Photochemical synthesis of formic acid from CO2 with formate dehydrogenase and water-soluble zinc porphyrin

Photochemical synthesis of formic acid was investigated from hydrogen carbonate ion with formate dehydrogenase (FDH) from Saccharomyces cerevisiae and methylviologen (MV2+) photoreduction by the visible light photosensitisation of zinc tetrakis(4-methylpyridyl) porphyrin (ZnTMPyP) in the presence of triethanolamine (TEOA) as an electron donating reagent. Irradiation of a solution containing TEOA, ZnTMPyP, MV2+, sodium hydrogen carbonate and FDH with visible light resulted in formic acid synthesis. The concentration of formic acid was 62 μM after 3 h irradiation under the condition of 30 μM MV2+, 20 units FDH and pH 8.