. 24/7 Space News .
TECH SPACE
High temperature step-by-step process makes graphene from ethene
by Staff Writers
Atlanta GA (SPX) May 10, 2017


Schematic of the pathway describing the evolution of adsorbed ethene (top left) to graphene (bottom left). The sequence of intermediates identified in the study and their respective appearance temperatures are indicated. Credit: Figure credit: F. Esch, R. Schaub, U. Landman

An international team of scientists has developed a new way to produce single-layer graphene from a simple precursor: ethene - also known as ethylene - the smallest alkene molecule, which contains just two atoms of carbon.

By heating the ethene in stages to a temperature of slightly more than 700 degrees Celsius - hotter than had been attempted before - the researchers produced pure layers of graphene on a rhodium catalyst substrate. The stepwise heating and higher temperature overcame challenges seen in earlier efforts to produce graphene directly from hydrocarbon precursors.

Because of its lower cost and simplicity, the technique could open new potential applications for graphene, which has attractive physical and electronic properties. The work also provides a novel mechanism for the self-evolution of carbon cluster precursors whose diffusional coalescence results in the formation of the graphene layers.

The research, reported as the cover article in the May 4 issue of the Journal of Physical Chemistry C, was conducted by scientists at the Georgia Institute of Technology, Technische Universitat Munchen in Germany, and the University of St. Andrews in Scotland. In the United States, the research was supported by the U.S. Air Force Office of Scientific Research and the U.S. Department of Energy's Office of Basic Energy Sciences.

"Since graphene is made from carbon, we decided to start with the simplest type of carbon molecules and see if we could assemble them into graphene," explained Uzi Landman, a Regents' Professor and F.E. Callaway endowed chair in the Georgia Tech School of Physics who headed the theoretical component of the research. "From small molecules containing carbon, you end up with macroscopic pieces of graphene."

Graphene is now produced using a variety of methods including chemical vapor deposition, evaporation of silicon from silicon carbide - and simple exfoliation of graphene sheets from graphite. A number of earlier efforts to produce graphene from simple hydrocarbon precursors had proven largely unsuccessful, creating disordered soot rather than structured graphene.

Guided by a theoretical approach, the researchers reasoned that the path from ethene to graphene would involve formation of a series of structures as hydrogen atoms leave the ethene molecules and carbon atoms self-assemble into the honeycomb pattern that characterizes graphene.

To explore the nature of the thermally-induced rhodium surface-catalyzed transformations from ethene to graphene, experimental groups in Germany and Scotland raised the temperature of the material in steps under ultra-high vacuum. They used scanning-tunneling microscopy (STM), thermal programed desorption (TPD) and high-resolution electron energy loss (vibrational) spectroscopy (HREELS) to observe and characterize the structures that form at each step of the process.

Upon heating, ethene adsorbed onto the rhodium catalyst evolves via coupling reactions to form segmented one-dimensional polyaromatic hydrocarbons (1D-PAH). Further heating leads to dimensionality crossover - one dimensional to two dimensional structures - and dynamical restructuring processes at the PAH chain ends with a subsequent activated detachment of size-selective carbon clusters, following a mechanism revealed through first-principles quantum mechanical simulations.

Finally, rate-limiting diffusional coalescence of these dynamically self-evolved cluster-precursors leads to condensation into graphene with high purity.

At the final stage before the formation of graphene, the researchers observed nearly round disk-like clusters containing 24 carbon atoms, which spread out to form the graphene lattice.

"The temperature must be raised within windows of temperature ranges to allow the requisite structures to form before the next stage of heating," Landman explained. "If you stop at certain temperatures, you are likely to end up with coking."

An important component is the dehydrogenation process which frees the carbon atoms to form intermediate shapes, but some of the hydrogen resides temporarily on, or near, the metal catalyst surface and it assists in subsequent bond-breaking process that lead to detachment of the 24-carbon cluster-precursors.

"All along the way, there is a loss of hydrogen from the clusters," said Landman. "Bringing up the temperature essentially 'boils' the hydrogen out of the evolving metal-supported carbon structure, culminating in graphene."

The resulting graphene structure is adsorbed onto the catalyst. It may be useful attached to the metal, but for other applications, a way to remove it will have to be developed. Added Landman: "This is a new route to graphene, and the possible technological application is yet to be explored."

