Hydrogenases as Catalysts in Renewable Energy Applications

This review details the role of the hydrogenase enzymes in the development of new electrode materials for proton reduction and dihydrogen oxidation. Platinum is the best catalyst for these reactions, but it is expensive and rare. Graphite electrodes functionalized by hydrogenase enzymes are one possible route to the synthesis of inexpensive electrodes for water splitting based on common, earth-abundant elements. The major shortcoming of these enzymes is there extreme sensitivity to oxygen. Experimental and theoretical study of the mechanisms of proton reduction, hydrogen oxidation, and oxygen inactivation of the hydrogenase enzymes are discussed. Natural and synthetic methods for increasing oxygen tolerance are also discussed. Keywords: hydrogenases; hydrogen production; hydrogen oxidation; proton reduction; biomimetic chemistry; electrochemistry; catalyst inactivation; catalysis; water splitting