An ion-migration and electron-transfer cycle containing graphene and copper substrate analyzed with Raman spectra

作者:Lin, Weiyi; Zhuang, Pingping; Tian, Bo; Liu, Tie; Zhang, Cankun; Shih, Tien-mo*; Cai, Weiwei*
来源:Carbon, 2017, 116: 15-19.
DOI:10.1016/j.carbon.2017.01.079

摘要

Due to its semi-metallic characteristics, graphene may allow electron transfer to take place between itself and electrically-contacted metals. Here, we discover a two-component (graphene and copper) and two-process (ion migration and electron transfer) cycle, in which (a) electrons travel from the copper substrate to graphene based on Fermi-level variations through the interface, and (b) ions migrate vice versa due to Coulomb force via the intercalated electrolyte. To validate this proposed cycle, we scrutinize the copper-oxide formation, graphene-lattice phonon-frequency variations, and the morphological evolution of copper oxides, primarily via Raman measurements. Our study may provide the guidance for fundamental research on other graphene-metal assemblies as well as may enhance the versatility of graphenebased applications.