More on PbO2 electrodes

Probably, gasses formed from electrolyte reaching the LD/graphite interface produce enough pressures to crack it eventually. Funnily, never seen any of the composite LD coated anodes crack like that...apart from the higher electrical resistance it is also likely the composite substrate anodes (or LD itself) were probably porous enough to let most of the gas pressure escape without catastropic failure like that. Might be interesting for forming solid LD anodes.

A thicker coat of better quality LD and pH control will probably also help...Since the part of the GSLD anode that is not submersed in the electrolyte is hardly eroded at all at the LD/graphite interface, I wonder if you could design an almost solid lead dioxide lower (submersed) part, which is attached to a almost complete graphite "base", which itself is not submersed, and mostly used as electrical connection. Something like that should be possible using 2 separate LD coating runs. Maybe using this scheme, even a relatively porous LD coating would prove quite durable, even with no pH control. Due to the very low surface area of the lower graphite part, a catastrophic failure would probably be unlikely.



Having read about some GSLD anodes having been gone through 2 years of continuous operation before failing...wonder if the LD coating and pH control were really good enough to protect the underlying graphite substrate for that long. A crazy thought would be that they were running an empty shell of very porous LD, still holding on to the unsubmerged upper part of the intact graphite substrate.

[Edited on 11-8-2020 by nitro-genes]

Yeah, I would kind of take such claims (2 years of continuous operation) with a slight grain of salt All the experience collected so far suggests that such durability is rare at best, if not totally impossible on most instances.

I have also included a pic of my lead ion perchlorate cell here with the lead ion feeder to buildup more PbO2 by continuous leeching of Pb(ClO3)2 via a second lead anode of smaller surface area than the immersed graphite.

so I first plated PbO2 onto EDM graphite and got a uniform coating that had lots of pits due to this membrane sucking hard!!.
I notice this PbO2 was unlike my one made with lead acetate which had really bad conductivity as the thickness grew up to like 3mm when it literally had electrical conductivity of 100 ohm or some crap.
This lead chlorate made PbO2 is highly conductive giving 0.3 ohm resistance when probed with multimeter.

This was plated at room temp with Pb(ClO3)2 and Pb(ClO4)2 solution made with membrane although this membrane isnt like my others which was properly constructed for ion exchange electrolysis for making exotic chlorates/perchlorates, this one is for a chloro alkali cell its more permeable to the solution and PVA would fuck off due to the strong acids involved.

anyway I added superglue to support the initial layer and it seemed to have helped stabalize the coating and after sometime the PbO2 grew around the superglue and made a nice thick coating that doesnt peel off.



[Edited on 12-11-2020 by mysteriusbhoice]

made another one of these this time plated with ultrasound and very low current density of 6ma/cm^2
flaky was from previous plating attempt which sucked cuz I used too high current density.
It was extremely hard to remove the old plating that was all bumpy because even while running it in NaCl at 300ma/cm^2 it just wouldnt come off.
I had to run it as a cathode which finally took out most of it away and then plated only using ultrasonic bath with low current for this currently nice even coating.



[Edited on 17-11-2020 by mysteriusbhoice]

one of my latest runs with it




old video on previous run
https://www.youtube.com/watch?v=JZWofKi_K8w

[Edited on 6-12-2020 by mysteriusbhoice]

Quote: Originally posted by Fyndium

What is the caveat in this: https://www.youtube.com/watch?v=bZMWEYiTtso If PbO2 electrodes are so trivial to make, why are everyone using expensive Pt anodes? I should try this as I still have the entire pack of purpose-cast lead plates hanging around. Electrolysis would be a fun side project for my boring days.

cuz ppl are not chad enough to use an ion exchange electrolysis cell and a polymer/ceramic composite on Ti carrier substrate base.

I run my cell at 225ma/cm^2 and have a video of my homemade PbO2 anodes

Also heres some ammonium perchlorate 200g

Quote: Originally posted by yobbo II

Lovly Jubbly. A dude once stated: Tartrate bath allows Co and Bi doping, is non smelly and easy to control. It is also convenient to prepare the bath by dissolving lead anodically. Low lead content seems to be an advantage regarding Ti substrate, because it's easy to prepare large anodes with thin coating. No need for stockpiling lead compounds by the 10's of kgs. Alpha seems to give way better CE too and is stress free without additives, so no peeling problems at all. Some modifications for ATX and 12V server power supplies for constant voltage and constant current mode. Ones of the best are "HEC" brand 300W ATX models with passive PFC. They are very easy to modify for 0-7V 0-40A use. While looking for ATX power supplies, it pays to take a look at the PCB. Ones with (TL)494 and LM339 are almost the same design regardless the brand. Beefier examples are HP PS-3701-1(12V 60A) Dell AHF-2DC 2100W(12v 175A). STYHI. Yob

