I would like to produce low concentrations of ozone through electrolysis of water. The standard setup to do this uses a graphite electrode and a platinum electrode in an $\ce{H2SO4}$ solution. However, I'd like to produce the ozone using only water and preferably using inexpensive electrodes. I don't seem to understand the exact chemistry of this, though. I'd like to know:

If I use different electrodes, what changes? I'm currently using zinc and graphite and, other than the fact that the zinc degrades, is there any downside to using it?

The $\ce{H2SO4}$ solution, I expect, increases the conductivity of the water, is that right? Why is it used? What if I don't use it?

How can I go about detecting the ozone in the water? When I run my system I seem to smell something ozone-y, but I'd like a much less subjective method than that.


First of all $\ce{H2SO4}$ produces $\ce{H2SO5}$ which is a peroxyacid during electrolysis which most electrolytes will not do, so I suspect that $\ce{H2SO4}$ will be mandatory unless phosphoric acid ($\ce{H3PO4}$) can. This peroxyacid give you a potential for a mechanism of ozone creation. $$\ce{H2SO5 + O2 -> H2SO4 + O3}$$
Note: I do not claim this to be the mechanism but only an explaination for why the $\ce{H2SO4}$ may be important.

The carbon and platinum electrodes are not only chemically resistant, but may likely have a catalytic effect in producing ozone. You can get platinum wire at a reasonable price if you look around.

In regard to testing if you have ozone, you can use paper strips that have potassium iodide impregnated in them. The ozone will oxidize the iodide ion and turn the paper strip brown.

  • $\begingroup$ Great, thanks. I'll try the new reaction and will try to hunt down some KI. $\endgroup$ – Michael Stachowsky Dec 14 '15 at 18:51

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