After six years of painstaking effort, a group of University of Wisconsin-Madison materials scientists believe the tiny sheets of the semiconductor zinc oxide they're growing could have huge implications for the future of a host of electronic and biomedical devices.
The group -- led by Xudong Wang, a UW-Madison professor of materials science and engineering, and postdoctoral researcher Fei Wang -- has developed a technique for creating nearly two-dimensional sheets of compounds that do not naturally form such thin materials. It is the first time such a technique has been successful.
The researchers described their findings in the journal Nature Communications on Jan. 20.
Essentially the microscopic equivalent of a single sheet of paper, a 2-D nanosheet is a material just a few atoms thick. Nanomaterials have unique electronic and chemical properties compared to identically composed materials at larger, conventional scales.
"What's nice with a 2-D nanomaterial is that because it's a sheet, it's much easier for us to manipulate compared to other types of nanomaterials," says Xudong Wang.
Until now, materials scientists were limited to working with naturally occurring 2-D nanosheets. These natural 2-D structures include graphene, a single layer of graphite, and a limited number of other compounds.
Developing a reliable method to synthesize and manufacture 2-D nanosheets from other materials has been a goal of materials researchers and the nanotechnology industry for years.
In their technique, the UW-Madison team applied a specially formulated surfactant -- a detergent-like substance -- onto the surface of a liquid containing zinc ions.
Due to its chemical properties, the surfactant assembles itself into a single layer at the surface of the liquid, with negatively charged sulfate ions pointed in the direction of the liquid. Those sulfate ions draw the positively charged zinc ions from within the liquid to the surface, and within a couple hours enough zinc ions are drawn up to form continuous zinc oxide nanosheets only a few atomic layers thick.
Xudong Wang first had the idea for using a surfactant to grow nanosheets during a lecture he was giving in a course on nanotechnology in 2009.
"The course includes a lecture about self-assembly of monolayers," he says. "Under the correct conditions, a surfactant will self-assemble to form a monolayer. This is a well-known process that I teach in class. So while teaching this, I wondered why we wouldn't be able to reverse this method and use the surfactant monolayer first to grow the crystalline face."
After five years of trial and error with different surfactant solutions, the idea paid off.
"We are very excited about this," says Xudong Wang. "This is definitely a new way to fabricate 2-D nanosheets, and it has great potential for different materials and for many different applications."
Already, the researchers have found that the 2-D zinc oxide nanosheets they've grown are able to function as semiconductor transistors called a p-type, the opposite electronic behavior of naturally occurring zinc oxide. Researchers have for some time attempted to produce zinc oxide with reliable p-type semiconductor properties.
Zinc oxide is a very useful component of electronic materials, and the new nanosheets have potential for use in sensors, transducers and optical devices.
But the zinc oxide nanosheets are only the first of what could be a revolution in 2-D nanomaterials. Already, the UW-Madison team is applying its surfactant method to growing 2-D nanosheets of gold and palladium, and the technique holds promise for growing nanosheets from all sorts of metals that wouldn't form them naturally.
"It brings a lot of new functional material to this 2-D material category," Wang says.
CONTACT: Xudong Wang, 608-890-2667, firstname.lastname@example.org
DOWNLOAD IMAGE: https:/
Will Cushman, 608-262-2481, email@example.com
Xudong Wang | EurekAlert!
Nanoimprinted hyperlens array: Paving the way for practical super-resolution imaging
24.04.2017 | Pohang University of Science & Technology (POSTECH)
Wonder material? Novel nanotube structure strengthens thin films for flexible electronics
24.04.2017 | University of Illinois College of Engineering
More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.
Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...
Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.
"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...
The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.
Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...
The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...
Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.
Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...
20.04.2017 | Event News
18.04.2017 | Event News
03.04.2017 | Event News
24.04.2017 | Physics and Astronomy
24.04.2017 | Materials Sciences
24.04.2017 | Life Sciences