−1. This work employs Ta4C3 MXene as a Na+ storage material for the first time, and it provides an idea to improve the Na+ storage performance of 2D materials by constructing a 3D heterostructure.

In recent years, crystalline-driven self-assembly (CDSA) has received enormous attention, but almost only for block copolymers (BCPs). Herein, we introduced perfluorocarbon chains into main-chain-type liquid crystalline alternating copolymers (ACPs) to obtain perfluoroalkane-containing ACPs with periodic C-I bonds in polymer backbones via step transfer-addition and radical-termination (START) polymerization, followed by an iodine reduction reaction of C-I bonds to induce CDSA of ACPs and put forward a novel concept of "reduction-induced crystallization-driven self-assembly" (RI-CDSA) of main-chain-type ACPs for the first time. Finally, we proposed the folded-chain model and mechanism to explain the novel RI-CDSA behavior, and its rationality has been proved by the corresponding experimental results.

Insulation failure and insufficient thermal management in electrical and electronic equipment threaten their safe and stable operation and restrict development toward high power and high integratio...

The article established a modelling that predicted and measured the quenching and pre-stretching stress in 7050 aluminum alloy thick plate in order to make the alloy suitable enough for manufacturing in the aerospace industries. The results show that both the rolling direction component stress and the transverse direction component stress have a “M” distribution along the plate thickness of 7050 aluminum alloy thick plate, but the level is slightly different, but the level is slightly different. The maximum value of quenching residual stress is about 187MPa in the 80mm thick of 7050 plate. Pre-stretching of the heat treated and quenched alloy to 0.5%, 1.0%, 1.5%, 2.0%, 2.5%, 3.0% and 3.5% to reduce the residual stresses. It has been recorded that more than 90% reduction of residual stresses were observed in a pre-stretching rage of 2-3%. Measuring the surface residual stresses of the alloy by ultrasonic methods and measuring the internal residual stresses of the alloy by crack compliance methods. The two methods are used to verify the model. The difference between the measurement and the simulation is within 40MPa. The experimental data of the ultrasonic and the crack compliance methods were found to correspond well with the simulated models. This shows that the simulation model can effectively predict the evolution of residual stress in 7050 aluminum alloy thick plate, and the simulation model can also be reconstructed and inspected through the experimentally measurement.

Sodium-ion capacitors (SICs) are extremely promising due to the combined merits of high energy-power characteristics and considerable price advantage. However, it is still difficult to achieve high energy-power outputs and cycle stability in a typical configuration of the metal-based battery-type anode and activated carbon capacitor-type cathode due to the kinetic mismatching. In this work, a carbon nanosheet (PSCS-600) with large interlayer spacing of 0.41 nm derived from the bio-waste pine cone shell was prepared. Besides, the covalent triazine framework derived carbon (OPDN-CTF-A) was obtained through ionothermal synthesis strategy, exhibiting beneficial hierarchical pores (0.5–6 nm) and high heteroatoms (5.6 at% N, 6.6 at% O). On this basis, the all-carbon SICs were fabricated by the integration of PSCS-600 anode and OPDN-CTF-A cathode. The device delivered high energy density 111 Wh kg−1, high power output of 14,200 W kg−1 and ultra-stable cycling life (∼90.7% capacitance retention after 10,000 cycles). This work provides new ideas in fabricating carbon-carbon architectural SICs with high energy storage for practical application.

Objectives The aim of this study is to improve the biological and mechanical properties of zirconia-based PICN (polymer-infiltrated-ceramic-network) materials by fabrication an enamel-like structure on its surface. Methods Fluorapatite (FA) arrays were fabricated on zirconia discs by hydrothermal treatment. After polymer infiltration, an enamel-like structure was obtained on zirconia-based PICN materials. Effects of hydrothermal treatment conditions on the FA arrays were investigated by XRD, FTIR and SEM. Human gingival fibroblast cells (HGFs) and Escherichia coli (E. coli) were used to evaluate the cytocompatibility and antibacterial properties. Nanoindentation method was employed to determine elastic modulus and hardness. Results A facile and pervasive method was developed in this study to fabricate an enamel-like structure constituted of controlled FA arrays and interstitial resin on zirconia-based PICN materials. The obtained FA arrays can significantly promote the adhesion and proliferation of human gingival fibroblasts (HGFs), and further effectively inhibit the growth of Escherichia coli. Owing to the hierarchical structure, the enamel-like structure has achieved a hardness of 1.79 GPa and a lower Young’s modulus of 37.4 GPa. Significances The enamel-like structure, with excellent biological and mechanical properties, is promising for various applications in dentistry.

Nanofibers with hollow or porous network structure have numerous prospective realistic applications in electrode materials of a hybrid supercapacitor. Herein, La0.7Sr0.3CoO3/Co3O4 nanofibers (LSC/Co3O4 NFs) with hollow network porous structure where Co3O4 nanoparticles evenly distributed in the LSC single tube both sides of hollow are successfully prepared by one-step electrospinning. Electrochemical characteristics of LSC-doped composite electrode materials with different proportions have studied in detail. The result showed the LSC (20 wt%)/Co3O4 electrode material displayed the eminent specific capacity of 215 C g-1 (430 F g-1) at 1 A g-1. Furthermore, the LSC (20 wt%)/Co3O4//AC hybrid supercapacitor showed remarkable cyclic stability after 5000 cycles with a capacity retention of 86.3% and it showed a tremendous energy density of 21.9 Wh kg-1 at a power density of 358.4 W kg-1. Hence, the prepared LSC/Co3O4 NFs have promised a new type of electrode for hybrid supercapacitors.

To investigate the effects of (Al0.5Ta0.5)4+ substitution on the crystal structure and dielectric characteristics of Li2Mg3TiO6, a set of Li2Mg3Ti1-x (Al0.5Ta0.5)xO6 (x = 0.0–0.12) samples were fabricated via solid-state process. XRD and Rietveld refinement results confirmed the formation of single rock salt structure in the space group Fm3m (No.225) within 0.0 ≤ x ≤ 0.12. Subsequently, some intrinsic factors were introduced to evaluate the structure dependence of dielectric characteristics in Li2Mg3Ti1-x (Al0.5Ta0.5)xO6 ceramics based on the unit cell parameters. The variation trend of dielectric constant (er) was explained by the relative density and average ionic polarizability. The quality factor (Q × f) showed the same trend as the packing fraction and lattice energy, indicating the intrinsic lattice anharmonicity might play vital roles in dielectric loss. Additionally, the temperature coefficient of resonant frequency (τf) was strongly associated with the bond energy of Etotal. Typically, the Li2Mg3Ti0.91(Al0.5Ta0.5)0.09O6 sample obtained at 1310 °C possessed remarkable dielectric performances: er = 15.06, Q × f = 169,600 GHz and τf = −27.45 ppm/°C.