Luzhao Sun

The deterministic synthesis of wafer‐scale two‐dimensional (2D) materials with programmable layer number, crystallographic orientation, and stacking order is essential for unlocking their layer‐dependent quantum properties and enabling scalable device integration. Here, we demonstrate a synchronous and unidirectional epitaxy strategy for chemical vapor deposition growth of layer‐controlled graphene on atomically flat oxidized single‐crystal Cu wafers. Using a Cu(111)–Cu ₂ O(111) heterogeneous catalytic substrate, we achieved 2‐inch single‐crystalline graphene films with precisely tunable layer numbers (2 to 5). By engineering the atomic steps of high‐index Cu surfaces, we created deterministic spatial patterning of alternating Bernal and rhombohedral stacking in trilayer graphene, as confirmed by near‐field nano‐optics and angle‐resolved photoemission spectroscopy. The resulting wafer‐scale films exhibit exceptional thickness uniformity, high crystallinity, and an ultra‐flat surface. This work provides a unified growth framework that concurrently resolves the intertwined challenges of layer control, wafer‐scale single crystallinity, and stacking order modulation, laying a material foundation for advanced device studies and potential applications.

Theoretically, defect-free monolayer graphene grown by chemical vapor deposition can block nearly all gases and moisture, making it a promising material for large-scale flexible encapsulation in future photonic and electronic applications. However, the lack of reliable transfer and fabrication methods that suppress the formation of transfer-induced cracks and interlayer transport of water molecules in stacked graphene films severely limits the barrier performance of current graphene-based barrier films. In this work, we employed a dopant-incorporated polyvinylidene difluoride with a concentration gradient as a transfer medium to suppress crack formation during transfer through conformal graphene–polymer contact and to dope graphene, thereby hindering water diffusion through enhanced water–graphene interactions. Consequently, the as-fabricated barrier film achieved an ultralow water vapor transmission rate value of 9.3 × 10–5 g m–2 day–1. In addition, a home-built roll-to-roll transfer system for continuous fabrication of graphene barrier films demonstrates the scalability of this strategy and its potential for large-scale flexible and transparent encapsulation.

Achieving thin ice with optimal thickness is a prerequisite for successful cryo-EM analysis of embedded macromolecules. Despite decades of effort, precise control of ice thickness in cryo-EM remains a major challenge. Here we reveal that the intrinsic instability of sub-100-nm liquid film, a previously overlooked determinant before vitrification, plays a critical role in controlling ice thickness. We found that well-designed graphene reservoirs can confine liquid film to an optimal thickness and overcome the limitations posed by liquid film instability, achieving precise control of ice thickness with robust reproducibility and large-area uniformity. These graphene reservoirs demonstrate superior liquid retention capabilities than conventional techniques, enabling tunable ice thickness through reservoir depth modulation. Moreover, this approach yields uniform confined ice in graphene sandwiches with controllable thickness and high efficiency, facilitating cryo-EM imaging of a broad range of macromolecule particles with high contrast, reduced motion and improved orientations for more robust high-resolution reconstruction.

Aqueous Zn metal batteries are promising candidates for large‐scale energy storage, yet their practical deployment is hindered by poor Zn reversibility. Although crystallographic engineering can improve Zn electrochemistry, the precise fabrication of single‐crystal Zn electrodes with full‐dimensional crystallographic coherence remains elusive. Here we report a remote electro‐epitaxy (REE) strategy to render high‐quality single‐crystal Zn electrodes. Using monolayer graphene‐skinned Cu(111) substrate as the epitaxial current collector, REE manages to preserve perfect crystallographic inheritance through substrate‐potential transmission and accommodate lattice mismatch via interfacial strain relaxation, which is evidenced by theoretical and instrumental characterizations. As a result, the Zn(002) deposits with uniform out‐of‐plane crystallographic orientation, in‐plane crystallographic coherence, and through‐thickness crystallographic continuity are achieved on both centimeter‐scale foils and 4‐inch wafer substrates. The resulting electrodes warrant reversible Zn plating/stripping behavior, enhanced stability under elevated depth‐of‐discharge conditions, and successful implementation in Ah‐scale pouch cells competing the state‐of‐the‐art. Beyond Zn, our strategy is extendable to a multitude of metals, offering a scalable pathway toward single‐crystal electrode fabrication for emerging energy storage.

The scalable synthesis of high-quality graphite materials remains a formidable challenge due to the inherent trade-off between crystalline perfection and manufacturing efficiency. Existing forms of graphite, such as highly oriented pyrolytic graphite (HOPG) and Kish graphite, suffer from sluggish pyrolytic processes, limited carbon diffusion rates and energy-intensive protocols, often requiring several days for production. Here, we report a pulsed Joule heating-induced carburization (PJHIC) strategy that exploits transient non-equilibrium states to enable rapid carbon diffusion and segregation in metal substrates. By applying instantaneous thermal shocks ( > 1300 °C, > 300 °C/s heating rate) to solid carbon precursor-coated nickel and cobalt foils, we demonstrate the rapid carbon transport in bulk metals and achieve a vertical graphite growth rate of 730 nm/min, which is an order of magnitude faster than conventional methods. Cyclic temperature pulses further enable the synthesis of 1–5 μm-thick ABA-stacked graphite films with millimeter-scale grain sizes. The resulting rapid epitaxially grown graphite films exhibit a highly ordered crystalline structure and exceptional thermal conductivity (1314 W m ^–1 K ^–1 ), comparable to high-quality HOPG and Kish graphite. This work establishes a non-equilibrium synthesis paradigm for high-quality layered materials, bridging atomic-scale precision with industrial-scale manufacturing.

