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Lead halide perovskite nanocrystals (PNCs) have emerged as new-generation light-emitting materials with important potentials in optoelectronic applications. However, the toxicity of lead metal and ...

Incorporation of nanoparticles into polymer blend to obtain finely dispersed morphology has been considered as an effective strategy to prepare nanocomposites. Owing to the renewable and degradable characters, cellulose nanocrystals (CNCs) have been proposed to tailor the phase morphology of poly (L-lactic acid) blend for producing high-performance fused deposition modeling (FDM) consumables. However, the main challenge associated with the ternary systems is the dispersion of the highly hydrophilic CNCs in nonpolar PLLA blend by industrial melt blending without involving solution. Herein, with polyvinyl acetate (PVAc) modified CNCs powder (a mixture of PVAc grafted from CNCs and PVAc homopolymer latex), the selective dispersion of CNCs in PLLA has been achieved by simple melt processing of PLLA/TPU (polyether polyurethane)/CNCs blend. This results in the ultra-fine TPU droplets at nanoscale in PLLA and improves the melt processibility of composites in FDM due to the decreased viscosity ratio of the dispersed/matrix and the enhanced melt elasticity of PLLA. Combined with the intensive shear and continuous stretch effect during FDM, aligned TPU nanofibers (TNFs) were in-situ formed along the elongational flow direction during deposition, which in turn contributed to the improvement of PLLA/TPU/CNCs with 5 wt% filler loading in tensile ductility by 418%, inter-layer adhesion strength and notched impact toughness by 261% and 210%, respectively, as well as achieved good dimensional accuracy and very fine surface quality.

Compared to the three-dimensional (3D) perovskite materials, the Ruddlesden−Popper (R-P) type two-dimensional (2D) organic-inorganic metal halide perovskites have indicated specific unique physical properties that include moisture-stable behaviours, exciton effects, and quantum confinements, making it a solid and potential candidate for optoelectronic applications. Nonetheless, while specific candidates have exhibited visible-blind ultraviolet (UV) photoelectric response, most R-P type 2D materials have been known to be photosensitive to visible light. In this study, an R-P type 2D lead bromide hybrid perovskite (C8H11FN)2PbBr4, (1, where C8H10FN is 4-Fluorophenethylamine) has been analyzed, which contained both inorganic frameworks and organic cations. Moreover, 1 exhibits a relatively wide optical bandgap of 3.30 eV, corresponding to that of the Br-based 2D R-P perovskites expected to exhibit selective photoresponse for the UV light. It is pertinent to note that the photodetectors based on the crystal of 1 exhibit spectral selective photoresponse for UV light with high detectivity up to ∼ 1.6×1011 Jones. Moreover, the trap density of 1 is estimated to be 1.34×1011 cm-3; the trap density of 1 was almost equal to that obtained in the high-quality 3D CH3NH3PbBr3 single crystals. Besides, under external environment, 1 illustrated excellent stability. The figures of merit for its photoconductivity make 1 a potential candidate for the visible-blind UV photodetection. This discovery opens up new vistas for the further development of optoelectric devices based on 2D R-P organic-inorganic hybrid perovskites.

A membrane-lytic mechanism-based nanodrug is developed for drug-resistant tumor therapy by anchoring the small-molecule quaternary ammonium salt (QAS) on cross-linked (R)-(+)-lipoic acid nanoparticles (cLANs). The anchoring of QAS on the nanoparticle avoids the direct attack of long alkyl chains to the cell membrane under physiological conditions, while after entering tumor cells, the QAS is released from the dissociated cLANs, migrates to the phospholipid bilayer via electrostatic interaction, and destroys the cell membrane by the puncture of long alkyl chains. Since the QAS is designed to finally be hydrolyzed to amino acid betaine and food additive cetanol and the cLANs degrade to dihydrolipoic acid (DHLA, reduced form of dietary antioxidant lipoic acid in cells), the QAS@cLANs hold superior biosafety. In addition to the drug-resistant tumors, the QAS@cLANs demonstrate significant inhibition of metastatic tumors. This work provides not only a general and clinic-promising treatment for the refractory tumors but also opens a door for the medicinal use of QAS.

This article presents a new type of microwave-induced atmospheric-pressure low-temperature dielectric barrier discharge source, based on the principle of parallel plate transmission lines (PPTLs). This source is a simple structure with small size, large plasma discharge area, and low discharge temperature. Experiments show that linear plasma discharge with width of 15 mm can be obtained with input power of only 25 W at 2.45 GHz. The temperature of sample placed 1 mm vertically away from the nozzle and treated for 3 min is about 45 °C even with 60-W microwave input power, which proved its thermal safety even for the biomedical applications. Emission spectroscopy diagnosis indicates that the electron density of plasma can be controlled easily by adjusting the discharge gap and the dielectric thickness. It makes this source available for various applications. This work provides a new approach to obtain uniform linear plasma.

