Mild hydrogen production from the hydrolysis of Al–Bi–Zn composite powder

The development of mild hydrogen-generating materials is of great significance to improve the working life of hydrogen–oxygen fuel cells. In this study, Al–Bi–Zn composite powders were designed by phase diagram calculation and then prepared via the gas atomization method. The results indicated that the conversion yield of Al–12Bi–7Zn (wt.%) powder reached 98% with stable hydrogen production within 280 min at 50 °C. When composite powder reacted with NaCl solution to produce hydrogen, the dormant period of the reaction process was significantly shortened, but the conversion rate was slightly reduced. Additionally, the evolution of powder morphology during the reaction was investigated. The results showed that the continuous cracking of the powder led to the continuous exposure of fresh Al to react.     

Ultrasonic-assisted soldering of sapphire through metallic transition layers of Al and Zn using Sn-xZn-2Al solder alloys

Ultrasonic-assisted soldering has potential in the electrical industry especially for the joining of ceramics. The Al-activated Sn-based alloys are promising ultrasonic solders due to simple preparation, while the current approaches required long ultrasonic action. In order to increase the efficiency and reduce ultrasonic-induced damage, this study investigated the soldering of sapphire (monocrystalline α-Al₂O₃) performed under an ultrasonic action for 0.5 s by using Sn-xZn-2Al(x = 9, 25, 45) solder alloys. Microstructures of interfacial transition layers between the sapphire and solders were focused on. It has been found that at the interfaces no interfacial reaction phases formed and the interfacial bonding was realized via metallic transition layers. Three kinds of interfacial structures existed, that is, sapphire/Al atomic layer/β-Sn, sapphire/Al atomic layer/(Zn enrichment layer)/β-Sn and sapphire/Al atomic layer/Zn nanocrystalline clusters/β-Sn. The elements of Al and Zn in the solder alloys underwent a selective and asynchronous adsorption process during the ultrasonic action. An Al atomic layer formed on the sapphire surface by the stronger chemical adsorption and acted as a transition layer between sapphire and β-Sn. The Zn enrichment layer was distributed locally along the interface and as the Zn content increased in the solder alloys, more localized Zn nanocrystalline clusters formed. These Zn transition structures strengthened the interfacial bonding by transforming the Al atomic layer/β-Sn interface into the Al atomic layer/Zn transition structures/β-Sn interfaces. The joints possessed a shear strength of up to 28 MPa when soldering with Sn–45Zn–2Al at 350 °C.     

Crystallization in a soda–lime-silicate glass after high pressure

This work explored the permanent changes a high pressure (HP) processing could cause on nucleation, Raman vibrational modes, thermal, and mechanical properties of the Na₂O • 2CaO • 3SiO₂ (N₁C₂S₃) glass. It was shown that, with higher pressure values, the number of nuclei per unit of volume, N_V, has decreased. Raman spectra showed no significant changes in the vibrational modes; however, the differential thermal analysis performed indicated that the glass transition temperatures, T_g, were higher than the pristine glass sample and that HP caused the glass to be less stable. The Vickers indentation radial cracks remained constant; however, the lateral cracks increased in size, indicating that the glass is more stressed after HP, and therefore, the relaxation time for nucleation will be higher, lowering N_V further, as observed.     

Transformation of Organonitrogen-Encapsulated MOFs into N-Doped Fe3O4@C Nanopolyhedron via CVD Super-Assembly for Photochemical Oxidation

Development of nano-structured metal oxides/heteroatom composites with controlled components and structure for photochemical oxidation still remains a great challenge. Here, a new and versatile strategy is reported for transformation of organonitrogen-encapsulated metal-organic frameworks (MOFs) into N-doped Fe₃O₄@C nanopolyhedron by chemical vapor deposition-induced super-assembly method. Strong confined interaction between organonitrogen guests (urea, thiourea, melamine, and dimethylimidazole) and Fe nodes of MOFs realizes reconstruction of crystal structure and introduction of N species. With the novel approach, the uniform dispersion of guests and perfect metallic/heteroatom interfacial is obtained. Compared with MOFs-derived Fe₂O₃/C, the heteroatom/defect-to-metal cluster charge transfer excitations lead N-doped Fe₃O₄@C to exhibit more superior activity for photocatalytic oxidation (turn-over frequencies as high as 3.72 h⁻¹). It demonstrates that the introduction of abundant pyrrole-N and oxygen vacancies on carbon interface boosts the advance of photo-generated carrier transfer. The study offers a simple and promising strategy for the design of novel metal oxides/heteroatom composite with adjustable structure and functions.     