The advent of 2D materials has revolutionized condensed matter physics and materials science, offering unprecedented opportunities to explore exotic physical phenomena, engineer novel functionalities, and address critical technological challenges across diverse fields. Over the past two decades, the exploration of 2D materials has expanded beyond graphene, encompassing a vast library of atomically thin crystals and their heterostructures. These materials exhibit extraordinary electronic, optical, thermal, mechanical, and chemical properties, and hold promise for breakthroughs in electronics, optoelectronics, quantum technologies, energy storage, catalysis, thermal management, filtration and separation, and beyond. Many exciting new physics and phenomena continue to emerge, while select 2D materials, such as graphene, h-BN, and the semiconducting transition metal dichalcogenides (TMDCs), are transitioning from laboratory-scale demonstrations to industrial applications. In this context, a holistic understanding of synthesis, structure-property relationships, integration, and performance optimization is essential. This roadmap reviews the multifaceted challenges and opportunities in 2D materials research, focusing on the synthesis, properties and applications of representative systems including graphene and its derivatives, TMDCs, MXenes as well as their heterostructures and moiré systems.

An ideal proton exchange membrane should only allow protons to pass and remain impermeable to fuels, as required in fuel cell applications. In methanol fuel cells, high proton conductivity enables high power density, whereas methanol crossover between the electrodes degrades the catalyst activity and lowers efficiency. In conventional polymer membranes, however, conductivity and selectivity are often antagonistic: long transport pathways are needed to achieve selectivity, but these introduce additional ionic resistance. Graphene, a two-dimensional material consisting of a single atomic layer of carbon, intrinsically addresses both requirements. Its basal plane is impermeable to water and other molecules, while still exhibiting a measurable degree of proton conductivity. Here, we show that chemical functionalization of monolayer graphene with sulfophenyl groups significantly enhances its proton transport properties. The conductance increases from 6.9 ± 1.1 to 30.9 ± 2.3 S·cm^-2, while the energy barrier for proton transport is reduced to 6.9 kJ·mol^-1. These findings propose functionalized graphene as an alternative to polymer membranes for electrochemical energy devices.

Proton selectivity of monolayer graphene offers promising opportunities in energy devices. The impermeability of graphene to methanol, on the other hand, offers potential as a membrane in direct methanol fuel cells (DMFCs). The integration of graphene in DMFCs requires samples larger than 1 cm² and therefore must be grown via chemical vapor deposition (CVD) instead of using exfoliation. CVD graphene─as opposed to exfoliated flakes─however, contains inherent defects and multilayer patches, both of which could be harnessed to tune the fuel cell performance controllably. Here, we investigated the impact of multilayer patches on the performance of centimeter-scale graphene films in DMFCs. While single-crystalline graphene (SCG) has no multilayer patches, polycrystalline graphene (PCG) can exhibit an areal ratio of multilayer patches up to ∼4%. While multilayer patches are less reactive to plasma etching, the monolayers within SCG and PCG exhibit similar reactivity, enabling precise control over the etching process. These shaded areas of the membrane contribute to higher proton selectivity, likely due to more constrained and controlled defect sites. Our findings indicate that plasma-induced defects yield a proton conductance 10% higher than pristine graphene, and we attribute the enhanced performance of defected PCG to the shading effects provided by the multilayer patches.

Multilayer graphene films demonstrate superior electrical and thermal conductivity, mechanical properties, and barrier performance compared to monolayer, thereby exhibiting greater potential for industrial applications. However, the synthesis of multi-layer graphene films continues to face critical challenges, primarily including uncontrollable layer numbers, incomplete under-standing of growth mechanisms, and poor reproducibility and scalability in mass production. This study introduces the "fractional layer" concept and corresponding mathematical model to precisely quantify graphene layers for the first time. Using this metric, we systematically establish growth principles and process windows for layer-controlled graphene synthesis on copper substrates, and elucidate the multilayer growth mechanism governed by modulating the lateral growth and vertical growth kinetics. Based on this theoretical framework, the continuous preparation of 2.3-layer graphene films was achieved via an industrial scale roll-to-roll chemical vapor deposition equipment, exhibiting exceptional macroscopic uniformity and demonstrating significant potential for applications in transparent, flexible electrothermal heaters. Our work will establish a solid material foundation for the industrial application of multilayer graphene films and offer novel insights into the layer-controlled synthesis of other two-dimensional materials.

Scalable synthesis of high-quality graphene via roll-to-roll chemical vapor deposition faces a fundamental conflict between rapid growth and crystallographic perfection. Conventional methane (CH₄)-derived growth suffers from disordered nucleation and orientation mismatch at elevated precursor pressures, limiting industrial adoption. This work resolves this challenge by employing acetylene (C₂H₂) as a carbon precursor to enable carbon dimer-mediated cyclotrimerization nucleation. First-principles calculations reveal that C₂H₂-derived carbon dimers (C₂) spontaneously assemble into hexagonal nuclei, bypassing defect-prone chain-to-ring transitions inherent to monatomic carbon pathway of CH₄. This mechanism ensures >98% lattice orientation consistency even at nucleation densities of 10⁴ mm⁻², in stark contrast to CH₄-derived graphene. Crucially, the enhanced surface adsorption of C₂ species enables continuous nucleation during lateral growth, achieving high growth rate of 500 mm/min at roll-to-roll process. Leveraging dimeric carbon precursors and Cu single-crystallization technique, we demonstrate roll-to-roll production of graphene films with high crystallographic orientation across meter-scale Cu(111) foils. This precursor-specific strategy decouples nucleation density from disorder accumulation, establishing a scalable pathway for industrial graphene manufacturing.