Carbon nanotubes (CNT) – like other nanostructured materials – have high sensitivity to a large number of different gases and vapours which are important in areas as diverse as process monitoring in industry, environmental monitoring, agriculture, personal safety, medicine, or security screening. Gas sensors often operate by detecting the subtle changes that deposited gas molecules make in the way electricity moves through a surface layer. One advantage that carbon nanotubes offer for gas sensors, compared to metal oxide materials, is their fast response time and the fact that they react with gases at lower temperatures, sometimes even as low as room temperature.
In one promising application, researchers demonstrated the detection of specific odorous molecules with high resolution using a functionalized carbon nanotube based sensor. While the possibilities for CNT-based gas sensors are huge, the problem lies with the fabrication technologies, more specifically with a lack of technology for batch fabrication.
In a groundbreaking series of experiments, scientists in the United States managed to develop a new method of analyzing how graphene sheets are stacked on top of each other. The technique is also suitable for determining which areas of the compound are subjected to most strain, when the material is placed inside more complex structures. All of this can be inferred using moire patterns, which are interference patterns that appear at an atomic scale, when two layers of atoms are placed on top of each other imperfectly, as in slightly askew (image courtesy of NIST).
The research team that conducted the new investigation features physicists from the US National Institutes of Standards and Technology (NIST) and the Georgia Institute of Technology (Georgia Tech). The experts say that the moire patterns can also be used on multiple grids or atom arrays, not only on two. They add that using “atomic moire interferometry” can also help scientists determine the rotational orientation of the graphene sheets used in a variety of technological applications. Their work is published in the Physical Review B journal.
Understanding energy dissipation and transport in nanoscale structures is of great importance for the design of energy-efficient circuits and energy-conversion systems. This is also a rich domain for fundamental discoveries at the intersection of electron, lattice (phonon), and optical (photon) interactions. A review article published in NanoResearch presents the recent progress in understanding and manipulation of energy dissipation and transport in nanoscale solid-state structures.
Some of the greatest challenges of modern society are related to energy consumption, dissipation, and waste. Among these, present and future technologies based on nanoscale materials and devices hold great potential for improved energy conservation, conversion, or harvesting. A prominent example is that of integrated electronics, where power dissipation issues have recently become one of its greatest challenges. Power dissipation limits the performance of electronics from handheld devices (~10–3 W) to massive data centres (~109 W), all primarily based on silicon micro/nanotechnology.
Rice University researchers have found a way to stitch graphene and hexagonal boron nitride (h-BN) into a two-dimensional quilt that offers new paths of exploration for materials scientists. The technique has implications for application of graphene materials in microelectronics that scale well below the limitations of silicon determined by Moore’s Law. New research demonstrates a way to achieve fine control in the creation of such hybrid, 2-D structures.
Layers of h-BN a single atom thick have the same lattice structure as graphene, but electrically the materials are at opposite ends of the spectrum: h-BN is an insulator, whereas graphene, the single-atom-layer form of carbon, is highly conductive. The ability to assemble them into a single lattice could lead to a rich variety of 2-D structures with electric properties ranging from metallic conductor to semiconductor to insulator.