mechanism is supported by experimental studies as illustrated in fig1 which shows a cyclic voltammogram cv of an ex situ cathode sample the thin line is a cv of an ex situ cathode sample that was refluxed for 1 week in air saturated 0 5m h 2 so 4 before being introduced to the electrolyte at 1 0v vs rhe starting from 1 0v and sweeping negative the oxide reduction peak normally seen at 0 72v is reduced and a second reduction peak at 0 57v has grown to replace it the second more stable peak likely represents the more stable platinum oxide resulting from the place exchange mechanism as in equation 4 above the second cycle restores the expected response the charge involved in both reductions are similar indicating that although there appears to be a stabilization of the oxide the oxide does not grow beyond a single monolayer of oxygen the thick line in fig1 is a cyclic voltammogram of the same cathode sample after exposure to ambient air while remaining in the cell for a further week prior to removal from the solution nitrogen was bubbled to remove air and a cv was performed as shown in fig1 it can be seen that the more stable oxide.