▎ 摘　　要

A novel "two-step annealing" method is proposed for the direct synthesis of graphene sheets on high-density dielectric silica nanowires without using metal catalysts. During the first annealing at 1000 degrees C, the extremely thin SiO2 layer on Si substrate shrinks and forms dense nanoparticles. Using these silica nanoparticles as templates, graphene sheets and silica nanowires are synthesized simultaneously after the second annealing process at 800-850 degrees C. The experiment results suggest that the graphene sheets grow along the nanowires and its crystalline quality and domain size are determined by the temperature and duration of the second annealing process. (C) 2015 Elsevier B.V. All rights reserved.