Figure 1

TEM phase image revealing patches of pristine graphene that surround disordered areas of high oxygen functionalization. Phase of an exit-plane wave reconstructed from a focal series of 12 members. The focal range of the series covers $+11.9$ to $+3.9$ nm with a third- and fifth-order spherical aberration of $-14$ $\mu$m and $+8$ mm using a monochromated illumination at 80 keV electron energy that provides a focal spread of about 1.2 nm.Reuse & Permissions

Figure 2

Simulation model with 864 carbon atoms and an island of 48 oxygen atoms (in green). The corrugation profile beneath and around the adatoms is shown, together with the lateral view showing the disordered agglomerate of epoxy groups.Reuse & Permissions

Figure 3

(a)–(d) Some configurations of two oxygen atoms on graphene: $•$ ($\circ$) denotes an atom above (underneath) graphene; (2,1), (2,2),$\cdots$ imply relative positions between the two atoms (see the text), (2,1) and (2,2) are the most stable structures. (e) and (f) Lowest energy configurations of investigated ones when more adatoms are added. (g) Energy difference when ($n-1$) adatoms are in the center of the cell, 1 adatom is in a corner of the cell box, and when $n$ adatoms are in the cell center $\Delta E^{☆}$; adsorption energy per oxygen atom $\Delta E$ against number of oxygen atoms $n$. (h)–(k) A possible diffusion mechanism of two adatoms: They simultaneously move in a hexagon (h) and then one-by-one move to a neighboring hexagon (i)–(k).Reuse & Permissions

Figure 4

Electron density difference in the dimer (2,2): Isosurface at 0.015 a.u., accumulation in pink and depletion in green.Reuse & Permissions

Figure 5

Order or disorder? 216 oxygen atoms on a 864 carbon atom periodic graphene sheet in an ordered arrangement by (a) 108 most stable (2,2) dimers (the blue rectangle indicates one of 108 “subunits”), (b) 54 tetramers, and (c) a disordered structure, the latter shows superior stability.Reuse & Permissions