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Two-dimensional (2D) atomic layers such as graphene, and metal chalcogenides have recently attracted tremendous attention due to their unique properties and potential applications. Unfortunately, in most cases, the free-standing nanosheets easily re-stack due to their van der Waals forces, and lose the advantages of their separated atomic layer state. Here, a bottom-up approach is developed to build three-dimensional (3D) architectures by 2D nanosheets such as MoS2 and graphene oxide nanosheets as building blocks, the thin nature of which can be well retained. After simply chemical reduction, the resulting 3D MoS2-graphene architectures possess high surface area, porous structure, thin walls and high electrical conductivity. Such unique features are favorable for the rapid diffusions of both lithium ions and electrons during lithium storage. As a consequence, MoS2-graphene electrodes exhibit high reversible capacity of ≈1200 mAh g−1, with very good cycling performance. Moreover, such a simple and low-cost assembly protocol can provide a new pathway for the large-scale production of various functional 3D architectures for energy storage and conversions. [ABSTRACT FROM AUTHOR]

Strong in-plane bonding and weak van der Waals interplanarinteractionscharacterize a large number of layered materials, as epitomized bygraphite. The advent of graphene (G), individual layers from graphite,and atomic layers isolated from a few other van der Waals bonded layeredcompounds has enabled the ability to pick, place, and stack atomiclayers of arbitrary compositions and build unique layered materials,which would be otherwise impossible to synthesize via other knowntechniques. Here we demonstrate this concept for solids consistingof randomly stacked layers of graphene and hexagonal boron nitride(h-BN). Dispersions of exfoliated h-BN layers and graphene have beenprepared by liquid phase exfoliation methods and mixed, in variousconcentrations, to create artificially stacked h-BN/G solids. Thesevan der Waals stacked hybrid solid materials show interesting electrical,mechanical, and optical properties distinctly different from theirstarting parent layers. From extensive first principle calculationswe identify (i) a novel approach to control the dipole at the h-BN/Ginterface by properly sandwiching or sliding layers of h-BN and graphene,and (ii) a way to inject carriers in graphene upon UV excitationsof the Frenkell-like excitons of the h-BN layer(s). Our combined approachcould be used to create artificial materials, made predominantly frominter planar van der Waals stacking of robust bond saturated atomiclayers of different solids with vastly different properties. [ABSTRACT FROM AUTHOR]

The study of two-dimensional (2D) electronic systems is of great fundamental significance in physics. Atomic layers containing hybridized domains of graphene and hexagonal boron nitride (h-BNC) constitute a new kind of disordered 2D electronic system. Magnetoelectric transport measurements performed at low temperature in vapor phase synthesized h-BNC atomic layers show a clear and anomalous transition from an insulating to a metallic behavior upon cooling. The observed insulator to metal transition can be modulated by electron and hole doping and by the application of an external magnetic field. These results supported by ab initio calculations suggest that this transition in h-BNC has distinctly different characteristics when compared to other 2D electron systems and is the result of the coexistence between two distinct mechanisms, namely, percolation through metallic graphene networks and hopping conduction between edge states on randomly distributed insulating h-BN domains. [ABSTRACT FROM AUTHOR]