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How Low Nucleation Density of Graphene on CuNi Alloy is Achieved
Advanced Science ( IF 15.1 ) Pub Date : 2018-03-12 , DOI: 10.1002/advs.201700961
Yifan Liu 1 , Tianru Wu 2 , Yuling Yin 1 , Xuefu Zhang 2 , Qingkai Yu 3 , Debra J. Searles 4 , Feng Ding 5, 6 , Qinghong Yuan 1, 4, 5 , Xiaoming Xie 2
Affiliation  

CuNi alloy foils are demonstrated to be one of the best substrates for synthesizing large area single‐crystalline graphene because a very fast growth rate and low nucleation density can be simultaneously achieved. The fast growth rate is understood to be due the abundance of carbon precursor supply, as a result of the high catalytic activity of Ni atoms. However, a theoretical understanding of the low nucleation density remains controversial because it is known that a high carbon precursor concentration on the surface normally leads to a high nucleation density. Here, the graphene nucleation on the CuNi alloy surfaces is systematically explored and it is revealed that: i) carbon atom dissolution into the CuNi alloy passivates the alloy surface, thereby drastically increasing the graphene nucleation barrier; ii) carbon atom diffusion on the CuNi alloy surface is greatly suppressed by the inhomogeneous atomic structure of the surface; and iii) a prominent increase in the rate of carbon diffusion into the bulk occurs when the Ni composition is higher than the percolation threshold. This study reveals the key mechanism for graphene nucleation on CuNi alloy surfaces and provides a guideline for the catalyst design for the synthesis of graphene and other 2D materials.

中文翻译:

如何在CuNi合金上实现石墨烯的低成核密度

事实证明,CuNi合金箔是合成大面积单晶石墨烯的最佳基材之一,因为它可以同时实现非常快的生长速率和低成核密度。可以理解,由于Ni原子的高催化活性,快速的生长速率是由于碳前驱体供应丰富。但是,关于低成核密度的理论理解仍存在争议,因为已知表面上的高碳前体浓度通常会导致高成核密度。在此,系统地研究了CuNi合金表面上的石墨烯成核,结果表明:i)碳原子溶解到CuNi合金中使钝化合金表面,从而大大增加了石墨烯成核壁垒;ii)表面的不均匀原子结构极大地抑制了碳原子在CuNi合金表面的扩散;iii)当Ni组成高于渗流阈值时,碳向主体中扩散的速率会显着增加。这项研究揭示了CuNi合金表面上石墨烯成核的关键机理,并为合成石墨烯和其他2D材料的催化剂设计提供了指导。
更新日期:2018-03-12
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