Diamond was grown from a liquid Ga-Fe-Ni-Si alloy near 1 atm, although bulk graphite is thermodynamically more stable under those conditions. This Perspective asks what must be true for a diamond growth front to continue advancing in such a metastable regime. I define a finite-difference transfer free energy for a specified interfacial event and identify the completed attachment of one carbon atom at a kink as the repeatable event that governs sustained growth. In the macroscopic limit, surface terms cancel, and the required carbon activity is fixed by the bulk free energy of diamond. On a graphite-normalized scale, the diamond equilibrium threshold is about 2.0 at 1300 K, whereas graphite saturation occurs at unity. Diamond growth therefore requires kinetic selection above the graphite threshold, not a reversal of bulk phase stability. The analysis distinguishes thermodynamic driving force, kinetic accessibility, experimental detection limits, and the carbon retained after an experiment. It gives isotope-resolved tests for distinguishing sustained diamond growth from seed survival, transient carbon attachment, or failure to detect graphite. A ^13C-enriched diamond seed provides a test of natural-abundance gas or condensed carbon sources: a registered, crystallographically continuous ^12C-rich layer outside the original seed can establish source-attributed overgrowth without isotopically labeling each feed. The same accounting is extended to cubic boron nitride. Separate boron and nitrogen chemical potentials are required, and ^10B/^11B and ^15N contrasts could distinguish reservoir supply from seed loss for each element. The resulting criteria make low-pressure metal-flux growth claims quantitatively testable and guide experiments, thermodynamic modeling, and atomistic simulation.

Graphene has attracted broad interest due to its electrical, thermal, mechanical and chemical properties, showing great promise for applications such as lightweight aerospace structures, high-performance microelectronics and efficient thermal management systems. Chemical vapor deposition on metal substrates is currently the most viable route for scalable production of large-area and high-quality graphene films. However, the synthesis typically relies on costly single-crystal metal substrates, while further refinement is needed in both efficient growth and transfer techniques to achieve reproducible high-performance materials. To address these challenges, home-made single-crystal Cu/Ni alloy foils with tunable Ni concentrations can enhance catalytic activity, thereby providing an ideal platform for controllable graphene epitaxy. Here we detail a comprehensive protocol covering the fabrication of large-area single-crystal Cu foils, preparation of single-crystal Cu/Ni alloy foils, chemical vapor deposition growth of monolayer graphene and electrochemical transfer of graphene. The entire procedure requires ~32-38 h. This protocol is intended for researchers in materials science, surface chemistry, condensed matter physics and nanotechnology, and engineers seeking to obtain high-quality single-crystal metal foils and single-crystal monolayer graphene films. It provides a reproducible, scalable approach for their preparation and characterization, targeting fundamental research and potential applications in electronics and photonics.

Large single crystals of graphene and hexagonal boron nitride (hBN) remain difficult to manufacture because batch growth and transfer limit area, throughput, and quality. This Perspective asks whether an atomically thin film could instead be grown, hot-delaminated, and regrown repeatedly on a long, reusable single-crystal metal surface. No integrated process is demonstrated. Once rapid full-area growth is available, hot film removal is likely to become the rate-limiting step, whereas usable single-crystal growth area sets the material produced per cycle. Two experiments determine whether the concept merits further development: rapid, damage-free delamination at or near the growth temperature, and acceptable film growth through repeated complete growth-dwell-peel-regrowth cycles. The analysis then examines the crystalline growth surface, layer control, interface and gas chemistries, product capture, quality criteria, energy, and scale. These provisional analyses expose known requirements, define early stop criteria, and guide experiments; they cannot anticipate every coupled constraint or failure mode. Graphene is the quantitative baseline. hBN requires its own M(111), product thickness, apparatus, and scaling strategy. Pilot-scale development is justified only if the two central experiments succeed and the remaining gates can then be refined experimentally.

