No abstract

We report on the structural analysis of graphene oxide (GO) by transmission electron microscopy (TEM). Electron diffraction shows that on average the underlying carbon lattice maintains the order and lattice-spacings of graphene; a structure that is clearly resolved in 80 kV aberration-corrected atomic resolution TEM images. These results also reveal that single GO sheets are highly electron transparent and stable in the electron beam, and hence ideal support films for the study of nanoparticles and macromolecules by TEM. We demonstrate this through the structural analysis of physiological ferritin, an iron-storage protein.

Photoemission measurements on exfoliated 2D heterostructures reveal detailed electronic structure and hybridization effects.

Van der Waals heterostructures is a unique class of layered artificial solids that offers the possibility of manipulating their physical properties via controlled composition, order and relative rotation of adjacent atomic planes. Here we use atomic resolution transmission electron microscopy to reveal the lattice reconstruction in twisted MoS 2 and WS 2 bilayers. For 3R stacking, a tessellated pattern of mirror reflected triangular 3R domains emerges, separated by a network of partial dislocations for the twist angles θ < 2 •. The electronic properties of these 3R domains appear qualitatively different from 2H TMDs, featuring layer-polarized conduction band states caused by lack of both inversion and mirror symmetry. In contrast, for 2H stacking, stable 2H domains dominate, with nuclei of a second metastable phase. This appears as a kagome-like pattern at θ ∼ 1 • , transitioning at θ → 0 to a hexagonal array of screw dislocations separating large-area 2H domains. The tunneling measurements show that such reconstruction creates strong piezoelectric textures, opening a new avenue for engineering of 2D material properties.