Nickel-based electrocatalytic material is considered one of the cost-optimal transition metal catalysts in alkaline water electrolysis due to its accessible industrial-applicability. Nevertheless, slow hydrogen evolution kinetics and low activation are still the grand challenges. Herein, we report a three-dimentional porous cluster structure vanadium oxide implanting into nickel-copper alloy electrocatalyst with phase-separation metallic nickel and copper as the main crystal phase mixed up with amorphous vanadium oxide phase, which is fabricated in situ on nickel foam (NF) by one-step cyclic voltammetry. The tri-hierarchical porous micro-nano structure of VOx-NiCu/NF was constructed by nanoparticles of whichmicropores were created by clusters. This nickel foam micropores endows the target catalyst with a 28-fold increased electrochemically active surface area (ECSA), comparable to Pt-like catalytic activity towards hydrogen evolution reaction (HER). Encouragingly, VOx-NiCu/NF needs merely 35 mV (η10) to drive -10 mA·cm-2 towards HER in alkaline medium. In addition, the as-prepared VOx-NiCu/NF exhibits excellent long-time stability and durability. These data suggest that the formation of cluster structure, piled by nanoparticles, creates a large number of surface micropores, which greatly enhance the active sites and provide abundant material transfer channels for HER. Formation of NiCu alloy and amorphous V2O5 phase synergically boost the intrinsic HER activity to a certain extent. Simultaneously, the ideal composition and unique structural characteristics of VOx-NiCu/NF contribute to the superior catalytic performance with the structural advantage responsible for the predominant effect. On the basis of kinetic analysis, the HER at VOx-NiCu/NF proceed via a Volmer-Heyrovsky mechanism, where chemical desorption of hydrogen adsorbed is regarded as the rate-limiting step. Therefore, this study lays a foundation for promotion electrocatalytic hydrogen production.

Cycle stability and specific capacity of cathode materials for sodium ion batteries play an important role in achieving their wide application. Based on the strategy of introducing specific heteroelements to optimize the structural stability and specific capacity of cathode materials, O3-Na0.9Ni0.5-xMn0.3Ti0.2SbxO2 (NMTSbx, x=0, 0.02, 0.04, 0.06) was prepared by a simple solid-state reaction method, and effects of Sb doping amount on the sodium storage properties of Na0.9Ni0.5Mn0.3Ti0.2O2 cathode materials were investigated. The characterization results show that the electrostatic repulsion force between oxygen atoms in the transition metal layer is reduced after Sb doping, while the lattice spacing is expanded, which is conducive to deintercalation of Na+. Meanwhile, the strong electron delocalization caused by Sb doping decreases energy of the whole system, leading to a stable structure, more conducive to cyclic charging and discharging. The electrochemical test shows that initial discharge specific capacity of undoped NMTSb0 is 122.8 mAh·g-1 at 1C(240 mA·g-1), and the capacity retention rate is only 41.5% after 200 cycles. But initial discharge specific capacity of doped NMTSb0.04 is 135.2 mAh·g-1 at 1C, and the capacity retention rate is up to 70% after 200 cycles. This study shows that Sb doped O3 type Na0.9Ni0.5Mn0.3Ti0.2O2 cathode material can significantly improve initial discharge specific capacity and capacity retention rate of sodium ion batteries. Our results suggest that Sb doping strategy might be a useful approach for preparation of high stable sodium ion batteries..

Combining thermoelectric materials with magnetocaloric materials enables a potential new all-solid-state cooling technology based on coupling enhancement of thermoelectric cooling and magnetic cooling, which is highly expected to achieve a technological change from thermoelectric cooling to thermoelectromagnetic cooling. However, the stability of thermal-electro-magnetic composites in service environment is still unknown. Herein, a series of Gd/BST thermo-electro-magnetic gradient composites were prepared by combining Bi0.5Sb1.5Te3 (BST) thermoelectric material and Gd magnetocaloric material via spark plasma sintering technology. Evolution of phase composition, microstructure, thermoelectric, and cooling performance of the gradient composites during the 12 d aging process at 338 K and 80% relative humidity(RH) were systematically studied. The results show that the phase composition and microstructure of Gd/BST thermal-electro-magnetic gradient composites have excellent service stability. The chemical composition and average thickness (~4.5 μm) of Gd-Te diffusion layer at Gd/BST heterogeneous interface doesn’t exhibit obvious change during the aging process. The test of thermoelectric and cooling performance along different Gd concentration gradient indicates that ZT of the materials negligibly changed before and after aging treatment, and the cooling temperature difference of the single-leg device is stable at about 6.5 K under the threshold current of 2.5 A. These results show that thermoelectric and cooling performance of the Gd/BST gradient composites have excellent service stability.

