Two-dimensional materials, such as graphene and monolayer hexagonal BN (h-BN), are attractive for demonstrating fundamental physics in materials and potential applications in next-generation electronics. Atomic sheets containing hybridized bonds involving elements B, N and C over wide compositional ranges could result in new materials with properties complementary to those of graphene and h-BN,...

Graphene multilayers are grown epitaxially on single crystal silicon carbide. This system is composed of several graphene layers of which the first layer is electron doped due to the built-in electric field and the other layers are essentially undoped. Unlike graphite the charge carriers show Dirac particle properties (i.e. an anomalous Berry’s phase, weak anti-localization and square root fiel...

We report on the existence of water-gated charge doping of graphene deposited on atomically flat mica substrates. Molecular films of water in units of ~0.4 nm thick bilayers were found to be present in regions of the interface of graphene/mica heterostacks prepared by micromechanical exfoliation of kish graphite. The spectral variation of the G and 2D bands, as visualized by Raman mapping, show...

A hierarchical N-doped carbon nanotube-graphene hybrid nanostructure (NCNT-GHN), in which the graphene layers are distributed inside the CNT inner cavities, was designed to effi ciently support noble metal (e.g., PtRu) nanoparticles. Well-dispersed PtRu nanoparticles with diameters of 2–4 nm were immobilized onto these NCNT-GHN supports by a low-temperature chemical reduction method without any...

We calculate, within the leading-order dynamical-screening approximation, the electron self-energy and spectral function at zero temperature for extrinsic (or gated/doped) graphene. We also calculate hot carrier inelastic scattering due to electron–electron interactions in graphene. We obtain the inelastic quasiparticle lifetimes and associated mean free paths from the calculated self-energy. T...

A metallic nanoantenna, under resonant illumination, injects nonequilibrium hot electrons into a nearby graphene structure, effectively doping the material. A prominent change in carrier density was observed for a plasmonic antenna-patterned graphene sheet following laser excitation, shifting the Dirac point, as determined from the gate-controlled transport characteristic. The effect is due to ...

Boron-doped graphene, synthesized by annealing a mixture of graphite oxide and B2O3, has shown a high conversion efficiency of 6.73% as a counter electrode (CE) for dye-sensitized solar cells, which is better than the Pt CE.

The existence of Dirac cones in the band structure of two-dimensional materials accompanied by unprecedented electronic properties is considered to be a unique feature of graphene related to its hexagonal symmetry. Here, we present other two-dimensional carbon materials, graphynes, that also possess Dirac cones according to first-principles electronic structure calculations. One of these materi...

We review the optical phonon dispersions of graphene. In particular, we focus on the presence of two Kohn anomalies in the highest optical phonon branch at the Γ and K points of the Brillouin zone. We then show how graphene can be used as a model for the calculation of phonons in carbon nanotubes. Finally, we present the beyond Born-Oppenheimer corrections to their phonon dispersions. These are...

Nitrogen doping has been a powerful way to modify the properties of carbon materials ranging from activated carbon to graphene. Here we report on a solution chemistry approach to nitrogen-doped colloidal graphene quantum dots with well-defined structures. N-doping was demonstrated to significantly affect the properties of the quantum dots, including the emergence of size-dependent electrocataly...