Carbon-13 (13C) isotopic labeling is a central experimental tool in carbon materials research, yet commercially available labeled carbon precursors are most often supplied at enrichment levels exceeding 99 at% 13C, at substantial cost. Here it is argued that, for a broad range of studies involving diamond, diamond-like carbon, graphite, graphene, carbon nanotubes, porous carbons, amorphous carbons, and mixed sp/sp2 carbon networks, such extreme isotopic purity is frequently unnecessary. Instead, enrichment in the range of approximately ∼20–50 at%—and in some cases even lower—often provides sufficient isotopic contrast to enable spectroscopic sensitivity, growth-mechanism discrimination, and carbon-source attribution. The analysis highlights why the scientific return of isotopic labeling saturates well below isotopic purity and why broader availability of partially enriched carbon feedstocks would benefit the carbon materials community.

The adsorption of boron and oxygen atoms onto mono- and multi-layer graphene leads to the formation of a buckled graphene layer (BO-graphane) and a 2D diamond-like structure (BO-diamane) sandwiched between boron monoxide layers per DFT calculations. BO-graphane has a calculated Young's modulus (E) of 750 GPa and BO-diamane 771 GPa, higher than the calculated E of -F, -OH, and -H diamanes; this is due to the presence of B-O bonds in the functionalizing layers. Electronic band structure calculations show BO-graphane and BO-diamane are wide band gap semiconductors with an indirect band gap up to a thickness of three layers (3L). Phonon dispersion and ab - initio molecular dynamics (AIMD) simulations confirm dynamic and thermal stability, maintaining structural integrity at 1000 K. The room-temperature lattice thermal conductivity of BOgraphane and BO-diamane is found to be 879 Wm-1K-1 and 1260 Wm-1K-1, respectively, surpassing BeO (385 Wm-1K-1), MgO (64 Wm-1K-1), and Al2O3 (36 Wm-1K-1); and F-diamane (377 Wm-1K-1), and comparable to H-diamane (1145-1960 Wm-1K-1), suggesting them as candidates for thermal management in applications.

Achieving precise structural control and functional integration in macroscopic multidimensional carbon heterostructures remains a significant challenge for advanced carbon research. Here, we report electrostatic layer-by-layer (LbL) assembly of cationic graphene-PEI nanosheets and anionic polyhydroxylated fullerene (PHF). Morphological and spectroscopic characterizations indicate that thermal annealing at 650 degrees C carbonizes the PEI linkers into a nitrogen-enriched amorphous carbon network and dehydroxylates the PHF molecules. This transformation leads to the formation of a continuous carbonaceous framework that integrates graphene sheets and fullerene domains. Prior to thermal annealing, photoluminescence (PL) measurements show integration of PHF, where a progressive increase in PL intensity with LbL deposition cycles, accompanied by film thickness evolution from similar to 33 nm at 10 cycles to similar to 1.47 mu m at 200 cycles, provides optical and structural evidence for the systematic stepwise buildup of the heterostructure. The 650 degrees C anneal changes the material from an electrical insulator to a conductor with the vertical electrical resistance lowered from 48.8 T Omega to 15.8 k Omega. This assembly and carbonization strategy provides a versatile platform for making functional carbon-rich hybrid architectures that can be used for advanced optical/electronic applications.

High-energy density materials are essential for the advancement of next-generation lithium-ion batteries, which power a wide range of applications from portable electronics to electric vehicles. Among them, high-Nickel (Ni) layered oxide cathodes have emerged as promising candidates due to their high capacity and cost-effectiveness. However, pores and excessive grain growth in high-Ni layered oxides compromise energy density and mechanical integrity, while oversized grains hinder lithium-ion diffusion kinetics, necessitating a sintering strategy that promotes densification without inducing abnormal grain growth. Here, a rapid Joule heating technique combined with two-step sintering is introduced that significantly improves the microstructural integrity of high-Ni cathodes. This approach enables fast densification while suppressing grain growth, resulting in cathodes with higher density, reduced porosity, and enhanced mechanical strength. Through in situ X-ray diffraction (XRD), small angle X-ray scattering (SAXS), and 3D ptychography analysis, it is found that the rapid Joule-heated cathodes exhibit mitigated phase separation, suppressed pore evolution, and improved resistance to crack propagation. They deliver superior cycling stability, coulombic efficiency, and rate performance. These results provide insights into the relationship between sintering dynamics and microstructural evolution, offering guidelines for synthesizing fully densified, high-energy density materials.

