but what kind of oxides? the dark oxide layer doesn't start to appear until the electrode is cycled repeatedly over and over many times with the polarity being reversed every time. and it does not show any green color. when its lighter it's slightly more brownish but when dark its just black.
and it also acts as a battery if paired with a suitable negative electrode like zinc graphite carbon iron or lead. I got over 1.4 amps of current briefly out of just a strip about 2.75 inches long and 8mm wide rolled up into a spiral with a thin separator to prevent shorts and was able to light up an LED for a good while.
it also holds a voltage identical to that of a nickel zinc battery if charged with a nickel and zinc electrode.