[HN Gopher] Tiny particles power chemical reactions - Massachuse...
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Tiny particles power chemical reactions - Massachusetts Institute
of Technology
Author : mardiyah
Score : 48 points
Date : 2021-06-08 12:19 UTC (10 hours ago)
(HTM) web link (news.mit.edu)
(TXT) w3m dump (news.mit.edu)
| imchillyb wrote:
| Ah. Good ol' carbon nanotubes...
|
| The only application CNTs fail -completely- at, is leaving the
| laboratory.
|
| Unlike those pesky CNTs, I'll just see my way out now.
| lumost wrote:
| This is a valid criticism. There are several threads in science
| that are seemingly funded indefinitely despite modest to
| negligible progress and other threads that are utterly starved
| for funding.
|
| Is there a bias at funding agencies that research in "carbon
| nanotubules" gets picked over "X research" year after year?
| pfdietz wrote:
| One long running research area that I'm reminded of is
| artificial photosynthesis. Let's make a combination PV cell
| and electrolytic cell, because optimizing both together is
| going to be totally easier than doing it separately. /s
| lumost wrote:
| From the perspective of a career minded professor sitting
| on a funding committee it's a good way to guarantee a
| growing set of citations. As long as people still research
| X the first papers in X will garner citations.
| jalk wrote:
| Oh like masers and lasers you mean ;-)
| malwrar wrote:
| This seems neat but I'm also a mere computer person and vaguely
| knowledgeable in electrochemistry. A few questions for anyone who
| knows more about this subject:
|
| I'm wondering where the electrons being yanked out of the
| particles come from, and how they end up flowing back into the
| nanotubes particles. Do they come from the carbon? Are they
| somehow stored in the tube structure? Also, how exactly do the
| electrons end up getting pulled back into the structure if
| they're yanked out in the first place. Wouldn't the system tend
| towards some equilibrium, rather than what I'm intuiting as an
| oscillation of charge?
|
| Also, how exactly does this give an advantage to nanomachines
| over a traditional battery? Do we just not know how to build them
| small enough, and therefore this is neat because we can (crudely
| worded, forgive me I'm not an expert) hook these particles up to
| nanomachines so they can generate power with the whole chassis
| suspended inside the solvent? Maybe it's just easier to
| manufacture than e.g. batteries?
| rpmuller wrote:
| This seems like a cross between a standard battery and a flow
| battery. A standard battery has an anode, separator, and
| cathode connected to each other, and counter-ions (eg Li+) flow
| from the anode to the cathode, allowing a wire connecting the
| anode and cathode to generate a potential, since the counter-
| ions "want" to be in the cathode more than in the anode. Many
| standard batteries can be recharged by reversing the voltage
| and making the electrons flow in the opposite direction.
|
| A flow battery uses a solvent for the anode and the cathode,
| which are then flowed through a tube containing a separator,
| across which the same voltage can be extracted. Flow batteries
| are recharged by taking the spent fuel out of the battery and
| re-oxidizing/reducing it, after which it can be reused in the
| flow battery.
|
| The way I'm reading this is that its the anode (CNTs) and
| separator (teflon) of a flow battery, with a reducible organic
| solvent molecule (CH3CN) serving the purpose of the cathode. I
| don't see anything playing the analogous role of the
| counterions, but perhaps this configuration doesn't need it
| because the distance traveled by the electrons is atomic-scale.
|
| So, the electrons come from the pi-shell of the CNTs, and flow
| into the pi-system of the CN group, where they can do some
| chemistry. The electrons don't flow back, since the band they
| flow into is lower than the band they come from (Fig 1b of the
| Nat Com paper). My reading of the paper is that the particles
| would be recharged by taking them out of the solvent and
| exposing them to a current.
|
| The advantage of this system over a traditional battery is that
| you can provide electrons at a higher potential to nanomachines
| that could then use that energy to do some work, without
| needing to be wired up to something. I'm thinking here of a
| molecule that "walks" along a fiber or something, and the
| higher enegy electron could cause a conformational change in
| the molecule to move it down the fiber.
|
| There's a nice analogy here to the way that biological systems
| use chemical species like NADH to fuel chemistry via redox
| reactions.
|
| Just the best guess I can make at this point, please reply if
| I've missed something.
| malwrar wrote:
| Thanks for this reply, makes sense to me now and now I have
| more things to Google! Any idea how they'd extract the
| particles from the solvent to recharge? I'll try reading the
| paper as well.
| rpmuller wrote:
| Filter paper? I'm only somewhat joking here, since I
| imagine the particles are micron-sized.
| rpmuller wrote:
| Correction: I meant "NADPH" instead of "NADH". It's been 25
| years since I've done any biochem, and obviously my skills
| have rusted (haha, electrochemistry joke).
|
| The Z-scheme in photosynthesis is exactly the type of way I
| could see this being used: put a high energy electron into
| one state, and generate a cascade of subsequent chemical
| reactions as the electron relaxes into a lower energy state:
| https://en.wikipedia.org/wiki/Photosynthesis#Z_scheme
| steve76 wrote:
| > Tiny particles power chemical reactions
|
| Yes. I'm sure they do.
|
| > Those electrons can be drawn out by submerging the particles in
| a solvent that is hungry for electrons.
|
| When I hear particle, I don't think of a little grain of matter.
| I think of anything that's discrete. If it moves a thermometer or
| a voltmeter, it's a particle, even if it's just a flash of
| brightness from something else.
|
| After reading the article, I immediately thought of a pipeline
| that's fully packed, not pumping oil, because of a cyber attack.
| Start lining the pipes in teflon. Look at parrafin oxidation.
| Inject a recipe into miles and miles of 40" pipe. And hook up
| cables to it. It turns into a giant battery, like how heat pumps
| have electric heaters on the outside unit when the temperature
| gets too cold. The petroleum oxidizes in the pipe, and at least
| you have some return on value. Probably will cost too much and
| not produce enough power, but better than just sitting there.
| Perhaps you can add really high pressure, and get good enough at
| some hot spots the reaction goes down to quantum chemistry, the
| entire thing is effectively plasma or quark matter for brief
| periods.
| thereisnospork wrote:
| My takeaways from the Nature article:
|
| The underlying driving enthalpy seems to be the solvent
| adsorption exotherm. By extension once full wetted the particles
| stop producing voltage, but can be dried and rewetted.
|
| As with typical electrochemistry both an oxidation and reduction
| are performed simultaneously: Oxidation on the PTFE side and
| reduction on the CNT side. Essentially each particle is its own
| little electrochemical cell, deriving its working potential from
| the solvent-surface interaction.
| refurb wrote:
| I was educated and worked as an organic chemist and did some
| organic electrochemistry and I have no freaking clue what this is
| about based on the press release. The attempt at putting it in
| plain English appears to have completely butchered any
| understanding of the science.
|
| It appears that by coating carbon nanotubes with telfon on one
| side (after ground into a film), they can create a potential
| gradient with an oxidizing solvent on one side? But so many
| pieces are missing - where do the electrons come from? What's on
| the Teflon side of the membrane? An electron donor?
| SKCarr wrote:
| Here's the link to the Nat. Comm. paper since I couldn't find it
| in the press release:
| https://www.nature.com/articles/s41467-021-23038-7
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