Development of low-resistance electrode/electrolyte interfaces is key for enabling all-solid-state batteries with fast-charging capabilities. Low interfacial resistance and high current density were demonstrated for Na-β''-alumina/sodium metal interfaces, making Na-β''-alumina a promising solid electrolyte for high-energy all-solid-state batteries. However, integration of Na-β''-alumina with a high-energy sodium-ion intercalation cathode remains challenging. Here, we report a proof-of-concept study that targets the implementation of a Na-β''-alumina ceramic electrolyte with a slurry-casted porous NaCrO₂ cathode with infiltrated sodium hydroborates as secondary electrolyte. The hydroborate Na4(B12H12)(B10H10) possesses similar sodium-ion conductivity of 1 mS cm^-1 at room temperature as Na-β''-alumina and can be fully densified by cold pressing. Using the Na₄(B₁₂H₁₂)(B₁₀H₁₀) secondary electrolyte as interlayer between Na-β''-alumina and NaCrO₂, we obtain a cathode-electrolyte interfacial resistance of only 25 Ω cm² after cold pressing at 70 MPa. Proof-of-concept cells with a sodium metal anode and a NaCrO2 cathode feature an initial discharge capacity of 103 mAh g^-1 at C/10 and 42 mAh g^-1 at 1 C with an excellent capacity retention of 88% after 100 cycles at 1 C at room temperature. Ion-milled cross-sections of the cathode/electrolyte interface demonstrate that intimate contact is maintained during cycling, proving that the use of hydroborates as secondary electrolyte and as an interlayer is a promising approach for the development of all-solid-state batteries with ceramic electrolytes.

Advanced high-strength steels are key structural materials for the development of next-generation energy-efficient and environmentally friendly vehicles. Medium Mn steel, as one of the latest generation advanced high-strength steels, has attracted tremendous attentions over the past decade due to its excellent mechanical properties. Here, the state-of-the-art developments of medium Mn steel are systematically reviewed with focus on the following crucial aspects: (a) the alloy design strategies; (b) the thermomechanical processing routes for the optimizations of microstructure and mechanical properties; (c) the fracture mechanisms and toughening strategies; (d) the hydrogen embrittlement mechanisms and improvement strategies.

Lithium phosphorus oxygen nitrogen (LiPON) as solid electrolyte discovered by Bates et al in the 1990s is an important part of all-solid-state thin-film battery (ASSTFB) due to its wide electrochemical stability window and negligible low electronic conductivity. However, the ionic conductivity of LiPON about 2 × 10−6 S cm−1 at room temperature is much lower than that of other types of solid electrolytes, which seriously limits the application of ASSTFBs. This review summarizes the research and progress in ASSTFBs based on LiPON, in the solid-state electrolyte of LiPON-derivatives with adjustable chemical compositions of the amorphous structure for the improvement of the ionic conductivity and electrochemical stability, in the critical interface issues between LiPON and electrodes, and in preparation methods for LiPON. This review is helpful for people to understand the interface characteristics and various preparation methods of LiPON in ASSTFBs. The key issues to be addressed concern how to develop solid-state electrolyte films with high conductivity and high-quality interface engineering as well as large-scale preparation technology, so as to realize the practical application of highly integrated ASSTFBs.

High harmonic generation (HHG) delivering attosecond pulse duration with photon energy in the extreme ultraviolet spectral range has been demonstrated as a robust table-top coherent light source, allowing for the observation and manipulation of ultrafast process within the shortest time window ever made by humans. The past decade has witnessed the rapid progress of HHG from a variety of solid targets and its application for photoemission spectroscopy in condensed matter. In this article, we review the HHG in solids and the understanding of the underlying physics of HHG, which allows all-optical band structure reconstruction. We also introduce combinations of HHG source and photoemission spectroscopy, such as angular-resolved photoemission spectroscopy and photoemission electron microscopy. With the capacity of exploring a wide momentum space and high temporal resolution, the extension of attosecond science to the field of condensed matter physics will lead to new insights into the fundamental ultrafast dynamics in novel quantum materials.