Most photochromic ceramics can back up post-irradiation to achieve color state transition. Unfortunately, color recovery usually requires exposure of material to external physical fields (such as light and heat), which severely limits the application as a convenient energy building material such as smart windows. Here, we report a kind of sodium niobate translucent ceramics whose photochromic effect can be completely self-recoverable without any external physical field stimulation. Based on the analysis of time-response transmittance, up-conversion emission spectra and thermoluminescence spectra, the behavior of carrier migration and trap capture/release in the process of self-recovery photochromic reaction has been proposed. It is believed that the emergence of intermediate trap level is an important factor to produce this spontaneous behavior. Moreover, by controlling the amount of rare earth doping and designing two types of materials with different carrier behaviors, Sm/Er-codoped NaNbO3 ceramics are regarded as an appropriate candidate for tracing the time of light irradiation and intelligent regulation of smart building materials. This work can promote the fundamental understanding and practical applications of self-recoverable photochromic bulk materials.

Droplets icing has important applications in real life. The icing process of droplets on microstructure is explored based on the MDPDE method in this study. Firstly, the correctness of the heat transfer model was verified by one-dimensional heat conduction simulation, and then the feasibility of the phase change model was verified by investigating the icing process of droplets. The influence of cold surface temperature, droplet volume and contact angle on freezing time of droplets was discussed, and it was found that the temperature of cold surfaces had a greater effect on freezing. We finally explored the influence of different microstructure surfaces on the icing of droplets, and results showed that the presence of microstructures greatly enhanced the anti-icing effect of the surface. In our research, the contact angle is a relatively large factor affecting the icing of droplets. In addition, it was discovered that the droplet had the strongest ability to delay freezing on the surface of triangle microstructures with a contact angle of 157.1°.

Mollusk shells generally consist of several macro-layers with different microstructures. To explore the specific role that different macro-layers play in the overall mechanical properties of shells, the microstructures, hardness distribution, and three-point bending behavior in the deep-sea Nautilus shell were investigated. It is found that the shell presents a hierarchical structure comprising three layers in thickness, that is, the outer, middle, and inner layers, which exhibit homogeneous, prismatic, and nacreous structures, respectively. Among them, the homogeneous structure in the outer layer is harder, which is beneficial for the shell to enhance resistance to wear and perforation. Furthermore, both the bending strength and fracture energy for group Up (loading from outer to inner surfaces) are far higher than those for group Down (loading from inner to outer surfaces), indicating that the inner nacreous layer is not only stronger but also tougher. Cracks tend to deflect at the interfaces in nacreous structure, and nacreous structure is thereby more resistant to breakage. Hence, the nacreous structure in the inner layer could protect the shell from breaking catastrophically in the deep sea with high pressure. In brief, the combination of a harder outside layer and a tougher inside layer provides an effective protective structure for the deep-sea shell, and the excellent environment adaptability of Nautilus shell can thus be interpreted in terms of its ingenious microstructure arrangement.

The luminous efficiency of the phosphors usually decreases as the operating temperature increases. Thermal stability is a crucial parameter for phosphors. The Ce3+/Dy3+ co-doped KCaLa(PO4)2 phosphors exhibited excellent thermal stability attributing to abnormal thermal quenching behavior. The energy exchange between trap charges and the level of Dy3+ ions may lead to this behavior. The structure of the phosphors was analyzed and studied. Under the excitation at 324 nm, the luminescence properties and energy transfer behavior were investigated in detail for Ce3+/Dy3+ co-doped KCaLa(PO4)2 phosphors. The energy transfer efficiency from Ce3+ to Dy3+ reached to 85.5% with dipole–quadrupole mode. The color coordinate points of the phosphor gradually move closer to (0.333, 0.333) as the operating temperature increased. Under the excitation at 324 nm, the internal quantum efficiency of the KCaLa0.88(PO4)2: 0.10Ce3+, 0.02Dy3+ phosphor was found to be 41.7%. Excellent thermal stability and high quantum efficiency would make the Ce3+/Dy3+ co-activated KCaLa(PO4)2 phosphor a promising application for white LEDs.

Background: TiO2 nanoparticles possess adsorption capacity and photocatalytic activity, and are thus fitted for removal of dyes from water. However, TiO2 nanoparticles are difficult to separate from the bulk solution due to high loss. Moreover, TiO2 can only use light with a wavelength of less than 387.5 nm, so the utilization efficiency of solar energy is very low. The present work prepared Fe3O4@C@TiO2-AgBr-Ag composites to overcome the shortcomings of TiO2. Objective: Adsorptive and photocatalytic performance of nano-magnetic materials Fe3O4@C@TiO2- AgBr-Ag. Methods: Fe3O4@C@TiO2 and Fe3O4@C@TiO2-AgBr-Ag magnetic nanocomposites were prepared by the sol-gel method. Their structure was characterized. Performances of Fe3O4@C@TiO2 and Fe3O4@C@TiO2-AgBr-Ag for removing Rh B were thoroughly investigated and compared. Langmuir– Hinshelwood kinetic model was applied to analyze the heterogeneous processes of adsorption and photodegradation. Results: Removal experiments were carried out with Rhodamine B as the subject. The effects of contacting time, pH, subject concentration, and doses of photocatalyst on the removal performance were studied. The removal of Rh B by Fe3O4@C@TiO2 and Fe3O4@C@TiO2-AgBr-Ag involved both adsorption and photodegradation, and the photocatalytic activity of Fe3O4@C@TiO2-AgBr-Ag was much higher than that of Fe3O4@C@TiO2. The optimum removal conditions were determined. Under the optimal conditions, the removal rate of Rhodamine B with Fe3O4@C@TiO2 was 77.8%, and the removal rate of Rhodamine B with Fe3O4@C@TiO2- AgBr-Ag was 87.3%. Conclusion: The coupling of the nanostructured metal Ag to the outer surface of TiO2 could effectively increase photocatalytic efficiency under visible light. The photocatalysts could be separated from bulk solutions by using a magnet and be easily recycled. The removal reaction kinetics fitted with the first-order model.

