Functional group inhomogeneity in graphene oxide using correlative absorption spectroscopy

Graphene oxide is a promising 2D material for industrial applications. However, understanding its hybrid electrical properties that result from different functional groups remains a fundamentally open question: experimental characterization of the electronic configuration contains convolved information, and identifying functional groups by classical approaches cannot adequately describe these groups at the nanoscale. Here, we correlate infrared and ultraviolet-visible absorption spectroscopy using imaging techniques. The C-H and C-O-rich regions are identified through infrared imaging, and their electronic behavior is analyzed via the ultraviolet-visible absorption spectra from the same region. We confirmed through correlation spectroscopy that C-H and C-O rich regions absorb relatively more at 280 nm (4.43 eV) and 380 nm (3.26 eV), respectively. These correlations are confirmed by analyzing several graphene oxide flakes and validated using density func-tional theory calculation.