The resilience of van der Waals (vdW) materials to large strain fields makes them an ideal platform for tuning electronic, optical and magnetic properties1-4. Although in-plane strain is readily mapped, non-invasive and quantitative characterization of out-of-plane strain remains a formidable challenge, particularly for picometre-scale deformations buried at interfaces. Here we demonstrate a polaritonic optical method that uses the mid-infrared out-of-plane hyperbolic polaritons (oHPs) mode to detect interlayer deformations in prototypical vdW polar insulator-hexagonal boron nitride (hBN). This method uses the softening mechanism of out-of-plane transverse optical (oTO) phonons induced by interlayer strain, enabling highly sensitive detection of picometre-scale deformations. Although these oTO phonon modes are typically spectroscopically 'dark', their strain response is activated through the oHPs, achieving an atomic displacement sensitivity of about 10 pm (about 8 × 10-7 times the probing wavelength), enabling ultradeep-subwavelength mechanical interlayer deformation detection. This is experimentally validated in both planar hBN and at the buried interface of quantum dot-hBN nanotube heterostructures. This polariton-based picometrology bridges nanomechanics and photonics, providing a non-destructive lens to visualize hidden stress landscapes with atomic precision.

Two-dimensional (2D) materials with phase transition attract tremendous interest in amplified electron-lattice interactions. However, 2D polymorphic materials beyond layered chalcogenides remain largely unexplored since non-layered solids are difficult to downscale due to high surface energy and strong interlayer forces. Here, we present a general layer-derived conversion strategy to synthesize 2D non-layered polymorphic metal oxides with controlled thickness. By exfoliating layered metal oxychlorides followed by dechlorination, large-area, high-quality oxide nanosheets with layer-by-layer thickness control are obtained. Taking VO2 as an example, this method enables the preparation of half-unit-cell nanosheets with aspect ratios exceeding 10 5 . Real-time structural and elemental analyses reveal subtle V-O coordination changes during conversion. The resulting monoclinic VO2 nanosheets exhibit a clear thickness-dependent phase transition, with the metastable rutile phase stabilized below room temperature at thicknesses down to 8.9 nm. This approach enables access to 2D non-layered materials and reveals their dimensionality-driven property evolution.

Rhombohedral (ABC)-stacked graphene has emerged as a platform for exploring correlated and topological physics. However, its large-scale, pure-phase synthesis has been hindered by intrinsic thermodynamic metastability and kinetic instability. In this work, we introduce a step geometry-guided epitaxial strategy to deterministically control interlayer slip, enabling the synthesis of pure-phase rhombohedral graphene. Using this approach, we obtained pure (phase purity > 99%) rhombohedral graphene with an area reaching 160 micrometers by 80 micrometers and thickness ranging from ~15 layers to ~120 nanometers. The resulting samples establish the first comprehensive reference dataset of Raman fingerprints and intrinsic band structures from few-layer films to ~200-layer bulk. Electronic transport measurements reveal a layer-antiferromagnetic state and the quantum anomalous Hall effect, enabling scalable exploration of next-generation quantum science and technology applications.

Single-walled carbon nanotubes (SWCNTs) act as one-dimensional (1D) nanoreactors capable of stabilizing reactive species and unique low-dimensional phases. Here, we report the synthesis of an unprecedented 1D Sc3Cl8 phase formed via the confinement-induced structural reconstruction of bulk ScCl3 within SWCNTs. The atomic structure of the Sc3Cl8@SWCNT heterostructure is determined by combining aberration-corrected electron microscopy (HRTEM/STEM) with machine-learning force field (MLFF) global structure searches. This reconstruction yields a metal-rich phase that exhibits two anomalous properties. First, unlike typical halide fillers that induce p-type doping, the Sc3Cl8 chain acts as a potent electron donor, driving a strong n-type charge transfer to the nanotube host (a phenomenon we term "redox inversion"). Second, spin-polarized density functional theory (DFT) predicts that the confined chain possesses a ferromagnetic ground state, emerging from a diamagnetic bulk precursor. These results identify Sc3Cl8@SWCNTs as a model heterostructure where confinement simultaneously inverts doping polarity and unlocks magnetic potential, offering a new platform for carbon-based spintronics.

