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Nanotechnology Spotlight

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Showing Spotlights 65 - 72 of 115 in category Graphene (newest first):

 

Novel phenomenon converts graphene into nanotubes via gold nanoparticles

nanoparticles_nanotubeNoble metal nanoparticles such as gold, silver or platinum are widely used by scientists to develop novel applications in sensing, energy, spectroscopy, and catalysis. For instance, the combination of metal nanoparticles and carbon nanomaterials - graphene and nanotubes - has met with great interest in the area of biosensor applications as well as composite fabrication for light-energy conversion. In these applications, researchers make use of the formation of organic/inorganic hybrid nanosystems by incorporating metal nanoparticles in or onto the graphitic structures of carbon nanotubes or graphene. Researchers have now discovered a novel phenomenon whereby graphene can be catalytically transformed into carbon nanotubes by gold nanoparticles at relatively low temperatures.

Posted: Feb 8th, 2012

Molybdenite-based phototransistor shows faster photoresponsivity than a graphene-based device

FET_deviceApart from graphene, other two-dimensional structures are also known to have unique properties which researchers are eager to exploit for novel nanotechnology applications in nanoelectronics and sensor or energy storage technology. Particular interest has been on semiconducting materials, such as molybdenum disulfide (MoS2), an abundant material in nature, which exhibits the unique physical, optical and electrical properties correlated with its single-layer atomic layer structure. Researchers have now fabricated a mechanically exfoliated single-layer MoS2 based phototransistor and investigated its electric characteristics in detail. These new findings show that, when compared with a 2D graphene-based device, the single-layer MoS2 phototransistor exhibits a better photoresponsivity.

Posted: Feb 3rd, 2012

Graphene sets new record as the most efficient filler for thermal interface materials

Thermal_interface_materialThermal interface materials (TIMs) are essential ingredients of thermal management. TIMs are applied between the heat source, e.g. computer chips, and heat sinks and their function is to fill the voids and grooves created by imperfect surface finish of mating surfaces. Conventional TIMs filled with thermally conductive particles require high volume fractions of filler particles. But now, researchers have achieved a record enhancement of the thermal conductivity of TIMs by addition of an optimized mixture of graphene and multilayer graphene. The thermal conductivity of the epoxy matrix material was increased by an impressive factor of 23 at the 10 volume % of graphene loading. The epoxy-graphene composite preserved all the properties required for industrial TIM applications.

Posted: Jan 30th, 2012

Simple green production of high quality graphene nanosheets and quantum dots in bulk amounts

grapheneA University of Ulster laboratory has found a simple, low cost and environmentally friendly way to turn common graphite flakes into bulk amounts of either high quality graphene nanosheets or quantum dots. Such structures could lead to new nanoelectronics and energy conversion technologies. The scientists discovered a simple process, which is quicker and environmentally friendlier than currently established techniques for making high quality graphene nanosheets and quantum dots at an industrial scale. The most important attribute of the produced graphene nanosheets and quantum dots compared to those reported in the literature is that they are clean from any solvent contamination and possess a low concentration of oxygen, which is inherited from the starting graphite powder.

Posted: Jan 18th, 2012

Catch and release sensing of single malaria-infected red blood cells

caturing_blood_cellsGraphene research papers are popping up left and right at what seems like an accelerating speed and growing volume. One of the areas that is seeing vast research interest is the biological interfacing of graphene for instance for sensor applications. Today, we are looking at another exciting graphene bio application where a graphene sensor is integrated with microfluidics to sense malaria-infected red blood cells at the single-cell level. Specific binding between ligands on positively charged knobs of infected red blood cells and receptors functionalized on graphene inside microfluidic channels induces a distinct conductance change. Conductance returns to baseline value when infected cell exits the graphene channel.

Posted: Nov 28th, 2011

Eavesdropping on cells with graphene transistors

transistor_with_cellsThe integration of biological components with electronics, and more specifically, the interfacing of complex biological systems is one of the current challenges on the path towards bioelectronics (or bionics for short). Up to know, and due to its technology maturity, most of the work has been done based on Si-FET technology. However, there have been some issues related to this technology which prevented a more successful implementation into real applications. Researchers have now demonstrated, for the first time, that CVD grown graphene can be employed to fabricate arrays of transistors which are able to detect the electrical activity of electrogenic cells.

Posted: Nov 22nd, 2011

Novel graphene electrode improves already promising lithium-air battery technology

graphene_sheetLithium-ion batteries have been widely used in many electronic devices that are important to our daily life. However, after a steady improvement of some 10-15% during the last two decades, the energy density of lithium-ion batteries is now approaching its theoretical limit set by the energies of cathode and anode materials used in these batteries. Therefore, in recent years, the pursuit of the next generation of energy storage systems has been intense globally. Among various electrochemical energy storage systems explored to date, the lithium-air (Li-air) battery is one of the most promising technologies, with a theoretical energy density nearly ten times that of conventional lithium-ion batteries. A novel air electrode consisting of an unusual hierarchical arrangement of functionalized graphene sheets delivers an exceptionally high capacity.

Posted: Nov 2nd, 2011

Graphene membranes open a new window into surface chemistry

graphene_membraneAnalyzing the physicochemical processes that take place at surfaces and interfaces is an important aspect in materials science, catalysis, biochemistry and other fields. For many years, surface scientists have relied on powerful tools like X-ray Photoelectron Spectroscopy (XPS) and other spectroscopy techniques based on the detection of electrons. XPS reveals the elemental composition and chemical and electronic states of surfaces by irradiating a material with a beam of X-rays and measuring the energy and electrons that escape. However, it still remains a great experimental challenge to adapt powerful, surface sensitive tools such as XPS or to explore objects at ambient conditions. Researchers now demonstrate that graphene oxide membranes are a very promising window material for environmental cells to enable XPS studies of samples immersed in liquid or dense gaseous media.

Posted: Oct 25th, 2011