Platinum and Iridium Electrodes in Fuel Cells

[njaohnt]

I was looking at platinum electrodes on the internet, and I noticed that they sell an alloy of platinum and iridium in a wire (80% platinum). It is a lot less money than other electrodes. Would that work for electrolysis of water, and as a catalyst in alkaline/PEM fuel cells?

[Enthalpy]

Would a graphite electrode work for your water electrolysis? For my teenager experiments, it was good enough, while the drawbacks of copper were obvious. Pencils are not pure graphite, but the central electrode of a saline zinc battery is.

 

For electrolysis, the contact area with the liquid matters a lot, hence a wire would not be my first choice. I'd pick something like a copper foil (or a printed circuit: 35µm copper on epoxy +glass fibers) plated with few µm gold.

[njaohnt]

Thanks, but still want to know weather the wire would work or not, and if so if it's better than graphite or not. Has anyone tried it?

[EdEarl]

Almost any conductor will work as an electrode. However, catalytic materials are better.

 

Leonard Niedrach, devised a way of depositing platinum onto the membrane, which served as catalyst for the necessary hydrogen oxidation and oxygen reduction reactions.

From: http://en.wikipedia.org/wiki/Fuel_cell#History

 

The wiki article does not mention iridium, but it is rare and may also be catalytic. Maybe there is a better one.

 

 

Diamond catalyst shows promise in breaching age-old barrier

In the world, there are a lot of small molecules people would like to get rid of, or at least convert to something useful, according to UW-Madison chemist Robert J. Hamers.

 

See: Homemade Diamonds

Edited July 3, 2013 by EdEarl

[Parshotam]

It is very amazing that graphite is non metal but it is used as the best elerode in electrochemical cells. It is just because of one free eletron in its pz orbital.

 

It means a pencil can behave as an electrode.

[Enthalpy]

Graphite is an assembly of molecules, not an atom.

[elementcollector1]

Pt/Ir alloy would be excellent for electrolysis, as it's pretty much immune to corrosion short of aqua regia.

(Do you have a source? I might look into buying some of this.)

[deltaH]

Pt/Ir would be great, but if you are just using a wire, then you will not be able to run very high current in your cell because the surface area of your wire is very small, however, as for durability and the especially water electrolysis, it should perform well on a small scale and for demonstration purposes.

[Sensei]

Thanks, but still want to know weather the wire would work or not, and if so if it's better than graphite or not. Has anyone tried it?

 

 

If you want to produce just Hydrogen from water, you don't need to worry too much about material from which there are made electrodes.

It's important only when you want to produce pure Oxygen or both.

 

f.e. when you will use aluminum plates or wires, on negative electrode there will be created 8 times more volume of Hydrogen than Oxygen on positive electrode f.e. 25 cm^3 H (single test tube) and 3.125 cm^3 O.

After a while you will see that aluminum is disintegrating and water is full of white suspenion. It's Al2O3.

 

While using different materials for electrodes you will create different oxides.

 

See post #9 and #11 in http://www.scienceforums.net/topic/79096-what-are-units-in-chemistry/

I have provided there more informations.