BaFuxa - 12-2-2018 at 12:40
Hi,
I am considering buying a platinum electrode. As of today, with my limited newbie knowledge, I can only think of H2SO4 from CuSO4 electrolysis as a
potential use. Even then it is cheaper to purify some drain cleaner. But, but, it might come useful some day and while I am still in the set up phase
why not go for one ?
Is it worth getting ? Surely there must be more than just that.
j_sum1 - 12-2-2018 at 16:53
Platinum is the holy grail of electrodes. If you have access to one at a reasonable price then by all means grab it. It will simplify just about any
electrolysis project you might want to undertake.
Fortunately, there are work-arounds. A MMO electrode on titanium substrate works well for chlorates and perchlorates. (Not so good on sulfuric acid.
Don't try it unless you want to throw away something expensive.) Lead dioxide works well for the CuSO4 to H2SO4 that you mentioned. Recommended is
a graphite substrate but I have made good use of a strip of lead that soon builds up an oxide coating. There are probably many other substitutes for
applications that are outside of my experience.
OTOH, if you are considering any appications where high purity is required or you are using exotic and expensive reagents then Pt is almost definitely
the way to go.
Bottom line, if it is cheap enough for you, grab it. Look after it. That probably means using other electrodes for random stuff where you don't
really know what you are doing. But if you are penny-pinching (like most of us) then there are other options.
Finally, you need to know that there are fakes and rip-offs out there. Nurdrage produced a "buyer beware" style video after he was sold a fake
electrode by an eBay merchant. Worth looking up. If the price you are quoted seems too good to be true then it just might be.
Cryolite. - 12-2-2018 at 17:54
I believe manganese/cobalt oxide on titanium also works for chlorate synthesis and maybe also for sulfuric acid from copper sulfate. The purity of the
starting materials is apparently crucial, though.
Sulaiman - 13-2-2018 at 00:25
Platinum is so expensive (30 USD/g) that I doubt the electrodes in question have much usable surface area,
which means low currents hence very slow production rates.
OR it could be that the platinum is just a fragile surface layer.
If you can get a large surface area solid platinum electrode cheaply,
then sell it at spot price and buy for yourself all of the equipment and chemicals that you want, including MMO electrodes 
For very small scale production or the investigation of electrochemistry
I expect a small platinum probe or wire to be very useful.
But remember, even platinum can dissolve in aqua regia
or have its active suface damaged by some sulfur compounds such as DMSO
... according to Wikpedia.
BaFuxa - 13-2-2018 at 01:44
This is what I am considering.
https://www.aliexpress.com/item/10-10-0-1mm-platinum-electro...
The seller also has some Nafion membranes up for sale, I do not think he sells c**p.
[Edited on 13-2-2018 by BaFuxa]
Sulaiman - 13-2-2018 at 02:13
If it is what I think it says it is, then
10 x 10 x 0.1 mm = about USD7 platinum cost.
A 1g platinum bar, including p&p would be half the cost, but 20 x 20 x 0.1 mm
(with some flattening required: hammer, press, between goods train wheel and rail ....) 
... but without a convenient connector. 
[Edited on 13-2-2018 by Sulaiman]