However, the nanowire and nanosheets are actually a single, three-dimensional structure consisting of a seamless series of germanium sulfide (GeS) crystals. The structure holds promise for use in the creation of new, three-dimensional (3-D) technologies.
The "shish-kebab" consists of two-dimensional nanosheets strung along a nanowire.
The researchers believe this is the first engineered nanomaterial to combine one-dimensional and two-dimensional structures in which all of the components have a shared crystalline structure.
Combining the nanowire and nanosheets into a single “heterostructure” creates a material with both a large surface area and – because GeS is a semiconductor – the ability to transfer electric charges efficiently. The nanosheets provide a very large surface area, and the nanowire acts as a channel that can transmit charges between the nanosheets or from the nanosheets to another surface. This combination of features means it could be used to develop 3-D devices, such as next-generation sensors, photodetectors or solar cells. This 3-D structure could also be useful for developing new energy storage technologies, such as next-generation supercapacitors.
“We think this approach could also be used to create heterostructures like these using other materials whose molecules form similar crystalline layers, such as molybdenum sulfide (MoS2),” says Dr. Linyou Cao, an assistant professor of materials science and engineering at NC State and co-author of a paper on the research. “And, while germanium sulfide has excellent photonic properties, MoS2 holds more promise for electronic applications.”
The process, Cao says, is also attractive because “it is inexpensive and could be scaled up for industrial processes.”
To create the nano-shish-kebabs, the researchers begin by creating a GeS nanowire approximately 100 nanometers in width. The nanowire is then exposed to air, creating nucleation sites on the wire surface through weak oxidation. The nanowire is then exposed to GeS vapor, which forms into two-dimensional nanosheets at each of the nucleation sites.
“Our next step is to see if we can create these heterostructures in other materials, such as MoS2,” Cao says. “We think we can, but we need to prove it.”
The paper, “Epitaxial Nanosheet–Nanowire Heterostructures,” was published online Feb. 18 in Nano Letters. The lead author is Dr. Chun Li, a former postdoctoral researcher at NC State. Co-authors are Yifei Yu, a Ph.D. student at NC State; Cao; and Dr. Miaofang Chi of Oak Ridge National Laboratory. The research was supported by the U.S. Army Research Office.
Note to Editors: The study abstract follows.
“Epitaxial Nanosheet–Nanowire Heterostructures”
Authors: Chun Li, Yifei Yu and Linyou Cao, North Carolina State University; Miaofang Chi, Oak Ridge National Laboratory
Published: online Feb. 18 in Nano Letters
Abstract: We demonstrate synthesis of a new type of heterostructures that comprise two-dimensional (2D) nanosheets (NSs) epitaxially grown at one-dimensional (1D) nanowires (NWs). The synthesis involves using materials with a graphite-like layered structure in which covalently bonded layers are held by weak van der Waals forces. GeS was used as a prototype material in this work. The synthesis also involves a seeded-growth process, where GeS NWs are grown first as seeds followed by a seeded growth of NSs at the pre-grown NWs. We observe that exposing the pre-grown NWs to air prior to the seeded growth is critical for the formation of NSs to yield NS?NW heterostructures. Our experimental results suggest that this might be due to a mild oxidation caused by the air exposure at the NW surface, which could subsequently facilitate the nucleation of NSs at the NWs. It also suggests that the surface oxidation needs to be controlled in a proper range in order to achieve optimized NS growths. We believe that this synthetic strategy may generally apply to the growth of NS?NW heterostructures of other layered chalcogenide materials.
NS?NW heterostructures provide capabilities to monolithically integrate the functionality of 1D NWs and 2D NSs into a 3D space. It holds great potential in applications that request complex nanomaterials with multiple functionality, high surface area, and efficient charge transport, such as energy storage, chemical sensing, solar energy conversion, and 3D electric and photonic devices.
Matt Shipman | EurekAlert!
Reliable and extremely long-lasting – high-voltage power electronics for network expansion
04.08.2015 | Fraunhofer Institute for Integrated Systems and Device Technology IISB
On the crest of the wave: Electronics on a time scale shorter than a cycle of light
30.07.2015 | Universität Regensburg
Verdichterscheiben für Flugzeugturbinen werden aus einem Materialstück herausgefräst. Bei der Bearbeitung fangen die Schaufeln an zu schwingen. Ein neuartiges Spannsystem steigert die Dämpfung der Schaufeln nun auf mehr als das 400-fache. Es lassen sich bis zu 5000 Euro Kosten bei der Fertigung einsparen.
Mal eben schnell in den Urlaub jetten oder für ein langes Wochenende nach Rom, Paris oder Madrid fliegen? Der Flugverkehr steigt, insbesondere der...
Der Gletscherschwund im ersten Jahrzehnt des 21. Jahrhunderts erreicht einen historischen Rekordwert seit Messbeginn. Das Schmelzen der Gletscher ist ein globales Phänomen und selbst ohne weiteren Klimawandel werden sie zusätzlich an Eis verlieren. Dies belegt die neueste Studie des World Glacier Monitoring Services unter der Leitung der Universität Zürich.
Seit über 120 Jahren sammelt der World Glacier Monitoring Service, mit heutigem Sitz an der Universität Zürich, weltweite Daten zu Gletscherveränderungen....
Glacier decline in the first decade of the 21st century has reached a historical record, since the onset of direct observations. Glacier melt is a global phenomenon and will continue even without further climate change. This is shown in the latest study by the World Glacier Monitoring Service under the lead of the University of Zurich, Switzerland.
The World Glacier Monitoring Service, domiciled at the University of Zurich, has compiled worldwide data on glacier changes for more than 120 years. Together...
Mit ultrakalten Atomen lässt sich ein neuer Materiezustand beobachten, in dem das System nicht ins thermische Gleichgewicht kommt.
Was passiert, wenn man kaltes und heißes Wasser mischt? Nach einer Weile ist das Wasser lauwarm – das System hat ein neues thermisches Gleichgewicht erreicht....
Using ultracold atoms trapped in light crystals, scientists from the MPQ, LMU, and the Weizmann Institute observe a novel state of matter that never thermalizes.
What happens if one mixes cold and hot water? After some initial dynamics, one is left with lukewarm water—the system has thermalized to a new thermal...
04.08.2015 | Veranstaltungen
03.08.2015 | Veranstaltungen
03.08.2015 | Veranstaltungen
04.08.2015 | Biowissenschaften Chemie
04.08.2015 | Geowissenschaften
04.08.2015 | Materialwissenschaften