Uniaxial tensile tests were carried out at room temperature (RT) and 250 °C, respectively, to investigate the effect of short-range ordering (SRO) on the mechanical properties and deformation micromechanism of fine-grained (FG) Cu–Mn alloys with high stacking fault energy. The results show that at RT, with the increase in SRO degree, the strength of FG Cu–Mn alloys is improved without a loss of ductility, and corresponding deformation micromechanism is mainly manifested by a decrease in the size of dislocation cells. In contrast, at a high temperature of 250 °C, the SRO degree becomes violently enhanced with increasing Mn content, and the deformation microstructures thus transform from dislocation cells to planar slip bands and even to deformation twins, significantly enhancing the work hardening capacity of the alloys and thus achieving a better strength-ductility synergy of FG Cu–Mn alloys.

Pullout tests for the deformed steel bars in early-aged cementitious grout by considering the variables of testing ages, cover thicknesses, and diameters of steel bar were conducted, and the local bond stress–slip relationship at different positions of the anchorage length of steel bar was studied. Results indicated that, with the increase of testing age, the load-slip curves exhibited a higher ultimate load and had steeper ascending and descending branches; however, the slippage at the ultimate load exhibited a decreasing trend. Moreover, with the increase of cover thickness and diameter of steel bar, the ultimate load of pullout specimens increased obviously, while the corresponding slips generally had no obvious correlations. According to an analysis of the measured rebar strain, the distributions of the steel stress and bond stress as well as the relative slip along the embedded length were obtained under different external loads. Steel stress transfer and bond stress distribution parameters were introduced to characterize the nonuniformity of the distributions of the steel stress and bond stress along the steel bar, and the effects of the testing age, cover thickness, and diameter of steel bar on these two parameters were analyzed. Results showed that the both of these two parameters increased with the increasing tensile load, testing age, and cover thickness and with the decreasing diameter of steel bar. Thereafter, the local bond stress-slip relationships along the anchorage length and position functions reflecting the variations of these relationships were proposed.

The large-scale manufacturing of lithium sulfur (Li-S) battery has been long hampered by the rapid capacity degradation and short cycle life, which is primarily attributed to the soluble polysulfides and subsequent continuing shuttling effect. The separator modification as a simple and effective technique has been extensively applied in Li-S batteries to solve inherent defects. Herein, the composite of Ketjen black (KB) and Ti4O7 was synthetized by carbothermal reduction and made into KB/Ti4O7-modified separator. The multifunctional layer can improve utilization of active substances and restrain shuttling effect by forming synergistic effect of physical obstruct and chemisorption for polysulides. The cell using KB/Ti4O7 separator exhibits enhanced electrochemical properties reflecting in higher specific capacity (1074 mAh g-1 at 1C) and longer cycling life (836 mAh g-1 after 100 cycles). The above results indicate that the composite of carbon and metallic oxide modified separator is pretty suitable for advanced Li-S battery.

An up-conversion luminescence (UCL) transparent ferroelectric oxide (KNN) introduced by rare-earth ions (Er3+ and Bi3+) has been demonstrated to exhibit a unique, high-purity, red emitting, high tr...

Lead halide perovskites have shown great potential in photovoltaic and photocatalytic fields. However, the toxicity of lead impedes their wide application. Herein composites of lead-free halide perovskite Cs2AgBiBr6 supported on nitrogen-doped carbon (N-C) materials were synthesized successfully through a facile one-pot method for the first time. Without deposition of noble metals as the cocatalyst, the optimal composite Cs2AgBiBr6/N-C (Cs2AgBiBr6/N-C-140) exhibits outstanding photocatalytic performance with a high hydrogen evolution rate of 380 μmol g-1 h-1 under visible light irradiation (λ ≥ 420 nm), which is about 19 times faster than that of pure Cs2AgBiBr6 and 4 times faster than that of physically mixed Cs2AgBiBr6/N-C-140, respectively. The Cs2AgBiBr6/N-C-140 composite also displays high stability with no significant decrease after six cycles of repeated hydrogen evolution experiments. The addition of N-C with a high surface area helps to prevent aggregation of Cs2AgBiBr6 NPs and provides more pathways for the migration of photoinduced carriers. The nitrogen dopant can facilitate photoinduced electron transfer from Cs2AgBiBr6 to N-C to result in spatially separated electrons and holes with prolonged electron time and greatly enhance the photocatalytic performance. This study indicates that Cs2AgBiBr6-based perovskite materials are promising candidates for photocatalytic hydrogen evolution.

