Fig. 4: In subsurface environments at stable high temperatures (e.g. 104 °C), neither significant H2O2 or H2 are produced.
From: Tectonically-driven oxidant production in the hot biosphere

H• is produced from reactions of water with Si•, but it is removed by reactions with SiO• (Eq. (3)). These reactions result in the depletion of SiO• as SiOH forms, inhibiting H2O2 production from SiO•.