Bilayer graphene provides a versatile platform for exploring a variety of intriguing phenomena and shows much promise for applications in electronics, optoelectronics, etc. Controlled growth of large-area bilayer graphene is therefore highly desired yet still suffers from a slow growth rate and poor layer uniformity. Meanwhile, graphene wrinkles, including folds and ripples, form during cooling due to the thermal contraction mismatch between graphene and the metal substrates, and have been far from suppressed or eliminated, especially in bilayer graphene, which would greatly degrade the extraordinary properties of graphene. Here we report the ultrafast growth of wafer-scale fold-free bilayer graphene by chemical vapor deposition. Through well-tuning the alloy thickness and strain regulation of the single-crystal CuNi(111)/sapphire, the full coverage of a 2-inch fold-free bilayer graphene wafer via mainly isothermal segregation has been achieved as fast as 30 s. The tensile-strained CuNi(111) film reduces the thermal contraction mismatch and suppresses the formation of graphene folds during cooling, which is directly observed through in situ optical microscopy. The ultraflat bilayer graphene exhibits wafer-scale uniformity in electrical performance and enhanced mechanical property comparable to the exfoliated ones. Our results offer a promising route for large-scale production of bilayer graphene and enable its various applications.

Chemical vapor deposition (CVD)-grown graphene films on Cu foils, exhibiting fine scalability and high quality, are still suffering from the adverse impact of surface contamination, i.e., amorphous carbon. Despite the recent successful preparation of superclean graphene through Cu-vapor-assisted reactions, the formation mechanism of amorphous carbon remains unclear, especially with regard to the functions of substrates. Herein, we have found that the crystallographic orientations of underlying metal substrates would determine the cleanness of graphene in such a way that slower diffusion of active carbon species on as-formed graphene-Cu(100) surface is the key factor that suppresses the formation of contamination. The facile synthesis of clean graphene is achieved on the meter-sized Cu(100) that is transformed from the polycrystalline Cu foils. Furthermore, a clean surface of graphene on Cu(100) ensures the reduction of transfer-related polymer residues, and enhanced optical and electrical performance, which allows for versatile applications of graphene in biosensors, functioning as flexible transparent electrodes. This work would offer a promising material platform for the fundamental investigation and create new opportunities for the advanced applications of high-quality graphene films.

Although single-particle cryogenic electron microscopy (cryo-EM) has been applied extensively for elucidating many crucial biological mechanisms at the molecular level, this technique still faces critical challenges, the major one of which is to prepare the high-quality cryo-EM specimen. Aiming to achieve a more reproducible and efficient cryo-EM specimen preparation, novel supporting films including graphene-based two-dimensional materials have been explored in recent years. Here we report a robust and simple method to fabricate EM grids coated with single- or few-layer reduced graphene oxide (RGO) membrane in large batch for high-resolution cryo-EM structural determination. The RGO membrane has decreased interlayer space and enhanced electrical conductivity in comparison to regular graphene oxide (GO) membrane. Moreover, we found that the RGO supporting film exhibited nice particle-absorption ability, thus avoiding the air–water interface problem. More importantly, we found that the RGO supporting film is particularly useful in cryo-EM reconstruction of sub-100-kDa biomolecules at near-atomic resolution, as exemplified by the study of RBD-ACE2 complex and other small protein molecules. We envision that the RGO membranes can be used as a robust graphene-based supporting film in cryo-EM specimen preparation.

Rechargeable sodium-ion batteries (SIBs) are promising candidates for large-scale energy storage owing to their excellent high-power performance. However, Al-based current collectorsat both anodes and cathodes of SIBs, which widely influence the power properties of a variety of electrodes in SIBs, have rarely been investigated. Here, we demonstrate that vertical graphene nanosheets grown on commercial Al foil by the plasma-enhanced chemical vapor deposition (PECVD) method, form a robust connection with the carbon-based conductive network of the electrode, thereby significantly reducing the electrode-current collector interfacial resistance. For sodium vanadium phosphate (NVP) anodes with vertical graphenenanosheetmodified Al foil (G-Al) current collectors, the interfacial resistance between the electrode and current collector is reduced 20-fold compared with that in the case of Al foil. The G-Al current collector reduces the polarization and improves the rate capability compared with that of Al current collectors within both cathodes and anodes of SIBs. At a high rate of 5 C, the capacity retention of NVP cathode with G-Al current collector is 74%, which is much higher than that with Al foil (22%).We believe that the obtained results support the prospect for the widespread use of G-Al current collectors in the further improvement of high-power profiles of SIBs.