Five new zero-dimensional hybrid manganese halides based on discrete [MnCl4]2− tetrahedrons were prepared and used as highly efficient green-light emitters. Through rational management of organic cations to tailor the Mn⋯Mn separation distances between neighboring [MnCl4]2− tetrahedrons, the photoluminescence quantum yield increased significantly from 7.98% to 81.11%.

A facile, green and economical preparation technique is critical for the cost-effective scale-up manufacture and optoelectronic device engineering of halide perovskites. Herein, we developed a viable solvent-free mechanochemical synthetic route to systematically prepare organic–inorganic hybrid perovskites. In this work, an enormous halide library comprising 16 zero-dimensional hybrid manganese halides with the formula of AnMnX4 (A = organic cations, X = Cl, Br, n =1, 2) was synthesized through an economically and environmentally friendly mechanical grinding solid-state reaction within a quite fast time of 40 s and 100% yield. Even without any crystallization process, these AnMnX4 display strong green light emissions with the highest photoluminescence quantum yield (PLQY) of 79.5%, which reaches up to the top rank of green-light-emitting halide perovskites. Moreover, the enormous structural library facilitates us to build up a direct correlation between intermolecular Mn⋯Mn distances and PLQY, which provides a feasibility of fine-tuning luminescence performance by reasonably managing organic species to tailor the Mn⋯Mn distance. This work not only paves a green assembly way of hybrid perovskite materials but also provides a generalized method to rationally optimize the luminescence performances of hybrid manganese halides, which is potentially extended to all emissive hybrid metal halides.

Summary All-inorganic perovskite solar cells (PSCs) have attracted wide attention for their excellent thermal stability. However, the detailed crystallization process and complicated phase-transition mechanism of the CsPbX3 film with different halide compositions (I, Br, Cl) remain mysterious. In this study, systematic investigations are performed via state-of-art in situ grazing-incidence wide-angle X-ray scattering to understand the role of the halide elements in all-inorganic perovskite crystallization kinetics, phase-transition, and stabilization mechanism as well as how film morphology and grain size are affected. Based on these results, we were able to fabricate high-performance ternary halide (I, Br, Cl) all-inorganic PSCs through a precise compositional engineering. Our results provide guidance for an in-depth understanding of all-inorganic perovskite materials and pave the way to obtain high-performance all-inorganic PSCs.

An ultrapure green phosphor with narrow emission range (525–535 nm) and full width at half maximum (FWHM < 25 nm) is critical for a backlit light-emitting diode to realize an ultrawide color gamut in liquid-crystal display (LCD), according to the Rec. 2020 standard. However, it is extremely formidable to achieve this goal for low-dimensional halide perovskites (LDHPs), which readily display broadband emissions arising from self-trapped excitons due to strong electron–phonon coupling. Herein, we report a new one-dimensional (1D) hybrid lead halide of [TMPDA]2Pb3Br10 (TMPDA = tetramethyl-1,3-diaminopropane) displaying unusual ultrapure green light emission. Benefiting from the synergistic work of weak electron–phonon interaction and strong quantum confinement, this 1D halide displays sharp green emission at 526 nm with narrow FWHM (25 nm), high photoluminescence quantum yield (71.95%) and color purity (91.1%), which achieves the Rec. 2020 standard and represents the purest green emitting LDHP to date. Remarkably, as a down-conversion green phosphor, [TMPDA]2Pb3Br10 provides an ultrawide color gamut covering 121.5% of NTSC and 90.7% of Rec. 2020 standards, showcasing the application in high-resolved LCD. The establishment of a fundamental structure–property relationship also paves a new way to rationally design novel narrow-band emitting LDHPs as a supplement of colloidal 3D perovskite nanostructures.

Recently, low-dimensional organic–inorganic hybrid metal halides have attracted considerable attention in solid-state optical application fields, especially in white-light emitting diodes (WLEDs) owing to intrinsic broadband luminescence performances. Herein, by selecting different types of organic cations as a structural decoration strategy, we designed a series of new 1D hybrid halides of A2Pb3Br10 (A = NPM, DMPDA, TMEN) based on same [Pb3Br10]4− chains composed of edge-shared [Pb3Br12]6− trimers. The low-dimensional crystal lattice results in the formation of self-trapped excitons, which leads to broadband light emissions covering the entire visible region for all A2Pb3Br10 homologues. Specifically, compound 1 exhibits yellowish-white light emission (0.34, 0.45) with a photoluminescence quantum efficiency of 2.51%. Both compounds 2 and 3 show bluish-white light emissions centered at 438 nm and 440 nm, respectively, with high color rendering index (CRI) of 96, which belongs to one of the highest values to date. The intrinsic broadband white light emissions enable them as promising candidates for single-component white-light emitting materials.

