Electrolysis is a simple chemical process of running electricity through stuff to separate the molecules.
If added as it’s own device or attached to a car, you could fill it with water for hydrogen(cars or weapons)/oxygen(maybe scuba tanks or like an adrenaline shot), sulfuric acid solution from storage batteries or something (concentrated acid and hydrogen peroxide), or maybe as a way of repairing or making tools more durable by using scrap metal or superalloy plating. Hydrogen peroxide could be used in place of ammonia, or maybe combined with something else and used in place of gunpowder, or even rockets with 0 min dispersion.
Hydrogen+oxygen combination could be used to power a flamethrower.
Having sulfuric acid powder available in garages could also be a new item to make/repair car batteries or for other things, and could be made by drying out the sulfuric acid solution.