Biomimetic CO₂ reduction based on Mg complexes

The development of cheap, robust and efficient photocatalytic cells for solar powered CO₂ reduction would allow the sustainable production of fuel from renewable resources. Progress in this field requires the development of efficient catalytic materials for multielectron reduction reactions and C-C bond formation from CO₂. Our photocatalytic cells for biomimetic CO₂ fixation are inspired by the Calvin cycle in Nature, where the enzyme RuBisCO facilitates the reaction of CO₂ with unsaturated sugar precursors. The cell has three components: (i) a photoanode where solar light is used to extract protons and electrons from water, releasing O₂, (ii) an intermediate redox neutral step where Mg²⁺ Lewis acids couple CO₂ with unsaturated polyols to form sugar, and (iii) a cathode where the oxidized polyol is catalytically reduced. We report the synthesis and spectroscopic characterization of two biomimetic Mg complexes as well as the computational analysis based on quantum chemistry modeling of reaction intermediates.