Solid electrolytes are promising candidates for safe, high-energy battery systems. Composite solid electrolytes, in particular, hold the potential to combine high ionic conductivity with stable electrode interfaces. However, a fundamental trade-off often exists between ion conduction and mechanical properties. Here we present a composite solid electrolyte design that decouples ion conduction from mechanical flexibility, achieving a high ionic conductivity of 10.2 mS cm−1 at 25 °C while maintaining close mechanical contact with the electrode. The composite architecture consists of alternating layers of perpendicularly aligned (PA) Li0.3Cd0.85PS3 nanosheets, to establish continuous superionic conduction pathways, and Li-containing polyethylene oxide (PEO) layers, to ensure flexibility and interfacial compatibility. At 25 °C, this PA-Li0.3Cd0.85PS3/PEO electrolyte enables Li||LiNi0.8Co0.1Mn0.1O2 coin cells (stack pressure during assembly <0.5 MPa) to retain 92

Hydrogen is a promising clean energy carrier to address global energy and environmental challenges. Although platinum (Pt)-based catalysts are the benchmark for the hydrogen evolution reaction (HER), their high cost and scarcity limit their widespread application. Two-dimensional transition metal dichalcogenides (TMDs), particularly with the unconventional 1T' phase, have emerged as promising alternatives, yet synthesizing them with high phase purity and stability remains challenging. Here, by using amorphous phosphorus (P)-doped Pd nanoparticles (a-PdP NPs) as templates, we develop a facile and general wet-chemical method to synthesize high-phase-purity and stable 1T'-TMD monolayers (MLs), including MoS2, WS2, and MoWS2, to construct a-PdP@1T'-TMD core-shell NPs. Experimental and theoretical analyses reveal that the formation and stabilization of 1T'-MoS2 MLs are attributed to the strong Pd-S interaction, electron donation from oleylamine, and amorphous nature of the template. The resulting a-PdP@1T'-MoS2 catalyst exhibits superior HER performance, requiring an overpotential of only -182.3 mV to achieve 1,000 mA·cm-2 and maintaining high stability for over 500 h at 500 mA·cm-2, outperforming the commercial Pt/C and placing it among the best reported MoS2-based catalysts. Impressively, the synthesized a-PdP@1T'-MoS2 can also be used as an efficient and stable support to grow single-atomically dispersed Pt with further enhanced HER activity, indicating its promise as a versatile platform for the design and preparation of advanced electrocatalysts.

Two-dimensional (2D) van der Waals (vdW) heterostructures have emerged as a groundbreaking candidate for future integrated circuits due to their tunable band structures, atomically sharp interfaces and seamless compatibility with complementary metal-oxide-semiconductor technologies. Despite their promise, existing synthesis methods, such as mechanical transfer and vapor-phase conversion, struggle to achieve the high-quality, scalable production for practical applications. In response to these longstanding challenges, our study unveils for the first time the direct epitaxial growth of wafer-scale 2D vdW heterostructures (MoS[Formula: see text]/SnS[Formula: see text]) with exceptional quality and uniformity. This achievement is made possible through fundamentally enhancing the adsorption interactions between intermediates and the underlying material. The heterostructures display pristine, defect-free interfaces, consistent crystal orientation and wafer-level thickness uniformity. The Raman peak shifts of MoS[Formula: see text] and SnS[Formula: see text] are constrained to below 0.5 cm[Formula: see text] across the entire wafer, with intensity deviations maintained within an impressive 2%, and thickness uniformity surpassing 99.5%. Owing to their exceptional crystallinity and interface quality, the heterostructures demonstrate extraordinary electron and hole transfer capabilities, showcasing a prominent rectification effect and an astounding responsivity of [Formula: see text] A/W, averaged from 30 devices. Our study signifies a pivotal advancement for the integration of 2D materials into semiconductor technologies, paving the way for next-generation integrated circuits.