The Eu-doped K0.5Na0.5NbO3 pellucid ceramics were first prepared via a conventional solid-state reaction, and they exhibited light illumination-induced high-contrast photochromism of both optical transmittance and photoluminescence behaviors. Through thermal treatment, the optical performances could return to their initial states and displayed excellent reversibility. Eu3+ ions were selected as the luminescent activator for detecting the local environment of the K0.5Na0.5NbO3 host. Meanwhile, the effects of the amount of Eu3+ present on phase structures, microstructures, optical transmittance and photoluminescence intensities were systematically investigated. The results suggest that Eu-doped K0.5Na0.5NbO3 transparent ceramics possess multifunctionality including photochromism, photoluminescence and optical switching properties, and that they exhibit promising potential for non-destructive optical data storage application.

Photochromic (PC) luminescent ferroelectric materials have aroused great interest because of their potential applications in non-contact smart information storage materials and devices. In this study, we adopted the effect of rare-earth ions to refine the grains, combined with the unequal replacement of donor doping and higher temperature sintering methods to introduce more vacancy defects, to simultaneously improve the transmittance and photochromic contrast of KNNLB-RE ceramics. The optical transmittance of a typical KNNLB-RE > 50%, and the modulation contrast of KNNLB-RE is relatively significant, such as ΔAbs = 16.2% and ΔR = ∼34% for KNNLB-Er. More interestingly, the Tc of KNNLB-RE increased by about 10%–18% (∼30 °C–50 °C) due to the degradation of the relaxor-feature and the increase of internal stress, which broadens the temperature application range of KNNLB-RE ferroelectric ceramics. In contrast to most opaque inorganic photochromic materials, the KNNLB-RE transparent ceramics can express multiple pairs of “off” and “on” codes by using the reversibly decreased and increased transmittance and PL intensity; thus, these materials have potential in the applications of optical sensors and memories or other optical data storage devices.

As an emerging route to further lower the production cost, reducing the thickness of Cu(In,Ga)Se2 (CIGS) absorber has drawn substantial attention and has been intensively studied in recent years. H...

Developing an effective method for improving the reproducibility of positive temperature coefficient (PTC) effect is of great significance for large-scale application of polymer based PTC composites, owing to its contribution to the security and reliability. Herein, we developed a carbon black (CB)/high density polyethylene (HDPE)/poly(vinylidene fluoride) (PVDF) composite with outstanding PTC reproducibility, by incorporating 1-octyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([OMIm][NTf2]) into the composite. After multiple repeated temperature cycles, the PTC performance of as-prepared material keeps almost unchanged and the varition of resistance at room temperature is less than 7%. Our studies revealed that [OMIm][NTf2] contributes to the improvement of PTC reproducibility in two ways: (i) it acts as an efficient plasticizer for refining the co-continuous phase morphology of HDPE/PVDE blends; (ii) it inhibits the crystallization of PVDF through the dilution effect, leading to more overlaps of the volume shrinkage process of HDPE and PVDF melt which results in the decrease of interface gap between HDPE and PVDF. This study demonstrated that ionic liquids as the multifunctional agents have great potential for improving the reproducibility in the application of the binary polymer based PTC composites.

Er3+-doped Ba0.85Ca0.15Ti0.9Zr0.1O3 (xEr-BCTZ, x = 0, 0.005, 0.01, 0.015) multifunctional thick films were prepared by the tape-casting method, using sol-gel-derived nano-sized powders as the matrix material. The surface morphologies, photoluminescence, and electrical properties were investigated. Dense microstructures with pure perovskite structure were obtained in the thick films. By doping an appropriate amount of Er3−, the samples exhibit superior up-conversion photoluminescence performance and simultaneously enhanced electrical performances. In addition, relatively higher texture fractions (with the largest value of 83.5%) were realized through introducing plate-like BaTiO3 templates to make the thick film grow by the [001]c orientation. And the ferro-/piezoelectric properties of the thick films were further improved, showing potential in the applications of micro-optoelectronic devices.

Air filters with a low resistance, high filtration efficiency, and long lifetime are important to ensure good indoor air quality. In this study, the lattice Boltzmann method is applied on six types of fibrous filter media with lognormal-distribution models, which consider the influence of the solid fraction, number of fibers, and average fiber diameter. The influences of the filtration velocity and fiber layout on the resistance, efficiency, and quality factor are discussed. The resistance is found to be relatively low when the solid fraction inside the filter media is uniformly distributed. The filter media with a random lognormal-distribution model demonstrated the best filtration performance in terms of quality factor. However, when the solid fraction is uniform along the thickness of the filter media, the comprehensive filtration performance is the best when a small fiber is near the inlet and a large one is close to the outlet. This study provides a viable numerical method for performance optimization of air-filtration devices for the next-generation cleanroom industry.

The PEDOT/TiO2 nanocomposites with different TiO2 particle sizes were fabricated by a simple soft chemical approach-assisted in situ synthesis route and used as an effective cathode of Li-S batteri...

