Tolerance to oxygen of hydrogen enzyme electrodes

Tolerance to oxygen of hydrogen enzyme electrodes was first shown. Despite hydrogenase activity is suppressed by O2, their active sites being wired to the electrode can be re-activated in the presence of sufficient amount of molecular hydrogen. As a result enzyme electrodes based on hydrogenase from Thiocapsa roseopersicina are active up to 20% of air content in hydrogen, which coincides with an explosion limit of H2–O2 mixture. Despite oxygen inhibition of hydrogen electrooxidation occurs, it is completely reversible, and enzyme electrodes restore 100% of their activity, when gas mixture is changed back to pure hydrogen. The observed tolerance to oxygen of hydrogen enzyme electrodes provides a possibility of their use in H2–O2 fuel cells improving efficiency of energy conversion compared with platinum based devices.