Chemical vapor deposition (CVD) is the most promising method for the preparation of high-quality and large-area graphene films, especially the epitaxial growth of graphene on large-area single-crystal Cu foils. While single-crystal Cu foils are normally achieved by thermally annealing the commercial polycrystalline Cu foils, their size and therefore the size of graphene films grown on them are limited to the size of the reaction chamber. We report a simple and feasible method to prepare large-area Cu foils with decimeter grains by thermally annealing the rolled-up Cu foils, where the Cu layers are separated by thin porous carbon fiber cloths. The carbon fiber cloths prevent Cu layers from sticking to each other at high temperatures while do not block the gas transportation. In such a way, the utilization efficiency of the reaction chamber is significantly improved, e.g., 0.2 m × (1–2) m Cu foils can be processed even in a 5 cm diameter quartz tube chamber. High-quality graphene films grown on such Cu foils are then demonstrated. This method may be suitable for the annealing of other metal foils to enlarge grain size and the synthesis of other two-dimensional materials on them such as h-BN.

Homogeneity is important to material applications for good performance of individual devices, for making AB-stacked bilayer graphene in a layer-by-layer stacking order, and from the point of view of industrial production. Among many properties to be controlled, for the case of graphene, the thickness (or layer number) uniformity is the prerequisite. Chemical vapor deposition (CVD) of C precursors on Cu substrates is the most popular method to produce large-area graphene films. To date, precise control on the number of graphene layers as well as the uniformity over a large area is still very challenging. In this work, with a further understanding of the factors affecting adlayer growth, the synthesis of large-area adlayer-free monolayer graphene (MLG) films was achieved up to tens of squared centimeters in area by just using untreated Cu foil and a normal CVD process. We found that keeping equal C precursor concentration on the two sides of the Cu substrate is a criterion in addition to other factors such as the ratio of H: C and the substrate surface morphology for the growth of adlayer-free MLG. This finding is not only of great significance for the industrial production of large-area adlayer-free MLG films but also instructive for the synthesis of homogeneous few-layer graphene.