The effect of short range ordering (SRO) on the strength-ductility match of low solid-solution hardening Ni-Cr alloys with high stacking fault energies (SFEs) were systematically investigated under tensile tests. With increasing Cr content, the SFE and friction stress keep almost unchanged but the SRO degree becomes enhanced; in this case, the deformation mechanism was evolved from wavy slip to planar slip, and deformation twinning was further induced as the Cr content exceeds 20 at.%, which leads to a unique two-stage strength-ductility match of Ni-Cr alloys. The action of SRO has merely played a decisive role for such an experimental phenomenon.

Given the efficiency, stability and sustainability, the carbon-based materials have become one of promising bifunctional electrocatalysts to the electrochemical water splitting, involving hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). However, there are still many challenges about the design and mechanism study of the carbon-based electrocatalysts. In this paper, we reported B, N co-doping carbon nanosheets which were synthesized via cationic intercalation stripping guar gum carbon aerogels pre-crosslinked by borate, B(OH)4-. This facile strategy not only realizes the structure tailoring, but also concurrently improves the doping efficiency and the stability of the hetero atoms. Specifically, the cost-efficient carbon-based bifunctional catalyst (B5/GCS) shows an outstanding HER and OER performance displaying a remarkable activity both in acidic and alkaline media, low onset potentials for both HER (39.12 mV) and OER (1.38 V) in the same electrolyte (0.5 M H2SO4). Notably, when employed as the bifunctional electrocatalysts with a two-electrode electrolyzer for water splitting, the B5/GCS generated a cell voltage of 1.45 V to attain 10 mA cm−2 in 0.5 M H2SO4. Furthermore, a series of experiments combining density functional theory calculations revealed that the observed superb water splitting activity could be attributed to a synergistic effect of N, B co-doping and the formation of fragmented nanosheets with topological defects, which collaboratively promotes the proton adsorption and catalytic kinetics.

Composite phase change materials (CPCMs) play a key role in solar energy conversion and storage. However, it is difficult to efficiently utilize solar energy due to their inherent low thermal conductivity, low light absorption and the usual competitive nature between thermal conductivity and latent heat. In this work, novel CPCMs were developed by using TiO2-TiC-C loaded expanded vermiculite (EVT) as a supporting matrix and lauric-myristic-stearic eutectic mixture (LA-MA-SA) as a PCM. The EVT was further acidized (EVTa) to enhance its PCM absorbability. Owing to the high thermal conductive and light absorption nature of TiO2-TiC-C nanocomposite, the prepared CPCMs exhibit efficient light-thermal energy conversion. The thermal conductivities of LA-MA-SA/EVT and LA-MA-SA/EVTa were 0.694 and 0.676 W/(m K), respectively. And the PCM content in LA-MA-SA/EVT and LA-MA-SA/EVTa were 64.5 and 70.6 wt%, respectively. Moreover, the feasibility of CPCM being a water heating source was experimentally confirmed. These novel CPCMs have good application prospect in low temperature solar-thermal installations, such as temperature adaptable greenhouse and water heating system.

A novel photochromic (PC) ferroelectric material, Nd3+-doped K0.5Na0.5NbO3 translucent ceramic, was fabricated by a conventional solid method. The ceramic shows moderate optical transparency due to its dense microstructure, as well as good photoluminescence (PL) properties of up-conversion (UC) emission in the visible region and down-shifting (DS) emission in the near-infrared region. Simultaneously, the colors of all the ceramics turn darker after 365 nm illumination, and then recover to their initial states upon thermal stimulus (210 °C, 10 min), exhibiting a typical PC phenomenon. In particular, the effect of the PC behavior on PL lifetimes of Nd3+ was investigated. Multi-mode reversible modulations of various optical behaviors were realized based on the PC behavior, especially for the regulation of near-infrared emission. And the maximum modulation ratios of transmittances, UC or DS PL intensities and luminescence lifetimes are 43.0%, 66.7%, 66.4% and 12.8%, respectively. Owing to high-temperature sintering and Nd3+ substitution in the ceramics, cation and oxygen vacancies appear to produce F′ and V1 color centers, which are in charge of the PC behavior and corresponding modulations. These results suggest that the ceramics are a promising PC material in visible and near-infrared optical data storage, photo-switches, and optoelectronic devices. Meanwhile, they also provide insights into the applications of rare-earth Nd3+ in other inorganic PC ferroelectric materials.

Pursuits of high-performance blue light-emitting perovskites have attracted intensive attention due to an insufficient photo-luminescence quantum yield (PLQY) of 90%) in the green and red emission spectral regions of CsPbX3 (X = Br and I), respectively. Hence, it is very significant to improve the blue light emitting PLQYs to balance the development of three-primary-colour in high-definition displays. In this study, we have proposed a new structural design strategy of reducing the lattice dimension to enhance quantum confinement effect and further improve the blue-light emission efficiency. Herein, by rationally choosing a long chain-like organic cation to slice the [PbCl3]− skeleton, we have successfully constructed the first 0D perovskite of [BAPrEDA]PbCl6·(H2O)2, in which the isolated [PbCl6]4− units are confined by a closely assembled organic matrix. As expected, the bulk crystals of the 0D perovskite display broadband blue-violet light emission (392 nm) of radiative transition arising from triplet exciton states. Remarkably, the synergistic effects of enhanced quantum confinement and highly localized excitons from the 0D perovskite significantly boost the PLQY of blue light emission to 21.3%, which far exceeds than that of the typical 3D CsPbCl3. To the best of our knowledge, this study first realizes the lowest-dimensional structural transformation from 3D perovskite to 0D molecule but holding the intrinsic blue light emission, and it also represents a new record of highest-energy blue-violet light emission in single-crystalline 0D metal halides.