Laser-induced damage is the fundamental cause of sudden rupture of fused silica vacuum optical elements. To investigate this damage on bending strength weakening to find safety design method, standard samples were made with fused silica vacuum optical elements in the final optics assembly of the SG-III prototype laser facility. The surface damage morphological characteristics of fused silica glass samples were statistically analyzed, and the influence of laser-induced damage on bending strength of fused silica glass samples was investigated. The results show that the damage morphology of laser-induced fused silica glass is typically semi-ellipsoid, the depth of the damage point increases with its length which is no more than 2 mm; The damage point has obvious influence on the bending strength of fused silica glass, whose average bending strength with damage point is only 0.41 times that of the samples without damage point. With increase of the length and depth of the damage point, the bending strength of the samples generally decrease. But when the length of the damage point exceeding 15 mm, its bending strength downward trend is significantly moderated, the ratio of length to depth of the damage point has no obvious effect on the bending strength. These data suggest that designing safe optical elements of fused silica glass vacuum window should comprehensively take into account dispersion of glass bending strength, persistent effect of the stress, and the maximum bending tensile stress distributed near the damage point should not exceed the design value of bending strength.

High energy particle bombardment of silicon carbide can lead to the accumulation of defects and lattice disorder, which can negatively affect physical property and reduce lifetime of SiC devices. Thus, it is essential to systematically study the damage of SiC in different radiation environment. Herein, 6H-SiC was irradiated by neutrons at the fluence of 5.74×1018, 1.74×1019, 2.58×1020 and 1.27×1021 n/cm2, and then annealed. Changes in lattice parameters from post-irradiation isochronal annealing for 30 min in the range of 500-1650 ℃ were measured using X-ray single crystal diffraction. The results showed that the lattice swelling and recovery behavior were isotropic. Based on the swelling data, it was concluded that the neutron irradiation-induced defects in 6H-SiC were primarity point defects. Both intrinsic and irradiation defects can introduce defect energy levels, which were mainly caused by vacancies and led to the absorption band edge redshift and band gap narrowing of SiC. The defect energy levels of these vacancies and vacancy-associated defects were determined by absorption spectra, luminescence spectra and Raman spectra. Experiments and first principles calculation showed that the silicon vacancies introduced defect levels above the valence band, while the carbon vacancies introduced levels below the conduction band. The infrared absorption at 1382 nm and 1685 nm and the emission at 550 nm of unirradiated 6H-SiC were mainly due to the intrinsic carbon vacancies. The luminescence of post-irradiated SiC at 415, 440 and 470 nm was mainly due to the silicon vacancy produced by irradiation and its related defect configuration. All above data revealed the luminescence mechanism of SiC based on the charge state and the defect energy level distribution.

Wide band gap γ-CuI is a p-type transparent semiconductor with excellent optoelectronic and thermoelectric property, which has recently attracted worldwide attention. However, as an emerging material, its luminescence mechanism that is impacted by defects is rarely reported and remains obscure, limiting its further applications. In this work, Cl-doped CuI film was prepared by gas-phase reaction method. Using cathodoluminescence spectroscopy, effects of Cl doping on the surface morphology and cathodoluminescence property of CuI films were investigated in detail, and main defects of Cl presence in CuI films were explored by combining first-principle calculations, revealing relationship between structure and luminescent property of Cl-doped CuI films. These data showed Cl-doped region had a smoother surface than that of the undoped region with granular morphology, which clearly demonstrated that Cl dopant altered surface structure of the undoped region. Compared with the undoped region, the Cl dopant induced doubled fluorescence signal of band-edge emission at 410 nm, but reduced the defect peak at 720 nm, indicating that a small amount of Cl dopant brought a great luminescent improvement to CuI. The formation energy calculations of various crystal defects suggest that Cl can inhibit the formation of deep-level defects such as I vacancy in CuI and reduce the probability of non-radiative transition of excitons, which is consistent with the cathodoluminescence results. The full width at half maximum of the band-edge luminescence peak of Cl-doped CuI film is as small as 7 nm, showing extremely high luminescence monochromaticity. Therefore, the present findings deepen our understanding on how halogen doping boosts the luminescence performance of CuI-based materials.