In recent years, topological quantum materials (TQMs) have attracted intensive attention in the area of condensed matter physics due to their novel topologies and their promising applications in quantum computing, spin electronics and next-generation integrated circuits. Scanning tunneling microscopy/spectroscopy (STM/STS) is regarded as a powerful technique to characterize the local density of states with atomic resolution, which is ideally suited to the measurement of the bulk-boundary correspondence of TQMs. In this review, using STM/STS, we focus on recent research on bismuth-based TQMs, including quantum-spin Hall insulators, 3D weak topological insulators (TIs), high-order TIs, topological Dirac semi-metals and dual TIs. Efficient methods for the modulation of the topological properties of the TQMs are introduced, such as interlayer interaction, thickness variation and local electric field perturbation. Finally, the challenges and prospects for this field of study are discussed.

Carbon, as an indispensable chemical element on Earth, has diverse covalent bonding ability, which enables construction of extensive pivotal carbon-based structures in multiple scientific fields. The extraordinary physicochemical properties presented by pioneering synthetic carbon allotropes, typically including fullerenes, carbon nanotubes, and graphene, have stimulated broad interest in fabrication of carbon-based nanostructures and nanomaterials. Accurate regulation of topology, size, and shape, as well as controllably embedding target spn-hybridized carbons in molecular skeletons, is significant for tailoring their structures and consequent properties and requires atomic precision in their preparation. Scanning probe microscopy (SPM), combined with on-surface synthesis strategy, has demonstrated its capabilities in fabrication of various carbon-based nanostructures and nanomaterials with atomic precision, which has long been elusive for conventional solution-phase synthesis due to realistic obstacles in solubility, isolation, purification, etc. More intriguingly, atom manipulation via an SPM tip allows unique access to local production of highly reactive carbon-based nanostructures. In addition, SPM provides topographic information of carbon-based nanostructures as well as their characteristic electronic structures with unprecedented submolecular resolution in real space. In this review, we overview recent exciting progress in the delicate application of SPM in probing low-dimensional carbon-based nanostructures and nanomaterials, which will open an avenue for the exploration and development of elusive and undiscovered carbon-based nanomaterials.

Scanning probe microscopy (SPM) allows the spatial imaging, measurement, and manipulation of nano and atomic scale surfaces in real space. In the last two decades, numerous advanced and functional SPM methods, particularly atomic force microscopy (AFM), have been developed and applied in various research fields, from mapping sample morphology to measuring physical properties. Herein, we review the recent progress in functional AFM methods and their applications in studies of two-dimensional (2D) materials, particularly their interfacial physical properties on the substrates. This review can inspire more exciting application works using advanced AFM modes in the 2D and functional materials fields.

Helium-3 (3He) is a noble gas that has critical applications in scientific research and promising application potential as clean fusion energy. It is thought that the lunar regolith contains large amounts of helium, but it is challenging to extract because most helium atoms are reserved in defects of crystals or as solid solutions. Here, we find large amounts of helium bubbles in the glassy surface layer of ilmenite particles that were brought back by the Chang’E-5 mission. The special disordered atomic packing structure of glasses should be the critical factor for capturing the noble helium gas. The reserves in bubbles do not require heating to high temperatures to be extracted. Mechanical methods at ambient temperatures can easily break the bubbles. Our results provide insights into the mechanism of helium gathering on the moon and offer guidance on future in situ extraction.

The remarkably high theoretical energy densities of Li–O₂ batteries have triggered tremendous efforts for next-generation conversion devices. Discovering efficient oxygen reduction reaction and oxygen evolution reaction (ORR/OER) bifunctional catalysts and revealing their internal structure-property relationships are crucial in developing high-performance Li–O₂ batteries. Herein, we have prepared a nanoflower-like NiP₄@NiSe₂ heterostructure and employed it as a cathode catalyst for Li–O₂ batteries. As expected, the three-dimensional biphasic Ni₅P₄@NiSe₂ nanoflowers facilitated the exposure of adequate active moieties and provide sufficient space to store more discharge products. Moreover, the strong electron redistribution between Ni₅P₄ and NiSe₂ heterojunctions could result in the built-in electric fields, thus greatly facilitating the ORR/OER kinetics. Based on the above merits, the Ni₅P₄@NiSe₂ heterostructure catalyst improved the catalytic performance of Li–O₂ batteries and holds great promise in realizing their practical applications as well as inspiration for the design of other catalytic materials.

