Graphene reduction dynamics probed by photo-electron spectroscopy
Wei-Yen Woon1*, Hung-Chieh Tsai1, Min-Chiang Chuang1, Andreas Johansson2, Mika Pettersson3, Chia-Hao Chen4
1Department of Physics, National Central University, Taoyuan, Taiwan
2Department of Physics, University of Jyväskylä, Finland
3Department of Chemistry, University of Jyväskylä, Finland
4National Synchrotron Radiation Research Center, Hsinchu, Taiwan
* presenting author:WEI YEN WOON,
The reduction dynamics of micron-sized defects created on chemical vapor deposition (CVD) grown graphene through scanning probe lithography (SPL) and pulsed laser two-photon oxidation are reported. CVD grown graphene was locally oxidized using either SPL or pulsed laser induced two-photon oxidation and subsequently reduced making use of a focused beam of soft x-rays. During this whole process, the reduction dynamics was monitored using a combination of micro-Raman spectroscopy (μ-RS) and micro-x-ray photoelectron spectroscopy (μ-XPS). After x-ray reduction, the graphene film was found to be chemically identical (μ-XPS) but structurally different (μ-RS) from the original graphene. By modelling the dynamics of conversion from C-O to C-C related bonds reduction process with coupled rate equations, the conversion from C-C to C=C bonds was found to be the limiting rate.

Keywords: Graphene, reduction, photoelectron spectroscopy