Remote Epitaxy of Electrodeposited Zn and Cu on Graphene

Control over the growth of metals on 2D materials is important for creating electrical contacts to 2D-material-based electronic devices, as well as for energy storage devices such as batteries in which 2D materials are used. Recently, it has been shown that graphene and other 2D materials allow for an underlying substrate to exert a structural influence on semiconductors grown onto the 2D material through “remote epitaxy.”^[1] Remote epitaxy has been observed primarily for semiconductors grown by vacuum deposition methods, and it represents an appealing method for versatile control over the orientation of deposited materials. However, it is unclear if remote epitaxy plays a role in the deposition of metals through methods such as electrodeposition. Here, we show that remote epitaxy acts to determine the growth characteristics of Zn and Cu electrodeposited on graphene/Cu substrates. Through a combination of three-electrode electrochemical experiments and extensive electron backscattered diffraction (EBSD) analysis, we show that the crystallographic orientation of the Cu grain below graphene determines the orientation of the electrodeposited metal, with the close-packed planes of the varying materials exhibiting epitaxial relationships. Transmission electron microscopy (TEM) is used to confirm the orientation relationship between the Cu substrate and the deposit through the graphene layer, providing atomic-scale information regarding the interface revealing that misfit strain is accommodated through edge dislocations. The graphene not only acts as a window layer, but also protects the underlying metal from oxidation to enable structurally continuous growth of the electrodeposit. These findings are important since they show that remote epitaxy can be achieved without vacuum methods using aqueous electrodeposition. Our results suggest that graphene coatings could be an effective way to enable controlled electrodeposition of a variety of metals, including those relevant to high-energy batteries (lithium, sodium).<br/><br/>[1] Y. Kim, S. S. Cruz, K. Lee, B. O. Alawode, C. Choi, Y. Song, J. M. Johnson, C. Heidelberger, W. Kong, S. Choi, K. Qiao, I. Almansouri, E. A. Fitzgerald, J. Kong, A. M. Kolpak, J. Hwang, J. Kim, <i>Nature</i> <b>2017</b>, <i>544</i>, DOI 10.1038/nature22053.