Artificial Photosynthesis for Production of ATP, NAD(P)H, and Hydrogen Peroxide

The initial product of photosynthesis is NADPH (dihydronicotinamide adenine dinucleotide phosphate), which is produced from the oxidized form (NADP + ) by reduction with two electrons and one proton released from Photosystem I (PSI) via ferredoxin. The proton gradient generated across the thylakoid membrane produces a proton‐motive force, which is utilized to synthesize ATP by the use of ATP synthase. NADPH is used as a hydride source in the Calvin–Benson cycle to produce sugars by photosynthesis. In addition to NADP + , PSI can reduce O 2 by two electrons with two protons to produce hydrogen peroxide (H 2 O 2 ), which can be used as a fuel in H 2 O 2 fuel cells. This Minireview focuses on artificial photosynthetic systems to produce the products of natural photosynthesis, such as ATP, NAD(P)H and H 2 O 2 from NAD + and O 2 with water using solar energy, respectively. ATP was produced by use of an artificial photosynthetic membrane, composed of a photosynthetic reaction center mimic that pumps protons into the interior of the liposome, where F‐type ATP synthase was incorporated. Solar‐driven catalytic water splitting produces hydrogen, which can reduce NAD + to NADH with an iridium complex catalyst in a slightly alkaline solution at room temperature. H 2 O 2 has been produced by the combination of four‐electron oxidation of H 2 O with four protons to evolve O 2 and two‐electron/two‐proton reduction of O 2 under sun‐light irradiation. H 2 O 2 can also be produced by direct reaction of H 2 and O 2 by the combination of an iridium complex catalyst and flavin coenzyme.