A series of polyphenylquinoxaline (PPQ) ultrafine non-woven fibrous membranes have been first successfully prepared via the electrospinning procedure with the soluble PPQ solutions as the starting materials. For this purpose, various organo-soluble PPQ resins were synthesized via the one-step high temperature polycondensation procedure from the aromatic ether-bridged bis(α-diketone) and bis(o-diamine) monomers. Flexible ether linkages and pendant bulky phenyl substituents endowed the PPQ resins good solubility in polar aprotic solvents. The high-molecular-weight PPQ resins were dissolved in N-methyl-2-pyrrolidone (NMP) to afford the PPQ electrospinning solution except PPQ-Ia derived from 4,4′-oxydibenzil (ODB) and 3,3′-diaminobenzidine (DAB) due to the limited solubility in the solvent. All the derived PPQ ultrafine non-woven fibrous membranes maintained good structure integrity after hydrolysis aging either at room temperature (25 °C) for 72 h or at refluxing temperature (100 °C) for 24 h in an aqueous sodium hydroxide (NaOH) solution at a solid content of 20 wt%. Comparatively, the polyimide (PI) reference electrospun membrane (PI-ref) derived from 1,2,4,5-pyrromellitic anhydride (PMDA) and 4,4′-oxydianiline (ODA) lost its original structure only after boiling in the same NaOH solution within 3 h. In addition, the developed PPQ ultrafine non-woven fibrous membranes exhibited good thermal stability with the 5 % weight loss temperatures (T5%) higher than 555.0 °C in nitrogen and glass transition temperatures (Tg) in the range of 248.1–266.1 °C, respectively.

Er3+-doped xK0.5Na0.5NbO3-(1-x)Ba0.85Ca0.15Ti0.9Zr0.1O3 (x = 0.04, 0.05, 0.06 and 0.07) translucent ceramics have been first prepared by conventional pressureless sintering. Owing to the effective suppression of grain growth induced by both Er3+ and K0.5Na0.5NbO3, the ceramics possess dense and fine-grained microstructure. The XRD patterns demonstrate cubic-like phase structure with minimal optical anisotropy. The ceramics perform good photochormic (PC) properties under 407-nm light irradiation and superior reproducibility after heat treatment (200 °C, 5 min). And PC reaction is responsible for coloration and decoloration processes. The up-conversion photoluminescence before and after irradiation have been studied. With increasing the K0.5Na0.5NbO3 content or elevating the sintering temperature of the ceramics, the luminescent quenching degree (ΔRt) gradually increases. The color centers induced by irradiation can be reversibly created or eliminated, resulting in invertible luminescent modulations. This work can guide other multifunctional PC transparent ferroelectric materials for optoelectronic applications.

Here, a unified 3D numerical model of gas-liquid two-phase flow in a horizontal pipe was established using the interface capture method based on the open source software package OpenFOAM. Through numerical simulation of the natural slugging and development process of slug flow under different working conditions, the motion, phase interface structure, pressure and velocity field distributions of the liquid slug were fully developed and analyzed. The simulation results are consistent with the experiment. The results showed that during the movement of the slug head, there is a throwing phenomenon and a wave-like motion of the liquid slug. In addition, the slug tail and body area have very similar velocity profiles, and the overall velocity field distribution becomes more uniform with the development of liquid slug. Moreover, there are sudden pressure fluctuations at the head and tail of the liquid slug.

Fluoride salt-cooled High-temperature Reactor (FHR) is one of the advanced non-Light Water Reactor (non-LWR) designs, which adopts a low-pressure fluoride salt as the primary coolant, high working temperatures, coated-particle fuel, and a passive safety system for decay heat removal. However, tritium management is perceived as a critical issue for FHRs since tritium is a radiation hazard when inhaled or ingested and its production rate in FHRs is expected to be significantly higher compared to that in LWRs. To reduce FHR tritium release rates into the ambient, two tritium mitigation options, such as using Double-Wall Fluted-Tube Heat eXchangers (DWFT-HXs) with a tritium carrier or Single-Wall Fluted-Tube HXs (SWFT-HXs) with a tritium barrier, are therefore proposed for key HXs in FHRs, which potentially provide major pathways for tritium release due to their elevated temperatures and large surface areas. Tritium carriers investigated include gases, such as helium, and liquids, such as FLiBe, FLiNaK, and KF-ZrF4, while the tritium barrier investigated in this paper is silicon carbide (SiC) due to its low permeability for tritium. These proposed HX designs are then optimized, using a Non-dominated Sorting in Generic Algorithms (NSGA) optimization approach, for the Advanced High-Temperature Reactor (AHTR), one of the FHR designs with a large power output. A system-level mass transfer model is developed to evaluate the tritium transport in the two proposed design options for tritium mitigation in FHRs and quantitively analyze the tritium release/leakage rate from the reactor primary system. Our study shows that both the DWFT-HX design with helium as the tritium carrier and SWFT-HX design with SiC coating as the tritium barrier are able to reduce the total tritium leakage rate in FHRs to the same order of magnitude of the typical average tritium leakage rate in LWRs (1.9 Ci/day).

