Fig. 3

Hybrid photosynthesis using photocatalyst. a Photocatalyst-driven microbial CO₂ reduction. In a tandem system, water is oxidized by a TiO₂ photocatalyst [102]. Electrons are transferred from TiO₂ to cystine via a MnPC cocatalyst. The resulting cysteine is then oxidized by a CdS photocatalyst. M. thermoacetica reduced CO₂ into acetate with electrons from CdS. b Photocatalyst-driven enzymatic reduction of CO₂ to methanol [116,117,118,119]. c Photocatalyst-driven enzymatic reduction of CO₂ to formate. In the first example, electrons are transferred from the photocatalyst to the formate dehydrogenase (FDH) via methylviologen [123]. In the second example, electrons are transferred from the photocatalyst to FDH via a rhodium complex and NADH [120, 121]