The structural evolution of gold clusters has been investigated by numerous density functional theory (DFT) studies. However, due to the slow computational efficiency of DFT, these studies tend to be scattered and lack systematicness. We have developed a robust machine learning force field (MLFF) of gold. The accuracy and robustness of the MLFF were validated by comparing DFT results. By integrating the highly efficient MLFF, which is about 1000,000 times faster than DFT calculations, with the CALYPSO global search method, we systematically explored Aun clusters spanning a wide range of sizes (n = 2-55) and uncovered several key issues: (i) revealing the critical transition points from planar to 3D structures (n = 14) and from cage-like to core-shell structures (n > 26); (ii) discovering new stable cluster structures; (iii) conducting an in-depth analysis of the core-shell model. This study shows that MLFF can be used to study complex structural systems like clusters and address systematic issues related to larger clusters. It also indicates the potential of MLFF in tackling more complex problems, including mixed and ligand-protected clusters.

Two-dimensional (2D) indium selenide, with its low effective mass, high thermal velocity, and exceptional electronic mobility, is a promising semiconductor for surpassing silicon electronics, but grown films have not achieved performance comparable with that of exfoliated micrometer-scale flakes. We report a solid‒liquid‒solid strategy that converts amorphous indium selenide films into pure-phase, high-crystallinity indium selenide wafers by creating an indium-rich liquid interface and maintaining a strict 1:1 stoichiometric ratio of indium to selenium. The as-obtained indium selenide films exhibit exceptional uniformity, a pure phase, and a high crystallinity across an entire ~5-centimeter wafer. Transistor arrays based on the produced indium selenide wafers demonstrate outstanding electronic performance surpassing that of all 2D film-based devices, including an extremely high mobility (averaging as high as 287 square centimeters per volt-second) and a near-Boltzmann-limit subthreshold swing (averaging as low as 67 millivolts per decade) at room temperature.

Gate-all-around (GAA) nanosheet field-effect transistors (FETs) with two-dimensional (2D) semiconductor channels surrounded by high-κ dielectrics show outstanding performance and hold promise for ultimate miniaturization in the post-Moore era. However, the synthesis of uniform wafer-scale 2D GAA nanosheet single crystals on industry-compatible substrates presents a considerable challenge. Herein, we report wafer-scale uniform growth of 2D high-κ oxide/semiconductor/high-κ oxide GAA single crystals on r-plane sapphire via buffered van der Waals (vdW) epitaxy. The 2D GAA heterostructures possess atomically flat interfaces, exhibiting superb uniformity and crystallinity across the wafer. Furthermore, the 2D GAA heterostructures can be transferred to diverse substrates owing to the vdW gap within the buffer oxide, leaving a reusable wafer. FETs based on 2D GAA heterostructures demonstrate exceptional performance with on/off ratio and optimal carrier mobility of > 10⁶ and 227 cm² V⁻¹ s⁻¹, respectively. The transferable wafer-scale 2D GAA heterostructures provide promising avenues for the fabrication of monolithic three-dimensional integrated circuits and extending Moore's law beyond the limitations of silicon.

The synthesis of multilayer van der Waals (vdW) film materials has attracted considerable interest in both fundamental and applied research. Recently, methods for synthesizing multilayer graphene films or graphite on single-crystal nickel foils are developed. However, the chemical vapor deposition (CVD) synthesis of thick-layer graphene films or graphite (TLG) on copper substrates remains a significant challenge due to the self-limiting growth phenomenon. In this study, a novel method to grow TLG on copper substrates by controlling the silicon additive is presented. The as-grown TLG exhibits high quality, with controllable thickness from a few layers to tens of nanometers. The growth of TLG films is achieved by the synchronous growth of multilayer graphene islands on a silicide copper surface, which is likely to be in a liquid state according to the Cu-Si phase diagram. On the Cu-Si surface, all graphene layers grow synchronously, circumventing the self-limiting mechanism and the antiwedding cake growth or wedding cake mode of van der Waals material growth. Based on this synchronous growth mode, the thickness of TLG can be precisely controlled, ranging from a few to tens of nanometers. The study provides a facile and scalable way to synthesize high-quality thick vdW films for various applications.

