To start with, Fe + 2H2O --> FeO2 + 2H...
Place iron fillings to fill 1/3 of a water bottle. Fill the rest with water, and place a balloon on top. Wait X days/weeks/months. The water reacts with the iron to extract the oxygen from the water, leaving only hydrogen, and rust in the products. In the reactants, the hydrogen was bonded to the oxygen.
Will someone tell me if this works? The energy that bonds this is the potential energy in the water.