Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Graphene oxide’s solubility disappears in the wash

09.03.2011
Graphene oxide has had a scrum of researchers fall upon it as it retains much of the properties of the highly valued super material pure graphene, but it is much easier, and cheaper, to make in bulk quantities; easier to process; and its significant oxygen content appears to make it soluble in water.

However new research led by University of Warwick Chemist Dr Jonathan P. Rourke and Physicist University of Warwick Physicist Dr Neil Wilson, has found that that last assumption is incorrect and unfortunately graphene oxide’s solubility literally comes out in the wash.

Drs Rourke and Wilson’s team made their discovery when treating the graphene oxide with sodium hydroxide (NaOH) in an attempt to increase the usefulness of the oxygen containing functional groups believed to be bound to the graphene. Unfortunately it seemed to make things worse rather than better. Indeed at high enough concentrations of NaOH Dr Rourke was left with a black suspension.

The Warwick led researchers recalled that it had been shown that oxidation debris adheres to carbon nanotubes but the weak nature of the connection of this oxidation debris to the carbon nanotubes meant that a wash with a base can simply remove the oxidative debris. Experiments showed that in that particular case oxidative debris was found to make up almost a quarter of the mass of the “oxidized carbon nanotubes”. The researchers felt a similar process maybe happening in the Graphene Oxide they were studying.

The results may also help explain the inordinately high levels of oxygen people were claiming to find in graphene oxide. Chemists were already struggling to identify enough plausible carbon to oxygen bonds to accommodate the amounts of oxygen believed to form part of graphene oxide.

On centrifuging the black liquid the Warwick team were left with a pile of black powder that turned out to be graphene oxide that may once have been soluble before the application of the base but which refused to show any significant sign of being easily soluble again in its current state. The black material was found to shown to be very similar to graphene itself; in particular it was shown to consist of very large sheets of electrically conducting carbon atoms, unlike the insulating “graphene oxide”.

The remaining liquid was also dried to give a white powder that the Warwick researchers showed contained the “oxidative debris” or OD; the OD was shown to be made up exclusively of small, low molecular weight compounds (i.e. less than 100 atoms).

The graphene oxide recovered from washing process formed about 64% of the mass of the “graphene oxide” at the start of the process. The recovered OD or oxidative debris formed at least 30% of the weight of the mass of the original “graphene oxide”.

Drs Rourke and Wilson’s team believe this shows that much of the oxygen that was believed to be closely bonded to the carbon in the graphene oxide was actually not bonded at all but simply lying on top of the graphene sheets, loosely connected to them as “oxidative debris”. This oxidative debris contained a large quantity of oxygen that simply came out in the wash when the graphene oxide was treated with sodium hydroxide.

This creates a significant problem for researchers depending on an easily soluble form of graphene oxide as the level of solubility found so far was directly dependent on the high quantities of oxygen believed to be bound to the carbon in the graphene oxide. If much of that oxygen so easily falls away, so will the levels of solubility.

Drs Rourke and Wilson say “Our results suggest that models for the structure of graphene oxide need revisiting. These results have important implications for the synthesis and application of chemically modified graphene particularly where direct covalent functionalization of the graphene lattice is required.”

The paper entitled:

The Real Graphene Oxide Revealed: Stripping the Oxidative Debris from the Graphene-like Sheets by Dr. Jonathan P. Rourke, Priyanka A. Pandey, Joseph J. Moore, Matthew Bates, Neil R Wilson (all of the University of Warwick), and Dr Ian A. Kinloch, Prof. Robert J. Young (The University of Manchester), has just been published in Angewandte Chemie DOI: 10.1002/anie.201007520.

Notes for editors:

The researchers thank Dave Hammond for help with thermogravimetric analysis (TGA), Lijiang Song for help with mass spectrometry, and Ajay Shukla for help with X-ray photoelectron spectroscopy (XPS), the Midlands Physics Alliance Graduate School for a scholarship. The TEM, TGA, and XPS instruments as well as the mass spectrometer used in this research were purchased with support from Advantage West Midlands (part funded by the European Regional Development Fund) as part of the Science City programme.

For further information please contact:

Dr Jonathan P. Rourke
Department of Chemistry, University of Warwick
email j.rourke@warwick.ac.uk tel: +44 (0)24 76523263
Peter Dunn, Head of Communications
Communications Office, University House,
University of Warwick, Coventry, CV4 8UW, United Kingdom
email: p.j.dunn@warwick.ac.uk
Tel: +44 (0)24 76 523708 Mobile/Cell: +44 (0)7767 655860

Dr. Jonathan P. Rourke | EurekAlert!
Further information:
http://www.warwick.ac.uk

Further reports about: Oxid TGA XPS carbon atom carbon nanotubes chemist graphene graphene oxide

More articles from Life Sciences:

nachricht Researchers identify potentially druggable mutant p53 proteins that promote cancer growth
09.12.2016 | Cold Spring Harbor Laboratory

nachricht Plant-based substance boosts eyelash growth
09.12.2016 | Fraunhofer-Institut für Angewandte Polymerforschung IAP

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Electron highway inside crystal

Physicists of the University of Würzburg have made an astonishing discovery in a specific type of topological insulators. The effect is due to the structure of the materials used. The researchers have now published their work in the journal Science.

Topological insulators are currently the hot topic in physics according to the newspaper Neue Zürcher Zeitung. Only a few weeks ago, their importance was...

Im Focus: Significantly more productivity in USP lasers

In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.

Even back in the 1990s, scientists were comparing materials processing with nanosecond, picosecond and femtosesecond pulses. The result was surprising:...

Im Focus: Shape matters when light meets atom

Mapping the interaction of a single atom with a single photon may inform design of quantum devices

Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...

Im Focus: Novel silicon etching technique crafts 3-D gradient refractive index micro-optics

A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.

Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...

Im Focus: Quantum Particles Form Droplets

In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.

“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ICTM Conference 2017: Production technology for turbomachine manufacturing of the future

16.11.2016 | Event News

Innovation Day Laser Technology – Laser Additive Manufacturing

01.11.2016 | Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

 
Latest News

Researchers identify potentially druggable mutant p53 proteins that promote cancer growth

09.12.2016 | Life Sciences

Scientists produce a new roadmap for guiding development & conservation in the Amazon

09.12.2016 | Ecology, The Environment and Conservation

Satellites, airport visibility readings shed light on troops' exposure to air pollution

09.12.2016 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>