A foundation of the modern technology that uses single-crystal silicon has been the growth of high-quality single-crystal Si ingots with diameters up to 12 inches or larger. For many applications of graphene, large-area high-quality (ideally of single-crystal) material will be enabling. Since the first growth on copper foil a decade ago, inch-sized single-crystal graphene has been achieved. We present here the growth, in 20 minutes, of a graphene film of 5 50 cm 2 dimension with > 99% ultra-highly oriented grains. This growth was achieved by: (i) synthesis of sub-metre-sized single-crystal Cu (111) foil as substrate; (ii) epitaxial growth of graphene islands on the Cu(111) surface; (iii) seamless merging of such graphene islands into a graphene film with high single crystallinity and (iv) the ultrafast growth of graphene film. These achievements were realized by a temperature-driven annealing technique to produce single-crystal Cu(111) from industrial polycrystalline Cu foil and the marvellous effects of a continuous oxygen supply from an adjacent oxide. The as-synthesized graphene film, with very few misoriented grains (if any), has a mobility up to ~ 23,000 cm 2 V -1 s -1 at 4 K and room temperature sheet resistance of ~ 230 □ ⁄ . It is very likely that this approach can be scaled up to achieve exceptionally large and highquality graphene films with single crystallinity, and thus realize various industrial-level applications at a low cost.

A trilayer single-crystalline GDY film on graphene was prepared through a solution-phase van der Waals epitaxial strategy.

Metal corrosion is a long-lasting problem in history and ultrahigh anticorrosion is one ultimate pursuit in the metal-related industry. Graphene, in principle, can be a revolutionary material for anticorrosion due to its excellent impermeability to any molecule or ion (except for protons). However, in real applications, it is found that the metallic graphene forms an electrochemical circuit with the protected metals to accelerate the corrosion once the corrosive fluids leaks into the interface. Therefore, whether graphene can be used as an excellent anticorrosion material is under intense debate now. Here, graphene-coated Cu is employed to investigate the facet-dependent anticorrosion of metals. It is demonstrated that as-grown graphene can protect Cu(111) surface from oxidation in humid air lasting for more than 2.5 years, in sharp contrast with the accelerated oxidation of graphene-coated Cu(100) surface. Further atomic-scale characterization and ab initio calculations reveal that the strong interfacial coupling of the commensurate graphene/Cu(111) prevents H O diffusion into the graphene/Cu(111) interface, but the one-dimensional wrinkles formed in the incommensurate graphene on Cu(100) can facilitate the H O diffusion at the interface. This study resolves the contradiction on the anticorrosion capacity of graphene and opens a new opportunity for ultrahigh metal anticorrosion through commensurate graphene coating.

Cation-deficient two-dimensional (2D) materials, especially atomically thin nanosheets, are highly promising electrode materials for electrochemical energy storage that undergo metal ion insertion reactions, yet they have rarely been achieved thus far. Here, we report a Tideficient 2D unilamellar lepidocrocite-type titanium oxide (Ti 0.87 O 2 ) nanosheet superlattice for sodium storage. The superlattice composed of alternately restacked defective Ti 0.87 O 2 and nitrogen-doped graphene monolayers exhibits an outstanding capacity of ∼490 mA h g −1 at 0.1 A g −1 , an ultralong cycle life of more than 10000 cycles with ∼0.00058% capacity decay per cycle, and especially superior low-temperature performance (100 mA h g −1 at 12.8 A g −1 and −5 °C), presenting the best reported performance to date. A reversible Na + ion intercalation mechanism without phase and structural change is verified by first-principles calculations and kinetics analysis. These results herald a promising strategy to utilize defective 2D materials for advanced energy storage applications.