Glutamine Induced High-Quality Perovskite Film to Improve the Efficiency of NIR Perovskite Light-Emitting Diodes

Formamidine lead iodide (FAPbI₃) is an important material for realizing high-performance near-infrared light-emitting diodes (NIR-LEDs). However, due to the uncontrollable growth of solution-processed films which usually causes low coverage, and poor surface morphology, the development of FAPbI₃-based NIR-LEDs is hindered, restraining its potential industrial applications. In this work, by employing glutamine (Gln) in perovskite precursor, the quality of FAPbI₃ film is improved significantly. Due to the ameliorated solution process by the organic additive, the film coverage over the substrate is substantially enhanced. Meanwhile, the trap state of grain is largely reduced. Consequently, NIR perovskite LEDs are demonstrated with a maximum external quantum efficiency (EQE) of 15% with the emission peak at 795 nm, which is four times higher than the device with pristine perovskite film.     

Transient and in situ Growth of Nanostructured SiC on Carbon Fibers toward Highly Durable Catalysis

Carbon is ubiquitously used as catalyst supports in various clean energy technologies, particularly emerging electrocatalysis, yet it often suffers slow oxidation and corrosion along with performance degradation. The harmonious combination of refractory silicon carbide (SiC, chemically inert) with carbon is alluring but often a great challenge, particularly to achieve desirable nanostructures and strong interfaces. Herein, a shockwave-type transient heating is designed (> 1750 °C for 1 s per pulse) for controllable growth of conformal SiC coating and massive SiC nanowires on carbon fibers (denoted as CF/SiC-NW), which serves as a high surface area and durable support for catalysis under harsh environments. The transient heating in SiO vapor triggers in situ transformation of the carbon surface into a seamless SiC protective layer, while the following fast cooling is essential for the growth of numerous self-assembled SiC nanowires. The CF/SiC-NW exhibits excellent structural stability in the air at high temperatures, in concentrated acidic/alkaline solutions after electrochemical stressing for 2000 cycles, and in oxygen evolution reaction after 10 h of continuous operation. This strategy enables delicate structure control in refractory carbides and is also general for various carbon/carbide functional materials (e.g., C/TiC, C/WC) for electro- or electrified catalysis under harsh conditions.     

Experimental analyses of the spatial varying temperature development of type-IV hydrogen pressure vessels in cyclic tests considering different length to diameter ratios

Establishing hydrogen as a reliable energy carrier is closely linked to the performance and safety level of the storage systems. During operation, the storage systems such as composite over-wrapped pressure vessels (COPVs) are exposed to complex physical, mechanical and thermal loads. Since the mechanical and physical properties of the used materials are strongly temperature-dependent, thermal influences must be taken into account for the vessel design. The effect of the vessel geometry, in particular the length-to-diameter ratio, as well as filling conditions on the temperature distribution within the fluid is analysed through the examination of cyclic tests in accordance with ANSI/CSA HGV2 and UN GTR N0.13/ECE R134. The gas temperature development during the cyclic tests is determined using a measuring device that allows a spatially distributed temperature measurement at eight vertical and horizontal positions. Two sizes of vessels are investigated characterised by the same inner and outer diameter but different length. It is observed that the length-to-diameter ratio substantially influences the temperature distribution within the fluid for room as well as elevated ambient temperatures at comparable filling conditions. Furthermore, the mass flow of the gas influences the temperature distribution within the fluid and shows an increased spatial and thermal inhomogeneity at higher gas mass flow. In addition, it can be observed that the temperature increase (ΔT) during filling depends significantly on the vessel temperature distribution. In the transient case of filling directly after emptying the vessel, a temperature increase of 36 K compared to the initially homogeneous vessel temperature has been found. Moreover, gas temperature differences of up to 97 K between the end of filling and the end of emptying can be observed, which is a significant thermal load for the vessels. Thus, the results presented here provide a broad data basis as input and boundary conditions for numerical fluid dynamic and structural analyses of pressure vessels made of carbon-fibre-reinforced plastics (CFRP).     