Quote: Originally posted by Jome

Pb/PbO2 anodes tend to have the PbO2 holding up for a while, then flaking off. I think the Pb(ClO3/4)2 bath-method seems really promising, electrolysis is easier than distilling HNO3 to get Pb(NO3)2, which involves noxious gas-evolution and restrictable chemicals. If I'm doing a perchlorate cell, I think the route would be a Pb/PbO2 cell to get some initial chlorates/perchlorates, then using a membrane cell to plate PbO2 onto some kind of ideally non-restrictable substrate. I do have a dead computer with a working PSU, but there's likely a better thread for that.

my latest Polymer-graphite substrate on Ti Beta-PbO2 plated electrode seems to work well at 207 ma/cm^2 even less errosion than the polymer-PbO2 on Ti beta-PbO2 plated electrode.
The feed was the remainder of my dirty NaClO3 not even crystalized just boiled down contains about 10% NaCl added a bunch of sulfate additives just now and forward feed of NaClO4 but only time will tell if it survives atleast one full conversion run past the ozone evolution stage!

The dirty chlorate feed usually causes this type of errosion to occur initially due to the chlorides.



Divide 27.3/17 = 16.06 amps
Surface area of one face = 77.42 cm^2
(16.06*10^3)/77.42 = 207ma/cm^2

[Edited on 20-1-2021 by mysteriusbhoice]

Quote: Originally posted by RogueRose

I saw some people mentioned making lead plates as electrodes and that is something I can certainly do very easily as I have a large ingot of very old, pure, soft lead. I also have some lead that has some antimony which is a good bit harder. Later this week, I will have some 99.95% pure: lead, antimony, tin, bismuth, zinc and copper from which I could make an allow for the places and I can make it as thick as necessary. do you think 3/16-1/4"+ will be fine? I don't think I can make them much thinner with something in the middle like this. So my question is whether I should try putting some wire mesh inside the plate electrode. I can use 1/4" square steel mesh or stainless mesh which I can get in just about any size. I can also get various mesh's in aluminum. Is there anything that needs to be done after making the plates - similar to how lead acid batteries are put in sulfuric acid to turn one side into PbO2? Or will this be done in the process of electrolysis?

Quote: Originally posted by mysteriusbhoice

Quote: Originally posted by RogueRose   I saw some people mentioned making lead plates as electrodes and that is something I can certainly do very easily as I have a large ingot of very old, pure, soft lead. I also have some lead that has some antimony which is a good bit harder. Later this week, I will have some 99.95% pure: lead, antimony, tin, bismuth, zinc and copper from which I could make an allow for the places and I can make it as thick as necessary. do you think 3/16-1/4"+ will be fine? I don't think I can make them much thinner with something in the middle like this. So my question is whether I should try putting some wire mesh inside the plate electrode. I can use 1/4" square steel mesh or stainless mesh which I can get in just about any size. I can also get various mesh's in aluminum. Is there anything that needs to be done after making the plates - similar to how lead acid batteries are put in sulfuric acid to turn one side into PbO2? Or will this be done in the process of electrolysis? The issue with surface oxidized lead as PbO2 anodes is that a perchlorate cell runs at ridiculously high current densities about 200 ma/cm^2 and that will just shred your electrodes!! hence why methods involving the use of a Ti substrate with a plating of conductive undercoat! like MMO or MnO2 via nitrate decomposition or cathodic deposition of MnO2 via manganate/permanganate are used. The salts used for PbO2 deposition I find useful are lead nitrate and lead perchlorate for conductive beta PbO2 and also lead acetate to plate some stress free alpha PbO2 intermediate layers. Dopants like iron and bismuth added to alpha PbO2 can even allow you to use it as an active surface layer but theres no point due to it erroding away after a few runs.

decided to also plate one of my older MMO anodes which looked like it was about to die due to being used for 8 years and the coating being highly discolored.
the PbO2 plating on this is quite thick about 0.2mm which should be quite decent for Ti substrate anodes.
The plating is produced by first using alpha PbO2 plating bath via lead acetate in membrane cell.
Then placed in the lead perchlorate bath to plate beta PbO2 with alternating between the 2 baths in this cycle.
12 hours in the beta PbO2 bath and 30 mins in the alpha PbO2 bath where hopefully it will make this coating stable as I drive 200ma/cm^2 through it.

about the superglue composite PbO2 on lead substrate PbO2 anodes they are amazing but not for perchlorates!! for making H2SO4 from CaSO4 with NaOH catalyst they can run at 200ma/cm^2 no problem at 12v!! across the membrane and not shed during the run because heres my crop from that latest run on that project plus a video showing the concentrated acid from the cell.
https://www.youtube.com/watch?v=t5gppFbrtWE

Quote: Originally posted by Laboratory of Liptakov

How you anyone opinion on this electrodes. The price seems pretty good. Even free shipping. 83 Euro only. Even with M8 thread rod. Easy solid montage. https://www.ebay.co.uk/itm/PbO2-MMO-Anode-Cathode-electrodes...

