If you want to make large amounts of hydrogen, then i would suggest taking some stainless steel wire/bolts, and then stick them in a jar(glass jar). Then fill the jar half full of Hydrogen Peroxide, or H3O, and the other half with regular tap water. Fill a plastic pop bottle full of water, and the put it upside down in the jar, just above the Anode and the Cathode(Make sure no air is in the bottles). I am not sure what side the hydrogen comes out of, i think it is the cathode. So, - = Hydrogen, and + = Oxygen. I have attached a diagram.