Monolayer hexagonal boron nitride (hBN) provides an atomically flat interface ideal for encapsulation and tunneling applications 1 . Beyond the monolayer limit, thick boron nitride (BN) emerges as a mechanically resilient dielectric, efficient thermal conductor, and epitaxial platform for high-power electronics, deep-UV optoelectronics, and quantum emitters 2–6 . However, wafer-scale synthesis of single-crystalline BN with controlled thickness remains a challenge. Here we present a solid–liquid interface-mediated epitaxy method that enables wafer-scale, thickness-tunable single-crystal rhombohedral BN (rBN) on atomically flat Ni(111). Introducing Si into Ni at the growth temperature forms a Ni–Si surface liquid layer that enhances B and N solubility and rBN thickness controllability, while underlying Ni(111) enforces epitaxial alignment of rBN. The resulting single-crystal rBN films can be transferred onto SiC to direct the epitaxy of AlN/GaN/AlGaN heterostructures for high-electron-mobility transistors (HEMTs). Compared with direct growth of GaN on SiC, thick rBN-buffered GaN shows ~91% lower screw dislocation density, ~93% reduced residual stress, and improved on-state current, on/off ratio, and reduced current collapse in HEMTs. This strategy establishes thick rBN as a universal platform for next-generation ultra-wide-bandgap electronics and quantum optoelectronics.

The behavior of vicinal Si(001) surfaces are a subject of intense research for years, yet the mechanism behind its step modulation remains unresolved. Step B, in particular, can meander randomly or form a periodic zigzag profile, a surface phenomenon that has eluded explanation due to the lack of appropriate simulation tools. Here, a multiscale simulation strategy, enhanced by machine learning potentials are proposed, to investigate this mesoscale behavior. The study reveals a phase transition in the step profile on vicinal Si(001) surfaces from random meandering to a zigzag wave pattern as the miscut angle decreases. This step-profile transition is corroborated by Monte Carlo simulations and experimental observations. Remarkably, this transition is robust across various surface conditions, including bare, hydrogen-saturated, boron-doped, or strained surfaces. The findings resolve the long-standing puzzle of step polymorphism on vicinal Si(001) surfaces and pave the way for exploring mesoscale phenomena using multiscale simulations.

A newly synthesized carbon allotrope, fully sp3-hybridized amorphous carbon (sp3-AC), has generated widespread research interest, especially in terms of structural stability and evolution. Here, the molecular simulations with machine learning force field to explore the origin of its stability and the structural transformation from sp3-AC to diamond is performed. It is found that the diffusion of carbon in the covalently bonded sp3-AC is extremely slow. Although the sp3-AC exhibits a higher energy than diamond, the nucleation of diamond within it remains thermodynamically unfavorable. The transformation from sp3-AC to diamond is impeded by an exceptionally high nucleation energy barrier of approximate to 17 eV, contributing to its kinetic stability. Analysis indicates that diamond nucleation within sp3-AC induces a localized density reduction, which may serve as the underlying mechanism that inhibits nucleation and suppresses continuous growth. As a result, annealing the sp3-AC at high temperature and high pressure leads to a specific type of composite, where randomly oriented diamond nanocrystals are evenly distributed in sp3-AC. The specific composite of sp3-AC-nanodiamond serves as an intermediate between sp3-AC and diamond, which reveals the underlying mechanism of recent experimental observation of sp3-AC-nanodiamond composite.

Innovations in device architectures and materials promote transistor miniaturization for improved performance, energy efficiency and integration density. At foreseeable ångström nodes, a gate-all-around (GAA) field-effect transistor based on two-dimensional (2D) semiconductors would provide excellent electrostatic gate controllability to achieve ultimate power scaling and performance delivering. However, a major roadblock lies in the scalable integration of 2D GAA heterostructures with atomically smooth and conformal interfaces. Here we report a wafer-scale multi-layer-stacked single-crystalline 2D GAA configuration achieved with low-temperature monolithic three-dimensional integration, in which high-mobility 2D semiconductor Bi2O2Se was epitaxially integrated by high-κ layered native-oxide dielectric Bi2SeO5 with an atomically smooth interface, enabling a high electron mobility of 280 cm2 V-1 s-1 and a near-ideal subthreshold swing of 62 mV dec-1. The scaled 2D GAA field-effect transistor with 30 nm gate length exhibits an ultralow operation voltage of 0.5 V, a high on-state current exceeding 1 mA μm-1, an ultralow intrinsic delay of 1.9 ps and an energy-delay product of 1.84 × 10-27 Js μm-1. This work demonstrates a wafer-scale 2D-material-based GAA system with valid performance and power merits, holding promising prospects for beyond-silicon monolithic three-dimensional circuits.