I have strong air cooling for cells. With the thermostat (sensor on the glass) set to 55 C. The transformer and rectifier also have their own fans. Why is necessary use the exact current range..? At least 200 - 215 mA/cm2...?
I thought the current might be lower. Process NaClO3 to NaClO4 will take longer. Thats all. I'm in no hurry. With a lower current, for example only 150mA / cm2, the life of the PbO2 surface increases. Electrode spacing 1.5 to 1.8 cm..?. Important, Thanks.
Operating voltage 4.5 V to 5.5 V. Thanks. Isn't that too much?
Thanks ....

Quote: Originally posted by nitro-genes

Was curious if using isostatic graphite as substrate would allow a good coat of LD to form from a more impure lead nitrate bath. An identical isostatic graphite rod was plated excactly as posted 2 posts above, using same setup and conditions. First 8 hours of plating at 30-40 mA (3-4 mA/cm2), then 1.5 hours of plating at 600 mA (50 mA/cm2), and finally, 6 hours of plating at 60 mA (4 mA/cm2). Only differences were (1) that both Cu(II) and Pb(II) concentrations were lower, (2) that the lead nitrate used in this bath was made from fishing weights and (3) the bath had been used several times for previous plating runs. Very little nitrite was present at the start of the run though. The result was a visibly good, 1mm thick, coating of lead dioxide. No pinholes or large imperfections. This is probably mainly a function of the isoelectric and smooth surface properties of the isostatic graphite. Overall the coating seemed very porous though and consisted of small spherical nodules and/or dendrites loosely held together. When a drop of water was placed on the anode, the water would slowly migrate as through filter paper. The anode failed after 5 days of use at 2 A (200 mA/cm2) in the cell. The part of the anode above the surface of the electrolyte was completely intact. The part immersed in the electrolyte completely powdered and eroded away. The LD on the intact part of the anode was extremely well adhered and could not be separated from the graphite substrate without breaking parts out of the graphite substrate. The LD was recovered as large shards at the bottom of the cell, without any graphite still attached to it. A cross section of the LD recovered seems to indicate that the porous nature of the LD is not limited to the surface only, so overall this seems the most likely cause of failure. Interesting what causes this effect...The lead nitrate produced from the fishing weights always produced these grainy textures, so it seems the purity of the lead nitrate is very important for plating. From what I've read a nodular appearance could also be due to break down products of the detergent used or maybe iron contamination. Just shows that even a visibly good coating of LD is no guarantee, it really needs to be dense and shiny. [Edited on 27-6-2020 by nitro-genes]

Wow you know my PbO2 anodes are from fishing weights and yea it produces a blue gray porous rough coating but thats not biggie I just put inbetween layers of alpha PbO2 using alkaline lead acetate bath to stabalize and strengthen the layers.

This process still leaves a somewhat porous coating which is why it never seemed to work for graphite but worked fine for plating on MMO or conductive epoxy composite.

The electrodes made from the 2 plating solutions method though can be run at really high current densities with no issues with the most ive run was at 250ma/cm^2

The pic below is my 3rd run with these electrodes with 0.35mm coating thickness and surprisingly the bath does not contain brown or anything and the coating is still on there.
The cloudiness is my additive of magnesium sulfate which due to pH increase PPT out some Mg(OH)2 which just sits there and is not an issue.
I use the MgSO4 to control the pH and maybe add some sulfates to reduce errosion from left over chloride in the fresh chlorate feed.

new copper plated Ti ready to be plated with alpha PbO2.
Copper plating directly on Ti requires a few really cursed reagents to get it to be adherent but after the fact even a belt sander tooks some time removing a thicker deposit of copper on a Ti plate.

Quote: Originally posted by macckone

mysteriusbhoice, What happened with your lead oxide on lead anodes? I know they have more problems with flaking but what kind of current were you able to get?

Quote: Originally posted by macckone

So the only real problem was the flaking. But sounds like you didn't test to failure on amperage.

OH it can take the amps but the fact that it fails due to diffusion and eventual attack of the base substrate means its unsuitable.
It eventually turns into a white cloudy mess and stops conducting then falls apart so easily.
There is also no real point in pursuing that further since alpha PbO2 from plumbate on Ti or any other substrate is really good for making chlorates.