"Ethene to Graphene: Surface Catalyzed Chemical Pathways, Intermediates, and Assembly"

TECH SPACE
Stenciling with atoms in 2-dimensional materials possible
University Park PA (SPX) May 10, 2017
The possibilities for the new field of two-dimensional, one-atomic-layer-thick materials, including but not limited to graphene, appear almost limitless. In new research, Penn State material scientists report two discoveries that will provide a simple and effective way to "stencil" high-quality 2D materials in precise locations and overcome a barrier to their use in next-generation electronics. ... read more

Related Links
Georgia Institute of Technology
Space Technology News - Applications and Research


Thanks for being here;
We need your help. The SpaceDaily news network continues to grow but revenues have never been harder to maintain.

With the rise of Ad Blockers, and Facebook - our traditional revenue sources via quality network advertising continues to decline. And unlike so many other news sites, we don't have a paywall - with those annoying usernames and passwords.

Our news coverage takes time and effort to publish 365 days a year.

If you find our news sites informative and useful then please consider becoming a regular supporter or for now make a one off contribution.
SpaceDaily Contributor
$5 Billed Once


credit card or paypal
SpaceDaily Monthly Supporter
$5 Billed Monthly


paypal only


Comment using your Disqus, Facebook, Google or Twitter login.

Share this article via these popular social media networks
del.icio.usdel.icio.us DiggDigg RedditReddit GoogleGoogle

TECH SPACE
NASA Receives Proposals for Future Solar System Mission

'Road to Nowhere': Retired Cosmonaut Reveals How It Feels to Walk in Space

Orion Motor Ready for Crewed Mission

Orbiting at 250 Statute Miles, Florida Tech Experiment Tested

TECH SPACE
Testing Prepares NASA's Space Launch System for Liftoff

GSLV Successfully Launches South Asia Satellite

ISRO Successfully Launches GSAT-9 'SAARC' South Asian Communication Satellite

First Contract under Booster Propulsion Technology Maturation BAA Complete

TECH SPACE
Seasonal Flows in Valles Marineris

NASA Rover Curiosity Samples Active Linear Dune on Mars

Is Anything Tough Enough to Survive on Mars

Japan aims to uncover how moons of Mars formed

TECH SPACE
China tests 'Lunar Palace' as it eyes moon mission

China to conduct several manned space flights around 2020

Reach for the Stars: China Plans to Ramp Up Space Flight Activity

China's cargo spacecraft completes in-orbit refueling

TECH SPACE
AIA report outlines policies needed to boost the US Space Industry competitiveness

Allied Minds' portfolio company BridgeSat raises $6 million in Series A financing

Blue Sky Network Targets Key Markets For Iridium SATCOM Solutions

How Outsourcing Your Satellite Related Services Saves You Time and Money

TECH SPACE
First luminescent molecular system with a lower critical solution temperature

Space radiation reproduced in the lab for better, safer missions

Stenciling with atoms in 2-dimensional materials possible

High temperature step-by-step process makes graphene from ethene

TECH SPACE
First SETI Institute Fellows Announced

Taking the pulse of an ocean world

Astrophysicists find that planetary harmonies around TRAPPIST-1 save it from destruction

Two Webb instruments well suited for detecting exoplanet atmospheres

TECH SPACE
Not So Great Anymore: Jupiter's Red Spot Shrinks to Smallest Size Ever

Waves of lava seen in Io's largest volcanic crater

The PI's Perspective: No Sleeping Back on Earth!

ALMA investigates 'DeeDee,' a distant, dim member of our solar system









The content herein, unless otherwise known to be public domain, are Copyright 1995-2024 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. All articles labeled "by Staff Writers" include reports supplied to Space Media Network by industry news wires, PR agencies, corporate press officers and the like. Such articles are individually curated and edited by Space Media Network staff on the basis of the report's information value to our industry and professional readership. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. General Data Protection Regulation (GDPR) Statement Our advertisers use various cookies and the like to deliver the best ad banner available at one time. All network advertising suppliers have GDPR policies (Legitimate Interest) that conform with EU regulations for data collection. By using our websites you consent to cookie based advertising. If you do not agree with this then you must stop using the websites from May 25, 2018. Privacy Statement. Additional information can be found here at About Us.