To explore the specimen size effect of mechanical behavior of ultrafine-grained (UFG) materials with different structures, UFG Al sheets processed by equal channel angular pressing (ECAP) were selected as target materials and the dependency of tensile behavior on sheet thickness (t) was systematically investigated. The strength and ductility of ECAPed UFG Al sheets were improved synchronously as t increased from 0.2 to 0.7 mm, and then no apparent change occurred when t reached to 0.7 and 1.0 mm. The corresponding microstructure evolved from dislocation networks in equiaxed grains into the walls and subgrains and finally into the dominated cells in elongated grains or subgrains. Meanwhile, dense shear lines (SLs) and shear bands (SBs) were clearly observed and microvoids and cracks were initiated along SBs with the increase of t. These observations indicated that the plastic deformation of UFG Al sheets was jointly controlled by shear banding, dislocation sliding, and grain-boundary sliding. Furthermore, the propagation of SBs became difficult as t increased. Finally, the obtained results were discussed and compared with those of annealed UFG Al and UFG Cu.

The weak rate capability and cyclic stability are stubborn issues limiting the application of intriguing lithium-rich layered oxide in the lithium-ion batteries. In this work, a glucose-based treatment was proposed to modify the microstructure and electrochemical properties of the lithium-rich layered oxide. A newly formed layered-spinel surface and chemically activated Li2MnO3 component were acquired through the glucose-based procedure. Notably increased initial coulombic efficiencies, discharge capacities, rate performance, and cyclic stability were observed in the modified samples. Typically, the discharge capacity and central voltage retentions after 100 cycles grow from 73.4% and 78.7% for the pristine to 84.1% and 86.2% for the treated sample. This improvement in electrochemical properties of the treated sample results from the co-contribution of the significantly promoted redox reaction at cathode surface, accelerated Li+ bulk diffusion rate, and tuned electrochemical evolution behavior of the lithium-rich layered oxide. This work provides a green and cost-efficient way for promoting the electrochemical properties of the lithium-rich layered oxide.

Transparent Er3+/La3+ co-doped (K0.5Na0.5)NbO3 ceramic was prepared by pressureless sintering. The XRD result shows that it possesses high symmetrical pseudo-cubic perovskite structure without impurity phase. The ceramic owns fine grains with the average size of ∼350 nm, uniform grain distribution, low porosity and high density. The optical transmittance of 0.3-mm ceramic is up to ∼60% in the visible region. Additionally, the ceramic has good dielectric properties with the relaxor-like behavior. Under an excitation of 980-nm, the temperature-dependent up-conversion luminescent color of Er3+ is stable below 523 K and adjustable (changing from green to tangerine color as temperature increases) above 523 K. The ratio of red to green emission intensity with temperature can provide a non-contact luminescent route to roughly detect the phase transition of this ferroelectric ceramic. Furthermore, the fluorescence temperature sensing performance of the ceramic was investigated and the maximum sensitivity is 0.003/K at 380 K. Due to optical, PL and electrical properties, the transparent ceramic shows potential in the application of electro-optical coupling devices.

Polyurethane (PU) nanofibers possess large specific surface area and excellent mechanical properties which have been used as the matrix for many applications. Phytic acid is the biocompatible and environment-friendly organic acid with excellent chelating ability of heavy metal ions due to it contains 6 phosphate groups. In this study, the PU/phytic acid nanofibrous membrane has been successfully produced by electrospinning which was used for Pb

Perovskite oxides with ionic and electronic conductivity are the key cathode materials of solid oxide fuel cells. Most of these materials, however, exhibit large cathodic polarization resistance which is mainly determined by their tardy oxygen transport kinetics. Herein, Pr 0.5 Ba 0.25-x Ca 0.25 CoO 3-δ is studied to understand the roles of Ba-deficiency in tuning oxygen transport and electrochemical behaviors in the system. Our findings indicate that Ba-deficiency can significantly accelerate oxygen surface exchange process and bring ∼77% reduction of polarization resistance in this process. It is interesting to note that Ba-deficiency can slightly slow oxygen ion bulk diffusion rate and induce a minor increase of polarization resistance in the corresponding process, which associates with the inhibited oxygen vacancy mobility caused by the interactions between negatively charged Ba vacancy and positively charged oxygen vacancy. These new findings pave a new path for solid oxide fuel cell design and chemical sensor developments.