Korean researchers fabricate ordered graphene quantum dot arrays

A new study led by the Ulsan National Institute of Science and Technology in South Korea reveals a technology capable of fabricating highly ordered arrays of graphene quantum dots.

Korean researchers fabricate ordered graphene quantum dot arrays imageGraphene quantum dots of various sizes in a stable, ordered array

The research team demonstrated a novel way of synthesizing GQDs, embedded inside a hexagonal boron nitride (hBN) matrix. Thus, they demonstrated simultaneous use of in-plane and van der Waals heterostructures to build vertical single-electron tunneling transistors.

Researchers create color-changing nanomaterials using graphene oxide

Researchers affiliated with UNIST (Ulsan National Institute of Science and Technology) in Korea have engineered a new type of carbon nanomaterials, reportedly capable of changing shapes and colors depending on the type of solvents used. Such materials have attracted much attention thanks to their unique optical properties and structures.

The research team has presented a unique design and synthesis of hybrid carbon nanosheets (CNSs), which show a strong solvatochromic behavior (the ability of a chemical to change color due to a change in solvent polarity) with wide color tunability ranging from blue to orange and even to white in various solvents. This unique hybrid CNS features clusters of carbon nanorings on the surface of graphene-oxide (GO) nanosheets as the product of the hydrothermal reaction of small molecular precursors in the presence of GO nanosheets. Moreover, under UV and visible-light excitation, the hybrid CNS exhibits tunable emission spanning the wide range of colors in a series of solvents with different polarities.

Scientists design a new way of making bi-layer graphene by using oxygen

Researchers at the University of Texas at Austin, Columbia University, and the IBS Center for Multdimensional Carbon Materials at Ulsan have developed a new way to make high-quality “Bernal-stacked” bilayer graphene – an important material for electronics and photonics.

The researchers have studied a way to make bilayer graphene that yields a high percentage of AB stacked material, and were able to produce sub-millimetre single-crystal AB-stacked bilayer graphene domains. In the CVD chamber used to grow their graphene, the researchers intentionally introduced a small amount of oxygen (parts per million concentrations). This oxygen, when combined with the copper foil substrate on which the graphene was grown, dissociates methane molecule precursors into carbon atoms. These atoms then diffuse through the copper foil and help form a second layer of graphene.

Novel catalyst could improve fuel cells and Li-air batteries

Researchers at the Ulsan National Institute of Science and Technology (UNIST) announced the development of an iron-carbon composite catalyst that can contribute to a reduction in the costs of fuel cells and Li-air batteries

The carbon composite catalyst contains iron and nitrogen and uses a graphene nanoplate. It is reportedly better than existing carbon catalysts in terms of durability and performance, and allows mass production at a low cost. The researchers hope that it will be able to contribute to the commercialization of metal-air batteries.

Graphene as a substrate for assembling small organic molecules and heterostructures

Researchers at the University of Stanford in the US, the Ulsan National Institute of Science and Technology (UNIST) in South Korea and Queen’s University in the UK showed that graphene is an excellent substrate for assembling small organic molecules and that such heterostructures might be used in applications like high-performance detectors, solar cells and flexible transistors.

The researchers began by preparing suspended graphene films. They then evaporated C60 molecules onto the films to form thin-film crystals.They then made the resulting structures up into vertical transistors doped with n-type semiconducting materials and found that these devices have current on/off ratios of more than 3 x 103. Various transmission electron microscopy techniques, including selective area electron diffraction, atomic resolution TEM imaging, and van der Waals-based first principles computational methods allowed the researchers to study the structure and grain size of the crystals in detail and carefully look at the graphene-C60 interface in particular. They also noticed that the C60 films lay uniformly on the graphene substrate and that the individual molecules can assume several different molecular orientations.

Versarien - Think you know graphene? Think again! Versarien - Think you know graphene? Think again!