Photosynthetic hydrogen production

Among various technologies for hydrogen production, the use of oxygenic natural photosynthesis has a great potential as can use clean and cheap sources—water and solar energy. In oxygenic photosynthetic microorganisms electrons and protons produced from water and redirected by the photosynthetic electron-transport chain via ferredoxin to the hydrogen-producing enzymes hydrogenase or nitrogenase. By these enzymes, e− and H+ recombine and form molecular hydrogen. Hydrogenase activity can be very high but is extremely sensitive to the photosynthetically evolved O2 that leads to reduced and unstable H2 production. However, presently, several approaches are developed to improve the energetic efficiency to generate H2. This review examines the main available pathways to improve the photosynthetic H2 production.