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Anode and cathode metals? (For electrolysis)

I want to seperate some water to get Hydrogen to play with, so I made a little electrolysis device with a 12v power supply. The only problem is that I have no idea what to use as the anode and cathode! Could I just use screws? Or pennies or something?

I have done quite a bit of anodizing and before that produced hydrogen for various experiments.

There is a lot of fance and expensive material out there that can be used, all have their good and bad sides, the later mostly in terms of being costly and hard to work with.

If neither extreme efficiency, nor extreme outputs are required you make a quite simple setup that takes out most of the contaminants that happen from corrosion.

Also it should be noted that the type of "salt" you add to the water plays a vital role to keep corrosion at a minimum.
For example sodium chloride is often used by starters, I prefer a just a few drops of Phosphoric Acid (rust remover).
As for the setup I used to produce small amounts of both oxygen and hydrogen:
Two 2L plastic bottles (one for O the other for H), connected with two hoses and a little in-line pump.

I connected the bottom hose from the first bottle to the outlet of the pump, the top hose to the bottom of the second bottle and from there the top hose back to the pump.

The pump itself was a sealed unit for the water dise with a magnetic drive, a filter capsule was attached to it - a filter is essential, but more later.

As electrodes I used just lead sheets that I rolled so they fit through the top of the bottles.

The electrical connection can be tricky if you want a proper seal, so I improvised by using hot glue to cover the wire (bend down on the bottle neck) and create an overall smooth surface on the screw top.

Gas collection was with simple balloons stuck on the top of the bottles.
The "trick" is that the connected pump not only assists to push the gas up but also filters out all solid contaminents.
Since all was sealed and a ceramic axle used there was no problem with corrosion or electrical failures within the setup.

Lead is far from perfect but it lasts quite a long time if phosphoric is used instead of salt.

I can't recommend on baking soda or even hydrochloric acid.

In a HV HHO generator normal water from the tap can be used withouth any additives but I guess that is a different topic.

Maltmash2 days ago

I found this image at: http://www.mikeblaber.org/oldwine/chm1046/notes/El...

(For a more comprehensive chart: http://en.wikipedia.org/wiki/Table_of_standard_ele... )

The way I understand it, the materials further down the chart will be better suited for use as an anode.

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Lovot24 days ago

The cathode can be made of regular steel because electrolysis actually reverses black rust and will not form more corrosion, in fact electrolysis is used to restore iron objects. I wouldn't suggest copper (including copper alloys) or aluminum for either electrode because they corrode rapidly when used for electrolysis. Carbon, high chrome stainless steel, chrome, any member of the platinum family, and gold all make good anode materials. The anode will definitely cost you more, if you want something that won't need a lot of maintenance and won't generate unwanted substances.

Qcks Lovot23 days ago

As a follow up to what Lovot has said here, when making an anode you have to choose whether you want something that's resistant to oxidation (chromium, gold, platinum) or cheap to replace without many chemical concerns (carbon).

The two properties tend to be mutually exclusive.

After that, any conductive material will work as an electrode, but certain shapes work better. You want a shape that allows for an increase in surface area. The more surface area touching a liquid, the more efficiently you will conduct electrolysis.

So... generally speaking, screws work better than nails. pennies work better then pins. you have to be conscious of the cost to fabricate a particular shape though.

hhocells1 year ago
You may use Stainless Steel grade 302 or grade 304 for the “Cathode” (the minus volt wire), but grade 316L is essential for the “Anode” (the plus volt wire).

If you're going to use both in one device, it is important o always make note which is which. Also remember to put a RED wingnut on the bolt connected to the 316L wire, and a BLACK wingnut on the 302/304 wire.
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djdole2 years ago
The different metals used for cathodes and anodes are not for electrolysis but are for acid batteries (and are usually zinc & copper).
You don't need specific metals for electrolysis, just a metal that conducts electricity, and the two electrodes don't need to be different metals (as they do if you were creating an acid battery).
The important part is having a solvent mixed with the water. (Pure water is non-conductive, so won't work.)

A little chemistry knowledge will help (polarity of hydrogen vs oxygen to identify which electrode is attracting which element).

Also be aware that certain metals will react differently in the electrolysis reaction, combining with either the oxygen or hydrogen to produce new compounds (and in doing so, corroding your electrodes over time).

For example, when I was in 6th grade I used a home-made electrolysis rig to split baking-soda water into 2 parts hydrogen to one part oxygen.
I also used large chunks of copper for my electrodes which meant that on the one polarity, some of the oxygen combined with the copper and created copper-oxide. Later I collected and concentrated the copper-oxide and used that as my solvent in the water. I then by clipping a quarter to the opposite electrode I reversed the reaction and copper-plated the quarter.
Science fun!
I cant remember what we used in general chemistry, but we were calculating columbs and Avogadros number and all that. Save the water that is left over because it has a higher % of "heavy water". I dont know how to make it more pure but its something to play with. :)
NachoMahma5 years ago
. For small batches of home-brew Hydrogen, electrode composition is not that important. Think of them as sacrificial and use something cheap (eg, Copper). . If you plan on making large quantities, then you may want to use something like Carbon, Platinum, &c, as mentioned by others.
Carbon, even pencil leads, for small stuff a mechanical pencil refill pack would do alright. Platinum would be best, I suppose a serious person might use platinum spark plugs as a substitute for buying platinum rods. Silver and gold would probably do well...
westfw5 years ago
Probably the easiest and most inert electrode material you can get easily is a graphite or "carbon rod", like from inside an old-style ("Heavy Duty", but NOT "alkaline") battery. Graphite rods are apparently available as as welding supply (?)
They are used at extremely high amps to cut metal. The arc heats it and then the molten metal is blown out by compressed air. I use them for welding thin sheet (I even made in instuctable about it)

Kiteman5 years ago
The perfect material would be platinum, but otherwise use carbon. I have had plenty of success with pencil-leads (the soft ones conduct better, but snap more easily), so I assume artists' charcoals will be as good.
oops, forgot about carbon, lol, my bad
guyfrom7up5 years ago
out of common materials, I think alluminum is the best
Login258 (author)  guyfrom7up5 years ago
So it doesn't really matter? I figures since stainless steel resists oxidizing (right?), then fewer oxygen bubbles would form and I'd get more hydrogen... Any idea? I'll try out aluminium and let you know how it works!
well, you get the same amount of hydrogen and oxygen, it's just stuff like iron and steel (not sure about stainless steel) will oxidize (rust/corode) really quickly, alluminum still will, just not as fast.
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