Water assisted oxydation of graphene on copper for large scale production of graphene

D. Luo, X. You, B-W. Li, X. Chen, H. Jun Park, M. Jung, T. Yeoung Ko, K. Wong, M. Yousaf, X. Chen, M. Huang, S. Hwa Lee, Z. Lee, H-J. Shin, S. Ryu, S. Kyu Kwak, N. Park, R.R. Bacsa, W. Bacsa, R.S. Ruoff
CEMES-CNRS and University of Toulouse,
France

Keywords: graphene, copper

Summary:

We examine the oxidation of a copper surface coated by graphene in water-saturated air at 50 °C. It was observed that oxidation started at the graphene edge and was complete after around 24 h. Isotope labeling of the oxygen gas and water showed that the oxygen in the formed copper oxides originated from water and not from the oxygen in air for both copper and graphene-coated copper. This has important implications for using graphene as a protective coating for copper in dry air conditions. A reaction pathway is proposed where surface hydroxyl groups formed at graphene edges and defects induce the oxidation of copper. DFT simulation shows that the binding energy between graphene and the oxidized copper substrate is smaller than that for the bare copper substrate. This facilitates delamination from copper oxide of graphene and the same process can be used for dry transfer of graphene from copper on an arbitary substrate. A demonstration was made using poly(bisphenol A carbonate) (PC) as the support layer. The quality of the transferred graphene was examined with Raman maps, XPS, STM, TEM, and sheet resistance measurements. This process makes it possible to re-use the copper substrate without any loss of graphene quality. This dry and clean delamination technique for CVD graphene grown on copper substrates is thus cost-effective and suitable for large-scale production of graphene. This work was supported by IBS-R019-D1.