Tolerance to oxygen of hydrogen enzyme electrodes

Tolerance to oxygen of hydrogen enzyme electrodes was first shown. Despite hydrogenase activity is suppressed by O-2, 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 H-2-O-2 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 H-2-O-2 fuel cells improving efficiency of energy conversion compared with platinum based devices. (c) 2006 Elsevier B.V. All rights reserved.