Efficient water splitting for H₂ evolution over semiconductor photocatalysts is highly attractive in the field of clean energy. It is of great significance to construct heterojunctions, among which the direct Z-scheme nanocomposite photocatalyst provides effective separation of photo-generated carriers to boost the photocatalytic performance. Herein, Z-scheme hydrated tungsten trioxide/ZnIn₂S₄ is fabricated via an in-situ hydrothermal method where ZnIn₂S₄ nanosheets are grown on WO₃⋅xH₂O. The close contact between WO₃⋅0.5H₂O and WO₃⋅0.33H₂O as well as ZnIn₂S₄ improve the charge carrier separation and migration in the photocatalyst, where the strong reducing electrons in the conduction band of ZnIn₂S₄ and the strong oxidizing holes in the valence band of WO₃⋅0.33H₂O are retained, leading to enhanced photocatalytic hydrogen production. The obtained WO₃⋅xH₂O/ZnIn₂S₄ shows an excellent H₂ production rate of 7200 μmol g^-1h^-1, which is 11 times higher than pure ZnIn₂S₄. To the best of our knowledge, this value is higher than most of the WO₃-based noble metal-free semiconductor photocatalysts. The improved stability and activity are attributed to the formation of the Z-scheme heterojunction, which can markedly accelerate the interfacial charge separation for surface reaction. This work offers a promising strategy towards the design of efficient Z-scheme photocatalyst to suppress electron-hole recombination and optimize redox potential.

P2-type layered oxides with the general Na-deficient composition NaxTMO₂ (x < 1, TM: transition metal) are a promising class of cathode materials for sodium-ion batteries. The open Na⁺ transport pathways present in the structure lead to low diffusion barriers and enable high charge/discharge rates. However, a phase transition from P₂ to O₂ structure occurring above 4.2 V and metal dissolution at low potentials upon discharge results in rapid capacity degradation. In this work, we demonstrate the positive effect of configurational entropy on the stability of the crystal structure during battery operation. Three different compositions of layered P2-type oxides were synthesized by solid-state chemistry, Na_0.67(Mn_0.55Ni_0.21Co_0.24)O₂, Na_0.67(Mn_0.45Ni_0.18Co_0.24Ti_0.1Mg_0.03)O₂ and Na_0.67(Mn_0.45Ni_0.18Co_0.18Ti_0.1Mg_0.03Al_0.04Fe_0.02)O₂ with low, medium and high configurational entropy, respectively. The high-entropy cathode material shows lower structural transformation and Mn dissolution upon cycling in a wide voltage range from 1.5 to 4.6 V. Advanced operando techniques and post-mortem analysis were used to probe the underlying reaction mechanism thoroughly. Overall, the high-entropy strategy is a promising route for improving the electrochemical performance of P2 layered oxide cathodes for advanced sodium-ion battery applications.

Material genetic engineering can significantly accelerate the development of new materials. As an important topic in material science and condensed matter physics, the development of metallic glasses (MGs) with specific properties has largely been the result of trial and error since their discovery in 1960. Yet, property design based on the physical parameters of constituent elements of MGs remains a huge challenge owing to the lack of an understanding of the property inheritance from constitute elements to the resultant alloys. In this work, we report the inherent relationships of the yield strength σ_y, Young’s modulus E, and shear Modulus G with the valence electron density. More importantly, we reveal that the electronic density of states (EDOSs) at the Fermi surface (E_F) is an inheritance factor for the physical properties of MGs. The physical properties of MGs are inherited from the specific element with the largest coefficient of electronic specific heat (γ_i), which dominates the value of the EDOS at E_F. This work not only contributes to the understanding of property inheritances but also guides the design of novel MGs with specific properties based on material genetic engineering.