14 June 2013

Graphene wired – atom by atom, and other stories

It can take just one chemical bond to make an electrical connection to a graphene ribbon. Researchers at Aalto University in Finland and Utrecht University in the Netherlands did this with “single atom contacts between gold and graphene nanoribbons”.

The researchers describe their work in a paper in Nature Communications, sadly, hidden behind a paywall. Fortunately, the people behind the research are so enthused about their work that they have produced a press release. This points out the small at which graphene electronics can work, less than 10 nanometres. “This means that the graphene nanostructures have to be only a few tens of atoms in width.” 

The experiments described in the paper, “Suppression of electron-vibron coupling in graphene nanoribbons contacted via a single atom” showed how to do this. The research involved using atomic force microscopy and scanning tunnelling microscopy “to map the structure of the graphene nanoribbons with atomic resolution”.

The most significant discovery, they say, is that “a single chemical bond forms an electronically transparent contact with the graphene nanoribbon”. They conclude that this finding “may be the key to using graphene nanostructures in future electronic devices, as the contact does not change the intrinsic ribbon properties”.

Tie a graphene ribbon round your battery
Problems with lithium ion (LI) batteries may have given Boeing a headache, but this popular energy store has plenty of fans and down to earth applications. Now researchers at Rice University in Houston, Texas, have come up with a new way of enhancing the efficiency of the LI battery. Their idea, according to the university’s press release, is to employ ribbons of graphene that start as carbon nanotubes.

The researchers made anodes out of graphene nanoribbons (GNRs) and tin oxide. (The anode is the bolt hole for the lithium ions, which move to the cathode as the battery discharges.) This novel anode material, “showed an initial capacity better than the theoretical capacity of tin oxide alone”.

It will cost you US$35 to read the paper in ACS Nano, “Graphene Nanoribbon and Nanostructured SnO2 Composite Anodes for Lithium Ion Batteries”. (If it is worth writing a press release, isn’t it also worth providing free access to potential readers?)  So we have to rely on what the release says for signs of the true significance of the research. This claims that “After 50 charge-discharge cycles, the test units retained a capacity that was still more than double that of the graphite currently used for LI battery anodes.”

As much as anything, the team sees the work as a testbed for applications of GNRs, a fertile area of research for our wonder material. A member of the group, Jian Lin, a postdoctoral researcher at Rice, describes the research as “starting point for exploring the composites made from GNRs and other transition metal oxides for lithium storage applications.”
The Manchester PR machine rolls on
There was an odd story in the Financial Times this week. The print edition carried the tag “Graphene research” but there wasn’t much of that in sight. The on-line version makes it appear even more graphene oriented, with its title “Graphene breakthrough shows Manchester’s science credentials”. In reality it was mostly a gushing piece about Manchester University and its commercialisation of research that goes on there.

The peg for the articles seems to have been the recent press release that we flagged up earlier in the week (see Manchester untied). That was all about magnetism in graphene. Only time will tell us whether or not the paper described there was, as the FT dubs it, another “breakthrough”, but it is certainly a breakthrough in PR.  What on earth do we make of the statement that “The university is also home to Professor Brian Cox, the physicist and broadcaster, Sir John Sulston, the Nobel Prize winner who was involved in decoding the human genome, and Jeanette Winterson, the novelist.”

The FT’s article also has some numbers that do not seem to have any relationship with the graphene bit of the story. What do we make of the information that “the university had won £200m in research funding in the first 10 months of the academic year”? How much for graphene?

Then there is the bit that says that the university’s “£32m spin-out fund is funding several attempts to find commercial uses for graphene”. How much of that money has gone into graphene? Can’t they tell us something about those investments?

After all, the writer just needed to read some back issues of the FT. It was on in January that Clive Cookson wrote the article Graphene: Faster, stronger, bendier. This mentioned one of the Manchester businesses, Graphene Industries. Over on the university;s own site, the paper’s journalist could have read the PDF file that describes the launch, last February, of another company, 2-­DTech Ltd.

Manchester is a fine university, one of the best, and has an excellent record in knowledge transfer, the sometimes fraught business of getting research into the hands of people who can make money out of it. And you can hardly blame it for the FT’s decision to write something as baffling as this, with its strange mixture of graphene researcher, general university background and throwaway comments from the likes of Eric Schmidt, the chairman of Google.
Heavy metal and the graphene connection
The eyebrows rise when a paper begins “Heavy metal ions and humic acid (HA) in underground water pose a severe threat to public health and ecological systems”. Lots of buzz words in there to appeal to a science watcher. Throw in the title of the paper, “Synergistic Removal of Pb(II), Cd(II) and Humic Acid by Fe3O4@Mesoporous Silica-Graphene Oxide Composites”, and you ask yourself what is graphene doing in there?

The paper appears in PLOS One, a peer reviewed open access journal, so anyone can read it and work out for themselves what is going on. It is about hierarchically structured composites containing polyethylenimine-modified magnetic mesoporous silica and graphene oxide (MMSP-GO), whatever they are. The good bit appears to be that “MMSP-GO composites have shown promise for use as adsorbents in the simultaneous removal of heavy metals and humic acid in wastewater treatment processes.”

So you can add cleaning up the environment to graphene’s repertoire.

This blog is a random sample of the many stories on graphene that gush by. Think of it as a poor person's alternative to the expensive newsletters that you can subscribe to from commercial organisations that really do know what they are talking about. 

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