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

Direct imaging of light-element impurities in graphene reveals triple-coordinated oxygen
Hofer C, Skakalova V, Görlich T, Tripathi M, Mittelberger A, Mangler C, Monazam M, Susi T, Kotakoski J, Meyer J
(2019)10:4570 | https://doi.org/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 aberrationcorrected
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.