Graphite films with large grain sizes have been reportedly obtained by using metal as catalysts, but the obtained graphite is mostly heavily wrinkled, thus containing defects that degrade its properties. We report the synthesis of mirror-like and large-grained graphite films with only a few nano kinks and controllable dimensions, achieved by using flat Ni-Mo alloy melts of the same lateral dimensions as the metal foils used to make this alloy melt. The graphite film exhibited few nano kinks and a mirror-like appearance because the deliberate evaporation of much of the Ni produced a porous substrate, which in turn dramatically weakened the substrate-graphite film interaction before cooling. The mirror-like graphite appears to be 100% AB-stacked with millimeter-sized grains that are much larger than the multi-micron grain size of highly oriented pyrolytic graphite and rivaled in size only by a small percentage of natural graphite. Our graphite films have an electrical conductivity of 2.25 × 104 S cm-1 at 300 K. Tensile loading of macroscale samples showed an average Young's modulus of 969 ± 69 GPa and average fracture strength of 1.29 ± 0.203 GPa, and Frequency Domain Thermoreflectance revealed an average in-plane thermal conductivity of 2034.4 ± 68 W m-1·K-1.

ABSTRACTThe biodegradable polymer poly(lactic acid) (PLA) is brittle. PLA‐based composites reinforced by indium selenide (InSe) particles or flakes are prepared; each is found to have outstanding plasticity. InSe nanosheets are prepared by sonication of solid InSe in N‐methyl pyrrolidone, followed by washing/dispersion in ethanol, and subsequent drying. These InSe nanosheets, or in separate studies InSe particles, are mixed with PLA to make composite materials. The PLA composite materials are 3D‐printed into “dogbone” samples that are tensile‐loaded. The optimum dogbone specimen is 1.5 times stronger and 5.5 times tougher than neat PLA specimens prepared in the same way. To the best of our knowledge, this concurrent improvement in tensile strength and toughness has not been achieved before in PLA with any filler type. Finite element analysis, together with experimental analysis of (i) fracture surfaces, (ii) the PLA crystal structure, and (iii) the internal structure by micro‐CT scanning, suggests that the exceptional mechanical performance is due to the intrinsic properties of InSe and, particularly, the emergence of crack shielding and crack deflection at the interfaces of PLA and InSe flakes. These findings indicate that PLA–InSe composites may offer opportunities to broaden the applications of PLA composites, including as load‐bearing materials.

Separation and capture technology for small molecules is of great significance, including for the goal of adsorbing and separating CO2. Accurately controlling the pore size to achieve separation of molecules with similar sizes remains a challenging task in rigid porous materials, such as inorganic zeolites. We propose precise pore size engineering of "larger pore" faujasite (FAU) zeolite by depositing carbon atoms inside its framework. Low-dose electron microscopy with high spatial resolution is used to visualize the carbon deposition process and the corresponding evolution of pore size. Pore size changes as a function of carbon deposition time are also studied by gas adsorption using N2. The carbon-modulated FAU samples with optimized pore sizes exhibit excellent gas separation of CO2 relative to other small molecules. For a 50/50 H2/CO2 mixture, the separation factor was increased by 31% with a breakthrough time difference over 1200 s/g as compared to the neat FAU. We thus tailor the gas adsorption of FAU through partial filling of pores with deposited carbon and note that this can be generalized for the pore size engineering of many porous materials for use in industrial gas separation applications.

Electrochemical functionalization of graphene facilitates simple and various modifications of graphene properties. However, the scope of the available functional groups and the electrochemical behavior of graphene is not fully understood. The electrochemical reactivity of single crystal and monolayer graphene-on-Cu(111) with various phenyl and alkyl iodides is investigated, and discovered different onset potentials, identifying the extent of the reaction with Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). Differential pulse voltammetry (DPV) and density functional theory (DFT) calculations are employed to elucidate the onset potential differences between the phenyl iodides with different substituents. A comprehensive understanding of graphene's electrochemical reactivity is presented.

