Chemical Vapor Deposition (CVD) is the method used to produce the highest quality graphene (usually on Copper). Several companies (Graphenea etc) have scaled up CVD and continue to work towards much lower $ / m^2 targets in the near future.
The main challenge in the industry is currently the transfer step. Current methods to transfer Graphene from growth substrate to target substrate are inefficient and not amenable to high volume manufacturing.
"Roll to Roll" (what the paper is referring to) aims to solve this - companies like Samsung, LG, and Sony have been exploring Roll to Roll systems for flexible electronics/display applications.
After flexible applications, the next step is to enable CMOS compatibility / transfer to Silicon wafers. I'm the co-founder of a company in Austin that is working towards this.
Can you give an insider's perspective on graphene's supercapacitor applications, if any? What does it mean in practice?
I realize given your disclaimer at the end if there are those kinds of applications you will want to promote them versus listing shortcomings, but if you would at least allude to the shortcomings too I would really appreciate the honesty: I saw a lot of articles about its supercap applications when graphene began to be synthesized but haven't heard much since (and it's not in your short list in your first sentence at all).
The Graphene Flagship is focused on developing methods for combining few-layer graphene and silicon nanoparticles to obtain high performance silicon-graphene anodes.
These new methods need to be cost- effective, scalable and compatible with commercial battery electrode fabrication methods (current bottlenecks). Progress continues to be made in scaling up capacity and size. Flexible graphene supercapacitors were on display at the recent Mobile World Congress
You might've seen this from Samsung - https://news.samsung.com/global/samsung-develops-battery-mat...
And How does graphene compare to carbon fiber in general? Will we make airplanes and spacecraft out of it someday?
Re: aerospace, from a recent report, "Graphene can give multifunctional benefits to composites, including increased mechanical properties and conductivity. To protect against lightning strikes, the composite structures of aircraft contain metal meshes or have embedded conduc- tive wires. Graphene-containing composites could provide lightning-strike protection with the advantage of a simplified production process and weight reduction.
This year, a team comprising engineers and scientists from Airbus, Aernnova and Grupo Antolin have developed a prototype aircraft component using a graphene- based composite material. A section of the horizontal tail plane leading edge (HTPLE) of the Airbus A350 XWB was manufactured using industry standard resin transfer moulding of a graphene-based composite. The performance of this prototype compo- nent will be validated through electrical, mechanical and impact testing during the Core 2 phase."
Major Conferences - Graphene Week, Mobile World Congress (Barcelona + SF), National Graphene Association (inaugural conference was Oct 2017)
Major universities in the US - UT Austin, UPenn, MIT, Stanford, Rice, Berkeley. Lot of activity in Korea, Japan, and China
Companies - Various companies on growth side. Lot of companies doing work in composites and coatings. Various startups looking into supercap, audio, sensor, battery, and water filtration applications
What is the approximate commercial cost of CVD-produced graphene sheets?
Treatment of fresh water is around 1kWh/m³, so it gets into the ballpark for freshwater treatment, though I presume some of the freshwater treatment needs to be performed on the desalinated seawater.
This places seawater as an equal to river or lake water for watering humans, but still expensive for watering crops; at 1kWh/m³, there would be about $1.50 of water in a $3.50 bushel of corn.
␄
† wikipedia: https://en.wikipedia.org/wiki/Desalination#Energy_consumptio...
‡ About page 12 of this presentation: http://www.nwri-usa.org/documents/Elimelech_000.pdf
https://electrek.co/2017/11/16/cheapest-electricity-on-the-p...
I suppose it helps the seasteading picture as well but I haven't really thought much about that.
Mostly if you can disconnect urban water planning from agricultural water planning it allows you to do things differently. Especially when it comes to water transport projects for coastal cities.
I wonder how one can stumble upon more presentations/summary reports like that on current state of other globally important issues.
It should also be hard to burn. It will probably require some water vapor to burn at all, and do it slowly.
Is helium really smaller than hydrogen?
hydrogen gas is two atoms
Continuous production allows for mass production, quality monitoring, and progressively increase in width, in a way that is not possible with batch process
For leak testing, it can be better than helium because the molecule is lighter. This raises the speed for any given temperature, and thus increases the rates of diffusion and effusion.
A downside is that hydrogen can burrow right into solid metal, one atom (proton) at a time, and then merge back into diatomic molecules. This creates a sort of internal pressure in the material, making it brittle. Hydrogen embrittlement is a significant problem, particularly with titanium.
All I can really remember from my thesis was I had a throwaway line describing graphene as a single layer of hybridized SP2 Bonded carbon atoms and examiner spent what felt like 15 mins of my allotted defense time grilling me about it (in reality it was probably only 1 or 2 mins but I was so freaking nervous at the time felt like it was dragging on forever)...
The result is, you'll see plenty of calculations telling it's possible. But it is probably not.
I also do not understand your second point. Surely, it is oxygen that is the missing ingredient in the burn rather than water vapor. What does water vapor provide to increase the rate of combustion?
With enough temperature and a high oxygen pressure, graphene will burn cleanly. But also will your furnace, and my bet is that both will do so at roughly the same temperature and pressure.
About the second point, oxygen does not react well with graphite because it's entire surface does not let its electrons go very easily. Graphene has similar properties. Water does catalyze the burning of graphite, it may very well do that to graphene too.
Pure carbon (as in graphene) should burn much more cleanly, provided abundant oxygen.