Practical considerations for electrolysis of water
I'm interested in electrolysis of water to form O$_2$ and H$_2$, as pure as possible given the constraints of a "household chemical" setup. I've read other questions on here (in particular, https://chemistry.stackexchange.com/questions/89728/best-settings-for-electrolysis-of-water, https://chemistry.stackexchange.com/questions/38952/does-the-electrolysis-of-water-produce-chlorine-gas, https://chemistry.stackexchange.com/questions/116145/why-would-water-and-not-saltwater-undergo-electrolysis and others), but still have some open questions, in particular concerning the used electrolyte and the material of which the anode/cathode are.
Electrolyte
I'll be using tap water for my reaction that is not chlorinated. However, unspecified salts/impurities might be present that I cannot closer define, but we're talking about infant-safe drinking water (with little Na present). To have an efficient reaction, I will need to dissolve an electrolyte. There are many choices:
* NaOH (lye): As far as I can tell, the "ideal" candidate for my requirements, but might not be present in a household and might be difficult to obtain. Should form pure H$_2$ and O$_2$ if I am not mistaken.
* NaCl (table salt): Present in every household. 870
Greatest drawback is that as far as I read Chlorine gas is formed during the electrolysis. My question would be, is the Chlorine emitted at the H$_2$ or O$_2$ electrode?
* NaHCO$_3$ or KHCO$_3$ (baking powder): Present in every household. Does not form Chlorine gas. However, as far as I have read, forms CO$_2$, but again I'm unsure at which electrode.
Electrode material
We can forget platinum and gold right off the bat for price reasons. Stainless steel would be a good choice, but I've also read that pure Nickel sheets should be working well. My main concern is corrosion and passivation of the electrode material which then slows down the overall reaction. Would Nickel sheets be preferrable over stainless steel? If we use some material that does corrode easily (e.g., regular steel or just run-of-the-mill hardware store items that are some combination of galvanized iron), would the corrosion and solutoin of the metal in the water affect the gas quality? If so, how? 662