Hydrogen peroxide from water
The only "hydroxyl"-type species whose recombination has been observed to yield  hydrogen peroxide are hydroxyl radicals.

$$\ce{HO^. + ^.OH -&gt; H2O2}$$

In order to generate these hydroxyl radicals from water, a lot of energy has to be provided, typically by radiolysis (short wave uv, $\gamma$, electron beam).

The conceivable steps yielding $\ce{HO^.}$ are either

$$\ce{H2O  -&gt; H^. + ^.OH}$$
or
$$\ce{H2O  -&gt; H2O^{+.} + e-}$$

$$\ce{H2O^{+.} -&gt; H+ + ^.OH}$$