The clogging of zeolites with carbon-containing precursors is an industrial challenge in some applications but when the deposition of carbon is deliberate and ‘works well’, a source of carbon material with intriguing properties in others. Zeolite-templated carbons (ZTCs) are often compared to activated carbons due to their shared characteristics, such as high surface area, chemical composition, and thermal and chemical stability under various conditions. However, the key distinction lies in their controllable pore size, which makes ZTCs exceptionally interesting materials. Since the late 1990s, extensive research has been conducted on ZTCs, exploring different zeolite templates, carbon precursors, and synthesis parameters. Yet, despite significant progress, the field still faces unresolved questions, controversies, and aspects that have been overlooked. We report synthesis and characterization of three-dimensional porous carbon structures by using ion-exchanged faujasite zeolite as template. The progression of carbon networks from the initial to the final stages of growth inside zeolite channels was studied by transmission and scanning electron microscopy, gas adsorption, thermogravimetric analysis, X-ray diffraction, Raman spectroscopy, and solid state nuclear magnetic resonance. Atomic-resolution images obtained with integrated differential phase contrast scanning transmission electron microscopy (iDPC-STEM) were used to study both the zeolite and carbon structure inside the zeolite pores. Argon and CO2 adsorption isotherms show that the inner and the outer pore volumes (that we label V1 and V2) and surface areas (that we label S1 and S2) of the hollow carbon networks can be distinguished in the pore size distribution curves; to the best of our knowledge, this is the first time that these pore volumes and BET surface areas have been separately determined. For this porous carbon product, V1=0.14 cm3/g and S1=500 m2/g, and V2=0.99 cm3/g and S2=1640 m2/g. The iDPC-STEM and gas adsorption studies, as a function of time of exposure to acetylene during synthesis, provide new insights into the growth of zeolite-templated carbons and thus of carbons having both “inner” (enclosing V1 and generating S1) and “outer” (enclosing V2 and generating S2) volumes and surfaces after removal of the zeolite.

Partial hydrogenation of the open surface of graphene, epitaxially grown by chemical vapor deposition (CVD) on a Cu(111) substrate, leads to the formation of a crystalline sp3 hybridized carbon monolayer stabilized by interface C-Cu covalent bonding. This transition is reversible, with heating yielding almost complete restoration of the original graphene-copper structure. The graphene-Cu system is characterized by weak van der Waals interactions and this is the first transformation to yield C-Cu bonding. Through extensive spectroscopic characterization (Raman, X-ray photoelectron, X-ray absorption fine structure and valence-band photo-emission spectroscopies) and theoretical analysis based on density functional theory (DFT), we find transformation from weak van der Waals binding in the graphene-Cu system to covalent bonding between partially (topside) hydrogenated graphene and the Cu(111) surface, with the potential to revert back to its initial physisorbed state via dehydrogenation through heating. This reversible control over the graphene-Cu interaction opens new avenues for the design and manipulation of graphenebased devices. Furthermore, this sp3 hybridized carbon monolayer, with its C-metal substrate bonds, could potentially serve as a seed layer for the growth of large-area diamond films.

We report the scientific and technical queries regarding the article reported by Kim et al.1 on the mechanical properties of graphene-poly(methyl methacrylate) (PMMA) composites. Our analysis finds that the current experimental data is insufficient to fully support the conclusions presented in the article. We suggest the enhancement in Youngs modulus and strength of the graphene-PMMA laminates (GPL) samples are mainly due to the heat treatment of the polymer rather than the incorporation of graphene. The Raman spectroscopy data (as per our analysis) for the GPL samples indicates that large cracks and defects were introduced during the hot rolling process used to fabricate the graphene-PMMA composite. We believe that the queries will aid the audience in better understanding the mechanical response of graphene-PMMA composites.

ADVERTISEMENT RETURN TO ISSUEViewpointNEXTDelivering C, B, and N Atoms into Liquid Metals in Which They Are Normally InsolubleRodney S. Ruoff*Rodney S. RuoffCenter for Multidimensional Carbon Materials, Institute for Basic Science, Ulsan 44919, Republic of KoreaDepartment of Chemistry, Department of Materials Science, School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology, Ulsan 44919, Republic of Korea*Email: [email protected]; [email protected]More by Rodney S. Ruoffhttps://orcid.org/0000-0002-6599-6764Cite this: Nano Lett. 2024, 24, 5, 1467–1470Publication Date (Web):January 26, 2024Publication History Received13 December 2023Published online26 January 2024Published inissue 7 February 2024https://pubs.acs.org/doi/10.1021/acs.nanolett.3c04918https://doi.org/10.1021/acs.nanolett.3c04918article-commentaryACS PublicationsCopyright © 2024 American Chemical Society. This publication is available under these Terms of Use. Request reuse permissions This publication is free to access through this site. Learn MoreArticle Views3265Altmetric-Citations-LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail PDF (2 MB) Get e-AlertscloseSUBJECTS:Carbon,Liquid metals,Liquids,Metals,Solubility Get e-Alerts