Intermediate-temperature solid oxide fuel cell (IT-SOFC) is promising for carbon neutrality, but its cathode is limited by the contradiction between thermal compatibility and catalytic activity. Herein, we propose a high-entropy double perovskite cathode material, GdBa(Fe0.2Mn0.2Co0.2Ni0.2Cu0.2)2O5+δ (HE-GBO) with improved compatibility and activity, in view of the high-entropy strategy by multi-elemental coupling, which possesses double perovskite structure and excellent chemical compatibility with state-of-the-art Gd0.1Ce0.9O2-δ (GDC). The polarization resistance (Rp) of the symmetrical cells with HE-GBO cathode is 1.68 Ω·cm2 at 800 ℃, and the corresponding Rp of HE-GBO-GDC (mass ratio 7:3) composite cathode can be greatly reduced (0.23 Ω·cm2 at 800 ℃) by introducing GDC. Dendritic microchannels anode-supported single cells with HE-GBO and HE-GBO-GDC cathodes realize maximum power densities of 972.12 and 1057.06 mW/cm2 at 800 ℃, respectively, indicating that cell performance can be enhanced by high-entropy cathodes. The results demonstrate that high-entropy double perovskite cathode material HE-GBO has a high potantial to solve the conflict problem of thermal compatibility and catalytic activity in IT-SOFCs.

S-scheme heterojunction has been extensively investigated for hydrogen evolution and environmental pollution issues. In this study, a monoclinic WO3/hydrothermally treated red phosphorus (HRP) S-scheme composite was prepared by hydrothermal method. XPS and EPR characterization confirmed that the monoclinic WO3/HRP composite formed S-scheme heterojunction. 5%WO3/HRP composite displayed the optimal photocatalytic activity under visible light irradiation, and its degradation rate of Rhodamine B (RhB) reached 97.6% after 4 min of visible light irradiation, while its hydrogen evolution rate reached 870.69 μmol·h-1·g-1 which was 3.62 times of that of pure HRP. This could be ascribed to the tight interfacial bonding between WO3 and HRP, and the formation of S-scheme heterostructure, enabling rapid separation of photogenerated carriers and therefore improving the strong redox capacity. This study provided a promising RP-based photocatalyst to meet the demand for clean energy and drinking water.

Borosilicate bioglass has attracted extensive attention due to its stable structure and excellent biological activity. However, the rate of its mineralization process is fast in the initial stage and slow in the middle and late stages, which limits the application of borosilicate bioglass. As an auxiliary method, the near-infrared (NIR) laser can accelerate the degradation of bioglass. Therefore, we prepared a core-shell borosilicate bioglass with titanium nitride as the core and bioglass (40SiO2-20B2O3-36CaO-4P2O5) as the shell, and used near-infrared laser regulation technology to intervene the mineralization process of the composite bioglass. The experimental results show that the core-shell bioglass exhibits a significant photothermal effect, and the photothermal ability increases with the increases of the doping amount of TiN NPs and the laser power density. During the in vitro immersion, near-infrared laser increased the degradation rate of bioglass. After immersion for 7 d, the contents of calcium and boron in the SBF are increased by 12%-16% and 8%-11%, respectively. Meanwhile, the formation efficiency of hydroxyapatite is significantly improved. Cell proliferation activity test shows that the sample has good biological safety. Therefore, near-infrared light can accelerate the degradation and mineralization of functional core-shell bioactive glass, which is expected to play a regulatory role.

2022 marks the 110th anniversary of X-ray diffraction (XRD), which is a powerful technique used to find out the nature of materials. Rietveld refinement method, as an important means of extracting material structure information, plays a significant role in establishing the relationship between structure and performance of materials. Cathode materials are a vital part of lithium-ion batteries (LIBs). In-depth understanding of their crystal structure and atomic distribution is extremely helpful to promote the development of cathode materials for LIBs. Cathode materials for LIBs are generally the hosts of lithium. Studies on lithium occupation and transfer are inseparable from a deep understanding of its structural characteristics. This review summarizes XRD Rietveld structure refinement and its application in cathode materials for LIBs. XRD Rietveld structure refinement in synthesis, degradation, and structural modification of cathode materials are analyzed by using several types of typical cathode materials as examples. XRD Rietveld method could provide useful structural information of the cathode materials, including phase ratio in composite and crystallographic parameters (e.g., cell parameters, key atomic occupation, and atomic coordinates). Therefore, exploring structure of cathode materials assisted with XRD Rietveld refinement method is of great significance for the development of high-performance cathode materials for LIBs. Finally, the opportunities and challenges in the field of X-ray diffraction technology in detecting structure of cathode materials for LIBs are prospected.