Development of titanium-doped SmBaMn2O5+δ layered perovskite as a robust electrode for symmetrical solid oxide fuel cells

It is a big challenge ahead of finding a symmetric electrode material that optimally works as both anode and cathode, with excellent structural and chemical stability and high catalytic activity. Herein, we propose a high-performance symmetric electrode material, SmBaMn_1.9Ti_0.1O_5+δ (SBMTi), with a single A-site layered perovskite phase in both reducing and oxidizing atmospheres. Owing to the high binding energy, titanium doping can enhance the structural stability and improve the catalytic activity to the hydrogen oxidation and oxygen reduction processes. The simple Ti-doping strategy enables a dramatic reduction in stoichiometric oxygen change upon oxidizing and reducing atmosphere alternation, and a considerable decrease in thermal expansion coefficient. The symmetrical cell with SBMTi electrode can provide a maximum power density of 603 mW cm⁻² at 900 °C, and shows a relatively stable thermal-cycle and atmosphere alternation performance. The developed SmBaMn_1.9Ti_0.1O_5+δ shows great potential as symmetric electrode in symmetrical solid oxide fuel cells.     

Luminescence enhancement of Cr3+ doped garnet phosphor for high-performance LED towards smart NIR light source

Cr³⁺ doped phosphor shows great potential for near-infrared (NIR) light-emitting diodes (LED), but it suffers from low quantum efficiency and poor thermal stability. Herein, a novel Cr³⁺ doped broadband NIR garnet Ca₃Sc₂Ge₃O₁₂ phosphor was developed. The multisite structure of the emission band is investigated by site-selective spectroscopy and is attributed to the octahedral Cr³⁺ perturbed by defects. Moreover, we propose different strategies to enhance the luminescence of the phosphor, including enhancement of crystallinity and elimination of defects. Compared with the initial sample, the emission intensity of the optimized phosphor is improved for 8.6 times. The optimal Ca₃Sc₂Ge₃O₁₂: 0.06Cr³⁺ phosphor exhibits excellent thermal stability. At 423 K, the integral emission intensity of the optimal sample remains 94.7% of that at room temperature. Finally, high-performance NIR LED was fabricated using a blue LED and the title phosphor. The packaged LED lamp has high radiance (109.3 mW@300 mA) and photoelectric efficiency (15.96%@40 mA). Our study not only provides a boulevard for enhancing the luminescence of Cr doped NIR phosphor, but also gives a new perspective for understanding the multisite luminescence of Cr³⁺ in garnet host.     

Anisotropic Interlayer Dzyaloshinskii–Moriya Interaction in Synthetic Ferromagnetic/Antiferromagnetic Sandwiches

The interfacial Dzyaloshinskii–Moriya interaction (DMI) in ferromagnetic/non-magnetic-metal bilayers is essential to stabilize chiral spin textures for potential applications. Recent works reveal that the interlayer DMI is beneficial to designing 3D chiral spin textures that possess fundamental importance and the associated technological promises. Here, the interlayer DM constants are determined quantitatively in synthetic ferromagnetic/antiferromagnetic Pt/Co/Pt/Ru/Pt/Co/Ta structures. The results demonstrate that the interlayer DMI shows uniaxial anisotropic characteristics. The first-principles calculations elucidate that the anisotropic interlayer DMI is induced by the in-plane symmetry breaking along two high symmetric directions, which favors the magnetization of adjacent ferromagnetic layers canting in different directions. The anisotropic interlayer DMI is also confirmed by spin-orbit torque driven asymmetric magnetization switching. Moreover, the interlayer DMI can be tuned by the Ru-layer-thickness and beneficial to designing 3D spin textures for future spintronic devices.     

