STM images of HOPG before and after oxygen plasma treatment. (a) HOPG control (b) HOPG after 12 passes of O2 treatment, (c) higher magnification of (b), (d) atomic scale image showing HOPG lattice structure between pits.
STM images of HOPG surfaces after CO plasma treatment. (a) HOPG after 12 passes of CO treatment, (b) higher magnification of (a), (c) atomic structure between nodules.
Schematic diagram representing the possible position of functional groups on surface. Carbon atoms are positioned at each corner of the hexagon which represent the structure of the HOPG substrate. STM can detect every other carbon, denoted by larger circles. Smaller circles represent the possible positions of –CO group.
Auger spectroscopy of CO APT treated specimen. (a) Scanning electron micrograph showing nodules. (b) Auger oxygen map showing well distribution of oxygen throughout surface.
O/C ratio of HOPG as a function of APT with CO and O2 as the active gas.
High-resolution C 1s XPS analysis showing functional groups formed as a function of gas and duration. (a) O2 on HOPG, (b) CO on HOPG.
High-resolution C 1s XPS analysis showing functional groups formed on Si wafer with CO plasma treatment passes.
Contact angle measurements of CO and O2 APT HOPG specimens as a function of gas and duration.
Raman spectroscopy of HOPG specimens treated with CO and O2 APT as a function of duration. (a) HOPG control, (b) O2 treated HOPG, (c) CO treated HOPG.
XPS analysis of CO and O2 APT of graphene nanoplatelets (xGnP) showing (a) O/C ratio and (b) Raman spectrum of O2 and CO treated samples after six passes (4.8 s duration).
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