Anyway heres an update on the PbO2 on copper coated Ti mesh down below.



[Edited on 5-8-2021 by mysteriusbhoice]

After adding a final plating in the Pb(ClO4)2 solution it now looks perfect!! ready for testing.
The Pb(ClO4)2 plating solution is doped with F- via 10ml of 10% HF and several unnamed alcohols surfactants were added.

The next update will be after testing the electrode with a full run from chloride to perchlorate at 250ma/cm^2 as per standard.

Ti substrate Cerium-Nickel doped PbO2 before and after coating of PbO2

cerium nanocomposite alpha PbO2 anode.




update:
The errosion rate after 1 hour was 1 micron then next hour less than a micron and the cell liquor changed to slight darker color.

The electrolyte for wear testing is KCl with pH control and current density is 200ma/cm^2.
PbO2 is erroded by chlorides and so far the previous anodes had measurable errosion rates but this one seems to be within the margin of error of the measuring scale.

I dub thee PbO2 nanocomposite metal oxide (NMO) electrodes

[Edited on 31-10-2021 by mysteriusbhoice]

Quote: Originally posted by mackolol

Could you elaborate? You say, that the alpha PbO2 layer must be done correctly to be resistant. So I guess that you put it in 0,1N Pb acetate , 0,4 N sodium acetate solution with lead carbonate as a source of lead ions (won't the lead acetate be enough?) and then put very low current at the copper-coated titanium strip to obtain the PbO2 layer as non porous as possible right? What would be the current and exact procedure? [Edited on 7-3-2022 by mackolol]

Quote: Originally posted by mysteriusbhoice

after making another anode id say the way to guarantee a good plating quality is to have 2 plating solutions and alternating between them. plate in alpha lead dioxide plating bath as initial layer made from 0.1N lead acetate with 0.4N sodium acetate mixture with exchess Pb(OH)2 or PbCO3 at 15ma/cm^2 initially for 15 minutes to get a strong adherent base coating.

I made another thick one

Quote: Originally posted by mekanochemical

A little question about the cell running Here the table salt came with a small amount of potassium iodide (around 40mg per kg), is it harmful to reaction or to electrodes?

Quote: Originally posted by wg48temp9

Quote: Originally posted by mekanochemical   A little question about the cell running Here the table salt came with a small amount of potassium iodide (around 40mg per kg), is it harmful to reaction or to electrodes? Its better to use dishwasher salt. Its much cheaper than than table salt and has no added spurious ingredients.

Quote: Originally posted by Waffles SS

I dont know here is right place to ask this question or not but what you think about using two Cathode one PbO2 electrode and another MMO electrode at same time in electrolysis of salt? This is possible to use those at same time as cathode?

Quote: Originally posted by mysteriusbhoice

you cannot use 2 different anodes PbO2 and Ir-Ru or Ir-Ta at the same time because one would sorta act like a cathode due to differences in operating potential thus causing reduction and damage to the electrode. Yes you can use 2 Ti/steel cathodes to get even current density loading.

Quote: Originally posted by Waffles SS

Thanks and sorry for my mistake (I write Cathode instead of Anode) My question was using two Anode(PbO2 and MMO) at same time and one Cathode(Ti) for electrolysis of brine. [Edited on 6-9-2022 by Waffles SS]

Does anyone currently, for example this year, have experience with purchased PbO anode? Which seller to choose? Low-quality goods, or even almost non-functional anodes, are often sold in this field.
Thanks.....

Quote: Originally posted by Laboratory of Liptakov

Does anyone currently, for example this year, have experience with purchased PbO anode? Which seller to choose? Low-quality goods, or even almost non-functional anodes, are often sold in this field. Thanks.....

mysteriusbhoice.........Thanks very much. Best looks 6 amps anode + 2 kathodes. I have seen your videos. Making your own anode (PbO) is a job for experts. Not for me. Your other work around, setting and etc. this is of course very valuable....

Quote: Originally posted by Laboratory of Liptakov

mysteriusbhoice.........Thanks very much. Best looks 6 amps anode + 2 kathodes. I have seen your videos. Making your own anode (PbO) is a job for experts. Not for me. Your other work around, setting and etc. this is of course very valuable....

Quote: Originally posted by Laboratory of Liptakov

Thanks. Way will 2x Ti cathode / MMO anode. For maximal concentration NaClO3. And after 2x Ti cathode / PbO2 andode on NaClO4. Is necessary add some trace compounds in process NaClO4? Respectively, is timelife of PbO2 sensitive on some acid od alkaline medium? Thanks.

Ingenious answer.....Thanks very much......