The synthesis of blue phosphorene (BLP), a two-dimensional (2D) allotrope of phosphorus, has attracted great attention in the last ten years. During the efforts of synthesizing BLP, three distinctive phases of phosphorus on the Ag(111) surface, phosphorus chains (PCs), phosphorus pentamers (PPs), and small BLP islands, have been observed while their formation mechanisms gained a deeper understanding based on previous studies. Here, by using the highly accurate machine learning force field (MLFF), we have successfully reproduced the three phases of phosphorus on the Ag(111) surface by molecular dynamic (MD) simulations. Our simulation shows that, on a Ag(111) surface, (i) PCs are more stable than both PPs and BLP at low coverage; (ii) with the increase of the coverage of phosphorus, the formation of PCs becomes less stable than the PPs at medium concentration; and (iii) further increasing the phosphorus coverage leads to the fusion of the pentamers, the nucleation of 2D BLP islands, and a transition from PPs to a BLP layer on the Ag(111) surface. The formation mechanisms revealed by the MLFF agree precisely with numerous experimental observations and thus show that the mechanisms revealed by theoretical studies empowered by the MLFF can be used to guide the experimental design of materials synthesis.

Structural superlubricity (SSL) is the wearless and nearly frictionless state of contact between solid surfaces, which are usually atomically smooth and subject to van der Waals forces or other non-bonding interactions. It provides a solution to friction and wear problems and offers unconventional design concepts for devices in a wide range of applications where energy efficiency and reliability are critical. Recent progress in device development using SSL can be found in sliding resonators, micro-/nanogenerators, sliding ferroelectrics, and mechanically reconfigurable devices. In this review the principles of SSL are discussed, followed by the design concepts of tiny sliding devices, which we introduce as “slidevices.” These slidevices can be integrated into multifunctional microsystems, where they can incorporate various functions and superlubric components.

Graphite has sparked extensive quantum physical discoveries and demonstrated numerous cutting-edge applications. However, existing graphite typically contains considerable impurities, and effective purification is still lacking. Here, a solid refining purification method is reported for obtaining ultrapure graphite. Through this design, impurities are filtered by the atomic lattice of a solid-state nickel (Ni). Suitable absorption, diffusion, and precipitation energy barriers are utilized in this method, allowing only carbon (C) atoms to effectively migrate through the Ni lattice to form high-quality graphite. The obtained ultrapure graphite shows the lowest elemental impurity density (<10 parts per million (ppm), which is one order of magnitude lower than that of the best available graphite), the highest structural purity (<0.2 parts per billion (ppb) of in-plane structural defect density and >99% Bernal stacking), and the highest doping purity (carrier doping density <2.0 × 1010 cm-2). Such superior purity of graphite facilitates the all-integer visible Landau levels and the ultralow quantum transition magnetic field in the fabricated graphene device. This solid refinement technique should inspire the purification of various layered crystals, leading to the discovery of new phenomena and the development of advanced applications.

2D transition metal tellurides (TMTs) possess fascinating properties for applications in ferroelectrics and optoelectronics. Nevertheless, it is still challenging to grow high-quality 2D TMTs with the desired phase (especially high-temperature phase) because of the weak bonding between the transition metal and Te as compared to S and Se atoms. Here, a strategy of siliconizing-driven layer-by-layer growth is reported to synthesize 2D ZrTe2 and ZrTe3 crystals with high crystallinity and desired thickness. Both as-synthesized crystals exhibit large-area uniform phases and atomically precise layered stacking structures. 2D ZrTe2 shows type-II Weyl semimetal characteristics with negative magnetoresistance, and 2D ZrTe3 demonstrates the existence of charge density waves and intrinsic superconductivity. Theoretical study reveals that silicon atoms can infiltrate and isolate a single layer of zirconium atoms and allow them to be tellurized in a layer-by-layer manner. The work paves the way for the synthesis of layer-controlled 2D TMTs and lays a material foundation for their physical property research.