Producing Hydrogen Gas Cheaply

[Archaeanimus]

I am trying to work out a method of producing hydrogen gas (H₂) cheaply. What I have so far is an electrolytic cell with carbon electrodes from a dry-cell battery powered by an A/C-D/C wall converter with output from 1.5V to 12V. I plan on using distilled water, but I don't want to rely on the water self-ionizing to split the molecules as this would take a VERY long time. The electrolytes I've looked at so far are sulfuric acid (H₂SO₄), hydrochloric acid (HCl), potassium hydroxide (KOH), and sodium hydroxide (NaOH). I'd like to use something relatively cheap and unlikely to produce poisonous gases (ie, Cl₂) and production of oxygen would be a plus. Any suggestions?

 

[Borek]

Go for sulfuric acid or one of hydroxides. HCl is out of the question.

If you start with NaCl you will initially get some chlorine, later you will be left with just a hydroxide solution.

If you start with HCl, once all chlorine is removed from the solution, you are left with just pure water.

 

[Archaeanimus]

Thanks, I figured HCl might do that.
Sulfuric acid (I believe) will produce peroxodisulfate ions at less than 1V, but electrolysis of water takes at least 1.23V.
I know KOH is used in the extraction of heavy water, but I don't know what else it produces, if anything. If I do decide on the hydroxide, though, I think I'll use NaOH because the chemical properties are similar and it's a bit cheaper.