期刊
NANO LETTERS
卷 20, 期 4, 页码 2279-2287出版社
AMER CHEMICAL SOC
DOI: 10.1021/acs.nanolett.9b04524
关键词
Graphene; nanomilling; edge engineering; subtractive manufacturing; in situ TEM
类别
资金
- National Natural Science Foundation of China [61471307]
- Fundamental Research Funds for the Central Universities
- National Program for Thousand Young Talents of China
- Double-First Class Foundation of Materials and Intelligent Manufacturing Discipline of Xiamen University
- Australian Research Council (ARC) [FL160100089]
- Center for Computational Science and Engineering of Southern University of Science and Technology, P. R. China
- Introduced Innovative R&D Team of Guangdong [2017ZT07C062]
- Australian Research Council [FL160100089] Funding Source: Australian Research Council
Full exploitation of graphene's superior properties requires the ability to precisely control its morphology and edge structures. We present such a structure-tailoring approach via controlled atom removal from graphene edges. With the use of a graphitic-carbon-capped tungsten nano-electrode as a noncontact milling tool in a transmission electron microscope, graphene edge atoms approached by the tool tip are locally evaporated, thus allowing a freestanding graphene sheet to be tailored with high precision and flexibility. A threshold for the tip voltage of 3.6 +/- 0.4 V, independent of polarity, is found to be the determining factor that triggers the controlled etching process. The dominant mechanisms involve weakening of carbon-carbon bonds through the interband excitation induced by tunneling electrons, assisted with a resistive-heating effect enhanced by high electric field, as elaborated by first-principles calculations. In addition to the precise shape and size control, this tip-based method enables fabrication of graphene edges with specific chiralities, such as armchair or zigzag types. The as-obtained edges can be further polished to become entirely atomically smooth via edge evaporation/reconstruction induced by in situ TEM Joule annealing. We finally demonstrate the potential of this technique for practical uses through creating a graphene-based point electron source, whose field emission characteristics can effectively be tuned via modifying its geometry.
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