Uniform Si-Infused UiO-66 as a Robust Catalyst Host for Efficient CO2 Hydrogenation to Methanol

Due to the weak nature of organic coordination bonds, metal–organic frameworks (MOFs) can hardly retain their intrinsic physicochemical properties and structural integrity when functioning in harsh heterogeneous reactions. Herein, a post-synthetic strategy to reinforce the MOF structure by inserting siliceous linkers inside is proposed, according to which a Si-infused UiO-66 (s-UiO-66) with well-developed porosity and exceptional thermal/structural stability is fabricated. This monodispersed Si-infused matrix with enlarged nanopores is then utilized as the catalyst host, and is highly conductive to confining ultrafine CuO nanoparticles with uniform dispersion. Targeting CO₂ hydrogenation to methanol reaction, the Cu-loaded s-UiO-66 (CuO/s-UiO-66) delivers a remarkable and efficient methanol production rate outperforming other Cu/ZrO₂-based catalysts and the commercial catalyst. Moreover, the robust structure of CuO/s-UiO-66 prevents both copper phase and host material from aggregation during the catalyst preparation procedure and the reaction. In addition to material-oriented studies, in situ characterization techniques are employed to identify the active Cu component and key intermediates formed during the CO₂ hydrogenation reaction, separately. It is envisioned that this Si infusion strategy can be applied to construct stable host materials with boundary-defined structures from the pristine MOFs for broadened applications under extreme circumstances.     

Wrapping up Metal–Organic Framework Crystals with Carbon Nanotubes

The presence of tetrazine units in the organic nodes of UiO-68-TZCD controls the formation of ultrathin coatings of single-wall nanotubes that decorate the surface of the crystal. These crystal hybrids can be prepared straightforwardly in one step and are extraordinarily respectful with the properties of the framework for combination of mesoporosity and surface areas ≈4.000 m² g⁻¹, with excellent stability in water, and conductivities at room temperature of 4 × 10⁻² S cm⁻¹ even at very low carbon weight contents (2.3 wt.%).     

Quasi-Liquid Gel Electrolyte for Enhanced Flexible Zn–Air Batteries

Flexible Zn–air batteries (FZABs) have attracted more attention due to their high specific energy, excellent stability, and unique rechargeability. However, these batteries are limited by the low conductivity of the gel electrolytes used. Here a quasi-liquid gel with ionic conductivity comparable to liquid electrolytes is presented. The gel pore structure is guided and modified in situ with large-size silica to achieve clear and unbroken pores. The reduced skeleton structure leads to a significant increase in ionic conductivity to 562.6 mS cm⁻¹, enabling a peak power density of 154 mW cm⁻² and a cycle life of over 40 h with a low charge–discharge gap. The FZABs also exhibit a high lifetime and potential advantages in 10 mA cm⁻² charge/discharge testing, and demonstrate excellent performance in practical applications. This study offers new possibilities for developing high-performance quasi-liquid gels and innovative concepts for FZABs.     

Ultrastrong Magnon–Magnon Coupling and Chirality Switching in Antiferromagnet CrPS4

As new information carriers, antiferromagnetic magnons have great potential in the fields of spintronics and quantum information. However, the strong exchange interaction between sublattice spins in conventional antiferromagnets results in their frequencies up to the terahertz (THz) range, hindering further exploration of related applications and physics. Recently, emerging van der Waals A-type antiferromagnets with the weak exchange interaction may bring about a change. In this study, it demonstrates two distinct tunable ultrastrong magnon–magnon couplings in the gigahertz (GHz) band using this type of antiferromagnet, CrPS₄, with a maximum normalized coupling strength (η) of 0.31. It establishes orthorhombic and monoclinic models for theoretical analyses, unambiguously showing that the ultrastrong coupling strength is caused by unique magnetocrystalline anisotropy rather than exchange enhancement. Furthermore, for the first time, it observes a continuous switching process of sublattice magnon chirality arising from the orthorhombic nature of anisotropy. These findings not only deepen the understanding of antiferromagnetic spin dynamics but also offer a powerful platform for building magnonic quantum systems and chirality-based spintronics.     

Strategies for Realizing Rechargeable High Volumetric Energy Density Conversion-Based Aluminum–Sulfur Batteries

Aluminum–sulfur batteries (ASBs) are deemed to be alternatives to meet the increasing demands for energy storage due to their high theoretical capacity, high safety, low cost, and the rich abundances of Al and S. However, the challenging problems including sluggish conversion kinetics, inferior electrolyte compatibility, and potential dendrite formation are still remained. This review comprehensively focuses on summarizing the specific strategies from polysulfide shuttling inhibition to form smooth anodic Al activation/deposition. Especially, innovations in cathodic side for achieving electrochemical kinetic modulations, electrolyte optimizations, and anodic interface mediations are discussed. Upon detailed elaborating the formation process, influencing factors, and their interactions in the Al–S electrochemistry, a comprehensive summary of their causative mechanisms and the corresponding strategies are provided, including optimization of electrolytes, innovative in situ detections, and precise electrocatalytic strategies. Based on such a systematic understanding in the Al–S electrochemistry, the possible electrochemical reaction mechanism is deciphered more clearly and enlightened practical strategies on the future development of stable ASBs. Furthermore, future opportunities and directions of high-performance conversion-based Al–S batteries for large-scale energy storage applications are highlighted.