Electronic Structure of Graphdiyne Probed by X-ray Absorption Spectroscopy and Scanning Transmission X-ray Microscopy

The electronic structure of graphdiyne exposed to air is investigated utilizing X-ray absorption spectroscopy and scanning transmission X-ray microscopy. It is found that carbon–carbon triple bonds at defect sites in graphdiyne have been changed to double bonds after 3 months in air. The experimental results reveal the existence of oxygen and nitrogen functional groups and indicate that the oxidation takes place throughout the aged graphdiyne while the nitrogen contamination is mainly on its surface. Buckling of the aged graphdiyne is observed, resulting from bond length change due to the opening of triple bonds. It is also shown that annealing at a high temperature such as 800 °C may remove most of the functional groups in the aged graphdiyne.