Electrochemical Investigations on the Inactivation of the [FeFe] Hydrogenase from Desulfovibrio desulfuricans by O2 or Light under Hydrogen-Producing Conditions.

The applicability of the extremely active [FeFe] hydrogenase from Desulfovibrio desulfuricans in H2 -producing devices is studied. Despite being the most active enzyme for H2 catalysis, its high sensitivity towards O2 has prevented its use in electrolytic water splitting cells. Using electrochemical methods, the catalytic activity of the enzyme at H2 -producing potentials and its inactivation upon exposure to limited amounts of O2 or under illumination is analysed. This enzyme is shown to maintain H2 production activity for extended periods of time at low potentials. At such potentials, the enzyme can deliver the required electrons to fully reduce O2 to H2 O, minimising the damage of the enzyme. Additionally, the robustness of this enzyme under illumination at negative applied potentials is demonstrated. These results show that the [FeFe] hydrogenase from D. desulfuricans is an excellent candidate to be used in devices to store solar energy in hydrogen.