We report the surface modification of nanochannels whose channels are formed from stacked and overlapping graphene oxide sheets, in which the high density of nitrogen/oxygen groups and networks of H bonds serve as excellent proton channels but block the transport of cations such as Li+ and Na+. The membrane has excellent stability when immersed for long periods under water and has an NaCl rejection rate of approximately 99% while maintaining permeability to water and performs well for at least 400 h for desalination. Our straightforward approach to achieving this type of two-dimensional channel material for selective ion conduction, efficient ion separation, and water desalination might open a host of possible new uses.

Despite extensive microscale studies, the macroscopic mechanical properties of monolayer graphene remain underexplored. Here, we report the Young’s modulus (E = 1.11 ± 0.04 TPa), tensile strength (σ = 27.40 ± 4.36 GPa), and failure strain (εf = 6.01 ± 0.92 %) of centimeter-scale single-crystal monolayer graphene (SCG) ‘dog bone’ samples with edges aligned along the zigzag (zz) direction, supported by an ultra-thin polymer (polycarbonate) film. For samples with edges along the armchair (ac) direction, we obtain E = 1.01 ± 0.10 TPa, σ = 20.21 ± 3.22 GPa, εf = 3.69 ± 0.38 %, and for chiral samples whose edges were between zz and ac, we obtain E= 0.75 ± 0.12 TPa, σ = 23.56 ± 3.42 GPa, and εf = 4.53 ± 0.40 %. The SCG is grown on single crystal Cu(111) foils by chemical vapor deposition (CVD). We used a home-built ‘float-on-water’ (FOW) tensile testing system for tensile loading measurements that also enabled in situ crack observation. The quantized fracture mechanics (QFM) analysis predicts an edge defect size from several to tens of nanometers based on chirality and notch angle. Through Weibull analysis and given that the fatal defects are confined on the edges of macroscale samples, we projected strength ranging from 13.67 to 18.43 GPa for an A4-size SCG according to their chirality. Our findings demonstrate exceptional mechanical performance of macroscale single crystal graphene (SCG) and pave the way for its widespread use in a very wide variety of applications.

Single-crystal Cu(111) foil promotes the lateral growth of lithium rhombic dodecahedra, preventing dendritic lithium growth during plating. This is achieved through surface migration and the interaction of lithium adatoms with individual grains.

Natural diamonds were (and are) formed (thousands of million years ago) in the upper mantle of Earth in metallic melts at temperatures of 900-1,400 degrees C and at pressures of 5-6GPa (refs.(1,2)). Diamond is thermodynamically stable under high-pressure and high-temperature conditions as per the phase diagram of carbon(3). Scientists at General Electric invented and used a high-pressure and high-temperature apparatus in 1955 to synthesize diamonds by using molten iron sulfide at about 7GPa and 1,600 degrees C (refs.(4-6)). There is an existing model that diamond can be grown using liquid metals only at both high pressure and high temperature(7). Here we describe the growth of diamond crystals and polycrystalline diamond films with no seed particles using liquid metal but at 1atm pressure and at 1,025 degrees C, breaking this pattern. Diamond grew in the subsurface of liquid metal composed of gallium, iron, nickel and silicon, by catalytic activation of methane and diffusion of carbon atoms into and within the subsurface regions. We found that the supersaturation of carbon in the liquid metal subsurface leads to the nucleation and growth of diamonds, with Si playing an important part in stabilizing tetravalently bonded carbon clusters that play a part in nucleation. Growth of (metastable) diamond in liquid metal at moderate temperature and 1atm pressure opens many possibilities for further basic science studies and for the scaling of this type of growth.