©Science China Press
These are schematic diagrams for epitaxial growth of single-crystal graphene on industrial Cu foil.
"Preparation determines the future". Since the discovery of graphene, the synthesis of graphene has long been a hot spot in graphene community. Using transition metals such as Cu or Ni as substrate, scientists have realized the preparation of large-area graphene films. Especially, high-quality large-scale continuous monolayer graphene has been successfully grown on Cu foils. This simple and low-cost method has been widely accepted as the most promising way for industrial-level graphene production. However, graphene films obtained by this method are usually polycrystalline with domain boundaries, which would greatly degrade the electrical, mechanical, thermal and optical properties. Therefore, to find a method to synthesize large-size single-crystal graphene is a big scientific problem needed to be solved.
Prof. K. H. Liu, Prof. D. P. Yu and Prof. E. G. Wang from Peking University cooperating with Prof. F. Ding from Ulsan National Institute of Science and Technology and other collaborators found a new way to prepare 5×50 cm2 single-crystal graphene on industrial Cu foils. They first transformed industrial polycrystalline Cu foils into single-crystal Cu(111) by thermal annealing using a temperature-gradient-driving technique. Graphene domains were epitaxially grown on the Cu(111) substrate and then seamlessly merged together to form a large single-crystal graphene films. Combined with their ultrafast graphene growth technique, the graphene growth rate and each individual graphene domain size were improved obviously. Also, oxygen released from oxide at high temperature was proved to further improve the domain alignment, which would greatly improve the quality of graphene films.
This reported technique allows the synthesis of large-size single-crystal graphene films, which possess superior properties for various high-end applications, especially in electronics, such as large-scale fabrication of THz devices and the transparent film replacing ITO. It will also enable the epitaxial growth of various other 2D single-crystal materials on graphene with meter-sized dimension.
Xiaozhi Xu, Zhihong Zhang, Jichen Dong, Ding Yi, Jingjing Niu, Muhong Wu, Li Lin, Rongkang Yin, Mingqiang Li, Jingyuan Zhou, Shaoxin Wang, Junliang Sun, Xiaojie Duan, Peng Gao, Ying Jiang, Xiaosong Wu, Hailin Peng, Rodney S. Ruoff, Zhongfan Liu, Dapeng Yu, Enge Wang, Feng Ding, Kaihui Liu; "Ultrafast epitaxial growth of metre-sized single-crystal graphene on industrial Cu foil"; Science Bulletin; 2017
Xiaozhi Xu, Zhihong Zhang, Lu Qiu, Jianing Zhuang, Liang Zhang, Huan Wang, Chongnan Liao, Huading Song, Ruixi Qiao, Peng Gao, Zonghai Hu, Lei Liao, Zhimin Liao, Dapeng Yu, Enge Wang, Feng Ding, Hailin Peng & Kaihui Liu; "Ultrafast growth of single-crystal graphene assisted by a continuous oxygen supply"; Nature Nanotechnology; 2017