Continuous preparation of composition-controllable Y–Ni alloy in LiF–YF3–Y2O3 molten salt

The Y–Ni alloy is a primary precursor for the preparation of high-performance La–Y–Ni-based hydrogen storage materials. However, it cannot be produced continuously at low cost, which limits the wide popularization and application of La–Y–Ni-based materials. In this paper, this problem was solved perfectly using electrochemical reduction of Y₂O₃ in the LiF-YF₃ system. It is found that the reversible reduction from Y³⁺ to Y on the W electrode takes only one step, namely a significant soluble–soluble reaction controlled by Y³⁺ diffusion throughout the melt. Four typical signals of square wave voltammetry (SWV) corresponding to different kinds of Y–Ni intermetallic compounds are observed in LiF−YF₃ and LiF–YF₃–Y₂O₃ melts, and reduction potential can become positive with the addition of Y₂O₃, probably because of the formation of more complexes in the melts. Homogeneous Y–Ni alloy samples were produced continuously and prepared via galvanostatic electrolysis by using bargain-price raw material (Y₂O₃) and setting the current density at 10 A/cm² on the nickel electrode, before they were collected into a bottom receiver. A series of analyses including scanning electron microscopy-energy idspersive X-ray spectroscopy (SEM-EDS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and inductively coupled plasma mass spectrometry (ICP-MS), demonstrate that concentration of yttrium in Y–Ni alloy is adjustable within the wide range of 44 wt% to 72 wt% by fine-tuning the electrolysis temperature (875–1060 °C) in the LiF-YF₃ system to ensure the optimal hydrogen storage performance and economic efficiency of La–Y–Ni-based hydrogen-storage materials.     

Computer modeling of Young's modulus and thermal conductivity changes during sintering without shrinkage

Sintering without shrinkage can occur when non-densifying sinter mechanisms are dominating. In this case, properties change without changes in porosity, but the key question is, what are the microstructural parameters determining the properties. In order to answer this question, digital random microstructures with a porosity of 0.50 ± 0.16 are generated from monosized spherical particles that are allowed to overlap. It is shown that with increasing grain overlap one obtains an increase of the size of solid domains, the sinter neck and pore throat diameters, and relative properties (Young’s modulus and thermal conductivity, which are correlated by a power-law cross-property relation with exponent 1.493). Empirical fits are given for the relative properties as functions of different non-dimensional size ratios and the relative surface area. Since the latter is accessible from specific surface measurements via gas adsorption, it can be recommended when planar sections for quantitative image analysis are not available.     

Electroextraction of neodymium from LiCl-KCl melt using binary liquid Ga-Al cathode

The electrochemical behaviour of Nd(Ⅲ) ion was investigated on inert W,active Ga and Ga-AI cathodes.It is established that the reduction of Nd(Ⅲ) ion on the inert electrode is a consecutive two-step process while that on the active electrodes is a one-step process.The apparent standard potential of the Nd(Ⅲ)/Nd redox couple at different temperatures was determined by open-circuit chronopotentiometry and semi-differential method,and the relationship between temperature and apparent standard poten...     

Optimal dispatch of hydrogen/electric vehicle charging station based on charging decision prediction

The hydrogen/electric vehicle charging station (HEVCS) is widely regarded as a highly attractive system for facilitating the popularity of hydrogen and electric vehicles in the future. However, conventional optimal dispatch of HEVCS could lead to poor performance due to the lack of adequate consideration of vehicle charging decision behaviours and neglection of the impacts of different information sources on it. This paper investigates a charging demand prediction method that considers multi-source information and proposes a multi-objective optimal dispatching strategy of HEVCS. First, an information interaction framework of integrated road network, vehicles and HEVCS is introduced. Road network model and HEVCS model are established based on the proposed framework. To improve the flexibility of dispatch, two charging modes are designed, which are intended to guide drivers to adjust their consumption behaviour by electricity price incentives. Furthermore, psychologically based hybrid utility-regret decision model and Weber-Fechner (W–F) stimulus model are developed to reasonably predict drivers' choice of charging stations and charging modes. The daily revenue of HEVCS and the total queuing time of drivers are the objective functions considered in this paper simultaneously. The above multi-objective optimization results that the proposed strategy can effectively improve the benefits of HEVCS and reduce energy waste. Additionally, this paper discusses the results of a sensitivity analysis conducted by varying incentive discount, which reveals the combined benefits of the HEVCS and the vehicles are effectively increased by setting reasonable incentive discounts.