I have a bottle of 3% h2O2. That is 3% hydrogen peroxide, 97% purified water. So there aren't any other chemicals in it. It's just diluted hydrogen peroxide.
Hydrogen peroxide spontaneously decomposes to H2O + O. Meaning, it is highly oxidizing!
In higher concentrations it is used as a bleaching agent, but it is used for antiseptic purposes at low concentrations (such as 3%). So, you don't want to use too much, because that shit will kill your plants. But you still want enough to provide that extra oxygen for your plants' roots.
Now we must experiment to find a general range that is beneficial.