Even if you never want to generate hydrogen, [Maciej Nowak’s] video (embedded below) is interesting to watch because of the clever way the electrode is formed from stainless steel washers. You’ll need heat shrink tubing, but you ought to have that hanging around anyway. Building the electrode using the techniques in the video results in a lot of surface area which is important for an electrochemical reaction.
A standard rechargeable cell provides power for the generator which resides in a modified plastic bottle. The overall build looks good even though it is all repurposed material.
The chemistry inside is ordinary water and drain cleaner — potassium hydroxide. We don’t need to tell you to be careful with that and also take care of what you do with the explosive gas. We say “explosive” rather than “flammable” because this design doesn’t separate the hydrogen from the oxygen, and the resulting mix is ready to go off. The video shows a few homemade rockets using the fuel and while they aren’t going to the moon, they do pack quite a bit of energy.
We were impressed with how much gas the little bottle produces. We just couldn’t think of a good reason we wanted explosive gas for the holidays. Maybe you want some coffee? Or you could experiment with hydrogen paste fuels.