Scrap Science - 2020-05-05
For a future project, I put together a graphite gas diffusion electrode. Normally, a gas diffusion electrode would require impregnation with a catalyst like platinum (which I may try in the future if I decide to build a fuel cell), however, the synthesis we'll be following doesn't call for a catalyst on the electrode, just a graphite surface. To make the electrode, I take a graphite rod and drill a hole down the centre. Pressurising this cavity with air allows gas to flow through the porous electrode and into the solution, creating a large amount of surface area to connect the gas, electrode, and electrolyte. Hopefully this electrode allows for electrochemical reactions involving reactants in the gas phase.
Cool, so you have a solution for making the gas diffusion electrode ! I don´t have to buy an expensive one. Great !!! Graphite should be plenty because it´s only in contact with an alkaline solution and being a cathode as you said at the other video it should last nearly forever. I think graphite only crumbles as an anode If I remember right. I tried it in the past for making chlorine from NaCl and that was my observation so far. Thanks for your credit anyway :D. I will also make a video to confirm you. And yes that is a good thing no catalyst needed haha. Do you know a method to make a membrane at home ?
That's the plan for the setup, hopefully using pots instead of membranes doesn't impact the yield too much
I'm afraid the glazing does block the current, as the liquid can't permeate through it. You'll either need to dremel it off as you said, or buy unglazed pots
@Scrap Science So would you use something like NaOH at the cathode and an acid at the anode? Then perhaps the OH- from the base and the H3O+ that ends up in the center (where H2O2 forms) would just form H2O? Though I don't know how the center region would conduct other than from the imperfect separation of ions which might defeat the purpose of using these two types at anode / cathode. Maybe I have the process all wrong though. Edit: Though I was just thinking... Maybe you could load the center with something like Na2SO4 and wait for conduction to drop to ineffective levels associated with the depletion of Na2SO4 and (hopefully) enriched H2O2.
@Sam Frazier You've pretty much got the exact idea of the synthesis. The paper uses dilute sulfuric acid in the centre chamber (H2O2 is quite stable in acidic conditions, and sulfuric acid conducts very well) and uses ion exchange membranes to specifically prevent depletion of the sulfuric acid in the centre chamber (anion exchange to the cathode, cation exchange to the anode). I'm hoping that using simple clay pot diaphragms instead of ion exchange membranes will simply result in the slow depletion of the sulfuric acid in the centre, along with a bit of a loss in efficiency.
Of course, the final H2O2 product will be contaminated with H2SO4, but I think that's okay. (In theory you could carefully react the acid with calcium hydroxide to precipitate the sulfate out of solution and get pure H2O2 like that, but I probably won't bother, keeping H2O2 in sulfuric acid is a good way to store it)
Love your channel man!
Glad you enjoy it!
I really look forward to seeing if you can make hydrogen peroxide by the method
I am a little sceptical of the paper, getting the reaction going without a catalyst seems a little too good to be true, but it'd be crazy not to give it a try given how easy it is to set up.
If it works, it should hopefully be very cool, I'm looking forward to trying it out
@Scrap Science if your setup works, i might try to make it myself!
@Scrap Science What is the paper called?
@morareduard The paper is:
'The Electrolytic Synthesis of Hydrogen Peroxide in a Dual Membrane Cell', doi:10.1149/1.2119897
@Scrap Science Thank you!
I think this channel will have 100 fold more subscribers inside 2 years
Cool Idea, man. That can be useful for something different too I guess.
Not right sure, but possibly glowing the electrodes while pressing the air through them, could increase porousity a bit more, due to oxidation of some Carbon in the wall. By the way, it also may be a way to impregnate the Carbon rod with Catalyst salts, as it should be possible to press a soltion (e.g. of a Titanium-salt) through them this way too and glow them after that. So you can make the Electrodes that are mentioned in this pdf https://patentimages.storage.googleapis.com/13/4d/99/dfbb875f401486/WO2010134717A2.pdf
Hello,
Do You know how can I make gdl on cloth?. Like ones available online?. Thanks
is that 1:24 Chlorine gas right? 6:09 there is oxygen gas! don't we inject oxygen gas into graphite?
Chlorine was just an example to describe my concept. Oxygen gas is what we really wanted to perform reactions with.
I have a Question! You showed us a partial phase of synthesizing hydrogen peroxide which is substitute for GDE, right? and The hydrogen peroxide hasn't synthesized in this video, then what is the gas in 8:28 is that HO2- ?
@김민석 I didn't take any steps towards synthesising H2O2 with this electrode in this video, I attempt that in a different video. At 8:28, I'm just running air through the electrode to test its permeability, no electrolysis is involved so HO2- is not generated, it's just acting as an air stone in this case.
@Scrap Science (O2 + H2O + 2e > OH- + Ho2- ) Is it right in order to make this chemical reaction arise, i have to do electrolysis every second? and keep pumping O2? I'm planning to make energy harvester like MAS(Metal Air Scavenger )that GDE is replaced with your video's Carbon Rod. So i should get OH- in solution.
I mean, that’s the reaction that’s meant to happen. I do have a video on trying to get it to work here: https://youtu.be/HjO8lv0qJnw
However, as I found in that video, the reaction doesn’t seem to proceed on the electrode without a catalyst. I don’t think this electrode is actually viable for reducing atmospheric oxygen I’m afraid.
Can you please make Na.
One day I'll get around to it. Eventually I'll probably build a down's cell and make some, but I don't have any plans to do so for a while.
Frank Ocean - 2020-06-04
You are making great videos! Consider recording reactions with tripod, it greatly rises video quality. peace