Highly-defective graphene as a metal-free catalyst for chemical vapor deposition growth of graphene glass

Direct synthesis of graphene on insulating substrates is highly desirable for practical applications. Herein, we present a new fabrication method for graphene on quartz which enables the direct growth of high-quality and large-scale graphene films with no metal involved. The growth rate of graphene on insulating substrates was typically extremely slow due to the low catalytic activity and the slow diffusion speed of carbon species on them. Thus, an extra catalyst is required. Instead of metal elements, such as Cu, Ni, and Ga, highly-defective graphene films were applied as the catalyst for methane decomposition. The key feature of our approach is that carbon itself was used as the catalyst for graphene fabrication, which completely avoided the contamination of other elements. As a result, the growth rate of graphene films increased significantly compared to the conventional CVD method. The excellent quality of graphene glass was verified by a series of experimental characterization and the fabrication of a transparent heating device without any transfer process. In addition, the energy barrier of the decomposition of methane was explored using the first principles calculation, which further confirmed the catalytic behavior of highly-defective graphene films.