In the chemical vapor deposition growth of large-area graphene polycrystalline thin films, the coalescence of randomly oriented graphene domains results in a high density of uncertain grain boundaries (GBs). The structures and properties of various GBs are highly dependent on the misorientation angles between the graphene domains, which can significantly affect the performance of the graphene films and impede their industrial applications. Graphene bicrystals with a specific type of GB can be synthesized via the controllable growth of graphene domains with a predefined lattice orientation. Although the bicrystal has been widely investigated for traditional bulk materials, no successful synthesis strategy has been presented for growing two-dimensional graphene bicrystals. In this study, we demonstrate a simple approach for growing well-aligned large-domain graphene bicrystals with a confined tilt angle of 30° on a facilely recrystallized single-crystal Cu (100) substrate. Control of the density of the GBs with a misorientation angle of 30° was realized via the controllable rapid growth of sub- centimeter graphene domains with the assistance of a cooperative catalytic surface-passivation treatment. The large-area production of graphene bicrystals consisting of the sole specific GBs with a tunable density provides a new material platform for fundamental studies and practical applications.

The fast growth of large single-crystalline graphene by chemical vapor deposition on Cu foil remains a challenge for industrial-scale applications. To achieve the fast growth of large single-crystalline graphene, understanding the detailed dynamics governing the entire growth process—including nucleation, growth, and coalescence—is important; however, these remain unexplored. In this study, by using a pulsed carbon isotope labeling technique in conjunction with micro-Raman spectroscopy identification, we visualized the growth dynamics, such as nucleation, growth, and coalescence, during the fast growth of large single- crystalline graphene domains. By tuning the supply of the carbon source, a growth rate of 320 μm/min and the growth of centimeter-sized graphene single crystals were achieved on Cu foil.

New types of antimicrobial systems are urgently needed owing to the emergence of pathogenic microbial strains that gain resistance to antibiotics commonly used in daily life and medical care. In this study, we developed for the first time a broad-spectrum and robust antimicrobial thin film coating based on large-area chemical vapor deposition (CVD)-grown graphene-wrapped silver nanowires (AgNWs). The antimicrobial graphene/AgNW hybrid coating can be applied on commercial flexible transparent ethylene vinyl acetate/ polyethylene terephthalate (EVA/PET) plastic films by a full roll-to-roll process. The graphene/AgNW hybrid coating showed broad-spectrum antimicrobial activity against Gram-negative (Escherichia coli) and Gram-positive bacteria (Staphylococcus aureus), and fungi (Candida albicans). This effect was attributed to a weaker microbial attachment to the ultra-smooth graphene film and the sterilization capacity of Ag+, which is sustainably released from the AgNWs and presumably enhanced by the electrochemical corrosion of AgNWs. Moreover, the robust antimicrobial activity of the graphene/AgNW coating was reinforced by AgNW encapsulation by graphene. Furthermore, the antimicrobial efficiency could be enhanced to ~100% by water electrolysis by using the conductive graphene/AgNW coating as a cathode. We developed a transparent and flexible antimicrobial cover made of graphene/AgNW/EVA/PET and an antimicrobial denture coated by graphene/ AgNW, to show the potential applications of the antimicrobial materials.

Two-dimensional layered IV–VI chalcogenides are attracting great interest for applications in next-generation optoelectronic, photovoltaic, and thermoelectric devices. However, great challenges in the controllable synthesis of high-quality IV–VI chalcogenide nanostructures have hindered their in-depth studies and practical applications to date. Here we report, for the first time, a feasible synthesis of single-crystal IV–VI SnSe nanoplates in a controlled manner on mica substrates by vapor transport deposition. The as-grown SnSe nanoplates have approximately square shapes with controllable side lengths varying from 1 to 6 μm. Electrical transport and optoelectronic measurements show that as-obtained SnSe nanoplates display p-type conductivity and high photoresponsivity.