Visible-light-driven CO 2 reduction to formate with a system of water-soluble zinc porphyrin and formate dehydrogenase in ionic liquid/aqueous media.

Visible-light-driven CO 2 reduction to formate with a system consisting of water-soluble zinc tetraphenylporphyrin tetrasulfonate (ZnTPPS), formate dehydrogenase from Candida boidinii (CbFDH) and methylviologen (MV) in the presence of triethanolamine (TEOA) as an electron donor in an ionic liquid, 1-ethyl-3-methylimidazolium dimethyl phosphate ([EMlm][Me 2 PO 4 ])/aqueous media was investigated. The catalytic activity of CbFDH for formate oxidation to CO 2 and CO 2 reduction to formate did not decrease significantly even in [EMlm][Me 2 PO 4 ]/aqueous media, compared with that in aqueous media. The visible-light-driven MV reduction by the photosensitization of ZnTPPS in [EMlm][Me 2 PO 4 ]/aqueous media proceeds more efficiently than in the aqueous media system. In the visible-light-driven CO 2 reduction to formate system of ZnTPPS, MV and CbFDH with [EMlm][Me 2 PO 4 ]/aqueous media, moreover, the formate production concentration after 180 min decreased by only 20% as compared with the system in aqueous media.