Chemical reducing agents (sodium dithionite) or bioglycerol (as H and e−-donor under irradiation in the presence of ZnS-A as photocatalyst) are able to back-convert NADP+ into NADPH, which is used as e−-donor in the enzymatic reduction of CO2 into CH3OH. In doing so, the molar ratio CH3OH/CO2 has been increased (without recycling of NADP+) using [...]