Hydrogen Peroxide Spider Mites. Hydrogen peroxide attacks the black, sooty mold caused by aphids. Second, and more importantly, it won't do much of anything to cure your spider mite infestation, if that is indeed what you have.
You might have heard that hydrogen peroxide helps eliminate dust mites. It can also control populations of aphids and spider mites which also love devouring your plants. The major exceptions are hard.