Well you could just goto the drug store, and by one of those protein removal contact solutions with cases.
They basically contain a dilute hydrogen peroxide solution along with a special case for it. The case contains this metal catalyst (so iron magnesium thing I'm guessing) that will cause the rapid decomposition of the hydrogen peroxide into Oxygen and water. It's alot easier than dealing with enzymes from liver, or blood. Alot cleaner too I may add.
Also this reaction doesn't produce hydrogen gas in any significant quantity just water and Oxygen so there isn't any need to seperate them, and yeah to get some hydrogen gas just disolve metal in acid... but be carefull...