Direct imaging of light-element impurities in graphene reveals triple-coordinated oxygen

• Published in: Nature communications 2019-10, Vol.10 (1), p.4570-4570, Article 4570
• Main Authors: Hofer, Christoph, Skákalová, Viera, Görlich, Tobias, Tripathi, Mukesh, Mittelberger, Andreas, Mangler, Clemens, Monazam, Mohammad Reza Ahmadpour, Susi, Toma, Kotakoski, Jani, Meyer, Jannik C.
• Format: Article
• Language: English
• Subjects: 147/137; 639/766/930/328/2082; 639/925/918/1053; Humanities and Social Sciences; multidisciplinary; Science; Science (multidisciplinary)
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-019-12537-3

Along with hydrogen, carbon, nitrogen and oxygen are the arguably most important elements for organic chemistry. Due to their rich variety of possible bonding configurations, they can form a staggering number of compounds. Here, we present a detailed analysis of nitrogen and oxygen bonding configurations in a defective carbon (graphene) lattice. Using aberration-corrected scanning transmission electron microscopy and single-atom electron energy loss spectroscopy, we directly imaged oxygen atoms in graphene oxide, as well as nitrogen atoms implanted into graphene. The collected data allows us to compare nitrogen and oxygen bonding configurations, showing clear differences between the two elements. As expected, nitrogen forms either two or three bonds with neighboring carbon atoms, with three bonds being the preferred configuration. Oxygen, by contrast, tends to bind with only two carbon atoms. Remarkably, however, triple-coordinated oxygen with three carbon neighbors is also observed, a configuration that is exceedingly rare in organic compounds. Annular dark field scanning transmission electron microscopy is able to distinguish the contrasts between light elements. Here, the authors directly image the bonding configurations of oxygen and nitrogen atoms in defective graphene, and surprisingly identify instances of unusual triple-coordinated oxygen with three carbon neighbors.