Published on January 8th, 2015 | by Tina Casey6
New Graphene Compound Could “Revolutionise” Clean Tech
January 8th, 2015 by Tina Casey
If you’re thinking that the screamingly fast drop in oil prices will beat clean tech into the ground for the foreseeable future, guess again. This is not your father’s oil price cycle, and the next generation of transformative energy technology is already on the horizon. Case in point: graphene, the “nanomaterial of the new millennium.”
In the latest development, researchers at the University of Exeter have developed a graphene compound that could help resolve some problems with a material commonly used in solar cells and other clean tech electronic devices.
Meanwhile, over here in the US, the Energy Department’s cutting edge funding agency ARPA-E has kicked off 2015 with an open call for $125 million in transformative energy technology, and the new LITECAR challenge for transformative auto design curated by Local Motors. We’re guessing graphene could play a role in some of those projects as well.
Meet Graphene’s Cousin GraphExeter
For those of you new the topic, graphene is a sheet of carbon only one atom thick, which you can DIY by taking a piece of sticky tape to a chunk of graphite (think pencils and now you know what graphite is used for, among other things).
The discoverers of graphene did exactly that back in 2004, and ever since then the materials research field has been head over heels in love with the stuff, generating thousands of papers detailing its unique and powerful conductive properties.
However, at one atom thick graphene presents some enormous problems in terms of commercial manufacturing, which is why some teams have taken to figuring out ways to combine graphene with other, more compliant materials.
The problem is how to find materials that will preserve graphene’s superior characteristics.
At the University of Exeter, the solution was developed in 2012. It’s a graphene sandwich, with two thick layers of graphene for the bread, and a nice thick layer of ferric chloride molecules for the meat (or veggies for you vegans out there).
The beauty of GraphExeter is the combination of the new and exotic — graphene — with a widely used, commercially available material. Also called iron chloride, ferric chloride is a common industrial material used for copper etching, sewage treatment, and water purification among other things.
The Next Step For Clean Tech, Via Graphene
So, here’s where things get interesting. It’s been two years since the development of GraphExeter was announced, and the folks over at Exeter haven’t been cooling their heels since then.
Apparently the team was not initially aware that GraphExeter was particularly durable, partly because ferric chloride has a tendency to melt at room temperature. Also it dissolves easily in water, which is a problem.
In other words, you can’t use ferric chloride all by itself, because it falls apart when exposed to air and weather.
When the team started putting GraphExeter through some stress tests, they found that graphene provides the stability that ferric chloride lacks. The results showed that their new graphene compound could even beat out indium tin oxide (ITO), which is commonly used as a conductive material in solar cells, LEDs, and other clean tech applications.
Specifically, they found that GraphExeter could hold up under high humidity, to the tune of 100 percent at room temperature, for 25 days.
They also found that it could withstand temperatures of up to 150 degrees Celsius (that’s 302 degrees Fahrenheit for those of you in the US).
In a vacuum, GraphExeter showed even better results, performing at up to 620 degrees Celsius (1,148 degrees Fahrenheit).
The figure below shows the results of subjecting a GraphExeter sample to heat at room temperature and up. The white scale bar corresponds to five nanometers (a nanometer is one billionth of a meter):
Here’s lead researcher Dr. Monica Craciun enthusing over the results:
By demonstrating its stability to being exposed to both high temperatures and humidity, we have shown that it is a practical and realistic alternative to ITO. This is particularly exciting for the solar panel industry, where the ability to withstand all weathers is crucial.
New Uses For Graphene-Enhanced Materials
Did we mention that GraphExeter is transparent? We didn’t? We must have skipped that part in the press materials, but we looked up the study online and we finally put two and two together.
ITO (indium tin oxide) is a transparent material, which makes it ideal for solar cells, LEDs, “smart” windows, and display electronics, but it has a couple of limitations, one major one being its brittleness.
If you can find something to sub in for ITO that’s flexible as well as transparent, and can at least equal ITO in efficiency and cost, then you’re talking transformation.
If you’re interested, the results of the study have just been published at Nature, in the journal Scientific Reports, under the title “Unforeseen high temperature and humidity stability of FeCl3 intercalated few layer graphene.”
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