Nitrogen-doped Graphene (IMAGE) Rice University Caption Three transmission electron microscope images of nitrogen-doped graphene show the relative presence of manganese atoms, contaminants from graphite precursors or reactants believed responsible for the material's ability to catalyze oxygen-reduction reactions, according to Rice University scientists. The top image shows many manganese atoms (white) remain on graphene that has been washed once; few on twice-washed graphene in the center image; and none on graphene washed six times at bottom. Twice-washed graphene with a scattering of manganese atoms proved best for catalysis. Credit Tour Group/Rice University Usage Restrictions For news reporting purposes only. License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.