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Author: Subject: Platinum foil suggestions needed
Sulaiman
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[*] posted on 3-1-2017 at 05:22
Platinum foil suggestions needed


I have a side-project that I would like to get right first time, so I would appreciate any input;

Santa sent me 5x (80mm x 80mm x 233nm) Pt transfer foils
that I want to make one or two electrodes with,
for general aqueous electrochemistry.
(optionally as a catalyst would be nice)
I suspect only at low current density, but that is OK for my purposes.
So I need a substrate.

stuff that I have available and may be suitable;
. glass tubing of various diameters
. glass sheet
. graphite rods, various diameters
. graphite foil, 0.4mm thick
. lead sheet, 2mm thick
. titanium, 2.2 x 45 x 80 mm

I favour the electrically conductive options as it may help with current paths,
but glass would be electrochemically 'inert' in the case of errosion of the Pt,

In any case, I have never 'gilded' anything so if anyone has advice on
the substrate or giliding techniques please give suggestions.


[Edited on 3-1-2017 by Sulaiman]




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[*] posted on 3-1-2017 at 06:28


I routinely attach copper wires to various metals, pot them into epoxy, cross-section, and then polish them for electrochemistry.

IMG_3097.JPG - 1MB

In the picture above, it may not be obvious, but the electrical connections are completely sealed in epoxy. The only thing exposed is the flat surface of steel, in this case. For for room temperature work I'd use a copper substrate, and then attach the platinum foil with silver conductive epoxy. The platinum would have to be sealed around the edges with more epoxy, to protect the substrate. If doing it this way, make sure that all your materials are compatible with whatever chemicals are being used. Epoxy may shrink or dissolve slightly in contact with certain chemicals, for example. The silver conductive epoxy should have somewhat low viscosity for this application, I think, since the film is so impossibly thin.

I'm sure there are other ways to do it, this is my idea. I've never worked with such thin films before, as a disclaimer.




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Sulaiman
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[*] posted on 3-1-2017 at 07:00


I have a little electrically conductive silver ink that may work both for electrically connecting wires and adhering the Pt to a substrate,
but I'm not keen on incorporating silver as it easily ionises,
and pinholes in the Pt are inevitable.

Epoxy resin seems like a good choice for an insulator for seams in the Pt,
or maybe hot melt glue.

EDIT ; for rods (magnesium here) ring crimps and screws give a reliable connection


Cropped4SM.jpg - 2.3MB

[Edited on 3-1-2017 by Sulaiman]




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[*] posted on 3-1-2017 at 08:10


You don’t state your intended goal, but if you were planning to use these in chlorate or perchlorate cells it would be better to avoid epoxy, hot melt and silver paint. They will fail when exposed to the electrolyte. Also, your foil is very thin. I believe the thickness of the Pt coating on commercial Platinized titanium anodes is of the order of a few micrometers.



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Sulaiman
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[*] posted on 3-1-2017 at 08:57


I only intend to do gentle electrochemistry, electrode potentials, mild electrolysis.
I did not imagine that a sheet of Pt only 1500 atoms thick would be useful for a chlorate cell :)

I tend to over-engineer stuff, the cell I showed above was designed for a 100 uA load !

EDIT : No it did not perform as expected.
The theory was so simple and obvious, trivial really ... in theory.
On long term hold pending some electrochemical experiments that would benefit from a platinum electrode :)

[Edited on 3-1-2017 by Sulaiman]




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[*] posted on 16-1-2017 at 12:00


Perhaps way more valuable as that foil to the right people than even 0.1 mm Pt sheet!



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[*] posted on 17-1-2017 at 07:40


I wonder if the thinnest foils could spontaneously start glowing red hot in hydrogen/air or methanol/air environments?

[Edited on 17-1-2017 by Morgan]
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[*] posted on 17-1-2017 at 08:16


the foils that I have are 'transfer' foils, lightly adhered to a paper backing, making transfer to objects easier,
but I do not think I could get a manageable foil.
These may be more appropriate
http://www.ebay.co.uk/itm/Zinc-Alloy-Hand-Warmer-Filler-Cup-...
http://www.ebay.co.uk/itm/3-X-REPLACEMENT-CATALYST-PADS-FOR-...




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[*] posted on 17-1-2017 at 12:40


I was just wondering if a bit of wispy foil held or dropped into say an Erlenmeyer flask with methanol vapor if it would have enough surface area to activate. I can imagine foil that thin is hard to manage. I've a spool of .002ths Pt wire and even something as "large" as that is hard to see if you accidentally drop a piece of it.
This wick of mine from a hand warmer does spontaneously warm if misted with methanol but I was just curious about an ultra thin foil. Do you know how your foil is made, the technical aspects?
https://www.youtube.com/watch?v=UtkEfzpZ4Sg
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