Ferroelectric superlattices are artificial film materials with layered periodic structure formed by an alternate growth of two or more ferroelectric materials or non-ferroelectric materials at unit cell scale. Ferroelectric superlattices can exhibit excellent ferroelectric, piezoelectric, dielectric, and pyroelectric properties due to the existence of a large number of heterogeneous interfaces and the remarkable interface effect, and even show new functional properties that are not available in their constituent materials. Therefore, ferroelectric superlattices not only provide an ideal platform for studying interactions between charges and lattices at the interface of complex oxide materials, but also play an indispensable role in the next generation of integrated ferroelectric devices. With the development of preparation and characterization methods, researchers can design and control the microstructure and chemical composition at atomic scale to improve the functional properties of ferroelectric superlattice thin films. Ferroelectric polarization is the most basic property of ferroelectric film materials. In addition to being used for information storage devices, ferroelectric polarization also plays an important role in regulating the energy conversion performance of integrated ferroelectric devices such as piezoelectric devices, photovoltaic devices and electrocaloric devices. Therefore, the ferroelectric polarization intensity of ferroelectric superlattices directly determines their functional characteristics and practical application value of integrated ferroelectric devices composed of them. In this short review paper, we firstly introduced the structural characteristics, classification and several typical functional characteristics of ferroelectric superlattices, and then focused on several factors affecting the polarization performance of ferroelectric superlattices based on recent research results, including strain effect, electrostatic coupling effect, defect effect, and period thickness. Finally, we looked forward to the future research directions in ferroelectric superlattices to provide reference for the research in this field.

Excessive emission of greenhouse gases has serious adverse effects on global climate. How to reduce carbon emissions has become a global problem. Supercapacitors have advantages of long cycle life, high power density and relatively low carbon emissions. Developing supercapacitor energy storage is an effective measure to build the reliable future energy system. In recent years, MXene materials have achievedgreat popularity in the field of supercapacitor energy storage applications due to their excellent hydrophilicity, electrical conductivity, high electrochemical stability, and surface chemical tunability. However, the serious self-stacking problem of MXene limits its performance in energy storage. Developing advanced MXene materials is critical for next generation high-performance electrochemical energy storage devices. This paper reviews the research progress of MXene material in the field of supercapacitor energy storage. Firstly, the structure and energy storage properties of MXene are introduced, followed by analysis of the energy storage mechanism of MXene. Secondly, nanoengineering of structure design to improve the performance of MXene electrode is depicted. Thirdly, structure-performance relationship of MXene composite materials and its latest research progress in application of supercapacitor are summarized. Finally, research and development trends of MXene as an electrode for supercapacitor are broadly prospected.

Silicon carbide ceramic matrix composites have been widely used in aerospace, friction brake, fusion fields and so on, and become advanced high-temperature structural and functional composites, due to their high specific strength and specific modulus, excellent ablation and oxidation resistance, and high conductivity and good thermal shock resistance. This paper reviews the latest research progress in preparation and property of silicon carbide ceramics matrix composites (CMCs) with high thermal conductivity. Researchers have improved the thermal conductivity of silicon carbide CMCs, including by introducing highly thermal conductive phases for reinforcing heat transport, such as diamond powders, and mesophase pitch-based carbon fibers (MPCF), by optimizing the interface between pyrolytic carbon (PyC) and silicon carbide matrix for reducing interfacial thermal resistance, by heat-treating for obtaining silicon carbide matrix with higher crystallinity and better thermal conductivity, and by designing preform structure for establishing continuous thermal conduction path. Meanwhile, research interests on silicon carbide CMCs are to explore new preparation with high efficiency and low cost through optimising their influencing factors, and to obtain isotropic highly thermal conductivity with dimensional stability and physical properties through deep understanding their thermal conductive mechanism, and flexible method based on the structure-activity relationship.